JPS5924038B2 - Boundary layer control device for moving aircraft wings - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a boundary layer control device for a movable wing such as an aileron of an aircraft.

In general, the ailerons of short takeoff and landing aircraft (STOL aircraft) are used in conventional aircraft (CTOL aircraft) in order to maintain good maneuverability during low-speed flight and eliminate the large unbalance moment that occurs when one engine is stopped. In comparison, a large aileron area and a deep rudder angle are required, but if the rudder angle is made deep, the airflow on the upper surface of the aileron separates, resulting in a problem in which the rudder effectiveness is conversely reduced.

In order to prevent this separation of airflow and obtain a large attitude control ability, a boundary layer control device is required. Conventionally, commonly used boundary layer control devices for ailerons blow out dinit from a slit-type nozzle opened at the rear end of the main wing body to prevent separation of airflow, but this has the following problems. There is.

(1) It is difficult to manufacture a slit with a constant height over the entire width of the aileron with tight tolerances.

(2) During operation, it is difficult to maintain the slit size at the design value due to deformation due to internal pressure, making it impossible to achieve the required boundary layer control effect.

(3) An auxiliary duct is required to guide compressed air from the high-pressure plenum chamber to the rear end nozzle of the main wing body, which complicates the structure and increases weight.

This also causes the center of gravity of the wing near the ailerons to move back, reducing flutter speed. By the way, STOL
Since takeoff and landing speeds are lower for CTOL aircraft than for CTOL aircraft, the required slit height is lower due to the fact that the required blowout air flow rate is smaller and there is a recent tendency to use more and more high-pressure bleed air to secure space for duct placement within the wing. As a result, the problems described in items (1) to (3) above become more serious. Therefore, the present invention provides a multi-hole nozzle near the plenum chamber for driving blade boundary control located forward of the rear end of the fixed wing,
The purpose of this is to eliminate the problems described in items (1) to (3) above. Furthermore, the inventor's test results revealed that simply arranging the multi-hole nozzles in this way causes the effectiveness of the aileron to decrease rapidly below a certain plenum chamber pressure. This is also an object of the present invention.

For this reason, the present invention provides a device for controlling the boundary layer of the wing surface of a movable wing located behind the fixed wing using a compressed air flow injected onto the fixed wing. The front wall is recessed inward from the wing outline to form a step in the spanwise direction, and the bottom surface smoothly extends from the lower end of the front wall to the wing outline. The basic structure is to include a plurality of nozzle holes for injecting compressed air.

In the above-mentioned basic configuration, the first invention provides an overgeneration device having a height lower than the thickness of the jet air flow in the vicinity of the separation point of the jet air flow from the nozzle hole or in the jet air flow upstream thereof. It is characterized by the fact that it is equipped with

Further, in the above basic configuration, when the movable wing rotates from a neutral position with respect to the fixed wing, the second invention is such that when the movable wing rotates from a neutral position with respect to the fixed wing, the front end portion of the movable wing that receives the jet flow from the nozzle hole is moved to the main wing body. It is characterized by being provided so as to protrude outward from the extension line of the main wing outline at the rear end.

Furthermore, a third aspect of the present invention is that, in the above-mentioned basic configuration, the front surface of the recess is provided with a plurality of nozzle holes for injecting compressed air rearward, and the nozzle holes are inclined downwardly toward the bottom surface of the recess. It is characterized by being placed in

The details of the present invention will be explained below with reference to Examples.

First, to explain the basic configuration of the present invention, as shown in FIG. A duct 3 provided leads the air to a blemish chamber 5 in front of an aileron 4 as a movable wing. The structure around the plenum chamber 5 is shown in detail in FIGS. 2 and 3. That is,
Blenheim chamber 5 attached to the rear surface of the main wing rear spar 23
The air guided through the plenum chamber 5 is ejected onto the upper surface of the wing through a nozzle 6 provided at the top of the plenum chamber 5. The nozzle 6 is a single-row multi-hole nozzle having a circular cross section and is provided through a stepped front wall 7 provided in the spanwise direction on the upper surface of the main wing so as to be recessed inward from the main wing outline 22. .

The bottom surface of the recess created by this step is smoothly connected to the main wing outline 22 by a straight portion 8 and a convex curved portion 9 starting from the lower end of the front wall 7 of the recess. If the axial direction of the nozzle 6 is in the same direction as the straight line part 8 on the bottom of the recess, the workpiece will fit well. In addition, the rear end 10 of the main wing body 1 and the aileron 4
A sealing material 11 is normally provided to seal the slot created between the main wing body 1 and the aileron 4, but this is because when an airflow is generated from the lower surface of the main wing body 1 to the upper surface of the aileron 4 through this slot, the boundary layer This is because the effectiveness of the control is usually reduced.

Since the air passing through the nozzle 6 has a very high speed, energy loss is large due to friction with the inner wall surface of the nozzle.

In order to reduce this loss, it is best to shorten the nozzle length, and this is the reason why the steps, recesses, etc. in the blade span direction are provided. Also, in this case, the points that need attention are:
This is the size of the radius of curvature of the convex curved portion 9 on the bottom surface of the recess, and if this is made too small, dinit ejected from the nozzle 6 will separate at this convex curved portion 9 and the boundary layer control effect will deteriorate. The aerodynamic performance of the multi-hole nozzle with the basic configuration described above is shown by curve 12 in Figure 7. Below a certain plenum chamber pressure, the effectiveness of the ailerons 4 rapidly decreases, causing fluctuations in extraction pressure. It is difficult to put this into practice on an actual machine. This test was conducted using a full-size model, and the diameter of the porous nozzle 6 was approximately 1 mj!
, the pitch is about 4 m11, which is within the range commonly used in practical use, so it can be seen as indicating the general performance of the multi-hole nozzle 6. Curve 12 is for the case where the aileron 4 has a rudder angle of 600, but there is a phenomenon in which the effectiveness of the aileron 4 suddenly decreases even at other rudder angles.
The cause of this was separation of the boundary layer control dinit near the tip of the aileron. Next, the first one having the above-mentioned basic configuration,
The second and third inventions will be explained.

In the first invention, as shown in FIG. 4, the dinit stream ejected from the porous nozzle 6 of the basic configuration is placed at a desired position near or upstream of point A where the dinit stream is separated from the blade surface. Vortex generators 15, 16 having a height lower than the thickness of the dinit stream are provided in the dinit stream.

The vortex generating devices 15, 16 may be rectangular flat plates, and are preferably provided with an angle of attack of 200 to 30 degrees in the direction of the dinit flow.

The dinit flow flowing on the upper surface of the aileron 4 becomes a vortex by the vortex generators 15 and 16, and energy is injected into the boundary layer of the dinit flow that is about to separate, so the separation point shifts backward and this The high-speed vortex attracts the airflow flowing above and can significantly delay the separation of the airflow on the aileron surface.

As the vortex generators 15 and 16, rectangular flat plates whose height is lower than the thickness of the Ginite flow at the attachment point are used.
This ensures that the boundary layer control effect is not inhibited.

In addition, peeling of dinit in the basic configuration normally occurs near the tip of the aileron 4 when the injection pressure is low, so if the vortex generator is located near the rear end of the main wing body 1 or on the top surface of the aileron 4,
It is desirable to provide it as far forward as possible so as not to interfere with the rear end of the main wing body when the aileron is assembled.

As described above, in the first invention, the front wall 7 forms a step on the fixed wing surface in the wing span direction so as to be recessed inward from the wing outline, and the bottom surface smoothly extends from the front wall 7 to the wing outline 22. The front wall 7 of the recess is provided with a plurality of nozzle holes 6 for injecting compressed air. It is characterized by having vortex generators 15 and 16 whose height is lower than the thickness of the vortex generator.

Therefore, according to the first invention, when the rudder angle of the aileron 4 as a movable blade is zero or so small that boundary layer control is not required, the recesses and low-height vortices in the blade outline 22 The vortices generated in the free air stream by the generators 15, 16 are so small that their influence can be ignored.

On the other hand, when the rudder angle of the aileron 4 becomes large and boundary layer control is required, the above-mentioned low-height vortex generators 15, 1
6, flow separation on the blade surface of the aileron 4 can be significantly delayed.

In other words, the speed of the compressed air injected from the nozzle hole 6 is much higher than that of free airflow, so simply by generating vortices in a thin layer of this injected airflow, the free airflow flowing along the side of the injected airflow can be reduced. The free airflow, which is attracted by the strong vortices and has just separated, can be drawn to the wing surface of the aileron 4. In addition,
In FIG. 4, a shows the flow of dinit in the basic configuration, and b shows the flow of dinit in the case of using the apparatus of the present invention.

As a result of recent aerodynamic research related to STOL aircraft, the following is generally known.

In other words, when a dinit of a constant height is flowed from the left side onto a convex part like the upper surface of an airfoil that is shaped like an "H" when viewed from the side, if the width of the dinit in the span direction is infinite, the dinit will flow well. The jet is bent and flows diagonally downward to the right, but as the width of the jet becomes narrower, the width of the jet becomes narrower near the bending point of the "F" shape, and peeling becomes more likely to occur. Therefore, the wider the dinit width, the greater the boundary layer control effect.
On the other hand, it has been generally known for a long time that when dinit flows from the left side into a recess such as the underside of an ``F''-shaped airfoil, dinit comes into contact with an obstacle and increases the dinit width. Therefore, before the dinit reaches the convex part where it is easy to peel off,
Providing a recess and increasing the dinit width has the effect of making peeling less likely to occur. The second and third inventions utilize such a phenomenon.

An embodiment of the second invention will be explained with reference to FIG. 5. Normal ailerons are made so that their outline does not protrude outside the airfoil outline of the main wing when the steering angle is adjusted, but in the case of the present invention , when the rudder is lowered, a part of the front end of the aileron 4 touches the rear end 10 of the main wing body 1.
A gently concave curved surface B is formed between the rear end portion 10 of the main wing body 1 and the protruding portion of the aileron 4, projecting from the extension line 22 of the main wing outline in .

Therefore, when dinit flows along this concave curved surface, it spreads laterally and becomes a thin layer, so that it flows easily along the aileron 4, and the occurrence of separation can be delayed.

In this way, making the front end of the aileron 4 protrude from the main wing outline during down-rudder is easily achieved by selecting the position of the rotation center 18 of the aileron 4 and the shape of the tip 19 of the aileron 4. can.

Next, an embodiment of the third invention is shown in FIG.

This FIG. 6 shows the vicinity of the multi-hole nozzle 6 in correspondence with FIG. 3. As mentioned above, when the dinit ejected from the multi-hole nozzle 6 passes through the convex curved portion 9 on the bottom of the recess, the width of each dinit becomes narrower and independence increases, and the dinits are separated at the convex curved portion 9 and the ailerons. The dinit distribution in the spanwise direction of the wing is no longer uniform, and the tendency for separation in various parts increases. Therefore, in the present invention, as shown in FIG. 6, the direction of the nozzle 6 is directed downward, and the dinit is applied to the straight part 8 or the convex curved part 9 on the bottom of the recess, and the dinit passing through the concave curved surface spreads laterally and becomes a thin dinit. With the same effect, the uniformity of dinit in the span direction is increased and the separation characteristics of the convex curved portion 9 and the upper surface of the aileron are improved.

Next, the effects of the first, second, and third inventions described above will be explained collectively with reference to FIG. 7. In FIG. ) is a graph showing the rolling moment that occurs when

In FIG. 7, the curve 12 is for the basic configuration as described above, and the effectiveness decreases rapidly below a certain pressure. Curve 13 shows the case where the vortex generator according to the first invention is used, and its characteristics are significantly improved.

However, this applies when the vortex generator is placed in a place where the flow adheres in the basic configuration, and when the vortex generator is placed in the separation area, there is no effect and the curve 12 remains. Curve 14 shows the effect of increasing the uniformity of the dinit in the case of a protrusion of the aileron leading edge according to the second invention or a downward nozzle direction according to the third invention.

In this case, the effect is generally less than when a vortex generator is provided, but unlike the case of a vortex generator, there is no loss due to increased resistance during cruising, which is preferable.
On the other hand, if the diameter of the porous nozzle 6 of the basic configuration is large and the pitch is rough, separation of dinit easily occurs at the convex curved portion 9 and the aileron soil surface as shown in FIG. Sometimes there is no place to install it.

In such a case, applying the second and third inventions to widen the area where dinit adheres and further providing a vortex generator will significantly improve the effect. As described above, the first to third inventions are effective not only when used alone, but also when used in combination of two or more. Note that when implementing the present invention, the following two points may become a problem, and countermeasures for these problems will be explained below.

(1) At high speeds when the aileron rudder angle is small and the boundary layer control dinit is not blown out, airflow turbulence generated from the recesses caused by the installation of the multi-hole nozzle may reduce the effectiveness of the aileron. .

(2) Due to structural soil conditions, the frenum chamber may not be integrated over the entire width of the aileron, but may be divided, and in this case, there may be a considerable length of missing part of the porous nozzle near the joint. , the boundary layer control effectiveness may be significantly reduced.

The above problem (1) can be easily solved by installing the vortex generator 20 shown in FIG. 8 near the front of the recess.

In addition, the problem mentioned in item (2) above is that, as shown in Figure 8, if there is a dinit missing part 21, the flow tends to separate behind it, and as shown in the figure, the area of the aileron where the boundary layer is controlled is greatly reduced. This is due to a decrease in

As a countermeasure against this problem, the direction of the porous nozzle 6 near the boundary between adjacent plenum chambers is slightly tilted laterally as shown in Fig. 11 showing the M-M cross section of Fig. 10. By reducing the area of the dinit from the plenum chamber 5 on the aileron soil surface as much as possible, a separation pattern as shown in Figure 10 will be created and a reduction in the effectiveness of the aileron will be prevented. . In the above explanation, only the case of boundary layer control of ailerons was illustrated, but the present invention is also applicable to boundary layer control of other movable wings provided at the trailing edge of fixed wings, such as elevators, rudders, and flaps. can do.

As described above, according to the present invention, sufficient boundary layer control of the movable wing can be achieved even by the dinit injected onto the upper surface of the fixed wing at a position far in front of the movable wing, and the structure of the entire device is therefore significantly simplified. This makes it easier to use and lighter.

In addition, since the air flow is ejected from multiple nozzle holes, it is easy to form extremely small dinit nozzles, and the problem of deformation of the dinit nozzle due to the use of high-pressure dinit is sufficiently prevented.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of high-pressure air piping inside a wing;
FIG. 2 is a partial cross-sectional view showing the basic configuration of a boundary layer control device using a multi-hole nozzle according to the present invention, and FIG. 3 is a partial cross-sectional view showing an enlarged detail of the portion shown in FIG. FIG. 4 is a partial sectional view showing an embodiment of the first invention, FIG. 5 is a partial sectional view showing an embodiment of the second invention, and FIG. 6 is a partial sectional view showing an embodiment of the third invention. A partial sectional view, FIG. 7 is a graph showing the aerodynamic performance of the boundary layer control device according to the present invention, and FIG. 8 is a graph showing the aerodynamic performance of the boundary layer control device according to the present invention.
FIGS. 9 and 10 are partial perspective views showing an example of the arrangement of the vortex generating device, and conceptual diagrams showing the state of peeling due to missing portions of dinit and its improved state, respectively. FIG. It is a sectional view along the M line. 1... Main wing body as a fixed wing, 2...
・Engine compressor part, 3... In-wing duct, 4...- Aileron as a movable wing, 5...
... Plenum chamber, 6... Porous nozzle,
7... Front wall of the recess, 8... Straight bottom surface of the recess, 9... Convex curved bottom surface of the recess, 10... Rear end of the main wing body 1, 11. ...Sealing material, 12...
...Performance curve for basic configuration, 13...1st
Performance curve when the invention is applied, 14...Performance curve when the second and third inventions are applied, 15, 16... reconnaissance generator, 18... of the aileron. Center of rotation, 19・
...Tip of the propeller blade, 20... Vortex generator, 2
1... Plenum chamber joint spacing, 22...
...Main wing soil surface contour line, 23...Spar.

Claims (1)

[Scope of Claims] 1. In a device for controlling the boundary layer of the wing surface of a movable wing located behind the fixed wing by using a compressed air flow injected to the fixed wing surface, the wing located in front of the rear end of the fixed wing surface A recessed portion having a front wall that forms a step in the spanwise direction so as to be recessed inward from the blade outline on the surface, and a bottom surface that smoothly extends from the lower end of the front wall to the blade outline, and the front wall of the recess has a A vortex generating device is provided with a plurality of nozzle holes for injecting compressed air rearward, and a vortex generating device having a height lower than the thickness of the jet air flow is provided in the jet air flow near the separation point of the jet air flow from the nozzle holes or upstream thereof. A boundary layer control device for a movable wing of an aircraft, characterized by comprising: 2. In a device for controlling the boundary layer on the wing surface of a movable wing located behind the fixed wing by using a compressed air flow injected onto the fixed wing surface, the boundary layer is applied to the wing surface forward of the rear end of the fixed wing surface in the spanwise direction. The movable blade includes a recessed portion having a front wall that forms a step and a bottom surface that smoothly connects to the blade surface, and a plurality of nozzle holes that inject compressed air rearward on the front wall of the recessed portion, and the movable blade is connected to the fixed blade. The front end of the movable wing, which receives the jet flow from the nozzle hole when rotated from a neutral position relative to A boundary layer control device for a movable wing of an aircraft. 3. In a device for controlling the boundary layer on the wing surface of a movable wing located behind the fixed wing using a compressed air flow injected onto the fixed wing surface, the airfoil is applied to the wing surface forward of the rear end of the fixed wing in the spanwise direction. The recess has a front wall that forms a step and a bottom that smoothly connects to the wing surface, and the front wall of the recess is provided with a plurality of nozzle holes that inject compressed air rearward, and the nozzle holes are connected to the recess. A boundary layer control device for a movable wing of an aircraft, characterized in that the device is disposed in a direction that slopes downward toward the bottom surface.