JP2015209839A - Variable nozzle mechanism and nozzle area change method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable nozzle mechanism and a nozzle area change method, capable of changing an exhaust area with a light-weight and simple mechanism, without complicating a structure and increasing its size, and capable of reducing thrust loss in cruising.SOLUTION: In a variable nozzle mechanism provided in the exhaust flow passage of a bypass jet 101 of a turbo fan engine 100, a rear end edge 111 of a cowing 110 is formed into a corrugated shape having a plurality of irregularities in a front-back direction; and on the outer periphery of a rear part containing the rear end edge 111 of the cowling 110, a rear end edge 121 has a rotatable ring member 120 formed into a corrugated shape having a plurality of irregularities in the front-back direction, which are the same shape as those of the rear end edge 111 of the cowling 110.

Description

  The present invention relates to a variable nozzle mechanism and a nozzle area changing method provided in an exhaust passage of a bypass jet constituted by an inner periphery of a cowling of a turbofan engine and an outer periphery of a core engine.

In current aircraft development, environmental adaptability, especially noise and emission reduction, is required.
In the jet engine, the engine noise has been reduced by improving the bypass ratio, but there is still a strong demand for reducing the noise of aircraft aircraft, particularly the noise of jet engines.
In particular, there are severe restrictions on noise at airports close to residential areas. For example, itami airports are prohibited from taking off and landing aircraft with three or more engines.
There is also a need to avoid the use of thrust reversers, which can be a significant noise source when landing.
On the other hand, low-noise aircraft are not restricted by available airports, which is a great attraction for operators.
The power of the early aircraft was a turbojet, but the noise of the exhaust jet was greatly reduced due to the transition to a turbofan jet and the high bypass.
Noise from the fan can be greatly reduced by using a sound absorbing liner on the inner surface of the fan cowling.
Also, since the early jets on the exhaust side, various mechanisms for reducing noise have been devised.

For example, Patent Document 1 proposes a method for reducing noise by promoting mixing of a high-speed jet and outside air using a lobe.
In Patent Document 2, the nozzle trailing edge is formed in a rectangular wave shape to excite longitudinal vortices in the jet exhaust, and noise is reduced by promoting mixing of the jet and the outside air.
In Non-Patent Document 1, an engine cowling called Chevron (hereinafter referred to as Chevron) is employed to reduce noise during takeoff and landing.
In this chevron, the trailing edge of the engine cowling is corrugated to excite the longitudinal vortex as in the above-mentioned Patent Document 2, and the noise is reduced by promoting the mixing of the bypass jet and the outside air.
However, since this chevron becomes a resistance source during cruising and thrust loss occurs, there is a movement to defer the adoption of the chevron due to a trade-off between fuel consumption and noise countermeasures.
In contrast, Non-Patent Document 2 proposes a variable chevron.

Non-Patent Document 3 proposes a noise reduction method using a notch.
This is because the exhaust area of the bypass jet required at takeoff is different from the exhaust area required at cruising, and the latter is preferably about 90% of the former, so the engine cowling is used by the thrust reverser used at the time of landing. The bypass jet deflected by the louver from the annular gap created at this time is ejected obliquely forward.
The exhaust area of the bypass jet can be increased or decreased by utilizing a mechanism that swings the engine cowling that is a part of the thrust reverser backward.
Patent Document 3 proposes a technique in which a large number of vanes are movable and the exhaust area is variable while suppressing engine noise on the same principle as the above-mentioned chevron.

US Pat. No. 6,718,752 US Pat. No. 3,153,319 U.S. Pat. No. 4,422,524

B. Herkes, 'The Quiet Technology Demonstrator 2 Flight Test', Aviation Noise & Air Quality Symposium, March 7, 2006. F. Calkins, J.M. Mabe, ‘Variable Geometry Jet Nozzle Using Shape Memory Alloy Actuators’, Boeing, 2007. Tsutomu Oishi (Outside 3), “Simple Noise Reduction Technology”, IHI Technical Report Vol. 47 No. 3 (2007-9), p. 127-133

The mechanisms described in Patent Documents 1 and 2 do not take into account the silencing of the exhaust flow path of the bypass jet constituted by the inner periphery of the cowling of the turbofan engine and the outer periphery of the core engine.
In consideration of the noise reduction of the exhaust flow path of the bypass jet, which is composed of the inner periphery of the cowling of the turbofan engine and the outer periphery of the core engine, the end of the engine cowling of the bypass jet is corrugated to excite longitudinal vortices in the bypass jet. The chevron as described in Non-Patent Document 1 that promotes mixing with the outside air is simple but effective and is an excellent method.
However, as described in Non-Patent Document 1, the chevron is designed for the purpose of reducing noise during take-off, and thus becomes a resistance source during cruising, resulting in thrust loss.
Since a variable chevron as in Non-Patent Document 2 uses a bimetal whose shape changes depending on the temperature as a driving device, accurate operation cannot be expected in a cold region of high latitude and a dry high temperature region.

In a mechanism such as Non-Patent Document 3, since the engine cowling receives a large axial force, the variable exhaust area mechanism according to this method requires an actuator that generates a large force, which increases the weight.
Further, as described above, since the use of the thrust reverser is also restricted, the regulation of the aircraft may be changed so as not to require the aircraft engine to be provided with the thrust reverser.
In a mechanism such as Patent Document 3, a large number of vanes are driven by a large number of actuators, so that the mechanism is complicated, and the direction in which the vanes are moved is a radial direction. To increase.

In general, the exhaust area of the bypass jet of the turbofan engine is fixed, but the fuel consumption rate can be improved by making this variable.
Generally, the exhaust area required for cruising is 90% of that at takeoff.
Therefore, the present invention can change the exhaust area using a light and simple mechanism without complicating and increasing the size of the structure, reducing noise during takeoff and landing, and reducing thrust loss during cruising. It is an object of the present invention to provide a variable nozzle mechanism and a nozzle area changing method that can be reduced in size.

  A variable nozzle mechanism according to the present invention is a variable nozzle mechanism provided in an exhaust passage of a bypass jet constituted by an inner periphery of a cowling of a turbofan engine and an outer periphery of a core engine, and a rear end edge of the cowling is The ring member is formed into a corrugated shape having a plurality of undulations in the front-rear direction, and has a rotatable ring member on the outer periphery of the rear part including the rear end edge of the cowling, and the rear end edge of the ring member The above-mentioned problem is solved by forming a wave shape having a plurality of front and rear projections and depressions of the same type as the rear edge.

  A nozzle area changing method according to the present invention is a method for changing a nozzle area of a turbofan engine, wherein a rear end edge of the cowling of the turbofan engine is formed into a corrugated shape having a plurality of undulations in the front-rear direction. The outer periphery of the rear part including the rear end edge has a rotatable ring member, and the ring member is formed into a corrugated shape having a plurality of front and rear projections and recesses of the same type as the rear end edge of the cowling. The angle of rotation of the ring member is such that the corrugated recess at the trailing edge of the cowling coincides with the corrugated recess at the trailing edge of the cowling during takeoff, and the trailing edge of the cowling during cruise The above-mentioned problem is solved by setting an angle at which the corrugated convex portion of the corrugated portion and the corrugated concave portion of the rear end edge of the cowling coincide with each other.

According to the variable nozzle mechanism according to claim 1 and the nozzle area changing method according to claim 6, the rear end edge of the cowling is formed in a corrugated shape having a plurality of undulations in the front-rear direction, and the rear end edge of the cowling The outer periphery of the rear part including the ring member has a rotatable ring member, and the ring member is formed in a corrugated shape having a plurality of undulations in the front-rear direction of the same type as the rear end edge of the cowling. By rotating the ring member in the circumferential direction, the exhaust area can be made variable including the same state as the above-mentioned chevron.
Since the ring member can be rotated with a small driving force, the exhaust area can be changed using a light and simple mechanism without complicating and increasing the size of the structure.
And at the time of take-off, by setting the angle of the corrugated recess at the trailing edge of the cowling to the corrugated recess at the trailing edge of the cowling, it becomes the same state as the above-mentioned chevron and reduces noise during take-off and landing can do.
Also, during cruising, the corrugated convex part on the trailing edge of the cowling and the corrugated concave part on the trailing edge of the cowling are aligned so that the exhaust area is smaller than during take-off and landing, and the thrust during cruising Loss can be reduced.

According to the configuration of the second aspect of the present invention, the corrugation of the rear end edge of the cowling and the rear end edge of the ring member is such that the convex portion on the rear end edge side is rectangular, so When the convex portion of the mold coincides with the corrugated concave portion at the rear end edge of the cowling, the rear end edge can be formed into a continuous circumferential shape, and the thrust loss can be further reduced.
According to the configuration of the third aspect, the ring member is rotatably supported by the bearing provided on the outer periphery of the rear portion of the cowling, and the outer surface of the ring member and the outer periphery other than the rear portion of the cowling are continuous. As a result of the configuration, air turbulence is less likely to occur at the outer periphery of the cowling, noise can be further reduced, and thrust loss can be reduced.
According to the configuration of the present invention, the core engine has a plurality of bumps projecting to the bypass jet exhaust flow path side on the outer peripheral surface, and the plurality of bumps correspond to the corrugated concave portion of the trailing edge of the cowling. By being arranged at a position opposite to the surface, it is possible to promote the flow of air from the corrugated concave portion at the rear end edge of the cowling to the outside in the radial direction during takeoff and landing, and further promote the formation of the vertical vortex. .
By this vertical vortex, mixing of low-speed outside air and high-speed bypass jet can be promoted, and noise can be further reduced.
Further, during cruising, the flow path of the bypass jet is further narrowed, the exhaust area is reduced to about 90% of that at takeoff, and the thrust loss can be further reduced in a state suitable for cruising.
According to the configuration of the present invention, the plurality of bumps are gently formed with curved surfaces that are continuous in the front-rear direction and the circumferential direction, so that noise is generated due to the high-speed bypass jet hitting the plurality of bumps. As a result, noise can be further reduced as a whole.

FIG. 2 is a half sectional side view and a rear view of a general turbofan engine. The half section side view of the ring member of the turbofan engine which has the variable nozzle mechanism concerning one embodiment of the present invention. 1 is a side view of a core engine of a turbofan engine having a variable nozzle mechanism according to an embodiment of the present invention. The cowling of the turbofan engine which has the variable nozzle mechanism which concerns on one Embodiment of this invention, and the half cross section side view of a core engine. The half section side view and back view of the corrugated convex part of the rear-end edge of a cowling in the state at the time of takeoff of the turbofan engine which has the variable nozzle mechanism which concerns on one Embodiment of this invention. The half section side view and rear view of the corrugated recessed part of the rear-end edge of a cowling in the state at the time of takeoff of the turbofan engine which has the variable nozzle mechanism which concerns on one Embodiment of this invention. The half section side view and rear view of the wavelike convex part of the rear end edge of a cowling in the state at the time of cruise of a turbofan engine which has a variable nozzle mechanism concerning one embodiment of the present invention.

  A variable nozzle mechanism according to the present invention is a variable nozzle mechanism provided in an exhaust flow path of a bypass jet constituted by an inner periphery of a cowling of a turbofan engine and an outer periphery of a core engine. The ring member has a rotatable ring member on the outer periphery of the rear part including the rear end edge of the cowling. The ring member has the same shape as the rear end edge of the cowling. In the nozzle area changing method of the present invention, the rear end edge of the cowling of the turbofan engine is formed into a corrugated shape having a plurality of longitudinal concavo-convex shapes. The outer periphery of the rear part including the rear end edge of the cowling has a rotatable ring member, and the ring member has a corrugated shape having a plurality of front and rear projections of the same type as the rear end edge of the cowling. Formed The angle of rotation of the ring member is the angle at which the corrugated recess at the trailing edge of the ring member coincides with the corrugated recess at the trailing edge of the cowling during takeoff, and the corrugation at the trailing edge of the ring member is used during cruising. The angle between the convex part and the corrugated concave part at the rear edge of the cowling is the same, and the exhaust area can be changed using a light and simple mechanism without complicating and increasing the size of the structure. As long as it is possible and can reduce noise during take-off and landing and reduce thrust loss during cruising, any specific embodiment may be used.

As shown in FIG. 1, a conventional general turbofan engine 500 includes a core engine 530, a front fan 532 provided in front of the core engine 530, and a cowling 510 that covers the outer periphery of the core engine. Yes.
Air taken in from the front of the turbofan engine 500 is accelerated by the front fan 532, partly flows into the core engine 530, exhausted rearward from the nozzle 531 as the main jet 502, and most of them are the cowling 510 and the core engine as the bypass jet 501. The air is exhausted as a bypass jet 501 rearward from the gap between the nozzles 531 of 530.
A propulsive force is obtained by the main jet 502 and the bypass jet 501.
Although many cowlings 510 have a thrust reverser, they are omitted here.

As shown in FIGS. 2 to 7, a turbofan engine 100 having a silencing mechanism according to an embodiment of the present invention is similar to the general turbofan engine 500 described above. It has a front fan 132 provided in front and a cowling 110 that covers the outer periphery of the core engine.
The cowling 110 has a rear edge 111 formed in a corrugated shape having a plurality of front and rear concave portions 113 and convex portions 112.
The outer periphery of the rear part including the rear end edge 111 of the cowling 110 has a ring member 120 rotatably supported by two rows of bearings 114. The outer periphery of the ring member 120 and the outer periphery other than the rear part of the cowling 110 are Are configured to form a continuous surface.

The ring member 120 is formed in a corrugated shape having a plurality of front and rear concave portions 123 and convex portions 122 whose rear end edge 121 is the same type as the rear end edge 111 of the cowling 110.
The corrugated corrugations provided on the rear end edges 111 and 121 of the cowling 110 and the ring member 120 are formed by folding the convex portions 112 and 122 and the concave portions 113 and 123 into a rectangular shape. The circumferential lengths of the recesses 113 and 123 are formed to be the same.
The ring member 120 is rotationally driven by an electric or hydraulic actuator (not shown) so that the rotation angle can be adjusted.

Although the ring member 120 structurally receives a load in the axial direction, the ring member 120 does not receive a large force in the rotational direction, the bearing 114 has a small rotational resistance, and the amount of rotation is the width of the convex portions 112 and 122 and the concave portions 113 and 123. Since only a minute amount is required, the driving force and stroke required for the actuator are small, and it may be small and light.
The core engine 130 has a plurality of bumps 133 projecting toward the exhaust passage side of the bypass jet on the outer peripheral surface.
The plurality of bumps 133 are arranged at positions facing the corrugated recesses 113 on the rear end edge 111 of the cowling 110.
Further, the plurality of bumps 133 are gently formed with curved surfaces continuous in the front-rear direction and the circumferential direction so as not to generate a shock wave in the flow of the bypass jet, and have an appropriate volume.

The operation of the turbofan engine 100 having the silencing mechanism according to the embodiment of the present invention configured as described above, that is, the silencing method according to the embodiment of the present invention will be described with reference to FIGS. To do.
First, at the time of takeoff, as shown in FIGS. 5 and 6, by the actuator, the convex portions 112 and 122 and the concave portions 113 and 123 provided on the rear end edges 111 and 121 of the cowling 110 and the ring member 120 overlap each other. The rotation angle of the ring member 120 is adjusted.
As shown in FIG. 5, the bypass jet 101 flows smoothly along the outer periphery of the core engine 130 at the convex portions 112 and 122 provided at the rear end edges 111 and 121 of the cowling 110 and the ring member 120.

As shown in FIG. 6, the bypass jet 101 has bumps 133 on the inside and recesses 113, 123 on the outside in the recesses 113, 123 provided on the rear edges 111, 121 of the cowling 110 and the ring member 120. For this reason, the vortex forming flow 103 is included and exhausted with a velocity component outside in the radial direction.
Then, by providing a radial speed difference between the exhaust from the convex portions 112 and 122 of the bypass jet 101 and the exhaust from the concave portions 113 and 123, the vertical vortex is excited to promote mixing with the outside air. By doing so, the noise of the turbofan engine can be reduced.

At the time of cruising, as shown in FIG. 7, the actuator has a circumferential shape in which a convex portion 112 provided on the rear end edge 111 of the cowling 110 and a concave portion 123 provided on the rear end edge 121 of the ring member 120 are overlapped and continuous by an actuator. The rotation angle of the ring member 120 is adjusted to a position where
As a result, even if the bumps 133 are present on the inner side, the longitudinal vortex forming flow 103 is not formed because there is no recessed portion 113 opened to the outer side, and thrust loss is reduced.
Further, since the recess 113 opened to the outside does not exist and the flow path is narrowed by the bump 133, the exhaust area of the bypass jet 101 is reduced, and the exhaust area is smaller than that at the time of take-off required during cruising.
Preferably, the volume of the bump is determined so that the reduction amount is 10%.

As described above, according to the variable nozzle mechanism and the nozzle area changing method of the present invention, the exhaust area can be changed using a light and simple mechanism without complicating and increasing the size of the structure. This makes it possible to reduce the noise and reduce the thrust loss during cruising.
In the above-described embodiment, in the drawing, the bumps 133 provided on the outer peripheral surfaces of the convex portions 112 and 122, the concave portions 113 and 123 provided on the rear end edges 111 and 121 of the cowling 110 and the ring member 120, and the core engine 130 are illustrated. However, although 20 are provided in each circumference, it is not limited to this.
Further, the length and shape of the convex portions 112 and 122 and the concave portions 113 and 123 in the front-rear direction and the length and shape of the bump 133 in the front-rear direction are not limited to those of the above-described embodiment, and may be optimally designed.

100, 500 ... Turbofan engine 101, 501 ... Bypass jet 102, 502 ... Main jet 103 ... Longitudinal vortex forming flow 110, 510 ... Cowling 111 ... Rear edge 112 ... Convex part 113 ... Concave part 114 ... Bearing 120 ... Ring member 121 ... Rear end edge 122 ... Convex part 123 ... Concave part 130, 530 ... Core engine 131, 531 ... Core engine nozzles 132, 532 ... Front fan 133 ... Bump

Also, the exhaust area of the bypass jet required at takeoff is different from the exhaust area required at cruising, and the latter is preferably about 90% of the former, so the engine cowling is controlled by the thrust reverser used at the time of landing. It is known that a bypass jet which is swung backward and deflected by a louver from an annular gap formed at this time is ejected obliquely forward.
The exhaust area of the bypass jet can be increased or decreased by utilizing a mechanism that swings the engine cowling that is a part of the thrust reverser backward.
Patent Document 3 proposes a technique in which a large number of vanes are movable and the exhaust area is variable while suppressing engine noise on the same principle as the above-mentioned chevron.

B. Herkes, 'The Quiet Technology Demonstrator 2 Flight Test', Aviation Noise & Air Quality Symposium, March 7, 2006. F. Calkins, J.M. Mabe, ‘Variable Geometry Jet Nozzle Using Shape Memory Alloy Actuators’, Boeing, 2007.

In the known thrust reverser, since the engine cowling receives a large axial force, the variable exhaust area mechanism according to this method requires an actuator that generates a large force, which increases the weight.
In addition, since the use of thrust reversers is also limited, the regulation of the aircraft may be changed so that the aircraft engine is not required to have a thrust reverser.
In a mechanism such as Patent Document 3, a large number of vanes are driven by a large number of actuators, so that the mechanism is complicated, and the direction in which the vanes are moved is a radial direction. To increase.

Claims (6)

A variable nozzle mechanism provided in an exhaust flow path of a bypass jet constituted by an inner periphery of a cowling of a turbofan engine and an outer periphery of a core engine,
The rear end edge of the cowling is formed into a corrugated shape having a plurality of front and rear unevenness,
On the outer periphery of the rear part including the rear end edge of the cowling has a rotatable ring member,
The ring member is formed in a corrugated shape having a plurality of undulations in the front-rear direction whose rear end edge is the same type as the rear end edge of the cowling.   2. The variable nozzle mechanism according to claim 1, wherein the corrugation of the rear end edge of the cowling and the rear end edge of the ring member has a rectangular convex portion on the rear end edge side. The ring member is rotatably supported by a bearing provided on the outer periphery of the rear portion of the cowling,
The variable nozzle mechanism according to claim 1 or 2, wherein an outer periphery of the ring member and an outer periphery other than a rear portion of the cowling form a continuous surface. The core engine has a plurality of bumps projecting to the bypass jet exhaust passage side on the outer peripheral surface,
The variable nozzle mechanism according to any one of claims 1 to 3, wherein the plurality of bumps are disposed at positions facing a corrugated concave portion of a rear end edge of the cowling.   The variable nozzle mechanism according to claim 4, wherein the plurality of bumps are gently formed with curved surfaces that are continuous in the front-rear direction and the circumferential direction. A method for changing the nozzle area of a turbofan engine,
The rear end edge of the cowling of the turbofan engine is formed into a corrugated shape having a plurality of unevenness in the front-rear direction,
On the outer periphery of the rear part including the rear end edge of the cowling has a rotatable ring member,
The ring member is formed in a corrugated shape having a plurality of front and rear projections and recesses of the same type as the rear end edge of the cowling,
The rotation angle of the ring member is an angle at which the corrugated concave portion at the rear end edge of the ring member coincides with the corrugated concave portion at the rear end edge of the cowling at takeoff,
A nozzle area changing method characterized in that at the time of cruising, the corrugated convex portion at the rear end edge of the ring member and the corrugated concave portion at the rear end edge of the cowling are set at an angle.

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