JPH11159399A - High by-pass ratio turbo-fan engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an engine size by having small size, light weight, and simple structure, reduce weight of the whole engine and airframe resistance, dispense with a sliding part, and enhance the reliability. SOLUTION: In a turbo-fan engine 10, a core engine 1 is surrounded by a bypass cowl 2 at a certain interval, and a bypass passage 4 is formed at the interval to bypass an intake air. A variable bypass nozzle 12 capable of continuously adjusting a passage area is provided at a downstream end of the bypass passage 4. The variable bypass nozzle 12 comprises a flexible tube 14 provided at the narrowest part of the bypass passage 4 and a gas pressure control device 16 for controlling the gas pressure inside the flexible tube 14, and changes the gas pressure inside the flexible tube 14 in accordance with a flight condition to expand or shrink the tube 14, whereby the area of the bypass nozzle is changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a turbofan engine in which a fan and a fan turbine are added before and after a core engine, and more particularly, to a high bypass ratio turbofan engine having a variable bypass nozzle.

[0002]

2. Description of the Related Art In the field of passenger jet engines, turbofan engines are mainly employed to improve fuel consumption in the subsonic range. As shown in FIG. 5, this turbofan engine uses a normal turbojet engine as a core engine 1 and adds a fan and a fan turbine before and after the core engine 1 so that a cowl 2 can bypass intake air around the core engine 1. And a large fan 3 is driven by a core engine to introduce air into the cowl.

In such a turbofan engine,
The fuel consumption rate is improved as the bypass ratio (engine bypass flow rate / core engine flow rate) is increased. For this reason, the bypass ratio of recent large engines has increased from about 5 in the past to about 7 to 9. Such a turbofan engine having a high bypass ratio is called a high bypass ratio turbofan engine.

In a conventional turbofan engine having a high bypass ratio, the core nozzle 1 and the cowl 2 have a fixed shape, and the area of the bypass nozzle formed therebetween is constant.
It should be noted that a low bypass ratio turbofan engine for a fighter jet has been put into practical use in which a core flow and a bypass flow are mixed, fuel is added, the fuel is burned again, and then exhausted from a variable nozzle. By way of example, US Pat. No. 5,485,959
"Axisymmetric Vectoring Exhaust Nozzle Thermal Shi
eld "etc.

[0005]

The high-bypass ratio turbofan engine described above has a good fuel consumption rate,
Large drop in output during high-speed flight. That is, when the bypass ratio is increased, the nozzle exit speed of the bypass flow becomes relatively small, so that the thrust at the time of high-speed flight is greatly reduced,
There have been problems such as a decrease in the rate of flight rise during high-speed flight and a decrease in the maximum flight altitude, which adversely affects the aircraft performance. In order to solve this, an engine having a large thrust had to be attached, and there was a disadvantage that the weight and the air resistance increased.

The problem is that the fuel consumption rate and thrust can be improved by changing the area of the bypass nozzle during flight. However, a known nozzle area variable mechanism (for example, the above-described variable nozzle) has a problem that it is difficult to avoid an increase in size and weight, and it is difficult to obtain a sufficient improvement.
In other words, in a high-bypass ratio turbofan engine, it is possible to improve the fuel consumption rate and thrust by adjusting the bypass nozzle area during flight, but the conventional variable mechanism (a plurality of flaps are connected by a link mechanism). However, when a mechanism operated by an actuator is applied, the weight and dimensions are increased, which may adversely affect the flight performance.

The present invention has been made to solve such a problem. That is, an object of the present invention is to provide a small and light-weight and simple mechanism, which can reduce the size of the engine, reduce the weight of the engine as a whole, reduce the body resistance, and have no reliability because there are no sliding parts. To provide a turbofan engine with a high bypass ratio.

[0008]

According to the present invention, there is provided a high-bypass-ratio turbofan engine in which a core engine is surrounded by a bypass cowl at intervals and a bypass flow path is formed therebetween to bypass intake air. At the downstream end of the flow path, a variable bypass nozzle capable of continuously adjusting the flow path area is provided, the variable bypass nozzle is provided with a flexible tube installed at the narrowest part of the bypass flow path, A gas pressure control device that controls the gas pressure in the tube, and changes the gas pressure in the tube according to the flight state to expand or contract the tube, thereby changing the bypass nozzle area. A high bypass ratio turbofan engine is provided.

With this configuration, it is possible to reduce the nozzle exit area of the bypass nozzle during high-speed flight, increase the jet flow velocity, increase the thrust, and prevent a decrease in output. By increasing the output during high-speed flight, the aircraft's kinematic performance such as the rate of climb and the maximum flight altitude are improved, and it is not necessary to increase the engine rating (combustor temperature) unnecessarily, and the life of parts can be extended. . Also, if the output during high-speed flight is constant, the engine size can be reduced, which leads to a reduction in weight and a decrease in body resistance.

Further, according to the structure of the present invention, the bleed gas from the compressor is supplied into the flexible tube, and the bleed gas is controlled by the gas pressure control device to change the pressure applied to the tube according to the flight condition. The tube can be expanded or contracted to change the bypass nozzle area. That is, a part of the bypass nozzle is made of, for example, a superelastic material (rubber).
, The nozzle area is expanded by applying pressure to change the nozzle area, and the pressure can be reduced to return to the original area.

Since the variable bypass nozzle comprises a flexible tube and a gas pressure control device, unlike an ordinary variable mechanism, it is lightweight and does not increase the outer diameter of the engine, so that the aerodynamic resistance of the body does not deteriorate. . In addition, it is simple and easy to reduce the size and weight of the components, such as pipes, valves, rubber tubes, etc., and has high reliability because there are no sliding parts. Even if the system is damaged, the rubber tubes will collapse. Just keep a safe flight.

According to a preferred embodiment of the present invention, the flexible tube is attached to a narrowest core engine or a bypass cowl. By providing in the narrowest part,
The nozzle area can be effectively changed by the small flexible tube.

Further, it is preferable to have a variable nozzle mechanism in which the area of the narrowest portion changes continuously due to expansion or contraction of the flexible tube. By using a highly durable light metal or the like for the variable nozzle mechanism, abrasion resistance and heat resistance are enhanced, and a highly durable variable bypass nozzle can be configured with a small, light, and simple mechanism.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. In the drawings, common parts are denoted by the same reference numerals. FIG. 1 is an overall configuration diagram of a high-bypass ratio turbofan engine according to the present invention, and FIG. 2 is an enlarged view of a portion A in FIG. As shown in FIG. 1, a high bypass ratio turbofan engine 10 of the present invention is configured such that a bypass cowl 2 surrounds a core engine 1 at intervals, and a bypass flow path 4 is formed therebetween to bypass intake air. Has become. This configuration is similar to the conventional high bypass ratio turbofan engine shown in FIG.

1 and 2, a high bypass ratio turbofan engine 10 of the present invention is provided at a downstream end (right end in the drawing) of a bypass flow passage 4 with a variable bypass nozzle capable of continuously adjusting the flow passage area. 12 are provided. The variable bypass nozzle 12 includes a flexible tube 14 installed at the narrowest portion of the bypass flow path 4 and a gas pressure control device 16 for controlling a gas pressure in the flexible tube 14. The flexible tube 14 is made of a highly elastic material (for example, synthetic rubber), is formed in a hollow ring shape, and is formed so as to expand to a desired shape by increasing the internal pressure and to contract to the original shape by reducing the internal pressure. I have. The gas pressure control device 16 supplies, for example, bleed gas from the compressor of the core engine 1 into the flexible tube, and changes the gas pressure in the tube according to the flight state to expand or contract the tube 14, As a result, the area of the bypass nozzle is changed as shown by a broken line in the figure. The bleed gas is not limited to bleed air, and another gas (for example, nitrogen) may be supplied from the machine body side to which the engine is attached.

FIG. 3 is a configuration diagram of another variable bypass nozzle of the present invention. In the embodiment of FIGS. 1 and 2, the flexible tube 14 is attached to the core engine 1 at the narrowest portion, but is attached to the bypass cowl 2 at the narrowest portion as shown in FIG. You may. As described above, by directly attaching the flexible tube 14 to the narrowest portion, the nozzle area can be effectively changed by the small-sized flexible tube 14 as shown by a broken line in the figure.

Further, as shown in FIG. 3B, a variable nozzle mechanism 18 in which the area of the narrowest portion continuously changes due to expansion or contraction of the flexible tube 14 may be provided. In this case, the variable nozzle mechanism 18 is connected to the joint 18 as shown in the figure.
The variable nozzle mechanism 18 is made of a highly durable light metal or the like to provide abrasion resistance and heat resistance by using a plate 18c connected by a (shown by ○) and a slide portion 18b (shown by ●). An enhanced and durable variable bypass nozzle can be configured with a small, lightweight and simple mechanism.

FIG. 4 is a performance diagram of a high bypass ratio turbofan engine according to the present invention. In this figure, the horizontal axis represents the Mach number and the vertical axis represents the engine thrust. The solid line in the figure represents the high bypass ratio turbofan engine of the present invention, and the broken line represents the conventional engine. From this figure, it can be seen that the high bypass ratio turbofan engine of the present invention can obtain a high engine thrust in a wide speed range.

With the configuration of the high-bypass-ratio turbofan engine 10 of the present invention described above, the nozzle exit area of the bypass nozzle can be reduced during high-speed flight, the jet velocity can be increased, the thrust can be increased, and the output can be prevented from lowering. By increasing the output during high-speed flight, the aircraft's kinematic performance such as the rate of climb and the maximum flight altitude are improved, and it is not necessary to increase the engine rating (combustor temperature) unnecessarily, and the life of parts can be extended. . Also, if the output during high-speed flight is constant, the engine size can be reduced, which leads to a reduction in weight and a decrease in body resistance.

Further, according to the structure of the present invention, the bleed gas from the compressor is supplied into the flexible tube 14, and the bleed gas is controlled by the gas pressure control device 16, so that the pressure applied to the tube according to the flight condition is increased. Can be changed to expand or contract the tube to change the bypass nozzle area. That is, since a part of the bypass nozzle is made of, for example, a tube made of a superelastic material (rubber), it can be expanded by applying pressure to change the area of the nozzle, and reduce the pressure to return to the original area.

Since the variable bypass nozzle 12 is composed of the flexible tube 14 and the gas pressure control device 16, unlike an ordinary variable mechanism, it is lightweight and does not increase the outer diameter of the engine, thereby deteriorating the aerodynamic resistance of the airplane. Nothing.
In addition, it is simple and easy to reduce the size and weight of the components, such as pipes, valves, rubber tubes, etc., and has high reliability because there are no sliding parts. Even if the system is damaged, the rubber tubes will collapse. Just keep a safe flight.

It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

[0023]

As described above, the high-bypass-ratio turbofan engine of the present invention has a small, lightweight and simple mechanism, which can reduce the size of the engine, reduce the overall weight of the engine and reduce the body resistance. And has effects such as high reliability without a sliding portion.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a high bypass ratio turbofan engine according to the present invention.

FIG. 2 is an enlarged view of a portion A in FIG.

FIG. 3 is a configuration diagram of another variable bypass nozzle of the present invention.

FIG. 4 is a performance diagram of a high bypass ratio turbofan engine according to the present invention.

FIG. 5 is a configuration diagram of a conventional high bypass ratio turbofan engine.

[Explanation of symbols]

 Reference Signs List 1 core engine 2 bypass cowl 3 fan 4 bypass flow passage 10 high bypass ratio turbofan engine 12 variable bypass nozzle 14 flexible tube 16 gas pressure control device 18 variable nozzle mechanism

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Noriyuki Nakamura 3-5-1 Mukodai-cho, Tanashi-shi, Tokyo Ishikawa Shima-Harima Heavy Industries Co., Ltd. Tanashi Plant

Claims (3)

[Claims] 1. A high bypass ratio turbofan engine in which a bypass cowl surrounds a core engine at intervals and forms a bypass flow passage therebetween to bypass intake air, wherein a flow passage area is provided at a downstream end of the bypass flow passage. A variable bypass nozzle capable of continuously adjusting the pressure, the variable bypass nozzle having a flexible tube installed at the narrowest portion of the bypass flow path, and a gas pressure controlling a gas pressure in the flexible tube. A high-bypass-ratio turbofan engine, comprising: a control device for changing a gas pressure in a tube according to a flight condition to expand or contract the tube, thereby changing a bypass nozzle area. 2. The high bypass ratio turbofan engine according to claim 1, wherein the flexible tube is attached to a core engine or a bypass cowl at a narrowest portion. 3. The high-bypass ratio turbofan engine according to claim 2, further comprising a variable nozzle mechanism in which the area of the narrowest portion continuously changes by expansion or contraction of the flexible tube. .