Spraying pipe resistance and noise reduction structure based on inner wall corrugations

Abstract

The invention discloses a spray pipe resistance and noise reduction structure based on inner wall corrugation, and relates to the technical field of low-resistance and low-noise control of aero-engines, the spray pipe structure comprises a spray pipe body, the spray pipe body comprises four revolution surfaces, namely an outer wall surface, an inner wall surface subjected to corrugation treatment, a nozzle lip surface and an inner wall surface which is not subjected to corrugation treatment; and the four revolution surfaces are curved surfaces obtained by rotating the boundary curve of the spray pipe body around the axis. The inner wall structure of the spray pipe does not need to be greatly changed, the installation layout of other structures of the engine is hardly influenced, and relevant structures such as the engine spray pipe do not need to be redesigned; installation is easy, operation is stable, implementation and maintenance are convenient in engineering, and jet flow noise is reduced while the thrust-drag ratio of the engine is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of low-drag and low-noise control of aircraft engines, and in particular to a nozzle drag and noise reduction structure based on inner wall corrugations. Background Art

[0002] The jet is the key to the thrust provided by the aircraft jet engine. The high-speed jet interacts with the nozzle lip and the atmosphere, providing thrust on the one hand and generating a lot of noise on the other. In the field of civil aviation, the acoustic performance of aircraft has become the core indicator for noise airworthiness certification and market competitiveness, and jet noise is still one of the main sources of aircraft noise.

[0003] The characteristics of jet noise mainly depend on the jet speed. The jets of running civil jet engines are all subsonic jets, and their main noise source is the turbulent mixing noise formed by the mixing of the jet plume and the atmosphere. The generation mechanism of turbulent mixing noise can be divided into two parts according to the flow structure scale: large-scale turbulent sound generation and small-scale turbulent sound generation. Among them, large-scale turbulent noise mainly radiates in the downstream direction of the jet, while small-scale turbulent mixing noise plays a dominant role in the upstream and sideline direction of the jet. Therefore, regulating the interaction between the jet and the atmosphere is an important means to achieve jet noise control.

[0004] After searching the prior art, it was found that enhancing the mixing of the jet and the atmosphere has been proven to effectively control the jet noise. Chevron nozzles (US7469529B2, US8887489B2) and nozzles with lobe mixers (Corrugated Nozzles, US4487017A) can effectively reduce large-scale turbulent mixing noise and have been widely used in aircraft engine jet noise control. This type of jet noise control measure will inevitably bring about a more serious thrust loss. At the same time, after the application of such control measures, the structural complexity of the nozzle is significantly improved, and its processing difficulty and operating reliability are correspondingly reduced. Therefore, those skilled in the art need to develop a new jet noise control structure to solve the technical problem of how to ensure that the propulsion capacity of the nozzle remains basically unchanged while reducing the jet noise. In response to this problem, the smallest possible geometric disturbance is used to make full use of the time accumulation effect of the flow structure and the drag reduction potential of the microstructure, and time is exchanged for space to enhance the mixing effect of the jet and the atmosphere as much as possible, while reducing the jet resistance.

[0005] How to develop a nozzle drag reduction and noise reduction structure based on inner wall corrugations, reconcile the contradiction between jet drag reduction and noise reduction, and reduce jet noise while ensuring engine thrust has become a technical problem that needs to be urgently solved by technical personnel in this field. Summary of the invention

[0006] The purpose of the present invention is to provide a nozzle drag reduction and noise reduction structure based on inner wall corrugations to solve the problems listed in the background technology.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] The present invention discloses a nozzle drag reduction and noise reduction structure based on inner wall corrugation, comprising a nozzle, wherein the nozzle comprises four revolving surfaces: an outer wall surface, an inner wall surface treated with corrugations, a nozzle lip surface, and an inner wall surface not treated with corrugations;

[0009] The four revolving surfaces are all curved surfaces obtained by rotating the nozzle boundary curve around the axis.

[0010] Preferably, the nozzle has a shape of contraction, equal diameter, expansion or double duct.

[0011] Preferably, the corrugated inner wall surface and the uncorrugated inner wall surface are integrally formed or connected in sections.

[0012] Preferably, the waveform of the corrugated inner wall surface is one or more combinations of a sine waveform, a square waveform, a triangular waveform, and a triangular waveform with rounded corners.

[0013] Preferably, the waveform of the corrugated inner wall surface is determined by a wavelength λ and a wave height h, and the distribution of the waveform along the corrugated laying range includes two forms: uniform distribution and uneven distribution.

[0014] Preferably, the corrugation laying direction of the corrugated inner wall surface is parallel to the inner wall of the nozzle when the inner wall corrugated structure is not laid, and the inner wall of the nozzle when the inner wall corrugated structure is not laid coincides with the tangent line of the wave crest of the corrugated wall surface.

[0015] Preferably, the corrugated section of the corrugated inner wall surface is laid at a position close to the nozzle lip surface, and the axial length of the corrugated section of the corrugated inner wall surface is L.

[0016] Preferably, it further comprises an exhaust cone, wherein the exhaust cone is installed inside the nozzle, and the center line of the exhaust cone coincides with the axis.

[0017] Compared with the prior art, the beneficial technical effects of the present invention are:

[0018] Various existing jet noise control technologies, such as sawtooth nozzles and lobe nozzles, have noise reduction principles mainly based on increasing the mixing of the jet with the atmosphere, and their effects have the characteristics of small axial distance and high intensity. The present invention uses inner wall corrugation noise control technology to start from the jet shear layer instability and jet mixing sound generation mechanism, and transforms the "small range strong effect" brought by sawtooth and lobe nozzles into the "large range weak effect" accumulated by the inner wall corrugated nozzle over time, thereby enhancing the jet mixing and reducing the noise while improving the propulsion performance and structural reliability of the nozzle; by transforming the "fixed phase disturbance" brought by the sawtooth and lobe nozzles into the "random phase disturbance" caused by the inner wall corrugation of the nozzle, the jet mixing is accelerated and the jet noise is further reduced; this corrugated structure does not require a significant change in the inner wall structure of the nozzle, and will hardly affect the installation layout of other structures of the engine, and does not require the redesign of the engine nozzle and other related structures; the inner wall corrugated structure has the advantages of simple installation and stable operation, and is easy to implement and maintain in engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below in conjunction with the accompanying drawings.

[0020] Figure 1 This is a schematic diagram of a nozzle drag reduction and noise reduction structure based on inner wall corrugations according to the present invention;

[0021] Figure 2 This is a schematic diagram of the nozzle structure of the present invention applied to an engine without exhaust cone;

[0022] Figure 3 This is a schematic diagram of the present invention applied to a nozzle structure of equal diameter;

[0023] Figure 4 This is a schematic diagram of the inner wall corrugation of the present invention being applied to a double-duct nozzle;

[0024] Figure 5 This is an enlarged schematic diagram of the applicable waveform of the inner wall corrugation of the present invention;

[0025] Figure 6 It is a schematic diagram of an integrated molding application mode of an inner wall surface treated with corrugations and an inner wall surface not treated with corrugations according to the present invention;

[0026] Figure 7 It is a schematic diagram of the combined installation and application mode of the inner wall surface treated with corrugations and the inner wall surface not treated with corrugations of the present invention;

[0027] Figure 8 It is a schematic diagram of an embodiment of the present invention in a single-duct convergent nozzle without an exhaust cone.

[0028] Explanation of reference numerals: 1. Outer wall surface; 1-1. Outer wall surface of inner channel; 1-2. Outer wall surface of outer duct; 2. Inner wall surface after corrugation treatment; 2-1. Corrugated surface of inner wall of inner channel; 2-2. Corrugated surface of inner wall of outer duct; 3. Nozzle lip surface; 3-1. Curved surface of lip of inner channel; 3-2. Curved surface of lip of outer duct; 4. Inner wall surface without corrugation treatment; 4-1. Inner wall surface without corrugation treatment; 4-2. Inner wall surface without corrugation treatment; 5. Exhaust cone ; 6. Axis; 7. Jet flow direction in the nozzle; 7-1. Jet flow direction in the inner duct nozzle; 7-2. Jet flow direction in the outer duct nozzle; 8. Fluid in the nozzle; 8-1. Fluid in the inner duct nozzle; 8-2. Fluid in the outer duct nozzle; 9. Fluid around the nozzle; 10. Fluid boundary; 10-1. Mixing surface of inner and outer duct flow; 10-2. Mixing surface of outer duct flow; 11. Inner wall of nozzle; 12. Tangent line of wave crest on the corrugated wall. DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] like Figure 1-8 As shown, a nozzle drag reduction and noise reduction structure based on inner wall corrugation includes a nozzle, wherein the nozzle includes four revolving surfaces: an outer wall surface 1, an inner wall surface 2 after corrugation, a nozzle lip surface 3, and an inner wall surface 4 without corrugation;

[0031] The four revolving surfaces are all curved surfaces obtained by rotating the nozzle boundary curve around the axis 6.

[0032] The invention and embodiments involve the following parameters:

[0033] D nozzle outlet diameter;

[0034] L is the axial length of the corrugated section;

[0035] L0 is the distance between the inner wall corrugation and the nozzle outlet;

[0036] λ is the wavelength of the inner wall corrugations;

[0037] h is the wave height of the inner wall corrugation;

[0038] η Inner wall corrugation wave height h wavelength ratio = h / λ;

[0039] λ1,λ2 are the wavelengths of the variable wavelength inner wall corrugations;

[0040] h1,h2 variable wave height h The wave height h of the inner wall corrugation.

[0041] Specifically, the shape of the nozzle is a contraction shape, a constant diameter shape, an expansion shape or a double duct shape.

[0042] Specifically, the corrugated inner wall surface 2 and the uncorrugated inner wall surface 4 are integrally formed or connected in sections.

[0043] Specifically, the waveform of the corrugated inner wall surface 2 is one or more combinations of a sine waveform, a square waveform, a triangular waveform, and a triangular waveform with rounded corners.

[0044] Specifically, the waveform of the corrugated inner wall surface 2 is determined by the wavelength λ and the wave height h, and the distribution of the waveform along the corrugated laying length includes two forms: uniform distribution and uneven distribution, wherein the wavelength λ of the corrugation is the distance between two wave crests or wave troughs, and the value range is 0.01D-0.25D, wherein D is the nozzle outlet diameter; the wave height h of the corrugation is the distance between the wave crest and the waveform equilibrium position, and the value range is 0.001D-0.02D; the wave height h and the wavelength ratio η range from 0.05 to 0.1; under the same flow rate, the wave height h of the corrugation determines the intensity of the inner wall boundary layer disturbance and the first characteristic disturbance frequency, and the wavelength of the corrugation determines the second characteristic frequency of the inner wall boundary layer disturbance.

[0045] Specifically, the corrugation laying direction of the corrugated inner wall surface 2 is parallel to the inner wall 11 of the nozzle when the inner wall corrugated structure is not laid, and the inner wall 11 of the nozzle when the inner wall corrugated structure is not laid coincides with the tangent line 12 of the corrugated wall surface crest, so as to ensure that the overall flow channel structure of the nozzle remains unchanged.

[0046] Specifically, the laying position of the corrugated section of the corrugated inner wall surface 2 is close to the nozzle lip surface 3, and the axial length of the corrugated section laid on the corrugated inner wall surface 2 is L. Furthermore, the axial length L of the corrugated section is a projection of the actual laying length on the axis 6. For the inner wall of the nozzle with a curved cross-section, the actual laying length is slightly larger than L. The value range of L is 0.5D-2.0D for the nozzle without the exhaust cone 5, and is 0.2D-1.0D for the nozzle with the exhaust cone 5.

[0047] The laying length is also the cumulative distance of the inner wall boundary layer disturbance. Under the same wavelength and wave height h parameters, the laying length determines the total intensity of the boundary layer disturbance. Furthermore, the distance L0 between the corrugated structure of the inner wall surface 2 treated with corrugations and the nozzle outlet is in the range of 0-2λ, which keeps the nozzle lip geometry the same as that of the simple nozzle, and helps to reduce thrust loss.

[0048] Specifically, it also includes an exhaust cone 5 , which is installed inside the nozzle, and the center line of the exhaust cone 5 coincides with the axis 6 .

[0049] Specifically, the fluid 8 inside the nozzle is ejected along the jet flow direction 7 inside the nozzle, and is mixed with the fluid 9 around the nozzle through the fluid boundary 10 .

[0050] like Figure 2 The figure shows the application of the present invention in a cone nozzle without exhaust. The laying method of the inner wall corrugation is the same as that of the cone nozzle with exhaust. The axial length of the corrugated section laid on the corrugated inner wall surface 2 is slightly larger than that of the cone nozzle with exhaust.

[0051] like Figure 3 The figure shows the application of the present invention in a constant diameter nozzle, which belongs to a non-exhaust cone nozzle, and the method for laying the inner wall corrugations is the same as that of the non-exhaust cone nozzle.

[0052] like Figure 4 The figure shows the application of the present invention in a double duct nozzle, the double duct nozzle comprises an inner duct nozzle, an outer duct nozzle and an exhaust cone 5, the inner duct nozzle and the outer duct nozzle are sequentially arranged on the outer circumference of the exhaust cone 5, and the center lines of the outer duct nozzle, the inner duct nozzle and the exhaust cone 5 are all coincident with the axis 6;

[0053] The inner channel nozzle includes an inner channel outer wall surface 1-1, an inner channel inner wall corrugated surface 2-1, an inner channel lip curved surface 3-1 and an inner channel non-inner wall corrugated surface 4-1, and the outer channel nozzle includes an outer channel outer wall surface 1-2, an outer channel inner wall corrugated surface 2-2, an outer channel lip curved surface 3-2 and an outer channel non-inner wall corrugated surface 4-2;

[0054] Laying the inner wall corrugated surface 2-1 of the inner duct on the inner wall of the inner duct helps the fluid 8-1 in the inner duct nozzle to introduce circumferential and axial disturbances into the inner and outer duct flow mixing surface 10-1 along the jet flow direction 7-1 in the inner duct nozzle, thereby accelerating flow mixing and reducing the inner duct jet noise; laying the outer duct inner wall corrugated surface 2-2 on the inner wall of the outer duct helps the fluid 8-2 in the outer duct nozzle to introduce disturbances into the outer duct flow mixing surface 10-2 along the jet flow direction 7-2 in the outer duct nozzle, thereby reducing the outer duct jet noise.

[0055] like Figure 5 As shown, the waveform types of the inner wall corrugated structure of the present invention are one or more waveform combinations e selected from the group consisting of a sinusoidal waveform a, a square waveform b, a triangular waveform c, and a triangular waveform d with rounded corners at the tip, and the corrugation parameters can be set to a gradual distribution f according to the development law of the flow state, that is, the wavelength and the wave height h can be functions of the laying position. Such a setting can improve the efficiency of introducing beneficial disturbances into the corrugated wall.

[0056] like Figure 6-7As shown, the inner wall corrugated structure of the present invention can be assembled in two ways: one-piece molding or segmented joining. The cutoff points at both ends of the corrugated section are the two wave peaks of the corrugation. The corrugated section of the inner wall of the nozzle is tangent to the unassembled corrugated section of the inner wall of the nozzle, and the transition is smooth.

[0057] like Figure 8 As shown, one of the embodiments is as follows: taking a non-exhaust cone convergent nozzle as an example, its outlet diameter is 0.05m, the jet Mach number is 0.9, the working fluid is air, the surrounding is the atmosphere, and an inner wall corrugation with a wavelength of λ=0.09D and a wave height h of h=0.005D is set, the laying range L=1.75D, and the distance between the corrugated section and the outlet L0=0.25λ. The nozzle thrust can be increased by 1% at most, and at the same time the total noise is reduced by 2dB.

[0058] The core research and development idea of ​​the present invention is to reduce the jet resistance and improve the propulsion efficiency while achieving jet noise reduction. Its theoretical basis is the interaction between boundary layer waves and vortices in fluid mechanics, and the circumferential and axial instability of the jet shear layer induced by the interaction between boundary layer waves and vortices; the inner wall corrugated structure changes the development of the internal boundary layer of the jet, weakens the momentum transfer between the jet mainstream and the boundary by generating a series of small shedding vortex structures, and reduces the wall resistance. In addition, waves and vortices always coexist in turbulent flow fields. When low-speed flow separates, nonlinear unstable waves prepare for the generation of separation vortices, and the vortex structure that has been formed causes shear in the flow field, creating conditions for a new level of unstable waves; the purpose of setting a corrugated structure on the wall is to introduce artificially designed boundary layer disturbances to control the interaction between boundary layer waves and vortices, and finally create a flow environment that is conducive to noise control. The main source of jet noise is the free shear layer formed after the high-speed jet mixes with the surrounding low-speed fluid. The shear flow develops downstream and evolves into turbulent coherent structures of various scales, generating turbulent mixed noise. The inner wall corrugations used in the present invention can enhance the mixing of turbulent structure, thereby changing the distribution of turbulent kinetic energy and weakening the spatiotemporal coherence of the jet flow structure, thereby controlling the generation and propagation of jet noise. The noise control principle of the present invention is similar to that of the sawtooth and lobe-shaped nozzles, but there are two key differences:

[0059] 1) The effects of sawtooth and lobe-shaped nozzles are characterized by small axial distance and high strength. The inner wall corrugated nozzle transforms the "small range strong effect" brought by the sawtooth and lobe-shaped nozzles into the "large range weak effect" accumulated by the inner wall corrugated nozzle over time, which effectively reduces the mixing resistance while enhancing the jet mixing and reducing the noise, and helps to improve the propulsion performance and structural reliability of the nozzle;

[0060] 2) The shear layer mixing disturbance brought by the sawtooth and lobe-shaped nozzles has a "fixed phase angle", while the disturbance introduced by the inner wall corrugated nozzle has turbulent randomness and belongs to a "random phase disturbance", which helps to destroy the coherent structure in the jet and achieve noise control more effectively.

[0061] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0062] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A nozzle drag reduction and noise reduction structure based on inner wall corrugations, comprising a nozzle, characterized in that: The nozzle comprises four revolving surfaces: an outer wall surface (1), an inner wall surface (2) subjected to corrugation, a nozzle lip surface (3), and an inner wall surface (4) not subjected to corrugation. The four revolving surfaces are all curved surfaces obtained by rotating the boundary curve of the nozzle around the axis (6).

2. The nozzle drag reduction and noise reduction structure based on inner wall corrugations according to claim 1 is characterized in that: The shape of the nozzle is a contraction shape, a constant diameter shape, an expansion shape or a double duct shape.

3. The nozzle drag reduction and noise reduction structure based on inner wall corrugations according to claim 2 is characterized in that: The inner wall surface (2) that has been subjected to corrugation treatment and the inner wall surface (4) that has not been subjected to corrugation treatment are formed in one piece or connected in sections.

4. The nozzle drag and noise reduction structure based on inner wall corrugations according to claim 3 is characterized in that: The waveform of the corrugated inner wall surface (2) is one or a combination of a sine waveform, a square waveform, a triangular waveform, and a triangular waveform with rounded corners.

5. The nozzle drag reduction and noise reduction structure based on inner wall corrugations according to claim 4 is characterized in that: The waveform of the corrugated inner wall surface (2) is determined by a wavelength λ and a wave height h, and the distribution of the waveform along the corrugated laying length includes two forms: uniform distribution and non-uniform distribution.

6. The nozzle drag and noise reduction structure based on inner wall corrugations according to claim 5, characterized in that: The corrugation laying direction of the corrugated inner wall surface (2) is parallel to the nozzle inner wall (11) when the inner wall corrugation structure is not laid, and the nozzle inner wall (11) when the inner wall corrugation structure is not laid coincides with the corrugated wall surface wave crest tangent (12).

7. The nozzle drag reduction and noise reduction structure based on inner wall corrugations according to claim 6, characterized in that: The corrugated section of the corrugated inner wall surface (2) is laid at a position close to the nozzle lip surface (3), and the axial length of the corrugated section of the corrugated inner wall surface (2) is L.

8. The nozzle drag and noise reduction structure based on inner wall corrugations according to claim 7, characterized in that: It also comprises an exhaust cone (5), wherein the exhaust cone (5) is installed inside the nozzle, and the center line of the exhaust cone (5) coincides with the axis (6).

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