JP3219177B2 - Switching method of turbo ram jet engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for switching the operation of a turbo ramjet engine.

[0002]

2. Description of the Related Art As a propulsion system for a Mach 5 class supersonic aircraft, a turbojet engine (operating Mach number range 0 to 3) and a ramjet engine (operating Mach number range 2.5 to 5) are coaxially integrated. A combined cycle engine (turbo ram jet engine) as shown in FIG. 5, which can achieve good fuel efficiency in a wide range of speeds from low speed (takeoff and landing) to about Mach 5, has been proposed.

In such a turbo ramjet engine, mode switching (operation switching) is an important technical problem. That is, when switching between the turbo mode and the ram mode, as shown in FIG. 5, the air flowing from the intake 1 is branched into the turbo side flow path 2 and the ram side flow path 3, and the front junction section 4 and the rear junction section 5 There is an operating state (dual mode) having a mixing area at two places. In this figure, 6 is a compressor (compressor) of a turbofan engine, 7 is a combustor (burner), 8 is a turbine, and 9 is a nozzle throat of an exhaust nozzle.

[0004]

Conventionally, in such a dual mode, there has been a problem that an unstable operating state such as a sudden change in flow rate, a backflow phenomenon, a blowout of a combustor, a sudden change in thrust, and the like may occur.

The present invention has been made to solve such a problem. That is, an object of the present invention is to switch the operation between the turbo mode and the ram mode while maintaining the total suction flow rate and the thrust of the engine constant, without causing an unstable operation such as a backflow phenomenon, a blowout of the combustor, and the like. It is an object of the present invention to provide a method for switching the operation of a turbo ram jet engine.

[0006]

According to the present invention, a turbofan engine having a fan and a bypass air duct, a fan bypass duct for bypassing the fan and supplying air to the bypass air duct, and an upstream side of the fan bypass duct And a front duct valve that opens and closes the upstream side of the bypass air duct.
A rear duct valve that opens and closes the downstream side of the bypass air duct; a ram burner arranged downstream of the turbofan engine; and an exhaust nozzle arranged downstream of the ram burner and having a variable nozzle throat area. 1. In the operating state of the turbofan engine in which the fan duct valve is fully closed, the entire amount of air flows into the turbofan engine, and the ram burner is off, 2. Open the exhaust nozzle to avoid fan stalls due to pressure spikes when the ram burner fires. Next, the ram burner is ignited to compensate for the reduction in the thrust of the turbofan engine during the switching process. Next, in order to prevent backflow in the fan bypass duct when the fan duct valve is opened, the front duct valve is closed to reduce the static pressure in the bypass air duct. Next, fully open the fan duct valve,
5. A part of the total air amount is led to the bypass air duct via the fan bypass duct; Then, open the rear duct valve as much as possible and slightly open the exhaust nozzle so that the total air volume and thrust of the engine are kept constant and the downstream flow velocity of the bypass air duct is as low as possible. Reduce the amount of air
7. Next, a method for switching operation of the turbo ramjet engine is provided, in which the burner fuel of the turbofan engine is cut off to stop the operation, and the operation is switched to the operation state of the ramjet engine.

Further, according to the present invention, a turbofan engine having a fan and a bypass air duct, a fan bypass duct for bypassing the fan to flow air to the bypass air duct, and a fan for opening and closing the upstream side of the fan bypass duct A duct valve, a front duct valve that opens and closes the upstream side of the bypass air duct, a rear duct valve that opens and closes the downstream side of the bypass air duct, a ram burner arranged downstream of the turbofan engine, and a downstream side of the ram burner An exhaust nozzle arranged and having a variable nozzle throat area; 1. In the operating state of the ramjet engine, in which the fan duct valve is fully opened, the total amount of air flows into the ram burner via the fan bypass duct, and the ram burner is burning, 2. Ignite the burner of the turbofan engine and start its operation. Then, while keeping the total air volume and thrust of the engine constant and keeping the downstream flow rate of the bypass air duct as low as possible, gradually close the rear duct valve and slightly close the exhaust nozzle, 3. increase the amount of air flowing in; Next, fully close the fan duct valve and guide the total air volume to the turbofan engine,
5. Next, the front duct valve is opened to increase the static pressure in the bypass air duct, and 6. Then, the fuel of the ram burner is shut off to stop its operation, and A method for switching operation of a turbo ramjet engine, comprising closing an exhaust nozzle and switching to an operation state of a turbo fan engine.

[0008]

According to the method of the present invention, when switching from the turbo mode to the ram mode, the exhaust nozzle is opened before the ram burner is ignited, so that a fan stall due to a pressure spike when the ram burner is ignited can be avoided. Igniting, it is possible to compensate for the decrease in thrust of the turbofan engine during the switching process,
Since the static pressure in the bypass air duct is reduced by closing the front duct valve, backflow in the fan bypass duct when the fan duct valve is opened can be prevented,
Next, since the fan duct valve is fully opened and a part of the total air amount is guided to the bypass air duct via the fan bypass duct, it is possible to stably switch to the operation state (dual mode) having a mixing area at two places. it can.

Next, while opening the rear duct valve as much as possible and slightly opening the exhaust nozzle so that the flow velocity on the downstream side of the bypass air duct is as low as possible,
By reducing the amount of air flowing into the turbofan engine, the operating ratio (thrust) of the ramjet engine is increased while keeping the total air amount and thrust of the engine constant and minimizing the pressure rise due to ram combustion. The ramjet engine can then be switched to full operation by shutting off and shutting down the burner fuel of the turbofan engine.

When the mode is switched from the ram mode to the turbo mode, the above-described operation is performed in reverse, and similarly, the total air amount and the thrust of the engine are kept constant.
The switching can be performed stably without causing an unstable operation such as a backflow phenomenon and a blowout of the combustor.

[0011]

Preferred embodiments of the present invention will be described below with reference to the drawings. In the drawings, common portions are denoted by the same reference numerals. FIG. 1 is an overall configuration diagram of a turbo ramjet engine to which the method according to the present invention is applied. In this figure, a turbo ram jet engine includes a turbo fan engine 12 having a fan 10 and a bypass air duct 11, a fan bypass duct 13 for bypassing the fan 10 and flowing air to the bypass air duct 11, and a fan bypass duct 13. Fan duct valve 14 for opening and closing the upstream side, and bypass air duct 1
1, a front duct valve 15 for opening and closing the upstream side of the bypass air duct 11, a rear duct valve 16 for opening and closing the downstream side of the bypass air duct 11, a ram burner 17 disposed downstream of the turbofan engine 12, and a downstream side of the ram burner 17. Exhaust nozzle 18 arranged and variable in nozzle throat area
And

The turbofan engine 12 is an engine in which a fan 10 is mounted on the front side of a core engine including a compressor 6, a burner 7, and a turbine 8, and a part of the air compressed by the fan 10 is supplied to the bypass air duct 1
1. Fan duct valve 1
4 has an upstream end rotatably attached to the engine casing 19, and is opened outward to introduce air into the fan bypass duct 13. The front duct valve 15 is arranged at a portion where the fan bypass duct 13 joins the bypass air duct 11, and its opening and closing change the inner area and the outer area. The upstream end of the rear duct valve 16 is rotatably attached to the engine casing 19, and opens outward to guide the air in the bypass air duct 11 to the ram burner 17. The exhaust nozzle 18 has, for example, an upstream end rotatably mounted on an engine casing 19 and an intermediate portion connected to each other by a pin, so that the nozzle throat area 9 can be changed by an appropriate driving device. I have.

The valves 14, 15, 16, 18
Is the direction that moves outward and the area of the inside increases,
"Open" and vice versa.

FIG. 2 is an operation flowchart of the method for switching the operation of the turbo ramjet engine according to the present invention. This figure shows a switching method from the turbo mode to the ram mode. In FIG. 2, this switching is performed in the operating state of the turbofan engine in S1, the opening operation of the exhaust nozzle 18 in S2, the ignition of the ram burner 17 in S3, the closing operation of the front duct valve 15 in S4, and the fan duct valve 1 in S5.
4, fully open, S6 rear duct valve 16 / exhaust nozzle 1
8 and an operation stop of the turbofan engine in S7.

FIG. 3 is a diagram showing the operation of each component of FIG. 1 corresponding to the operation switching of FIG. In this figure, the horizontal axis indicates steps S1 to S7 from the turbo mode to the ram mode. The vertical axis indicates the turbo flow ratio (the amount of air flowing into the turbo fan / the total amount of air) and the opening and closing operations of the fan duct valve 14, the front duct valve 15, the rear duct valve 16, and the exhaust nozzle 18. It should be noted that only the fan duct valve 14 has two-position control of opening and closing, and the indication of opening and closing is shown in reverse.

1 to 3, in S1, the fan duct valve 14 is fully closed, the entire amount of air flows into the turbo fan engine, and the ram burner 17 is turned off, and the turbo fan engine is operating. Next, in S2, the exhaust nozzle 18 is slightly opened, whereby the ram burner 17 is opened.
Avoid fan stalls due to pressure spikes during ignition. Next, at step S3, the ram burner 17 is ignited to compensate for a reduction in the thrust of the turbofan engine during the switching process.

Next, in S4, the front duct valve 15 is closed to reduce the static pressure in the bypass air duct 11, thereby preventing backflow in the fan bypass duct 13 when the fan duct valve 14 is opened. Next, in S5, the fan duct valve 14 is fully opened, and a part of the total air amount is led to the bypass air duct 11 via the fan bypass duct 13. Thereby, the front duct valve 1
5 and a downstream side of the rear duct valve 16 can be stably switched to an operation state (dual mode) having a mixing area.

Next, in step S6, the rear duct valve 16 is opened as much as possible and the exhaust nozzle 18 is slightly opened so that the total air amount and thrust of the engine are kept constant and the flow velocity downstream of the bypass air duct 11 is as low as possible. While opening, reduce the amount of air flowing into the turbofan engine. As a result, the operating ratio (thrust) of the ramjet engine can be increased while keeping the total air amount and thrust of the engine constant and minimizing the pressure rise due to the combustion of the ram burner 17.

Next, in step S7, the ramjet engine can be switched to a completely operating state by shutting off the burner fuel of the turbofan engine and stopping its operation.

FIG. 4 is an operation flowchart of the method for switching the operation of the turbo ramjet engine according to the present invention, similar to FIG. This figure shows a switching method from the ram mode to the turbo mode. In FIG. 4, this switching is performed in S1
1, the operation state of the ramjet engine, the ignition of the turbo burner in S12, the closing operation of the rear duct valve 16 / exhaust nozzle 18 in S13, and the fan duct valve 14 in S14.
, The opening operation of the front duct valve 15 in S15, the fuel cutoff of the ram burner 17 in S16, and the closing operation of the exhaust nozzle 18 in S17.

In S11 of FIG. 4, the fan duct valve 1
4 is fully opened, the total amount of air flows into the ram burner through the fan bypass duct 13, and the ram jet engine in which the ram burner 17 is burning is operating. Then S1
At 2, the burner of the turbofan engine is ignited and its operation is started, and then at S13, the total air amount and thrust of the engine are kept constant and the downstream flow velocity of the bypass air duct 11 is made as low as possible. While closing the rear duct valve 16 little by little and closing the exhaust nozzle 18 slightly, the amount of air flowing into the turbofan engine is increased.

Next, in S14, the fan duct valve 14 is fully closed to guide the entire air flow to the turbofan engine. Then, in S15, the front duct valve 1 is closed.
5 is opened to increase the static pressure in the bypass air duct 11, then, in S16, the fuel of the ram burner 17 is shut off to stop its operation.
Is closed slightly to its original position, and the turbo fan engine is switched to the operating state.

That is, when the mode is switched from the ram mode to the turbo mode, the operations shown in FIGS. 2 and 3 are performed in reverse, and similarly, the reverse flow phenomenon, Switching can be performed stably without causing unstable operation such as blowout of the combustor. It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various changes can be made without departing from the spirit of the present invention.

[0024]

As described above, the method for switching the operation of the turbo ramjet engine according to the present invention can be performed while maintaining the total suction flow rate and the thrust of the engine at a constant level, and can cause unstable flow such as a backflow phenomenon and a blowout of the combustor. There is an excellent effect that the operation can be switched between the turbo mode and the ram mode without operation.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a turbo ramjet engine to which a method according to the present invention is applied.

FIG. 2 is a flowchart of an operation switching method from a turbo mode to a ram mode according to the present invention.

FIG. 3 is a diagram showing the operation of each component corresponding to the operation switching of FIG. 2;

FIG. 4 is a flowchart of an operation switching method from a ram mode to a turbo mode.

FIG. 5 is a configuration diagram of a turbo ram jet engine.

[Description of Signs] 1 Intake 2 Turbo-side flow path 3 Ram-side flow path 4 Front junction 5 Rear junction 6 Compressor (compressor) 7 Combustor (burner) 8 Turbine 9 Nozzle throat of exhaust nozzle 10 Fan 11 Bypass Air duct 12 Turbo fan engine 13 Fan bypass duct 14 Fan duct valve 15 Front duct valve 16 Rear duct valve 17 Ram burner 18 Exhaust nozzle 19 Engine casing S1 to S7 Operation steps up to ram mode S11 to S17 Operation steps up to turbo mode

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-58203 (JP, A) JP-A-3-210053 (JP, A) JP-A-3-194158 (JP, A) 134232 (JP, A) JP-A-2-28661 (JP, A) JP-A-2-28662 (JP, A) US Pat. No. 5,311,735 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) F02K 7/16 F02K 1/08 F02K 3/06 F02K 3/075

Claims (2)

(57) [Claims] A turbo fan engine having a fan and a bypass air duct; a fan bypass duct for bypassing the fan to flow air to the bypass air duct; a fan duct valve for opening and closing an upstream side of the fan bypass duct; A front duct valve that opens and closes the upstream side of the duct, a rear duct valve that opens and closes the downstream side of the bypass air duct, a ram burner arranged downstream of the turbofan engine, and a nozzle throat area arranged downstream of the ram burner With a variable exhaust nozzle,
1. 1. In the operating state of the turbofan engine in which the fan duct valve is fully closed, the entire amount of air flows into the turbofan engine, and the ram burner is off, 2. Open the exhaust nozzle to avoid fan stalls due to pressure spikes when the ram burner is ignited. Then, the ram burner is ignited to compensate for the reduction in the thrust of the turbofan engine during the switching process; 4. Then, in order to prevent backflow in the fan bypass duct when the fan duct valve is opened, the front duct valve is closed to reduce the static pressure in the bypass air duct. Next, the fan duct valve is fully opened, and a part of the total air amount is guided to the bypass air duct via the fan bypass duct. Next, keep the total air volume and thrust of the engine constant,
6. reduce the amount of air flowing into the turbofan engine while opening the rear duct valve as much as possible and slightly opening the exhaust nozzle so that the downstream flow velocity of the bypass air duct is as low as possible; Then, the burner fuel of the turbofan engine is cut off to stop its operation, and the operation is switched to the operation state of the ramjet engine, thereby switching the operation of the turbo ramjet engine. 2. A turbofan engine having a fan and a bypass air duct, a fan bypass duct for bypassing the fan and flowing air to the bypass air duct, a fan duct valve for opening and closing an upstream side of the fan bypass duct, and a bypass air. A front duct valve that opens and closes the upstream side of the duct, a rear duct valve that opens and closes the downstream side of the bypass air duct, a ram burner arranged downstream of the turbofan engine, and a nozzle throat area arranged downstream of the ram burner With a variable exhaust nozzle,
1. 1. In the operating state of the ramjet engine in which the fan duct valve is fully opened, the total amount of air flows into the ram burner through the fan bypass duct, and the ram burner is burning. 2. Ignite the burner of the turbofan engine and start its operation; Next, keep the total air volume and thrust of the engine constant,
3. increasing the amount of air flowing into the turbofan engine while gradually closing the rear duct valve and slightly closing the exhaust nozzle so that the downstream flow velocity of the bypass air duct is as low as possible; 4. Then, fully close the fan duct valve to guide the total air flow to the turbofan engine; Then, open the front duct valve to increase the static pressure in the bypass air duct; 6. Then the fuel of the ram burner is shut off to stop its operation; A method for switching operation of a turbo ram jet engine, comprising closing an exhaust nozzle and switching to an operation state of a turbo fan engine.