JP4238751B2 - Engine performance prediction analysis method, prediction analysis system and control program thereof - Google Patents

Description

  The present invention relates to a predictive analysis method, a predictive analysis system, and a control program therefor for analyzing the motion of a fluid in an engine using CFD (Computational Fluid Dynamics) and thereby predicting the performance of the engine.

  Conventionally, in order to evaluate the performance of an engine, a transmission, and the like, various measurement / test methods as disclosed in Patent Document 1 have been proposed. Patent Document 2 discloses a simulation system that can evaluate powertrain performance without waiting for completion of engine development.

  As such a simulation technique, it is generally performed to analyze engine intake / exhaust flow and combustion gas motion by applying CFD and to predict engine performance based on the analysis result. That is, for example, a virtual experiment (simulation) for simulating a complicated flow of intake air sucked from the intake port into the combustion chamber by numerical calculation using a computer is performed, and for example, the shape of the intake port is determined based on the result of the simulation. As a result, it is possible to reduce the development man-hours spent on repeating trial productions and experiments, and to perform efficient design and development.

  Especially in recent years, the remarkable progress of computer computing ability has made it possible to simulate the complicated shape of intake / exhaust ports and intake / exhaust manifolds and the flow of intake air in three dimensions. The overall intake / exhaust flow can be simulated by a simple one-dimensional simulation, and a three-dimensional simulation can be performed for parts that are particularly important for analysis, and the engine performance can be predicted from both simulation results. Has been done.

  The inventors of the present application are based on simple one-dimensional simulation as described above, and automatically convert a part of the physical model (analysis model, numerical calculation model) to a three-dimensional model as necessary. A system that can be operated by replacement has been proposed and a patent application has already been filed (for example, Japanese Patent Application No. 2003-27826, Japanese Patent Application No. 2003-27843). In this proposed system, the boundary condition of the three-dimensional model is automatically determined from the intake and exhaust flow fields of the entire engine obtained in one dimension. Therefore, the one-dimensional and three-dimensional CFD operations are performed in parallel. Can be done automatically.

In the system described above, in particular, in order to cope with the enormous amount of computation of the three-dimensional CFD, a plurality of high-speed server computers are connected in parallel to perform distributed processing by a so-called multi-CPU, and to these server computers. A large number of client computers connected via a network are arranged in, for example, an engine design department, a development department, and an experiment department so that engineers (users) of the respective departments can easily access the system.
Japanese translation of PCT publication No. 2002-526762 JP 2002-148147 A

  By the way, in the system of the proposed example, the job input to the system by the user is to calculate the flow of engine intake / exhaust, cooling water, etc. by one-dimensional or three-dimensional CFD as described above. Since the dimensions of the space that simulates the flow are different, and there are steady operation and non-stationary operation, depending on the size of the analysis model, the amount of calculation of the input job is completely different depending on the type, For example, a job for performing a one-dimensional steady operation and a job for performing a one-dimensional and three-dimensional non-stationary operation have significantly different time required for completion.

  For this reason, in the system of the proposed example, if jobs submitted from each user are processed in the order of submission, for example, the system is busy and the time required for heavy jobs (for example, three-dimensional unsteady computation) When a plurality of long jobs are being executed or waiting to be executed, a user who has submitted a light job that requires only a few minutes to several tens of minutes, such as the one-dimensional steady-state calculation, is required to obtain the calculation result. The day can be waited for, which is very irrational.

  Therefore, for example, priorities are assigned to each job being executed and waiting for execution according to the required time, importance, or submission frequency, and when a job with a higher priority is submitted, Even when a low job is being executed, it may be possible to interrupt the job and execute a job with a higher priority first.

  However, when a job being executed is interrupted in this way, it is necessary to pay close attention to the timing. This is because when numerical computation by the computer is stopped halfway, depending on the timing, a part of the calculation up to that point is wasted or the accuracy of the calculation after the restart is reduced, and further, the interruption. This is because the calculation results up to that time can be used for analysis or not.

  The present invention has been made in view of such a point, and an object of the present invention is to suspend a job being executed in a computer system that performs several types of CFD calculation jobs, each of which requires significantly different time. To improve practicality as a system design / development tool by devising the procedure, preventing re-calculation due to interruptions and reducing accuracy, and reducing user dissatisfaction with interrupted jobs. .

  In order to achieve the above object, the present invention does not cause at least re-calculation or a decrease in accuracy according to the type of operation of the job being executed and its progress, and if possible, until the interruption. The calculation job being executed is interrupted at an appropriate timing so that the calculation result in the middle can be used for analysis.

More specifically, the invention of claim 1 is directed to a predictive analysis method for causing a computer device to execute a CFD operation job that simulates a fluid flow in an engine and predicting engine performance based on the operation result. And When the calculation job is of a plurality of types that perform flow calculation in either a steady state or an unsteady state using at least one one-dimensional or three-dimensional CFD analysis model, The priority of each computation job that is being executed or waiting to be executed is determined according to a preset criterion, and when the priority of the computation job that is waiting to be executed is higher than that of the currently executing operation job, at least It is interrupted at a predetermined timing corresponding to the type and progress of the operation, and the high-priority operation job waiting for execution is started . Specifically, the operation job being executed is one-dimensional. In the case of performing either steady state or non-steady state calculation, the calculation job is interrupted when the combustion cycle of the cylinder of the engine to be simulated is completed. To.

  According to the above-described method, first, even when several kinds of operation jobs having different required times from one-dimensional steady state to three-dimensional unsteady state are input to the computer apparatus, the execution order of these operation jobs is changed. By switching according to the priority, for example, particularly important jobs can be processed with priority, and relatively light jobs can be processed efficiently by interrupting moderately during processing of heavy jobs. it can.

  More specifically, for example, the priority of a job that ends during the business hours of the current day may be increased based on the original required time of calculation and the progress status up to now. In addition, for a computation job that is already being executed, if a technically useful computation result is not obtained when the computation job is interrupted, it is preferable to increase its priority. Further, when distributed processing is performed by a plurality of CPUs as the computer device, it is preferable to determine the priority in consideration of the difference in the number of CPUs required for each job.

When interrupting a computation job that is being executed according to the priority thus determined, the computation job is suspended at an appropriate timing corresponding to at least the type of computation and its progress. That is, for example, if the simulation of a four-cycle engine, it suspends separated by computation jobs ranging 720 degrees crank angle corresponding to the combustion cycles of each cylinder (hereinafter, also referred to as iteration), by a computer system It is possible to prevent the occurrence of errors due to the stop or restart of numerical calculation, to prevent the calculation accuracy from being lowered, and it is not necessary to repeat the calculation.

  In addition, if the simulation of unsteady operation state that simulates how the engine's operation state changes, or calculation of unsteady flow in which the flow field fluctuates greatly, such as intake and exhaust, the change in the operation condition and flow field respectively It is preferable to interrupt the operation job in a state where the change is relatively small.

  In addition, the calculation results up to the point (predetermined timing) when technically significant calculation results are obtained in consideration of the type of calculation and its progress so that the calculation results before the interruption can be used for analysis. It is preferable to proceed with the operation and then interrupt the operation job.

Another point of view, this gun onset Ming, by performing the operation job to simulate the flow of fluid in the engine by the application of CFD, thereby targeting the computer system for predicting the performance of the engine, wherein If the computation job is of multiple types that perform flow computation in either steady state or unsteady state using at least one one-dimensional or three-dimensional CFD analysis model, it is being executed or is waiting to be executed Job priority determination means for determining the priority of each calculation job according to a preset criterion, and the priority of the calculation job waiting for execution determined by the job priority determination means is higher than the calculation job being executed And a job switching means for interrupting the ongoing operation job at a predetermined timing and starting the operation job waiting for execution with a high priority. And things, on the timing suspend the operation job sets in association with the type of operation in at least the operational jobs and its progress, either the calculation job is one-dimensional steady or unsteady operation In the case of performing the above, it is assumed that the combustion cycle of the cylinder of the engine to be simulated is completed (the invention of claim 5) .

  According to the computer system, first, basically, when several types of operation jobs having significantly different required times are submitted, the priority of each operation job is determined by the job priority determination means, and accordingly Thus, the execution of the arithmetic job is switched by the job switching means, and efficient processing is performed. At that time, since the operation job being executed is interrupted at an appropriate timing corresponding to at least the type of operation and its progress, the accuracy of the calculation may decrease accordingly, and it may be necessary to restart the calculation. In addition, it is possible to effectively use the calculation result in the middle of the interruption.

In other words, according to the computer system of the fifth aspect of the present invention, it is possible to automatically execute the predictive analysis method according to the first aspect of the present invention and easily obtain the effects thereof.

Here, the job priority determining means, have the preferred to shall be determined based on the time required for at least calculating a priority of the operation job and the progress. For example, the priority of a light job with a processing time of about several minutes may be increased, and even for a relatively heavy job with a processing time of about several days, most of the calculation has already been completed. For those that end during the scheduled work time of the user on that day, it is preferable to increase the priority.

The calculation job in execution is the case and performs one-dimensional steady-state operation, respectively of a plurality of simulated driving conditions, when to abort it, the operation corresponding to one of the simulated driving conditions It is preferable to finish the process (inventions of claims 2 and 6 ). In this way, the result of the steady operation simulation for at least one simulated operation condition is obtained from the calculation result in the middle of the interruption, and even the calculation result in the middle has technical significance. It can be used effectively in advance, and the user's dissatisfaction with the job being interrupted is reduced.

On the other hand, when the computation job being executed is for performing one-dimensional unsteady computation under simulated operation conditions that change in time series, the degree of change in the simulated operation conditions is less than or equal to a predetermined timing. It is preferable that the above is satisfied (the inventions of claims 3 and 7 ). In other words, when the simulated operating conditions change greatly, the calculation conditions (time step, relaxation coefficient) and model can be corrected based on the calculation history up to that point even in the middle of the calculation to cope with the change. This is because if the calculation is stopped at such timing, the accuracy of the calculation after the restart is greatly lowered, and the restart may not be possible.

  Also, for example, if the calculation that simulates the acceleration operation of the engine is canceled halfway, the calculation result is not obtained enough from the calculation result, so the calculation is continued at least until the acceleration operation ends. In this sense, the calculation job is preferably interrupted when the degree of change in the simulated operation condition is relatively small.

Furthermore, when the computation job being executed is for performing a three-dimensional unsteady computation under a boundary condition that changes in time series, the degree of change in the boundary condition is less than or equal to a predetermined timing. It is preferable that the calculation of the flow field in the analytical model is completed under any boundary condition (the inventions of claims 4 and 8 ).

  By doing so, it is possible to prevent a reduction in calculation accuracy as in the case of the one-dimensional non-stationary calculation, and it is possible to avoid resuming the calculation. In the case of three-dimensional CFD computation, the flow field in the analysis model is almost stationary when the boundary conditions are first given to the inlet and the outlet of the analysis model to start the calculation of the flow field. Therefore, it is preferable not to stop the calculation until the numerical vibration is settled and the flow field in the model is stabilized.

In addition, the prediction analysis system is provided with a storage device having a temporary storage area for temporarily storing data for the CFD operation and other storage areas, and an operation being executed by the job switching means. When a job is interrupted, if the calculation result in the middle of the job has technical significance, the calculation result in the middle is stored in a storage area other than the temporary storage area and saved. It is preferable to provide means (invention of claim 9 ).

  In this way, since the data obtained by the subsequent calculation is not overwritten in the storage area in which the calculation result in the middle of the interrupted calculation job is stored, the user of the interrupted job can always execute the intermediate job. This calculation result can be referred to and used for analysis, further improving convenience.

Next, an invention according to claim 10 of the present application provides a computer system control program for executing a calculation job for simulating a fluid flow in an engine by application of CFD, thereby predicting the performance of the engine. set to target. And when the calculation job is a plurality of types for performing flow calculation in either steady state or unsteady state using at least one of the one-dimensional and three-dimensional CFD analysis models, A job priority determination step for determining the priority of each operation job waiting for execution according to a preset criterion, and an operation job for which the priority of the operation job waiting for execution determined in this job priority determination step is being executed A job switching step that interrupts the currently executing arithmetic job at a predetermined timing and starts the arithmetic job waiting for execution with a high priority. computing job interrupt timing is set corresponding to the type of operation in at least the operational jobs and its progress, the operation job If it is intended to do one of one-dimensional steady or unsteady operation shall combustion cycle of the cylinders of the engine to be simulated is the time of completion.

By controlling the computer system by the control program, become predictive analysis system of the engine performance computer system according to an invention of claim 5, whereby the same effect as the invention of the claim 5 is obtained.

Wherein the job priority determination step of the control program, not is preferably to determine on the basis of the time required for at least calculating a priority of the operation job and the progress.

The calculation job before SL running, as long as it performs the one-dimensional steady operation by a plurality of simulated driving conditions, the calculation job when the operation is finished corresponding to the one of the simulated operating conditions Preferably, it is interrupted (invention of claim 11 ). On the other hand, if one-dimensional unsteady calculation is performed under simulated operation conditions changing in time series, the degree of change in the simulated operation conditions is less than a predetermined value. It is sometimes preferable to interrupt the operation job (invention of claim 12 ). Thus, the same effect as that of the sixth and seventh aspects of the invention can be obtained.

Alternatively, when the operation job being executed is a three-dimensional unsteady operation under a boundary condition that changes in time series, the change degree of the boundary condition is less than or equal to a predetermined value in the job switching step. When the calculation of the flow field in the analysis model under any of the boundary conditions is completed, the calculation job is preferably interrupted (invention of claim 13 ). Thus, the same effect as that attained by the 8th aspect can be attained.

Furthermore, a storage device having a temporary storage area for temporarily storing data for CFD calculation in the prediction analysis system and a storage area other than that is provided, and the control program is being executed in the job switching step. When the calculation job is interrupted, if the calculation result in the middle of the calculation job has technical significance, the calculation result in the middle is stored in a storage area other than the temporary storage area and saved. It is preferable to further include an intermediate result storing step (invention of claim 14 ). Thus, the same effect as that attained by the 9th aspect can be attained.

  As described above, according to the engine performance prediction analysis method, the prediction analysis system, and the control program thereof according to the present invention, in the computer system that performs several types of CFD operation jobs with significantly different required times, the respective calculation jobs Is switched according to the priority, and when executing an operation job to be interrupted, the operation is interrupted at an appropriate timing corresponding to the type of operation and progress of the job. It is possible to prevent the re-execution of calculation and a decrease in accuracy, reduce the dissatisfaction of the user of the interrupted operation job, and improve the practicality as a system design / development tool.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature, and is not intended to limit the present invention, its application, or its use.

(Overall system configuration)
FIG. 1 is a conceptual diagram showing an overall configuration of an engine performance prediction analysis system A according to an embodiment of the present invention. This system simulates the flow of intake / exhaust air and cooling water, which are fluids in the engine, by one-dimensional to three-dimensional CFD calculations, simulates combustion in a cylinder by a chemical reaction equation, or This is done in combination. That is, in this system, a job (computation job) for performing a one-dimensional flow simulation (CFD), a job for performing a three-dimensional flow CFD, and a job for performing a chemical reaction simulation (chemical reaction SIM) are executed separately. In addition to this, it is possible to execute a job for performing an overall operation simulation of the engine by automating exchange of calculation data between these simulations.

  Reference numerals 1, 1,... Shown are computer apparatuses that mainly execute CFD operations. In this embodiment, in particular, a plurality of high-speed server computers are arranged in parallel in order to cope with an enormous amount of operations of three-dimensional CFD. Connected and used (hereinafter referred to as “calculation server”). Each of these calculation servers 1 has a RAM (temporary storage area) and a ROM as well known, and has a built-in storage device (storage area other than the temporary storage area) such as a hard disk drive and an image such as a display. The display device 10 is connected, and although not shown, an output device such as a printer, an input device such as a keyboard and a mouse for receiving an input operation by an operator are also connected.

  In addition, the storage devices of the arithmetic servers 1, 1,... Each include at least one-dimensional and three-dimensional CFD programs for simulating the flow of intake and exhaust, and physical models (analysis model, numerical calculation model) for that purpose. ), A chemical reaction simulation program for simulating the combustion state, and an image processing program for displaying an image of the simulation result of each program. Further, the storage device distributes a plurality of jobs input to the system to a predetermined number of arithmetic servers 1, 1,... According to the load, and assigns priorities to the jobs for efficient processing. A job management program is stored.

  The arithmetic servers 1, 1,... Can access the model database DB11 by a general method as needed during the operation. The model DB 11 stores a physical model of an engine used for one-dimensional and three-dimensional CFD calculations, and stores the model in a state classified for each part of the engine. A model newly constructed by the preprocessor is also stored. The template is a basic shape of a portion through which intake and exhaust flows, such as an intake system surge tank, an independent intake passage, an intake port, an exhaust system exhaust port, an exhaust manifold, an EGR passage, and the like. Is a part model that can change physical characteristics such as dimensions, shape and material, surface condition, thermal conductivity (hereinafter referred to as template parts), and by combining these template parts, The model can be easily built.

  Further, the operation servers 1, 1,... Can access the CFD operation database DB12 by a general method as needed during the operation. The CFD operation DB 12 stores various data used for the CFD operation, in addition to calculation conditions such as the time interval of the calculation in the CFD operation, the discretization scheme, the relaxation coefficient, and the like. For example, although detailed explanation is omitted in the CFD calculation DB 12, the distribution distribution of the intake and exhaust flows on the boundary surfaces on the inlet side and the outlet side is correlated with the three-dimensional physical model stored in the model DB 11. Stores set bias distribution data.

  Further, the arithmetic servers 1, 1,... Can access the chemical reaction database DB13 by a general method as needed during the operation. This chemical reaction DB 13 is filled with a cylinder combustion chamber of an engine and contributes to combustion with representative ones of various gas components (chemical species) in intake air having various physical quantities representing the state in the cylinder. They are stored in a state of being grouped in advance in association with the set. Therefore, as will be described in detail later, according to the state in the cylinder obtained as a result of the CFD calculation, a corresponding group of gas components is read from the chemical reaction DB 13, and the chemical reactions of these gas components are respectively simulated. By this, the combustion state can be simulated.

  Reference numeral 2 shown in the figure is a computer device that is connected to an experimental data database DB 14 (experiment DB) that mainly stores engine specification values, physical characteristics, and performance characteristics in association with each other and manages the data ( Hereinafter, this is referred to as an experimental DB server). In other words, the data accumulated in the past experiments and developments related to engines and transmissions are organized by well-known statistical analysis methods, and the engine specifications and their physical characteristics (for example, volumetric efficiency, combustion characteristics, loss factor, etc.) Etc.) and their performance characteristics (for example, output, fuel consumption, emission, etc.) are stored in the experiment DB 14 as empirical formulas associated with each other. Based on this empirical formula, for example, performance characteristics can be predicted from engine specification values and physical characteristics.

  Reference numeral 3 shown in the figure is a computer device of a three-dimensional CAD system for supporting engine design (hereinafter referred to as a design CAD server). The design CAD server 3 executes a general-purpose CAD program for machine design and structural analysis, and accesses the design database DB15 (design DB) by a general method as necessary during the operation. It is possible to call engine design CAD data, or change them and store them in the design DB 15 anew. That is, three-dimensional design CAD data of various engines is stored in the design DB 15 in a state where it can be individually extracted and used for each part of the engine.

  Reference numerals 5, 5,... Are terminals (PC terminals) each composed of a personal computer, which are arranged in a plurality of units such as an engine and transmission design department, a development department, an experimental department, etc. Are connected to the arithmetic servers 1, 1,..., The experiment DB server 2 and the design CAD server 3 so as to be capable of bidirectional communication. .. Are connected to the calculation servers 1, 1,... Via the network 6 (login) to form a so-called server / client environment. ,... And simulation servers (jobs) are executed mainly by exchanging commands and files between the computing servers 1, 1,.

  The experiment DB server 2, the design CAD server 3, and the PC terminal 5 each have a built-in storage device such as a hard disk drive, as in the calculation server 1, and are connected to a display 10, an output device, an input device, and the like. Yes.

(Simulation contents)
Next, the specific contents of the simulation job (arithmetic job) executed by the computer system A will be described for the operation simulation of a four-cycle four-cylinder gasoline engine.

-One-dimensional CFD calculation-
First, for example, as shown in FIG. 2 (a), the one-dimensional CFD calculation is performed from the throttle valve thv upstream of the intake passage of the engine to the catalytic converter cat through the combustion chambers of the first to fourth cylinders c1 to c4. The overall intake / exhaust flow of the engine is simulated using the physical model M1 of the dimension CFD. In the illustrated example, the model M1 represents an independent intake passage from the surge tank st to each of the cylinders c1 to c4 and a common intake passage from the throttle valve thv to the surge tank st as a collection of pipes, respectively. In addition, an independent exhaust passage from each of the cylinders c1 to c4 to the collection portion of the exhaust manifold exm and a common exhaust passage from the exhaust collection portion to the inlet of the catalytic converter cat are shown as a collection of pipes. The surge tank st and the first to fourth cylinders c1 to c4 are represented as containers.

  In such a one-dimensional model M1, the flow of intake and exhaust flowing in the pipe is regarded as a one-dimensional flow of a compressible viscous fluid, and each of pressure p, density ρ, velocity u, and temperature T representing the state of the flow. The well-known equations for mass conservation, momentum conservation and energy conservation are solved by numerical calculation under given operating conditions (simulated operating conditions). That is, the value of the flow variable is calculated using, for example, the characteristic equation obtained from each of the conservation equations, and the intake / exhaust flow from the throttle downstream to the catalyst upstream is described for each predetermined time interval (for example, crank angle). . At this time, it is assumed that the internal state of the container is uniform and the fluid flowing in from the pipe is instantaneously and uniformly distributed. In addition, it is preferable to give an appropriate boundary condition at the joint portion between the tubes or between the tube and the container, and to further consider the influence of bending of the tube, friction on the wall surface, heat loss and the like.

  Then, for example, in order to obtain a throttle full-open torque curve as shown in FIG. 5B, each of the operating conditions under a plurality of simulated operating conditions such as 1000 rpm full open (full load), 2000 rpm full open, 3000 rpm full open,. A one-dimensional steady-state calculation is performed with a constant value and the calculation results are collected to obtain the illustrated graph. More specifically, starting from an initial state in which all intake and exhaust flows are stationary under the individual simulated operation conditions, a crank angle corresponding to the combustion cycle of each cylinder of the engine is in a range of 720 degrees (iteration). For example, the convergence calculation may be performed by repeating the cycle calculation that simulates the reciprocating motion of the piston in each cylinder and the flow of intake and exhaust, for example. Such a one-dimensional steady operation is usually completed in several minutes to several tens of minutes using one or two calculation servers 1, 1,.

  In addition, as in the 10/15 mode shown in FIG. 10C, the one-dimensional unsteady operation that simulates the repetition of the engine idle operation, acceleration operation, steady operation, and deceleration operation takes time to the steady operation. The idea of adding an axis may be used, and the one-dimensional simulation as described above is continuously performed by giving simulated operation conditions that change in time series in response to such changes in the operation state. Such a one-dimensional unsteady calculation is usually completed in several hours to several days using one or two calculation servers 1, 1,.

-3D CFD calculation
On the other hand, the three-dimensional CFD calculation simulates only a specific part set according to the purpose of analysis in three dimensions. For example, an exhaust manifold model M3 as shown in FIG. Describes the flow of exhaust in three dimensions. This model M3 simulates the shapes of the independent exhaust passages s1 to s4 for each cylinder and the common exhaust passage s5 downstream thereof, and sets a layered region (layer L) so as to cover the inner wall surface of the passage. The mesh is cut into the inside of the layer L and other areas, that is, the passage space inside the layer L, and divided into calculation grids.

  In the three-dimensional CFD, each conservation equation representing the state of the exhaust flow in the passage is solved in three dimensions. That is, by using, for example, a difference equation representing each of the conservation equations in a time and space manner, the flow field in the passage is defined under the boundary condition given by the one-dimensional CFD calculation or the chemical reaction SIM described later. By calculating in three dimensions and repeating this calculation at predetermined time intervals, the state of the flow in the exhaust manifold that changes from time to time can be described in three dimensions.

  In that case, for example, in the steady calculation for examining the steady tumble flow flowing into the cylinder from the intake port and the steady flow coefficient of the intake port, the boundary conditions of the inlet and outlet of the three-dimensional model are made constant, The calculation is started from the initial state where the flow velocity is zero at each of the calculation points, and the cycle calculation is repeated until the initial numerical vibration is attenuated and the flow variable value at each calculation point is settled. Such a three-dimensional steady state calculation varies depending on the scale of the analysis model, but is normally performed using 4 to 8 or more arithmetic servers 1, 1,... And is completed in several hours to several days.

  Further, for example, in the three-dimensional unsteady calculation for examining the deviation of the exhaust flow with respect to the oxygen concentration sensor of the exhaust system or the catalytic converter, the flow state on the inlet side and the outlet side boundary surface of the three-dimensional model is 1 described above. A flow field in the model that balances the boundary condition for each moment is obtained in the same manner as in the steady calculation while the boundary condition is changed in time series based on the CFD calculation of the dimension. Such a three-dimensional unsteady calculation is normally performed using 4 to 8 or more calculation servers 1, 1,.

-1 + 3D CFD operation-
Furthermore, in the prediction analysis system A of this embodiment, the one-dimensional steady or non-stationary calculation and the three-dimensional non-stationary calculation can be automatically combined to perform both in parallel. That is, at every calculation time step, the flow field of the intake and exhaust of the entire engine at a certain moment is obtained by the one-dimensional model M1, and, for example, the three-dimensional model M3 of the exhaust manifold is input to the inlet side and the outlet side from the flow field data. Given boundary conditions, the internal flow field is calculated in three dimensions. Then, the calculation of the one-dimensional and three-dimensional flow fields is repeated in the same time step.

  In this case, in order to reduce the calculation amount of the three-dimensional CFD, the exhaust manifold model M3 can be divided into, for example, the independent intake passages s1 to s4 and the common exhaust passage s5, and the entire exhaust manifold of the one-dimensional model M1 is 3 Instead of replacing the three-dimensional model M3, the independent exhaust passage for each cylinder is replaced with the three-dimensional model s1 to s4 only when the corresponding cylinders c1 to c4 are in the exhaust stroke. The models s1 to s4 are combined with the common exhaust passage model s5.

  Further, when a three-dimensional boundary condition is given from one-dimensional flow field data, the average flow variables p, ρ, u, and T at each boundary surface obtained in one dimension are stored in the DB 12. Appropriate weighting may be performed according to the bias distribution data, and the entire boundary surface may be developed. While automatically passing data in this way, the overall intake / exhaust flow is simply simulated in one dimension, and only the parts that require high accuracy are simulated in three dimensions, so that the actual operating state of the engine Can be realized easily without troublesome setting work. Such a 1 + 3 dimensional unsteady calculation is usually completed in a few days to 20 days using eight or more calculation servers 1, 1,.

-Chemical reaction simulation-
Next, a chemical reaction simulation for simulating the combustion state in the cylinder will be briefly described. Unlike the CFD that simulates the flow of the intake and exhaust of the engine as described above, the combustion reaction is described by a chemical reaction formula while ignoring the movement of the air-fuel mixture and combustion gas in the cylinder. Specifically, first, the state of the intake air charged in the cylinder, that is, the pressure p and the temperature T of the combustion chamber at the initial stage of the compression stroke, are obtained by the one-dimensional to three-dimensional CFD calculation as described above. Further, the strength of in-cylinder flow is determined from the intake air flow velocity u. On the other hand, the air-fuel ratio of the air-fuel mixture, the amount of burned gas (internal EGR gas) remaining in the combustion chamber, the cylinder wall temperature, etc. are preliminarily determined based on the engine operating conditions (for example, engine load and rotational speed) in the simulation. It is obtained from the set map.

  If a plurality of physical quantity values representing the state of the combustion chamber at the beginning of the compression stroke are obtained, a group of gas components corresponding to the set of physical quantities is read from the chemical reaction DB 13. The data of the gas component group in the DB 13 includes various hydrocarbons mainly supplied as fuel, nitrogen and oxygen in the air, hydrocarbons contained in EGR gas, carbon dioxide, water vapor, and the like. A representative one corresponding to a set of physical quantities representing the state of the cylinder is extracted and stored together with its reaction formula.

  Based on the gas components (chemical species) of the group extracted as described above, first, in the compression stroke of the cylinder, the pressure p of the combustion chamber rises as the piston rises, and the temperature T rises accordingly. Considering that heat is taken away by heat exchange with the cylinder wall surface, the reaction of each gas component under such conditions will be described sequentially. Also, in the vicinity of the compression top dead center of the cylinder, the ignition of the air-fuel mixture by spark ignition is simulated, and the progress of the chemical reaction (combustion) is taken into account when the expansion stroke ends while taking into account the increase in the combustion chamber volume in the cylinder expansion stroke Describe sequentially.

  And the composition of burned gas in the cylinder obtained as a result of the chemical reaction simulation in the expansion stroke, the total calorific value and heat exchange with the cylinder wall surface, the work applied to the piston, the lowering of the piston The state of burned gas (exhaust gas) discharged from the combustion chamber when the cylinder moves to the exhaust stroke is obtained based on the expansion of the combustion chamber volume accompanying the above. This data can be used as the initial value of the exhaust flow in the CFD program described above.

(Job management according to priority)
As described above, in the computer system A of this embodiment, simulation jobs are input from the engine design department, the development department, the experiment department, etc., respectively, to perform one-dimensional and three-dimensional steady and unsteady CFD calculations. It is. Depending on the size of the physical model, the number of computation servers 1, 1,... (Hereinafter also referred to as the number of CPUs) and the time required for executing each job are completely different depending on the type of computation. The time required for completion differs significantly between a job that performs a one-dimensional steady operation and a job that performs a one-dimensional and three-dimensional unsteady operation.

  Therefore, if jobs submitted from users in each department are processed in the order of submission as described above, for example, the system is complicated and there are a plurality of heavy jobs with long required times such as 1 + 3D unsteady computation. If it is being executed, a user who has submitted a light job that requires only a few minutes to several tens of minutes, such as a one-dimensional steady-state calculation, may have to wait many days before obtaining the calculation result. It was reasonable.

  Therefore, in this embodiment, as a feature of the present invention, a plurality of jobs input to the system A as described above are mainly processed according to the load (calculation amount, required time) according to a predetermined number of operation servers 1, 1,. ... and list the jobs that are running or waiting to be executed, prioritize them according to the required time, importance, or input frequency for each job, and execute the jobs with the highest priority first. Like to do. For this reason, when a job with a higher priority is newly input, the job with a lower priority than that is interrupted in order to execute this job first.

  However, generally, if the CFD flow calculation is stopped at a bad break, an error may occur when the flow field data is saved or read again, and the calculation accuracy may be reduced. Also, especially in the case of unsteady computation, when the simulated operation conditions and boundary conditions change greatly, even during the calculation, calculation conditions such as time increments and relaxation factors, or models based on the calculation history so far If the calculation is stopped at such timing, the calculation data at the time of the interruption can be saved, but if the storage capacity of the memory, disk, etc. is taken into account, the calculation history Since all cannot be saved, the calculation accuracy is greatly reduced, and it may be impossible to restart the calculation.

  In addition, the user of a job that has been interrupted usually feels more or less dissatisfied, but in general, the CFD operation can be used for the analysis result of the intermediate operation up to that time depending on the timing of interrupting the operation. Therefore, depending on the timing of the interruption, the convenience of the user of the interrupted job is greatly different, and the degree of dissatisfaction felt by the user is significantly different.

  In this regard, this embodiment pays close attention to the timing at which a job that is being executed is interrupted, and at least does not cause re-calculation or a decrease in accuracy, depending on the type and progress of the calculation. If possible, the operation result is interrupted at an appropriate timing so that the calculation result can be used for analysis.

  In the following, the job management procedure executed by assigning priorities to a large number of jobs to be executed in the computer system A of this embodiment will be specifically described with reference to the flowcharts of FIGS.

  The flow shown in the figure starts each time a new job is input from the PC terminals 5, 5,... As clients in the arithmetic servers 1, 1,..., And first, in step SA1, the type of CFD calculation included in the new job. In the case of reading the necessary number of CPUs, calculation conditions, etc., and calculating the amount of calculation until the job is completed in the subsequent step SA2 based on the type of calculation, calculation conditions, etc. thus read, Estimate the time required to complete the job for each recommended number of CPUs.

  Subsequently, in step SA3, the same job is listed in the job list of system A (a list in which identification information of jobs being executed and waiting for execution is stored together with information such as the type of operation and progress). Search how many users are there. If the number of jobs of the same user is less than a preset threshold value, the process proceeds to step SA4 to increase the priority coefficient (priority) of the new job by a predetermined value, while the number of jobs is the set value. If it is equal to or greater than the threshold value, the process proceeds to step SA5 to decrease the priority order coefficient by a predetermined value.

  In step SA6 following steps SA4 and SA5, it is determined from the required time estimated in step SA2 whether or not the new job is completed during the working hours of the day. The working hours in this case may be working hours according to company regulations, or may be the scheduled working hours of the user's day including overtime schedules. If the job ends during working hours, the process proceeds to step SA7 to increase the priority coefficient by a predetermined value. If the job does not end during working hours, the process proceeds to step SA8 to set the priority coefficient to a predetermined value. Lower.

  Note that the determination in step SA6 is not limited to a new job, but is performed at least once a day for all jobs being executed and waiting for execution in consideration of the fact that the job being executed is interrupted or restarted. It is preferable to make the same determination for each time and change and update the priority coefficient as needed. In this case, for the job being executed, the scheduled completion time is determined based on the original required time and the progress status up to the current time.

  In step SA9 following steps SA7 and SA8, it is determined whether or not the job is completed by tomorrow morning in the same manner as in step SA6. If the job ends by tomorrow morning, the process proceeds to step SA10. If the priority coefficient is increased by a predetermined value, but does not end by tomorrow morning, the process proceeds to step SA11 to decrease the priority coefficient by a predetermined value. Further, whether or not the job is completed by the end of the week may be added to the criterion.

  Subsequently, in step SA12, based on the type of calculation, it is determined whether the intermediate calculation result obtained when the job is interrupted has technical significance (whether the intermediate result is meaningful). If a technically useful calculation result is not obtained when the job being executed is interrupted, the process proceeds to step SA13 to increase the priority coefficient by a predetermined value. If a useful calculation result can be obtained, the process proceeds to step SA14 to decrease the priority coefficient by a predetermined value. In other words, in principle, if there is no point in completing it, it will be completed quickly without interruption.

  Subsequently, in step SA15, it is determined whether or not the job has “urgent job restriction”. If there is an urgent restriction, the process proceeds to step SA16 to increase the priority coefficient by a predetermined value, but if there is no urgent restriction. Proceeding to step SA17, the priority order coefficient is decreased by a predetermined value. In other words, jobs with special importance are executed earlier with higher priority.

  In step SA18 following steps SA16 and SA17, the job list is updated to reflect the priority coefficient whose value is increased or decreased in each step, and then the flow proceeds to the job switching flow shown in FIG. In this way, a plurality of types of jobs with significantly different required times from one-dimensional steady to three-dimensional non-stationary are submitted by processing with priority given mainly considering the job completion schedule and importance. Even those that can be processed efficiently.

  After updating the job list as described above, in step SA19 of the flow shown in FIG. 5, the job list is searched to read the priority of each job being executed and waiting for execution, and in the subsequent step SA20, the new job is read. Is determined to be higher than any of the jobs being executed (the target of this determination may be limited to the number of CPUs required is the same as that of the new job, or a larger number of CPUs may be selected) You may include what you need).

  When the priority of the new job is the same as or lower than any of the jobs being executed, the process proceeds to step SA21, and the new job is awaiting execution and returns, while the priority of the new job is any of the jobs If it is higher, the process proceeds to step SA22, where the low priority job being executed is interrupted and a new job is started. In other words, an interrupt command is sent from the main routine of the job management program to a subroutine described in detail below, and the job is started at a timing set in advance according to the type of job calculation and its progress by the subroutine started. Is interrupted, the interrupt signal is returned to the main flow.

  Subsequently, in step SA23, it is determined whether or not the calculation result so far of the interrupted job has technical significance. If there is significance, the process proceeds to step SA24 to indicate that the job is interrupted. Information is displayed on the PC terminals 5, 5,... Until the job is interrupted, and then the process returns. On the other hand, if the intermediate calculation result is not technically significant, the process proceeds to step SA25 to display only the interruption information on the PC terminals 5, 5,...

-Job suspension procedure-
Next, the procedure for interrupting the job being executed in steps SA22 to SA25 will be described in more detail based on the flowchart of the subroutine shown in FIG. 6. In step SB1 after the start, an interrupt command from the main flow is accepted. Later, in step SB2, it is determined whether the type of operation currently being performed in the job to be interrupted is one-dimensional steady, one-dimensional unsteady, three-dimensional steady or three-dimensional unsteady (the job is one-dimensional and three-dimensional). (Even if a combination of dimensional CFD operations is combined, the operation being performed at a certain point in time is any one of the four).

  First, if the job being executed is a one-dimensional steady state operation, the process proceeds to step SB3 to monitor the calculation status, and whether or not the calculation has come to an iteration break in step SB4. In SB5, it is determined whether or not the calculation corresponding to any simulated operation condition has been completed (for example, whether or not the convergence calculation for any rotation speed in FIG. 2 (b) has been completed, that is, whether or not the rotation speed is divided). If any of these determinations is NO, the process returns to step SB3. If both determinations are YES, the process proceeds to step SB6.

  In step SB6, the job is interrupted, and interruption information (information indicating job interruption) is output from the PC terminals 5, 5,. Subsequently, in step SB7, a restart model that includes flow field data at the time of job interruption, calculation conditions, and the like that can restart the calculation from the time of interruption is created and stored in a hard disk or the like. Subsequently, in step SB8, the calculation results in the middle of the interruption are displayed on the PC terminals 5, 5,... And stored in the hard disks of the calculation servers 1, 1,. Then, the process proceeds to step SB9, an interruption signal indicating interruption of the job is returned to the main flow, and the control is ended (END).

  In other words, one-dimensional steady-state calculation basically prevents a decrease in calculation accuracy by interrupting the job at a break (development) range of 720 degrees in the crank angle corresponding to the combustion cycle of a predetermined cylinder of the engine. Like to do. Also, by suspending at the intervals of each simulation operation condition such as the rotation speed in FIG. 2 (b), the simulation result is obtained for at least one simulation operation condition from the calculation result in the middle and analyzed by the user. This can be used effectively in proceeding with the process, so that the user's dissatisfaction with the job interruption can be reduced.

  Second, if it is determined that the job being executed is a one-dimensional non-stationary operation performed while changing the simulated engine operating conditions in time series (SB2), the process proceeds to step SB10 and the calculation status is monitored. In the subsequent step SB11, it is determined whether or not the calculation has come to an iteration break. If this determination is NO, the process returns to step SB10, whereas if the determination is YES, the process proceeds to step SB12 to set a predetermined time interval (for example, if data is stored every second, the second It is determined whether it has come at every break).

  If it is determined in step SB12 that the second break has not been reached (NO), the process returns to step SB10, while if it is determined that the second break has been reached (YES), the process proceeds to step SB13, and this time, It is determined whether or not the degree of change is equal to or less than a predetermined value (for example, in the 10.15 mode shown in FIG. 2 (c), whether or not it is in a mode partition that simulates the steady operation state after the engine deceleration operation is completed). If this determination is NO, the process returns to step SB10. If the determination is YES, the process proceeds to steps SB6 to SB9 to interrupt the job, and then the control is terminated.

  That is, in the case of unsteady computation, first, basically, as in the case of the steady computation, the computation is interrupted at the break of the iteration. Considering that the model is corrected, the timing of such correction is avoided and the calculation is interrupted in a steady operation state such as a mode separation. As a result, it is possible to prevent the calculation accuracy from being lowered and the job cannot be resumed.

  Normally, when saving calculation result data, if the storage capacity of the memory or disk is taken into consideration, the calculation results performed in minute time increments are not saved for all the time increments, but set separately from the time increments. The data for each time interval (or crank angle) is saved, so if you stop the calculation at this time interval break (such as the second break), the previous calculations will be wasted. There is no.

  Furthermore, when simulating the state in which idle operation, acceleration operation, steady operation, and deceleration operation are repeated as in the 10.15 mode, for example, if calculation is stopped during acceleration operation, Since sufficient knowledge about the acceleration performance cannot be obtained, it is preferable to continue the calculation at least until the acceleration operation is completed. From this point of view, the job is interrupted at the mode division.

  Third, when it is determined that the job being executed is a three-dimensional non-stationary operation performed while changing the boundary condition in time series (SB2), the process proceeds to step SB14 and the calculation status is monitored. In SB15, it is determined whether or not the calculation of the flow field of the entire three-dimensional model corresponding to the boundary condition on the inlet side and the outlet side at a certain moment has been completed (whether it is a break of the calculation cycle). And whether the degree of change in the exit-side boundary condition is less than or equal to a predetermined value (small change in boundary condition?).

  If either determination is NO, the process returns to step SB14. If both determinations are YES, the process proceeds to steps SB6 to SB9 to interrupt the job, and then the control ends.

  In other words, in the case of a three-dimensional unsteady operation, since there is not much calculation amount for obtaining a flow field at a certain moment, it is preferable not to interrupt the job until the calculation is completed. Similarly to the case, the calculation can be prevented from being degraded by interrupting the calculation when the change in the boundary condition is relatively small.

  If it is determined that the job being executed is a three-dimensional steady operation (SB2), the process proceeds to step SB17 without monitoring the calculation status as described above, and the job is interrupted. 5 and so on. Subsequently, in step SB18, a restart model is created and stored in the hard disk or the like. Then, the process proceeds to step SB9, an interruption signal indicating job interruption is returned to the main flow, and the control is terminated. The reason why the job is immediately interrupted in this way is that, in most cases, the three-dimensional steady-state calculation has no technical significance in the calculation result in the middle, but the priority of the job is increased accordingly. There is very little interruption.

  The flow shown in FIG. 4 (steps SA1 to SA18) as a whole corresponds to a job priority determination step for determining the priority of each job being executed or waiting to be executed in accordance with a preset criterion. Step SA22 of the flow of FIG. 6 and steps SB2 to SB7, SB10 to SB18 of the flow of FIG. 6 interrupt the job being executed at a predetermined timing and start a job waiting for execution with a higher priority than that. Corresponds to the switching step.

  Further, when the job being executed in the job switching step is interrupted when step SB8 in the flow of FIG. 6 is interrupted, if the result of the operation up to the point of interruption has technical significance, this is calculated. This corresponds to the intermediate result saving step of storing the data in the hard disk of the server 1, 1,.

  In the predictive analysis system A of this embodiment, in the arithmetic servers 1, 1,..., Steps SA1 to SA18 in the flow in FIG. 4 are performed, and steps SA22 in the flow in FIG. 5 and steps SB2 in the flow in FIG. .. SB7, SB10 to SB18, and step SB8 of the flow of FIG. 6 are executed, respectively, so that the calculation servers 1, 1,... Have job priority determining means 1a, job switching means 1b, The intermediate result storing means 1c is configured.

  Therefore, according to the engine performance prediction analysis system A according to this embodiment, there are several types of CFD calculation jobs having significantly different required times from one-dimensional steady-state calculation to three-dimensional unsteady calculation and further chemical reaction simulation. In computer system A that is randomly input, the priority of those jobs is determined based on the importance, significance of intermediate results, scheduled completion time, etc., and the execution order is changed according to the priority thus determined. Therefore, a particularly important job can be preferentially processed, and a relatively light job can be efficiently processed by appropriately interrupting a heavy job.

  Furthermore, when a job being executed is interrupted, as described above, depending on the type of calculation such as one-dimensional steady / non-stationary, three-dimensional steady / non-stationary, the progress status of the job at the time when the interruption is determined respectively. Computation is stopped at an appropriate timing in consideration of this, so that it is possible to prevent recalculation of numerical calculations and degradation of calculation accuracy due to interruption, and to analyze the calculation results in the middle until interruption By making it available, user dissatisfaction with an interrupted job can be reduced. Therefore, the utility as a system design / development tool is extremely high.

(Other embodiments)
In addition, this invention is not limited to the said embodiment, Other various embodiment is included. That is, for example, as shown in the flow of FIG. 6 in the embodiment, when the three-dimensional steady operation is interrupted, the calculation status is not monitored and is immediately interrupted. After the flow field calculation is started by giving boundary conditions to the inlet side and the outlet side of the model, the calculation may be continued a predetermined number of times until the flow field settles, and during that time, the calculation may not be interrupted.

  This is because, as described above, when the calculation is started by first giving the boundary condition, a numerical vibration is generated due to the fact that the flow field in the three-dimensional model is substantially stationary. Because it is preferable not to stop the calculation until the numerical vibration is settled and the flow field in the model is stabilized, that is, at least until it is found that the model is properly formed. is there.

  In the above-described embodiment, the specific job management method is mainly described for the CFD calculation job. However, it is preferable that the chemical reaction SIM is also prioritized or interrupted at an appropriate timing. On the other hand, the present invention can also be applied to a case where the flow of engine intake and exhaust is simulated only by one-dimensional and three-dimensional CFD without performing chemical reaction simulation.

  Moreover, although the said embodiment demonstrated the case where the simulation about a 4-cycle engine was performed, it is not restricted to this, and it cannot be overemphasized that a 2-cycle engine and a rotary engine can also be simulated.

  As described above, the engine performance prediction analysis system according to the present invention is a computer system that analyzes the flow of fluid in an engine by applying CFD, and a plurality of CFD calculation jobs having significantly different processing times are randomly selected. Can be processed efficiently according to priority, and user convenience is high, so it is particularly suitable for large-scale systems that span various departments such as engine design, development, and experiments. Is.

1 is an overall configuration diagram of an engine performance prediction analysis system A according to an embodiment of the present invention. (a) is a schematic diagram of a one-dimensional model for CFD computation, and (b) and (c) are explanatory diagrams showing results of steady computation and non-steady computation and simulated operation conditions, respectively. It is a schematic diagram which shows an example of the three-dimensional model for CFD calculation. It is a flowchart figure of the procedure which gives the priority to a job. It is a flowchart figure of the procedure which switches a job according to a priority. It is a flowchart figure of the subroutine which interrupts a job at a suitable timing according to the kind of calculation.

Explanation of symbols

A Engine performance prediction analysis system M1 One-dimensional CFD analysis model M3, s1 to s5 Three-dimensional CFD analysis model 1, 1,... Operation server 1a Job priority determination means 1b Job switching means 1c Intermediate result storage means

Claims (14)

A predictive analysis method for causing a computer device to execute a CFD operation job that simulates a fluid flow in an engine and predicting engine performance based on the operation result,
When the calculation job is of a plurality of types that perform flow calculation in either a steady state or an unsteady state using at least one of the one-dimensional and three-dimensional CFD analysis models,
The priority of each calculation job being executed or waiting to be executed by the computer device is determined according to a preset criterion,
When the priority of the operation job waiting for execution is higher than the operation job being executed, the operation job being executed is interrupted at a predetermined timing corresponding to at least the type of operation in the operation job and its progress. And start a high-priority execution job waiting for execution ,
The timing at which the operation job being executed is interrupted is set to the time when the combustion cycle of the cylinder of the engine to be simulated is completed if the operation job is to perform either one-dimensional steady or non-steady operation. This is a method for predicting and analyzing engine performance. When the computation job being executed is for performing one-dimensional steady computation under a plurality of simulated operation conditions, the timing at which the computation job is interrupted is when the computation corresponding to one of the simulated operation conditions is completed. The prediction analysis method according to claim 1, wherein the prediction analysis method is set. When the computation job being executed is for performing one-dimensional unsteady computation under simulated operation conditions that change in time series, the timing at which the computation job is interrupted is such that the degree of change in the simulated operation conditions is less than or equal to a predetermined value. The prediction analysis method according to claim 1, wherein the prediction analysis method is sometimes set. When the computation job being executed is for performing a three-dimensional unsteady computation under a boundary condition that changes in time series, the timing at which the computation job is interrupted is such that the degree of change in the boundary condition is less than a predetermined value. The prediction analysis method according to any one of claims 1 to 3, which is set when calculation of a flow field in an analysis model under any boundary condition is completed. A computer system for executing a computation job that simulates the flow of fluid in an engine by applying CFD, thereby predicting the performance of the engine,
The calculation job is a plurality of types for performing a flow calculation in either a steady state or an unsteady state using at least one one-dimensional or three-dimensional CFD analysis model.
Job priority determination means for determining the priority of each operation job being executed or waiting to be executed according to a preset criterion;
When the priority of the operation job waiting for execution determined by the job priority determination unit is higher than the operation job being executed, the operation job being executed is interrupted at a predetermined timing, and the execution with the higher priority is performed. Job switching means for starting a waiting calculation job,
The timing at which the operation job being executed is interrupted is set in association with at least the type of operation in the operation job and its progress, and the operation job performs one-dimensional steady or unsteady operation If so, the engine performance prediction analysis system is characterized in that the combustion cycle of the cylinder of the engine to be simulated is ended . When the computation job being executed is for performing one-dimensional steady computation under a plurality of simulated operation conditions, the timing at which the computation job is interrupted is when the computation corresponding to one of the simulated operation conditions is completed. predictive analysis system of claim 5, characterized in that it is set. When the computation job being executed is for performing one-dimensional unsteady computation under simulated operation conditions that change in time series, the timing at which the computation job is interrupted is such that the degree of change in the simulated operation conditions is less than or equal to a predetermined value. The prediction analysis system according to claim 5 , which is sometimes set . When the computation job being executed is for performing a three-dimensional unsteady computation under a boundary condition that changes in time series, the timing at which the computation job is interrupted is such that the degree of change in the boundary condition is less than a predetermined value. The prediction analysis system according to claim 5 , which is set when calculation of a flow field in an analysis model under any boundary condition is completed . A storage device having a temporary storage area for temporarily storing data for CFD computation and a storage area other than that is provided;
When an operation job being executed by the job switching means is interrupted, if the operation result halfway up to the point of interruption has technical significance, the intermediate operation result is stored in a storage area other than the temporary storage area. The prediction analysis system according to claim 5, further comprising an intermediate result storage unit that stores and stores the result. A computer system control program for executing a computation job that simulates the flow of fluid in an engine by applying CFD, thereby predicting the performance of the engine,
The calculation job is a plurality of types for performing a flow calculation in either a steady state or an unsteady state using at least one one-dimensional or three-dimensional CFD analysis model.
A job priority determination step for determining the priority of each computation job being executed or waiting to be executed according to a preset criterion;
When the priority of the operation job waiting for execution determined in the job priority determination step is higher than the operation job being executed, the operation job being executed is interrupted at a predetermined timing, and the execution with the higher priority is performed. A job switching step for starting a waiting calculation job,
The timing at which the operation job being executed is interrupted is set in association with at least the type of operation in the operation job and its progress, and the operation job performs one-dimensional steady or unsteady operation If so, the control program for the engine performance prediction analysis system is characterized in that the combustion cycle of the cylinder of the engine to be simulated is ended . If the computation job being executed is one-dimensional steady computation under multiple simulated operation conditions, the job switching step interrupts the computation job when the computation corresponding to one of the simulated operation conditions is completed to, the control program according to claim 10, characterized in that. In the case where a one-dimensional unsteady calculation is performed under a simulated operation condition in which the operation job being executed changes in time series, the job switching step is performed when the degree of change in the simulated operation condition is equal to or less than a predetermined value. The control program according to claim 10 , wherein the control program is interrupted . When the operation job being executed is a three-dimensional unsteady operation under a boundary condition that changes in time series, in the job switching step, the degree of change in the boundary condition is less than or equal to a predetermined value. when the flow field calculation in the analysis model ended at Kano boundary conditions, one of the control program of claim 10 to 12 suspend operation job, which is characterized in that to. The prediction analysis system is provided with a storage device that includes a temporary storage area for temporarily storing data for CFD computation and a storage area other than that,
When an operation job being executed in the job switching step is interrupted, if the operation result halfway up to the point of interruption has technical significance, the intermediate operation result is stored in a storage area other than the temporary storage area. The control program according to any one of claims 10 to 13 , further comprising an intermediate result storing step of storing and storing the result .

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