JP2000002155A - Turbofan engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a by-pass ratio and improve engine performance by extending a low speed fan having an outside diameter larger than that of a fan on an outer periphery side of a windmill, decelerating and revolving the windmill by air flow generated by revolution of the fan and generating main by-pass thrust by revolution of the low speed fan. SOLUTION: A turbo fan engine 20 is provided with a windmill 22 and a low speed fan 23 across a duct 21 on a front side. A fan 38 connected with a low pressure turbine 33 via a rotary shaft 34 and the windmill 22 which is freely rotatably located at the rear side constitute a torque converter, and air flow from the fan 38 imparts rotational torque to the windmill 22. Revolving air flow from the low speed fan 23 is straightened in a shaft direction by a straightening vane 44b, becomes by-pass flow and imparts main engine thrust. After air flow by the fan 38 imparts rotational torque to the windmill 22, a part becomes by-pass flow and contributes to engine thrust, and a part is compressed by low pressure and high pressure compressors 46, 47 and becomes air flowing into a combustion chamber 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbofan engine widely used for an aircraft navigating at a subsonic speed, particularly for a passenger aircraft.

[0002]

2. Description of the Related Art Conventionally, turbofan engines have been widely used in aircraft that travel at subsonic speeds. One of such turbofan engines is shown in FIG.

In this turbofan engine 1, the low-pressure turbine 6 is directly connected to a fan 9 via a rotating shaft 10 to rotate the fan 9. The air flow from the fan 9 becomes a bypass flow to give thrust to the engine, and a part of the air is compressed by the low-pressure compressor 11 and the high-pressure compressor 7 to become air flowing into the combustion chamber 3. The high-temperature gas flow discharged from the combustion chamber 3 gives rotational energy to the high-pressure turbine 5 and the low-pressure turbine 6, and the remaining energy is directly discharged rearward and becomes a part of the engine thrust.

[0004]

In the above turbofan engine, the performance can be improved by increasing the bypass ratio. However, if the outer diameter of the fan is increased to increase the bypass ratio, the peripheral speed of the fan becomes excessively high. Propulsion efficiency decreases. On the other hand, if the peripheral speed is reduced while the outer diameter of the fan is kept large, there is a problem that the turbine peripheral speed becomes too small and the turbine efficiency is reduced because the fan and the turbine are directly connected via the rotating shaft.

Therefore, a technique has been proposed in which a planetary gear reducer is provided on a rotating shaft to which the fan is connected, and the fan is rotated at a reduced speed. As a result, the rotation of the fan can be decelerated while maintaining the good turbine efficiency without lowering the rotation speed of the rotating shaft of the turbine, and the fan efficiency can be improved. In this case, the above-described reduction gear is required to be extremely lightweight and to have absolute reliability.

However, due to the material problems and the need for a structural design that can achieve a delicate balance, in the current gear technology, a lightweight and highly reliable gear that can be used for this purpose is used in some small engines. It has only been put to practical use and has not yet been put into practical use in large engines. further,
No mechanism other than gears suitable for this application has been put to practical use.

The present invention has been made in view of such circumstances, and uses a torque converter type fluid reduction device using a combination of a fan and a wind turbine without using a complicated gear-type reduction mechanism, thereby improving fan efficiency and turbine efficiency. It is an object of the present invention to provide a turbofan engine capable of significantly increasing a bypass ratio and improving engine performance while maintaining good efficiency.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a wind turbine that is rotatably provided behind a fan that rotates while being connected to a turbine portion. A low-speed fan having an outer diameter larger than the outer diameter of the fan is extended on the outer peripheral side of the wind turbine while forming a fluid speed reducer, and the wind turbine is decelerated and rotated by an air flow generated by the rotation of the fan. Thus, the main bypass thrust is generated.

In this turbofan engine, after the airflow from the fan imparts rotational energy to the windmill, part of the airflow is added to the bypass flow to contribute to engine thrust, and part of the airflow is compressed by the low-pressure compressor and the high-pressure compressor for combustion. It becomes the air flowing into the room. The high-temperature gas flow discharged from the combustion chamber gives rotational energy to the high-pressure turbine and the low-pressure turbine, and the remaining energy is directly discharged rearward and becomes a part of the engine thrust. Further, the wind turbine is rotated at a reduced speed so that the propulsion efficiency of the low-speed fan extending on the outer periphery is optimized.

In order to separate the air flow passing through the fluid reduction device composed of the fan and the wind turbine from the air flow passing through the low-speed fan, a cylindrical duct is provided on the outer periphery of the fan and the wind turbine.

In order to optimize the energy transfer efficiency of the fluid speed reducer including the fan and the windmill, one or more of the fan and the windmill are provided, or one or more stages are provided between the respective stages of the windmill. A multi-stage speed reducer provided with the stationary vanes may be configured. In order to optimize the efficiency of the windmill and the low-speed fan, a contra-rotating configuration may be adopted.

Next, a turbofan engine according to the present invention will be described with reference to the drawings.

[0013]

FIG. 1 shows a turbofan engine 20 according to an embodiment of the present invention. The rear side of the turbofan engine 20 has substantially the same configuration as the turbofan engine 1 shown in FIG. 9, and a windmill (air turbine) 22
And the point that the low-speed fan 23 is provided. Hereinafter, this will be described in detail.

The fan 38 directly connected to the low-pressure turbine 33 via the rotating shaft 34
Is rotated at a rotational speed that maintains good efficiency. The fan 38 and the wind turbine 22 rotatably positioned behind the fan 38 form a torque converter.
2 is given a rotational torque. The wind turbine 22 is rotated at a reduced speed at an appropriate speed so as to optimize the efficiency of the low-speed fan 23 extending around the wind turbine 22. Therefore, it can be said that the fan 38 and the windmill 22 form a reduction gear.

A cylindrical duct 21 is provided on the outer periphery of the fan 38 and the windmill 22 in order to separate the airflow passing through the fluid reduction device composed of the fan 38 and the windmill 22 and the airflow passing through the low-speed fan 23. I have. In FIG. 1, the duct 21
Is connected to the windmill 22, but may be connected to the fan 38 or the cowl 42.

The swirling airflow from the low-speed fan 23 is rectified in the axial direction by the rectifying blades 44b, and becomes a bypass flow to give a main engine thrust. On the other hand, the airflow from the fan 38 gives a rotational torque to the windmill 22 and then partly becomes a bypass flow to contribute to the engine thrust, and partly compressed by the low-pressure compressor 46 and the high-pressure compressor 47 to form the combustion chamber 25. It becomes the inflow air to the.

A cylindrical partition 45 which is continuously connected to the rear of the duct 21 without being connected thereto, and a movable portion 45a movably attached to the rear end of the partition 45 are provided. Movable part 4
5a is adjusted so as to prevent loss due to interference between the airflow from the low-speed fan 23 and the airflow from the windmill 22.
That is, the velocity of the air passing through the windmill 22 and added to the bypass flow is adjusted so as to approach the bypass flow velocity of the low-speed fan 23.

FIG. 2 is a simplified view of the turbofan engine 20 of FIG. 1 similar to the turbofan engine 1 of FIG. FIG. 3 shows fluid velocity triangles at the leading edges 1, 3, 5 and trailing edges 2, 4, 6 of the fan 38, the windmill 22, and the straightening vanes 44a in the AA ′ plane of FIG.
Each pre slow fan 23 and the rectifying vanes 44b in the plane B-B 'in FIG. 2 edge _{j 1,} j ₃ and the trailing edge _j 2, _{j 4}
FIG. 4 shows the velocity triangle of the fluid according to FIG.

The speed triangle will be described with reference to FIG. Fa
38 is peripheral speed U₁, U₂(However, U ₁= U₂)
Inflow velocity V from the front₁(Fan 38 side
Looking at W₁Of the incoming air is at the leading edge of the fan 38
Enter 1. Then, it is compressed and accelerated by the fan 38,
In the trailing edge 2, the speed V₂(When viewed from the fan 38 side, W ₂
At the speed). Wind speed 22 is peripheral speed U₃, U₄(However
Then U₃= U₄), In front of the windmill 22
V on edge 3₂Speed V slightly smaller than₃(View from the windmill 22 side
And W₃Speed). Then, the rotational torque is applied to the windmill 22.
And the speed V₄(W from the windmill 22 side₄Speed
Spill out at Then, in the circumferential direction (FIG. 3)
) Component is set to 0, and the speed from the trailing edge 6
V_m6Leaked at

Similarly, the speed triangle will be described with reference to FIG.
You. The low-speed fan 23 has a peripheral speed U_j1, U _j2(However, U
_j1= U_j2> U₃), From the front
Inflow velocity V_j1(W from the low-speed fan 23 side_j1of
(At speed) the leading edge j of the low speed fan 23₁Enter
You. Then, the speed is increased by the low-speed fan 23, and
₂Then, the speed V_j2(When viewed from the low-speed fan 23 side, V
_j2At the speed). Then, the air flows around the rectifying wing 44a.
The component in the direction (vertical direction in FIG. 4) is set to 0, and the trailing edge
j₄To speed V_j4Leaked at In addition, the movable portion 45a
By adjusting the direction, the speed V_j4The speed V_m6To
Closer, the air flow from the low-speed fan 23 and the
Losses due to airflow interference can be reduced.

The shaft portion 41 of the wind turbine 22 has a bearing 39,
It is rotatably attached to the frame part 50 via 40. Since the axial load of the wind turbine 22 is balanced in the opposite direction to that of the low-speed fan 23, the bearings 39 and 40 do not need to consider excessive axial load. For this reason, when manufacturing this turbofan engine 20, special materials and techniques are not particularly required, and conventional techniques can sufficiently cope with them.

FIG. 5 shows a turbofan engine 51 according to another embodiment of the present invention. This turbofan engine 51 has a configuration in which another windmill 52 and a fan 53 are added between the windmill 22 and the fan 38 in the turbofan engine 20 shown in FIG.
In this case, the fan 53 is fixed to the rotating shaft 34 and the windmill 5
2 is fixed to the duct 21.

FIG. 6 also shows a turbofan engine 54 according to another embodiment. In the turbo fan engine 54, the turbo fan engine 20 shown in FIG.
, A further rectifying blade 55 and another wind turbine 56 are provided between the wind turbine 22 and the rectifying blade 44a. The configuration of the other parts is the same as that of the turbofan engine 20, and the same parts are denoted by the same reference numerals.

FIG. 7 also shows a turbofan engine 60 according to another embodiment. In this turbofan engine 60, in order to optimize the efficiency of the windmill and the low-speed fan, the two-stage windmills 61 and 62 and the low-speed fan 63,
64 are provided to be opposite to each other.

FIG. 8 shows a turbofan engine 70 according to another embodiment. The turbofan engine 70 includes a three-stage fan 71 fixed to the rotating shaft 34.
The two-stage windmill 72 disposed between the fans 71 receives the airflow generated by the rotation of the fan 71, and applies the rotation torque to the windmill 72 at a reduced speed. Therefore, the combination of the fan 71 and the windmill 72 forms a torque converter type fluid reduction device. Further, the combination of the fan 71 and the windmill 72 also has a function of compressing inflow air. That is, while the inflow air passes through the fan 71 and the windmill 72,
It is sequentially compressed in the space partitioned by the duct 21. A part thereof is guided to the high-pressure compressor 47, further compressed by the high-pressure compressor 47, and guided to the combustion chamber 25. The remainder is led to the expansion turbine.

The expansion turbine includes a moving blade 76 and a stationary blade 7.
3 and a moving blade 74. The upstream moving blade 76 has an annular subduct 21a fixedly provided on the inner periphery thereof, and a blade 75 fixedly provided on the inner periphery of the subduct 21a. The sub duct 21a has a function of preventing the inflow air compressed to be guided to the high-pressure compressor 47 from escaping to the expansion turbine side. The shape and direction of the wings 75 are set so that the wings 75 do not hinder the air flow so as to flow from the fan 71 to the high-pressure compressor 47.

Thus, in the expansion turbine, the pressurized inflow air applies rotational torque to the two-stage moving blades 76 and 74 while sequentially reducing the pressure. Then, the inflow air is rectified through the rectifying blades 44a, and joins with the airflow from the low-speed fan 23 to become a part of the thrust. In the present embodiment, since the wind turbine 72 constituting the low-pressure compressor 47 rotates together with the low-speed fan 23, it is difficult to change the angle of attack. However, by variably controlling the directions of the stationary blades 73 and the movable portion 45a of the expansion turbine on the outlet side, the compression ratio as a low-pressure compressor can be stably secured, and the reduction ratio as a fluid reduction device can be optimized.

[0028]

As described above, since the turbofan engine according to the present invention is constituted, a large amount of bypass airflow is obtained by the rotation of the low-speed fan, and the air after driving the windmill as the working fluid of the torque converter is obtained. A stream is also added as part of the bypass air stream. As a result, the bypass ratio can be greatly increased, and the performance can be improved. Even if a large-sized and large-output core engine according to the related art is used, for example, a turbofan engine having an ultra-high bypass ratio of 10: 1 or more can be realized.

Further, since the low-pressure turbine can be rotated at a rotation speed that maintains good turbine efficiency, the number of low-pressure turbine stages can be reduced, and the engine weight can be reduced and maintenance work can be simplified. In addition, the operation cost will be reduced. Further, the conventional low-pressure compressor can be omitted, or the number of stages of the high-pressure compressor can be reduced.

[Brief description of the drawings]

FIG. 1 is a partially cutaway sectional view showing a turbofan engine according to an embodiment of the present invention.

FIG. 2 is an explanatory view obtained by simplifying FIG. 1;

FIG. 3 is an explanatory diagram using a speed triangle at A-A ′ in FIG. 2;

FIG. 4 is an explanatory diagram using a speed triangle at B-B ′ in FIG. 2;

FIG. 5 is an explanatory view showing a turbofan engine according to another embodiment.

FIG. 6 is an explanatory view showing a turbofan engine according to still another embodiment.

FIG. 7 is an explanatory view showing a turbofan engine according to another embodiment.

FIG. 8 is an explanatory diagram showing a turbofan engine according to another embodiment.

FIG. 9 is an explanatory view of a turbofan engine according to the related art.

[Explanation of symbols]

 20, 51, 54, 60 Turbo fan engine 21 Duct 21a Sub duct 22, 52, 56, 72 Wind turbine 23 Low speed fan 25 Combustion chamber 26 High pressure turbine 33 Low pressure turbine 34 Rotating shaft 38, 53, 71: Fan 75: Blade 73: Static blade of expansion turbine 74, 76: Moving blade of expansion turbine 77: Bearing

Claims (10)

[Claims] A wind turbine is rotatably provided behind a fan that rotates while being connected to a turbine portion, and a torque converter type fluid reduction device is formed by a combination of the fan and the wind turbine. A turbofan engine, comprising: extending a low-speed fan having an outer diameter larger than the outer diameter, decelerating and rotating a windmill by an airflow generated by the rotation of the fan, and generating a main bypass thrust by the rotation of the low-speed fan. . 2. A structure according to claim 1, wherein a cylindrical duct is provided on the outer periphery of the fan and the windmill to separate an airflow passing through a fluid reduction device comprising the fan and the windmill and an airflow passing through the low-speed fan. The described turbofan engine. 3. The fluid speed reducer includes both a fan and a windmill,
3. The turbofan engine according to claim 1, wherein a plurality of any one of the plurality of speed reducers is provided to constitute a multi-stage speed reducer. 4. The turbofan engine according to claim 3, wherein one or more stages of vanes are provided between each stage of the wind turbine. 5. The turbofan engine according to claim 1, wherein the wind turbine and the low-speed fan are configured to be doubled and rotated in reverse. 6. A turbofan engine having a structure in which a windmill and a low-speed fan are doubled and each of them is rotated in a reverse direction, wherein a plurality of both or one of the fan and the windmill is provided, or between each stage of the windmill. The turbofan engine according to claim 5, wherein one or more stages of vanes are provided. 7. The turbofan engine according to claim 2, wherein a cylindrical duct is provided on the outer periphery of the fan and the windmill.
A turbofan engine having a structure in which a movable portion is provided at a rear end portion of a partition provided continuously with a duct and the speed of air passing through the speed reducer can be adjusted to approach a bypass flow speed of a low-speed fan. 8. The turbofan engine according to claim 1, wherein a speed reducer and a low-speed fan are arranged behind the core engine. 9. The turbofan engine according to claim 1, wherein the fluid reduction device is constituted by a combination of the fan and the wind turbine, and a low-pressure compressor for supplying compressed air to a high-pressure compressor. Become a turbofan engine. 10. The bypass thrust according to claim 9, wherein a part of the air flow that has passed through the fluid reduction gear is combined with the air flow that has passed through the low-speed fan through an expansion turbine to become a part of the bypass thrust. Turbo fan engine.