Open rotor and blade noise reduction structure

Abstract

The noise reduction structure is arranged on an open type rotor blade noise reduction structure on a front-row blade and a rear-row blade which are axially adjacent, the noise reduction structure comprises an arc-shaped fluid director and a noise reduction appearance, and the arc-shaped fluid director is arranged in the area, close to a blade tip, of a pressure surface and / or a suction surface of the front-row blade and used for preventing airflow on the surface of the blade from flowing from bottom to top; the noise reduction appearance is arranged on the front edge of the rear-row blade and the rear edge of the front-row blade. According to the noise reduction structure, through sequential matching of the arc-shaped fluid director and the noise reduction appearance, the airflow direction can be changed, rolling and forming of vortexes are restrained, blade tip vortexes and hub vortexes are broken into smaller vortexes, and therefore the good noise reduction effect is achieved. An open rotor is also provided.

Description

Technical Field

[0001] The invention relates to the field of open rotor blades, and in particular to the field of blade noise reduction. Background Art

[0002] An open rotor engine is a gas turbine engine that generates thrust by driving a propeller fan through the output shaft power of a power turbine. It is a new type of engine between a turboprop and a turbofan, also known as a propeller fan engine or an unducted fan engine. It mainly includes a gas generator, a power turbine, a transmission device and a propeller fan. According to the different positions of the propeller fan in the engine, it can be divided into traction type and propulsion type; according to the drive mode, it can be divided into two types: gear drive and direct drive. The open rotor engine has high propulsion efficiency and its fuel consumption rate can be reduced by 25% to 30% compared with the current engines. It is an ideal power solution for the next generation of narrow-body passenger aircraft. For example, as a new type of propeller for an open rotor engine, the rotary-static open fan has the advantages of high subsonic cruising speed, simple and compact structure, and can be installed without changing the wing hanger. It is an ideal propulsion solution for commercial engines with both performance and cost advantages.

[0003] In recent years, with the continuous improvement of environmental protection requirements, the International Civil Aviation Organization has gradually increased the civil aviation airworthiness noise requirements, and has made regulations on the takeoff, sideline and approach noise levels of civil aircraft during the takeoff and landing phases, requiring that they must not exceed the noise limits of the Airworthiness Regulations CCAR36 / FAR36. This makes the aircraft airworthiness noise level a necessary condition for the successful commercial operation of the aircraft.

[0004] Since there is no nacelle shielding and containment on the outside of the open rotor engine propeller, the noise problem of the blades is particularly prominent. The fan noise of the open rotor engine mainly includes single-tone noise and broadband noise. Among them, single-tone noise is caused by the periodic interaction between the blades and the incoming flow, and is usually related to the blade passing frequency and its harmonics. The sources of single-tone noise include the interference single tone of the tip vortex, the interference single tone of the viscous wake, the interference single tone of the front and rear potential fields, the single tone of the single rotor, the single tone of the airflow incident angle, and the steady-state distortion single tone. Broadband noise is mainly caused by the blade pulsation force of random characteristics such as the turbulent boundary layer developed along the blade surface, the vortex shedding on the surface of the object, and the interference between the blade and the incoming flow turbulence. Among them, the single-tone noise of the open rotor is the type of noise component with a larger proportion.

[0005] At present, there are some measures to reduce noise, starting from reducing rotor self-noise and interference noise. For example, appropriately reducing the tip speed, optimizing the design of wide chord swept thin blade profile to reduce rotor self-noise, appropriately increasing the number of blades, and reasonably selecting parameters such as the ratio of the number of front and rear blades or the ratio of the diameter or the axial distance to reduce interference noise. In addition, there are noise reduction measures such as blowing off the wake of the pylon, installing sound-absorbing lining on the sound-reflecting surface of the fuselage, and using the sound shielding of the fuselage and tail. However, the above solutions still have the problems of strong wingtip vortex and hub vortex sound sources and large interference noise of the front and rear rows of blades. Summary of the invention

[0006] An object of the present invention is to provide an open rotor blade noise reduction structure having a better noise attenuation effect.

[0007] To achieve the above-mentioned purpose, an open rotor blade noise reduction structure is arranged on the axially adjacent front row blades and rear row blades, including an arc-shaped deflector and a noise reduction shape. The arc-shaped deflector is arranged in the area near the tip of the pressure surface and / or suction surface of the front row blades to block the airflow from bottom to top; the noise reduction shape is arranged on the leading edge of the rear row blades and the trailing edge of the front row blades.

[0008] In one or more embodiments, the noise reduction shape includes one or more of a sawtooth structure, a wavy structure, an arc structure, and a W-shaped structure.

[0009] In one or more embodiments, the arc-shaped guide device includes arc-shaped surfaces located at upper and lower sides and perpendicular to the pressure surface and / or the suction surface.

[0010] In one or more embodiments, the length of the arcuate surface in the axial direction ranges from 10 to 15 mm.

[0011] In one or more embodiments, the cross section of the arc-shaped guide vane along the blade height direction is configured to gradually increase along the axial direction.

[0012] In one or more embodiments, the cross-section of the arc-shaped guide vane in the blade height direction is a triangular cross-section on the side close to the trailing edge of the blade.

[0013] In one or more embodiments, the front row of blades are stationary blades or moving blades, and the rear row of blades are stationary blades or moving blades.

[0014] In one or more embodiments, the height of the arc-shaped deflector in a direction perpendicular to the pressure surface or the suction surface ranges from 5 to 10 mm.

[0015] In one or more embodiments, a plurality of continuously distributed arc-shaped flow guides are disposed on the pressure surface and / or the suction surface.

[0016] Another object of the present invention is to provide an open rotor, including a gas generator, a turbine, a propeller fan and a transmission member, wherein the propeller fan includes a plurality of rows of blades, and the blades adopt the above-mentioned open rotor blade noise reduction structure.

[0017] The above-mentioned open rotor blade noise reduction structure plays a role in regulating the airflow field and promoting airflow exchange on both sides by arranging arc-shaped deflectors on the pressure side and suction side of the blade to block the airflow from flowing further upward. It can significantly inhibit the rolling up and formation of tip vortex, and cooperate with the noise reduction structure arranged on the leading edge of the rear row of blades and the trailing edge of the front row of blades to break the tip vortex and the hub vortex into smaller vortices, thereby effectively reducing the interference noise of the front and rear rows of blades. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other features, properties and advantages of the present invention will become more apparent through the following description in conjunction with the accompanying drawings and embodiments, in which:

[0019] Figure 1 is a schematic diagram of an open rotor;

[0020] Figure 2 It is a schematic diagram of the noise reduction structure of the open rotor blade;

[0021] Figure 3 It is a schematic diagram of the structure of an open rotor blade without the tip;

[0022] Figure 4 It is a structural schematic diagram of an embodiment of an arc-shaped deflector.

[0023] Symbols and Markings

[0024] 11 Gas generator

[0025] 12 Power Turbine

[0026] 13 Transmission

[0027] 14 Propeller Fan

[0028] 21 Arc deflector

[0029] 22 Noise Reduction Shape

[0030] 24 Leaf tip

[0031] 210 Triangular cross section

[0032] 211 curved surface

[0033] 212 Triangle Tip

[0034] 223 No.1 noise reduction shape

[0035] 224 Second noise reduction shape

[0036] 225 Third noise reduction shape DETAILED DESCRIPTION

[0037] The present invention is further described below in conjunction with specific embodiments and drawings. More details are elaborated in the following description to facilitate a full understanding of the present invention. However, the present invention can obviously be implemented in a variety of other ways different from the description herein. Those skilled in the art can make similar generalizations and deductions based on actual application situations without violating the connotation of the present invention. Therefore, the protection scope of the present invention should not be limited by the content of this specific embodiment.

[0038] It should be noted that these and other subsequent drawings are only examples and are not drawn to scale, and should not be used to limit the actual scope of protection required by the present invention.

[0039] Open rotor Figure 1 As shown, it includes a gas generator 11, a power turbine 12, a transmission device 13 and a propeller 14. The propeller 14 includes multiple rows of blades, which can be a multiple-row rotor blade structure or a rotor blade-stator blade configuration. Because the open rotor engine propeller has no nacelle shielding and containment outside, it is necessary to limit the blade noise of the open rotor.

[0040] The open rotor blade noise reduction structure disclosed in the present invention is applied to the open rotor and can effectively reduce the noise. Figure 2 and Figure 3 As shown, the noise reduction structure is arranged on the front row blades F and the rear row blades B which are adjacent in the axial direction. The front row blades F can be stationary blades or moving blades, and the rear row blades B can also be stationary blades or moving blades. Figure 2 The X direction shown represents the axial S direction of the open rotor, and the Y direction represents the blade height direction, which is also the radial direction.

[0041] The noise reduction structure comprises two parts, namely, an arc-shaped flow guide 21 and a noise reduction profile 22. Preferably, a plurality of continuously distributed arc-shaped flow guides 21 are arranged on the pressure surface and / or the suction surface.

[0042] The arc deflector 21 is arranged on the pressure surface and / or suction surface of the front row of blades near the blade tip 24 to block the airflow from bottom to top. That is, the arc deflector 12 forms a "barrier" to block the airflow on the blade surface from flowing from bottom to top, thereby inhibiting the formation of the blade tip vortex at the blade tip.

[0043] Preferably, the blade provided with the arc-shaped deflector 21 is a moving blade.

[0044] The noise reduction shape 22 is arranged in conjunction with the arc deflector 12 to secondary attenuate the airflow. The noise reduction shape 22 can be one or more of a sawtooth structure, a wavy structure, an arc structure, and a W-shaped structure. The noise reduction shape 22 is arranged at the leading edge of the rear row of blades and the trailing edge of the front row of blades, and is mainly arranged at the blade portion where the airflow mainly flows after being blocked by the arc deflector 12.

[0045] Specifically, refer to Figure 3 and Figure 4 As shown, the arc deflector 21 includes arc surfaces 211 perpendicular to the pressure surface or the suction surface and located at the upper and lower sides. The curvature of the arc surface 211 is adapted to the streamline of the airflow at this location, with the purpose of promoting the separation of the airflow.

[0046] The length range of the arc surface 211 along the axial direction is preferably 10 to 15 mm. In some embodiments, the height range of the arc deflector 21 perpendicular to the pressure surface or the suction surface, that is, the height of the protrusion perpendicular to the XY plane, is 5 to 10 mm, making the arc deflector 21 a micro arc deflector.

[0047] Those skilled in the art will appreciate that the size of the arc-shaped flow guide 21 includes but is not limited to the above-mentioned embodiments, and the size of the arc-shaped flow guide 21 is related to the overall size of the blade. Generally speaking, the larger the overall size of the blade, the larger the size of the arc-shaped flow guide 21 should be.

[0048] The arc-shaped guide vane 21 is arranged near the blade tip 24, and the upper surface of the arc-shaped guide vane 21 is lower than the blade tip 24, so that the rising airflow is blocked, and the airflow on the blade surface is blocked from flowing from the blade root to the blade top, and this part of the airflow is forced to flow axially backward along both sides of the arc-shaped guide vane 21, thereby playing a role in regulating the flow field.

[0049] The cross section C of the arc-shaped flow guide 21 along the blade height direction is set to gradually increase along the axial direction to achieve a local deceleration effect on the trailing edge. For example, the cross section of the arc-shaped flow guide 21 along the blade height direction is a triangular cross section 210 on the side close to the blade trailing edge, and the side close to the blade leading edge is the starting point of the two arc-shaped surfaces 211, which is a triangular tip 212.

[0050] Since the airflow is easy to separate and produce vortex shedding when the incoming flow angle is large, the design of the arc deflector can suppress the separation of the flow field. The flow field is attached to the rear half of the blade, promoting the exchange of airflow on both sides, thereby reducing the formation of separated flow, breaking the aeroacoustic feedback loop that controls the formation of unstable waves inside the boundary layer, and avoiding the airflow rolling up at the blade tip, the formation of blade tip vortex, and the rolling up and shedding of blade tip vortex. Therefore, by suppressing the rolling up and formation of blade tip vortex, the problem of strong sound source of wing tip vortex and hub vortex in the existing solution is solved.

[0051] Compared with the traditional blade tip deformation design, the arc deflector 21 can fundamentally suppress the formation of the wing tip vortex, while the traditional blade deformation design either uses the peak and trough phase control to reduce noise or reduce the vortex shedding intensity, but the process of blade tip vortex formation, blade tip vortex rolling up and shedding still exists, but the process is weakened. Therefore, the arc deflector 21 described in the present disclosure has a more significant noise reduction effect.

[0052] After the arc-shaped deflector 21 changes the direction of the airflow, the noise reduction shape 22 behind the arc-shaped deflector 21 plays a role in further attenuating the airflow. The two cooperate with each other to have a continuous impact on the airflow.

[0053] like Figure 3 In one embodiment of the noise reduction profile 22 shown, a wavy first noise reduction profile 223 designed at the trailing edge of the blade tip of the front row of blades F can promote fluid mixing at the trailing edge of the blade tip and break the tip vortex into smaller vortices; a wavy second noise reduction profile 224 designed at the trailing edge of the blade root of the front row of blades F can promote fluid mixing at the trailing edge of the blade root and break the root vortex, or hub vortex, into smaller vortices; a wavy third noise reduction profile 225 designed at the leading edge tip of the rear row of blades B can break the front row wake vortex into smaller vortices, reduce the strength of the front row wake, and thus reduce interference noise. The wavy profile can reduce the probability of the front row rotor wake hitting the rear row blades. Through the design of the above-mentioned matching structure, the formation of the tip vortex is suppressed, the interference effect of the front and rear row blades is weakened, and the problem of large interference noise of the front and rear row blades in the existing solution is solved.

[0054] In particular, the second noise reduction shape 224 designed at the trailing edge of the blade root of the front row of blades F can accelerate the mixing of the airflow at the trailing edge of the blade root, eliminate the hub vortex which is one of the important noise sources, and further improve the noise reduction effect.

[0055] The above-mentioned open rotor blade noise reduction structure redesigns the front and rear rows of blades, and uses a combination of an arc-shaped deflector and multiple noise reduction shapes on the front and rear edges of the front and rear rows of blades. The airflow is first made to flow backward along the airflow on both sides of the micro-arc deflector through the arc-shaped deflector. When the airflow passes through the root of the trailing edge of the front row of blades and the top of the trailing edge of the front row of blades, it hits the leading edge of the blade top of the rear row of blades. The wavy shape structure at the leading edge of the blade top of the rear row of blades performs a secondary attenuation effect on the airflow, reducing the effect of hitting the surface of the rear row of blades. The wavy shape structure can accelerate the mixing of the airflow on the pressure surface and the suction surface at the trailing edge, inhibit the formation of blade tip vortex and hub vortex, and accelerate the mixing effect of the trailing edge, thereby performing noise control in the sound source design, reducing the intensity of the blade pulsation force, and weakening its acoustic influence, so as to achieve a better noise reduction effect.

[0056] Combined with the introduction of the above-mentioned open rotor blade noise reduction structure, we can also understand an open rotor. Figure 1As shown, it includes a gas generator, a turbine, a propeller fan and a transmission part. The propeller fan includes multiple rows of blades. The noise reduction structure of the two adjacent front and rear open rotor blades changes the direction of airflow through the combined action of a micro-arc deflector and a local trailing edge of the blade top, thereby fundamentally suppressing the formation of vortices and having a better noise reduction effect.

[0057] The present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or multiple times in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0058] Although the present invention is disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope defined by the claims of the present invention.

Claims

1. An open rotor blade noise reduction structure is provided on the front row blades and the rear row blades adjacent to each other in the axial direction, characterized in that: include: An arc-shaped deflector is arranged on the pressure surface and / or the suction surface of the front row of blades in the area close to the blade tip, and is used to block the airflow on the blade surface from flowing from bottom to top; as well as A noise reduction shape is arranged on the leading edge of the rear row of blades and the trailing edge of the front row of blades.

2. The open rotor blade noise reduction structure according to claim 1, characterized in that: The noise reduction shape includes one or more of a sawtooth structure, a wave structure, an arc structure, and a W-shaped structure.

3. The open rotor blade noise reduction structure according to claim 1, characterized in that: The arc-shaped flow guide comprises arc-shaped surfaces perpendicular to the pressure surface or the suction surface and located at upper and lower sides.

4. The open rotor blade noise reduction structure according to claim 3, characterized in that: The length of the arc surface along the axial direction ranges from 10 to 15 mm.

5. The open rotor blade noise reduction structure according to claim 3, characterized in that: The cross section of the arc-shaped flow guide along the blade height direction is arranged to gradually increase along the axial direction.

6. The open rotor blade noise reduction structure according to claim 5, characterized in that: The cross section of the arc-shaped deflector in the blade height direction is a triangular cross section on the side close to the trailing edge of the blade.

7. The open rotor blade noise reduction structure according to claim 1, characterized in that: The front row of blades are stationary blades or moving blades, and the rear row of blades are stationary blades or moving blades.

8. The open rotor blade noise reduction structure according to claim 1, characterized in that: The height of the arc-shaped deflector in a direction perpendicular to the pressure surface or the suction surface ranges from 5 to 10 mm.

9. The open rotor blade noise reduction structure according to claim 1, characterized in that: The noise reduction structure comprises a plurality of continuously distributed arc-shaped flow guides arranged on the pressure surface and / or the suction surface.

10. An open rotor, comprising a gas generator, a turbine, a propeller fan and a transmission member, wherein the propeller fan comprises a plurality of rows of blades, characterized in that: The blade adopts the open rotor blade noise reduction structure as described in any one of claims 1-9.

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