Noise reduction liner and low-noise stator blade

Abstract

A noise reduction liner and a low-noise stator blade, the noise reduction liner (10) including a plurality of acoustic liner units (11) formed in a hollow cylindrical shape, each of the plurality of acoustic liner units (11) forming a separate resonant cavity (11a), the heights of the resonant cavities (11a) being different from each other, and the acoustic liner units (11) being formed in a hollow cylindrical shape. The resonant cavity is filled with acoustic soft materials, the low-noise stator blade (1) comprises the noise reduction lining (10), and a plurality of open holes (H) are formed in the low-noise stator blade (1). According to the low-noise stator blade, the multiple open holes are formed, the stator blade can be softened, the interference intensity of wakes of the front row and the rear row is reduced, noise entering the noise reduction lining is dissipated under the combined action of the resonant cavity, the acoustic soft material and the open holes in the low-noise stator blade, and the noise can be reduced more ideally.

Description

Technical Field

[0001] The present invention relates to a noise-reducing lining and a low-noise stator vane, and more particularly, to a noise-reducing lining capable of reducing the noise of a stator vane and a low-noise stator vane including the noise-reducing lining. Background Art

[0003] An open rotor engine is a gas turbine engine that drives a propfan to generate thrust by the power output from a power turbine output shaft, and is a new type of engine between a turboprop and a turbofan, also known as a propfan engine or a ducted fanless engine, mainly composed of four components: a gas generator, a power turbine, a transmission device, and a propfan. According to the different positions of the propfan in the engine, it can be divided into two categories: tractor type and pusher type; according to the drive mode, it can be divided into two categories: gear drive type and direct drive type. The open rotor engine has a high propulsion efficiency under high subsonic cruise conditions, and therefore, is an important technical development direction for commercial aircraft engines.

[0004] In recent years, the open rotor engine, as a propeller between a propeller and a fan, has experienced significant development in the aviation field. Due to the characteristics of low fuel consumption rate of a turboprop engine and suitability for high-speed flight of a turbofan engine, compared with a conventional turbofan engine of the same thrust level, the fuel consumption rate and CO 2 emissions of the open rotor engine can be reduced by 20% - 30%, and it can be used as the power for civil airliners and military transport aircraft. Therefore, with the advantages of high propulsion efficiency and low fuel consumption rate, the open rotor engine has become one of the potential power alternatives for the next generation of civil aircraft.

[0005] However, with the continuous improvement of the performance requirements of the propfan and the requirements for energy conservation and environmental protection, in addition to focusing on high aerodynamic performance, the research on its noise level has also become very popular. The noise control of large airliners involves many aspects such as the airworthiness, comfort, and safety of the aircraft. Ensuring that the external noise generated by the takeoff, sideline, and approach noise levels of a civil aircraft during the takeoff and landing phases does not exceed the noise limit specified by the airworthiness regulations CCAR36 / FAR36 is a necessary condition for the aircraft to obtain an international airworthiness certificate.

[0006] Although the open rotor engine has very great fuel-saving potential, due to the lack of nacelle shielding and containment components outside the propfan, its noise problem is quite prominent. The open rotor engine has a relatively large bypass ratio and a low jet velocity, and its maximum noise mainly comes from the open fan blades.

[0007] The noise sources of an open rotor mainly include: tip vortex interference tones, viscous wake interference tones, interference tones of the front and rear potential fields, and the tonal noise of an individual rotor, etc. In addition, for the fan noise of an open rotor engine, the main noise components include fan rotor-stator interference noise, blade self-noise, and broadband noise.

[0008] As one of the main components of open fan noise, the above-mentioned fan rotor-stator interference noise is discrete noise generated by the interference between the front row of fan rotors and the rear row of stators. The above-mentioned blade self-noise is the noise generated by the rotor blades themselves, including blade thickness noise and blade loading noise. The above-mentioned blade self-noise is the noise generated by the rotor blades themselves, including blade thickness noise and blade loading noise.

[0009] Among them, the above-mentioned open fan is a fan that inherits the design characteristics of the front row of blades of an open rotor and the principle of recovering energy and increasing efficiency of the rear row of blades. The difference is that the rear row of blades is no longer designed as a rotor, but as a stator blade, also known as a swirl recovery stator blade. This fan with a rotor-stator configuration is also called an open fan. Specifically, the open fan with a rotor-stator configuration consists of a row of rotating blades plus a row of swirl recovery stators. The two rows of blades jointly generate forward thrust, and the open fan has a relatively high efficiency under high-subsonic cruise conditions; moreover, the single-row rotor configuration has a more concise and compact structure, and the rear stator has the potential to reduce interference noise and eliminate stator loading noise.

[0010] Regarding the noise reduction of open rotors, a large amount of research work has been carried out at home and abroad, and a series of noise reduction measures have been developed.

[0011] For example, increasing the number of rotor blades to reduce blade loading noise; using thin airfoil blades and increasing the maximum thickness reduction of the airfoil to reduce blade thickness noise; reducing the tip speed of rotor blades to reduce rotor loading noise; by increasing the top cutting of the rear stator, increasing the distance between the front and rear rotors, and reducing the strength of the tip vortex of the front row of rotors, to weaken the interference effect of the wake and tip vortex of the front row of blades on the rear stator, thereby reducing rotor-stator interference noise; reducing fan noise through blade sweep design; and also being able to reduce the noise transmitted from the open fan through different installation methods, such as rear fuselage installation; in addition, by blowing the pylon wake, acoustically softening the rear stator, installing acoustic liners on the acoustic reflection surface of the airframe, and using the acoustic shielding of the airframe and tail wing, etc., can effectively reduce the noise of the open rotor.

[0012] However, it should be noted that when attempting to apply noise reduction measures to an open fan, it must be on the premise of not significantly affecting the aerodynamic performance of the open fan. The above-mentioned noise reduction measures will all more or less affect the aerodynamic characteristics of the open fan, thus affecting the overall efficiency of the engine.

[0013] Therefore, how to design a stator blade that can effectively reduce the fan noise of an open rotor while weakening its impact on aerodynamic performance has become a technical problem to be solved urgently. Summary of the Invention

[0014] The present disclosure is made to solve the above technical problems, and its purpose is to provide a noise reduction liner and a low-noise stator blade including the noise reduction liner. Through the above noise reduction liner and the above low-noise stator blade, it is possible to effectively reduce the fan noise of the open rotor without affecting the aerodynamic performance of the open rotor.

[0015] To achieve the purpose of the present disclosure, a noise reduction liner is provided. The noise reduction liner is disposed on the surface of the stator blade. Among them, the noise reduction liner includes: a plurality of acoustic liner units. The plurality of acoustic liner units are formed into a hollow cylindrical shape, and each of the plurality of acoustic liner units is formed with a separate resonance cavity, and the heights of the resonance cavities are different from each other.

[0016] According to the above configuration, since the heights of the resonance cavities in the plurality of acoustic liner units are different from each other, it is possible to expand the range of noise frequencies that can be absorbed, thereby being able to better reduce the blade noise.

[0017] Preferably, an acoustic soft material is filled in the resonance cavities of the plurality of acoustic liner units.

[0018] According to the above configuration, by filling the resonance cavities with an acoustic soft material, it is possible to absorb noise through the acoustic soft material. Through these two noise reduction measures of the resonance cavity and the acoustic soft material, it is possible to more ideally reduce the stator blade noise.

[0019] Preferably, the noise reduction liner further includes a back plate and a perforated plate. A plurality of through holes are provided on the back plate and the perforated plate, and the back plate and the perforated plate are fixed relative to each other in a manner that sandwiches the plurality of acoustic liner units in the middle.

[0020] According to the above configuration, by providing the back plate and the perforated plate, it is possible to conveniently assemble the plurality of acoustic liner units, with simple manufacturing, convenient operation, and strong practicability.

[0021] Preferably, one surface of the back plate is provided with the plurality of acoustic liner units, the other surface of the back plate is attached to the surface of the stator blade, and a plurality of openings are provided on the surface of the stator blade.

[0022] According to the above configuration, it is possible to install the noise reduction liner on the surface of the stator blade through a simple operation, with simple operation.

[0023] Preferably, the diameters of the plurality of through holes in the back plate and the perforated plate are smaller than the diameters of the resonance cavities in the plurality of acoustic liner units.

[0024] Constructed as described above, it can make the sound energy generated by noise enter the resonance cavity through the through holes on the perforated plate as much as possible, so as to better attenuate the noise. And the noise after passing through the resonance cavity can also enter the openings of the low-noise stator blades through the back plate for attenuation, thereby being able to better improve the noise reduction effect.

[0025] The present disclosure also provides a low-noise stator blade. The above low-noise stator blade includes the noise-reducing lining as described above, and a plurality of openings are provided on the above low-noise stator blade.

[0026] Constructed as described above, by providing a plurality of openings on the low-noise stator blade, the stator blade can be softened, and the interference intensity of the wakes of the front and rear rows can be reduced, and the unsteady effect of the wake of the front-row blade can be weakened, thereby reducing the interference noise between the front and rear rows. In addition, through the synergistic effect of the above noise-reducing lining and the above plurality of openings, the noise can be further reduced.

[0027] Preferably, the above plurality of openings are only provided on the suction surface of the above low-noise stator blade.

[0028] Constructed as described above, by providing the plurality of openings only on the suction surface that has a greater aerodynamic impact on the low-noise stator blade, the noise can be reduced without significantly affecting the aerodynamic performance of the blade as much as possible.

[0029] Preferably, the above plurality of openings are evenly arranged at equal intervals on the above suction surface of the above low-noise stator blade.

[0030] Constructed as described above, by evenly arranging the plurality of openings at equal intervals on the suction surface, the influence on the aerodynamic performance can be further reduced, and the noise reduction effect can be more ideally achieved.

[0031] Preferably, the opening depths of the above plurality of openings are different from each other.

[0032] Constructed as described above, the frequency range of the noise that can be reduced can be further expanded.

[0033] Preferably, the above noise-reducing lining is arranged such that the through holes in the above resonance cavity partially overlap with the above plurality of openings.

[0034] Constructed as described above, the noise after passing through the resonance cavity of the noise-reducing lining can also enter the openings that partially overlap with the through holes of the resonance cavity for further attenuation, thereby being able to further improve the noise attenuation effect. Description of the Drawings

[0035] For the above purposes, the technical features of the present invention are clearly described in the following technical solutions, and its advantages are obvious from the following detailed description with reference to the accompanying drawings, which illustrate the preferred embodiments of the present invention by way of example and do not limit the scope of the inventive concept.

[0036] Figure 1 shows a schematic diagram of the overall arrangement of the low-noise stator blades of the present invention.

[0037] Figure 2 is a schematic diagram showing the overall structure of the low-noise stator blades of the present invention as viewed from the suction surface.

[0038] Figure 3 is a schematic diagram showing the overall structure of the noise-reducing lining of the present invention. Symbol Explanation

[0039] 1 Low-noise stator blade; 1a Suction surface; 1b Pressure surface; 10 Noise-reducing lining; 11 Acoustic lining unit; 11a Resonant cavity; 12 Back plate; 13 Perforated plate; 2 Stator main body; H Opening; M Porous medium material. Detailed Embodiments

[0040] Hereinafter, the present invention will be further described in conjunction with the specific embodiments and the accompanying drawings. More details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention is clearly capable of being practiced in many other ways different from this description. Those skilled in the art can make similar generalizations and deductions according to the actual application situation without departing from the connotation of the present invention. Therefore, the scope of protection of the present invention should not be limited by the content of this specific embodiment.

[0041] For example, when the first feature described subsequently in the specification is formed above or on the second feature, it may include embodiments in which the first feature and the second feature are formed by direct connection, and may also include embodiments in which additional features are formed between the first feature and the second feature, so that the first feature and the second feature may not be directly connected. Further, when the first element is described as being connected or combined with the second element, this description includes embodiments in which the first element and the second element are directly connected or combined with each other, and also includes embodiments in which one or more other intervening elements are added to indirectly connect or combine the first element and the second element.

[0042] Hereinafter, with reference to Figure 1, the overall arrangement of the low-noise stator blade 1 of the present invention will be described. Figure 1 It is a schematic diagram showing the overall arrangement of the low-noise stator blade 1 of the present invention.

[0043] As Figure 1 shown, a plurality of low-noise stator blades 1 of the present invention are provided and are erected on the stator main body 2 in a manner that the blade roots are connected to the stator main body 2.

[0044] In addition, the above-mentioned low-noise stator blade 1 includes a suction surface 1a and a pressure surface 1b. A plurality of openings H are only provided on the above-mentioned suction surface 1a, and a noise reduction lining 10 is arranged, while no openings H are provided on the above-mentioned pressure surface 1b, and no noise reduction lining 10 is arranged either.

[0045] Hereinafter, with reference to Figure 2 , the overall state of the suction surface 1a of the low-noise stator blade 1 of the present invention will be described. Figure 2 It is a schematic diagram showing the overall structure of the low-noise stator blade 1 of the present invention as observed from the suction surface 1a.

[0046] The inventor of the present invention obtained through computational simulation that the pressure pulsation and aerodynamic load on the suction surface of the open stator blade are much greater than the aerodynamic disturbance amount on the pressure surface. Therefore, the present invention mainly reduces noise by reducing the pulsating pressure disturbance amount on the suction surface of the stator blade.

[0047] As Figure 2 shown, a plurality of openings H are provided on the suction surface 1a of the low-noise stator blade 1 of the present invention. The diameters of the above-mentioned plurality of openings H are about 1-2 mm, and they are uniformly arranged at equal intervals on the above-mentioned suction surface 1a, and the depths of the above-mentioned plurality of openings H are substantially the same.

[0048] Noise is dissipated and absorbed when it enters the interior of the blade through the suction surface 1a of the low-noise stator blade 1. This noise reduction design does not make any modifications to the rotor blade, but only performs acoustic treatment on the stator blade. Therefore, it can reduce noise on the premise of minimizing the impact on aerodynamic performance.

[0049] Specifically, when the air flow passes through the above-mentioned suction surface 1a and through the above-mentioned plurality of openings H, the unsteady disturbing force on the suction surface 1a is dissipated through the viscous effect of the walls of the plurality of openings H, thereby dissipating the sound energy caused by the air flow.

[0050] In addition, by providing a plurality of openings H on the suction surface 1a of the above-mentioned low-noise stator blade 1, the stator blade can be softened, and the interference intensity between the front and rear row wakes can be reduced, and the unsteady effect of the wake of the front row blade can be weakened, thereby reducing the interference noise between the front and rear rows.

[0051] As is well known, the flow on the upper surface, i.e., the suction surface, of the guide vane of the open stator is the most intense and has the greatest impact on the flow field. The flow on the lower surface, i.e., the pressure surface, is relatively stable and has a smaller impact on the flow field.

[0052] Compared with the conventional designs that achieve noise reduction by influencing flow characteristics, the present invention only provides a plurality of openings H on the lower surface, i.e., the suction surface 1a, of the stator guide vane, and no openings are provided on the upper surface, i.e., the pressure surface 1b, of the stator guide vane. Noise enters the blade interior through the lower surface, i.e., the pressure surface 1b, of the stator guide vane and is dissipated and absorbed. This noise reduction design hardly makes any modification to the shape of the stator guide vane. Therefore, the effect of noise attenuation can be achieved without affecting the aerodynamic performance of the stator guide vane.

[0053] In addition, as Figure 2 shown, a noise reduction lining 10 is also arranged on the suction surface 1a of the above-mentioned low-noise stator blade 1, and the above-mentioned noise reduction lining 10 is arranged in a staggered manner with respect to the above-mentioned plurality of openings H.

[0054] Hereinafter, with reference to Figure 3 , the overall structure of the noise reduction lining 10 of the present invention will be described. Figure 3 is a schematic diagram showing the overall structure of the noise reduction lining 10 of the present invention.

[0055] As Figure 3 shown, the noise reduction lining 10 of the present invention mainly consists of a plurality of acoustic lining units 11, a back plate 12, and a perforated plate 13.

[0056] The above-mentioned plurality of acoustic lining units 11 are composed of hollow cylinders, and acoustic soft materials such as porous medium materials M are filled in the interior of the cylinders in the circumferential direction, so that individual resonance cavities 11a are formed in each acoustic lining unit 11. In addition, the heights of the cylinders of the above-mentioned plurality of acoustic lining units 11 are different from each other, so as to form a stepped structure as a whole. And the above-mentioned plurality of acoustic lining units 11 are laid on the above-mentioned back plate 12.

[0057] In addition, as Figure 3 shown, although the heights of the above-mentioned plurality of acoustic lining units 11 are made different from each other, when manufacturing the plurality of acoustic lining units 11 with different heights, it is not necessary to keep the cutting surfaces of the plurality of acoustic lining units 11 absolutely flat, and the manufacturing is simple and easy to operate.

[0058] The above-mentioned back plate 12 is formed as a thin plate provided with a plurality of through holes (not shown). One side of it is attached to the suction surface 1a of the above-mentioned low-noise stator blade 1, and the pores on the above-mentioned back plate 12 partially overlap the openings H on the above-mentioned low-noise stator blade 1, and the above-mentioned plurality of acoustic lining units 11 are arranged on the other side.

[0059] A perforated plate 13 is provided on one side of the above-mentioned back plate 12 of the above-mentioned multiple acoustic lining units 11. A plurality of through holes (not shown) are provided on the above-mentioned perforated plate 13. By fastening members such as bolts (not shown), the four corners of the above-mentioned perforated plate 13 are fixed to the above-mentioned back plate 12 in such a way that the above-mentioned multiple acoustic lining units 11 with different heights are sandwiched in the middle, thereby constituting the noise-reducing acoustic lining 10 of the present invention.

[0060] When the airflow collides with the low-noise stator vane 1 of the present invention, the sound energy generated by the collision enters the resonance cavity 11a of the above-mentioned noise-reducing acoustic lining 10 after passing through the multiple through holes on the above-mentioned perforated plate 13, and then vibrates and attenuates vertically in the up-and-down direction inside the resonance cavities 11a with different heights, and enters the inside of the porous medium material M through the micropores in the porous medium material M and is absorbed and attenuated.

[0061] In addition, since the heights of the resonance cavities 11a of the above-mentioned noise-reducing acoustic lining 10 are different from each other, and the noise frequencies that can be absorbed are related to the heights of the resonance cavities, therefore, by arranging the above-mentioned noise-reducing acoustic lining 10, multiple different-frequency noises can be absorbed, so that the noise-reducing acoustic lining 10 of the present invention has broadband sound absorption characteristics.

[0062] The above-mentioned noise-reducing acoustic lining 10 is arranged in such a way that the above-mentioned back plate 12 is along the surface of the suction surface 1a of the above-mentioned low-noise stator vane 1.

[0063] Preferably, the apertures of the through holes provided on the above-mentioned back plate 12 and the above-mentioned perforated plate 13 are smaller than the aperture of the above-mentioned resonance cavity 11a.

[0064] By setting such a structure, the sound energy generated by the noise can be made to enter the above-mentioned resonance cavity 11a through the through holes on the perforated plate 13 as much as possible, so that the noise can be better attenuated.

[0065] More preferably, the above-mentioned noise-reducing acoustic lining 10 is arranged such that the through holes in the above-mentioned resonance cavity 11a partially overlap the above-mentioned multiple openings H.

[0066] Part of the noise generated by the front row rotor wake enters the opening H around the noise-reducing acoustic lining 10 and then enters the stator interior for dissipation, and the other part enters the interior of the noise-reducing acoustic lining 1 for dissipation. The noise entering the interior of the noise-reducing acoustic lining 1 will be dissipated under the combined action of the resonance cavity 10a, the acoustic soft material M, and the opening H on the stator.

[0067] Specifically, in the conventional noise-reducing lining, the bottom layer is formed as a non-porous back plate, and noise cannot penetrate the back plate but can only continue to dissipate in the resonance cavity. The noise-reducing lining 10 of the present invention designs the bottom layer as a back plate 12 with small holes, and a part of the noise entering the resonance cavity 11a can enter the opening H of the stator blade through the small holes of the back plate 12 at the bottom layer for further attenuation.

[0068] That is to say, by setting such a structure, the noise after passing through the resonance cavity 11a of the above-mentioned noise-reducing lining 10 can also enter the opening H overlapping with the through-hole part of the resonance cavity 11a to continue attenuation, so that the noise attenuation effect can be further improved.

[0069] Therefore, compared with the conventional noise absorption measures, by opening a plurality of openings on the suction surface of the stator blade, arranging a noise-reducing lining staggered with respect to the above-mentioned plurality of openings, and using acoustic soft materials such as porous medium materials, a variety of different noise attenuation paths can be provided. A part of the noise enters the blade interior along the opening H on the suction surface 1a of the stator guide vane and is dissipated by the viscous effect of the opening wall surface, and a part of the noise enters the noise-reducing lining 10 and dissipates the sound energy, which can maximize the purpose of multi-stage noise attenuation, thereby further enhancing the effect of reducing blade noise.

[0070] Moreover, through a plurality of resonance cavities 11a with different heights and a plurality of openings H, noises of different frequencies can be absorbed, thereby further broadening the noise absorption frequency.

[0071] Although the structure and working principle of the present invention have been described above in combination with the preferred embodiments, those of ordinary skill in the art in this technical field should recognize that the above examples are only for illustration and do not constitute a limitation to the present invention. Modifications and variations can be made to the present invention within the scope of the spirit of the claims, and these modifications and variations will fall within the protection scope of the present invention.

[0072] For example, in the present invention, an example is shown in which the diameters of the above-mentioned plurality of openings H are about 1-2 mm and are evenly arranged at equal intervals on the above-mentioned suction surface 1a, but the present invention is not limited thereto. The diameters of the plurality of openings H can also be designed as other values and arranged at unequal intervals on the above-mentioned suction surface 1a, as long as the noise attenuation effect of the blade can be enhanced.

[0073] For example, in the present invention, an example is shown in which the depths of the above-mentioned plurality of openings H are substantially the same, but the present invention is not limited thereto. The depths of the above-mentioned plurality of openings H can also be set to different depths. The noise frequencies that can be absorbed are related to the height of the resonance cavity and are also related to the depth of the opening H to a certain extent. By setting the openings to different depths, the range of noise frequencies that can be absorbed can be broadened to a greater extent.

Claims

1. A noise-reducing lining (10), the noise-reducing lining (10) being disposed on the surface of a stator vane, characterized in that, the noise-reducing lining (10) comprises: a plurality of acoustic lining units (11), the plurality of acoustic lining units (11) being formed in a hollow cylindrical shape, and each of the plurality of acoustic lining units (11) being formed with a separate resonance cavity (11a), the heights of the resonance cavities (11a) being different from each other.

2. The noise-reducing lining (10) according to claim 1, characterized in that, an acoustic soft material (M) is filled in the resonance cavity (11a) of the plurality of acoustic lining units (11).

3. The noise-reducing lining (10) according to claim 2, characterized in that, the noise-reducing lining (10) further comprises a back plate (12) and a perforated plate (13), a plurality of through holes being provided in the back plate (12) and the perforated plate (13), and the back plate (12) and the perforated plate (13) being fixed relative to each other in such a manner that the plurality of acoustic lining units (11) are sandwiched therebetween.

4. The noise-reducing lining (10) according to claim 3, characterized in that, one surface of the back plate (12) is provided with the plurality of acoustic lining units (11), the other surface of the back plate (12) is attached to the surface of the stator vane, and a plurality of openings (H) are provided in the surface of the stator vane.

5. The noise-reducing lining (10) according to claim 3 or 4, characterized in that, the aperture diameters of the plurality of through holes in the back plate (12) and the perforated plate (13) are smaller than the aperture diameter of the resonance cavity (11a) in the plurality of acoustic lining units (11).

6. A low-noise stator vane (1), characterized in that, the low-noise stator vane (1) comprises the noise-reducing lining (10) according to any one of claims 1 to 5, and a plurality of openings (H) are provided in the low-noise stator vane (1).

7. The low-noise stator vane (1) according to claim 6, characterized in that, the plurality of openings (H) are provided only in the suction surface (1a) of the low-noise stator vane (1).

8. The low-noise stator vane (1) according to claim 7, characterized in that, the plurality of openings (H) are uniformly arranged at equal intervals on the suction surface (1a) of the low-noise stator vane (1).

9. The low-noise stator vane (1) according to claim 8, characterized in that, the depths of the plurality of openings (H) are different from each other.

10. The low-noise stator vane (1) according to any one of claims 6 to 9, characterized in that, the noise-reducing lining (10) is arranged such that the through holes in the resonance cavity (11a) partially overlap the plurality of openings (H).

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