Noise reduction device and noise reduction method for spray pipe of vortex generator

Abstract

The invention discloses a vortex generator spray pipe noise reduction device and method. The vortex generator spray pipe noise reduction device comprises a spray pipe of a reducing structure and a vortex generator installed on the inner surface of the spray pipe. A plurality of vortex generators are circumferentially arranged near the outlet of the spray pipe; the vortex generator comprises a curved mounting surface attached to the inner wall of the spray pipe, two triangular side surfaces distributed in a bilateral symmetry manner and an inclined third surface; a jet flow channel is formed in the vortex generator, a jet flow hole outlet is formed in the center of the third face, and a jet flow hole inlet is formed in the installation face. High-temperature and high-pressure gas main flow is sprayed out through the spray pipe at a high speed and flows through the vortex generator located at the tail, the high-temperature and high-pressure gas main flow flows in the directions of the two side faces of the vortex generator, the flowing state originally attached to the surface of the spray pipe is broken, in the process, the flowing direction of the part of gas is forced to change, and the gas flow direction is changed. The original uniform airflow has difference in direction to generate a turbulent vortex; then, the fuel gas with the changed flowing direction and the fuel gas with the unchanged flowing state meet and act; cold flow is injected into the high-temperature and high-pressure gas main flow through the jet flow holes and mixed with the gas main flow, a large-scale turbulent flow structure is converted into a small-scale turbulent flow structure under the combined action of the vortex generator and the cold flow, and therefore the purpose of reducing noise is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of nozzle noise reduction, and particularly relates to a nozzle noise reduction device and a noise reduction method for a vortex generator nozzle. Background Technique

[0002] As the core equipment of the sixth-generation aerospace navigation system, hypersonic aircraft have made breakthroughs in the fields of aerodynamics and thermodynamics in recent years. With the ability to continuously fly at a Mach number of more than 5 and three-dimensional maneuvering characteristics, such aircraft demonstrate unique advantages. However, their aerodynamic and thermodynamic characteristics also bring significant flow noise problems. According to the latest experimental data of NASA, the aerodynamic noise generated by a typical hypersonic aircraft during cruise is as high as 185 - 190 dB, and the local flow field noise intensity even exceeds the 195 dB threshold.

[0003] Analyzed from the principles of fluid mechanics, the working mechanism of the aircraft propulsion system is the fundamental cause of noise generation. When the high-temperature and high-pressure gas generated by the combustion chamber of a turbojet / fan engine flows through the nozzle and is accelerated and discharged into the free flow field, it interacts violently with the stationary air medium. This unsteady flow process triggers three main noise sources: 1. Quasi-ordered noise generated by the interaction between the turbulent quasi-ordered structure and the shear layer; 2. Magnus vortex shedding noise caused by the development of the gas jet boundary layer; 3. Aeroacoustic coupling effect between the nozzle exit flow field and the external atmosphere.

[0004] Currently, in the aviation field, a multi-dimensional solution system for suppressing nozzle jet noise has been formed. The main technical paths include: Firstly, noise reduction is achieved through the optimization of the power system. Typical measures include the implementation of internal and external bypass mixed exhaust technology using a large bypass ratio turbo fan engine design, and the optimization of the nozzle expansion ratio to reduce the exhaust speed; Secondly, focus on the innovation of flow field control technology. For example, the application of a lobed nozzle to control the jet boundary layer structure, combined with shock control technology to suppress the generation of shock noise; Thirdly, develop new muffler devices and active noise reduction arrays (acoustic cancellation technology based on the phased array principle). Summary of the Invention

[0005] The purpose of the present invention is to provide a nozzle noise reduction device and a noise reduction method based on a vortex generator, and the invention can reduce the noise by about 3 decibels.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A noise reduction device for a vortex generator nozzle, comprising a nozzle with a tapered structure and a vortex generator installed on the inner surface of the nozzle; the vortex generator is installed at a position 0.2D - 0.3D away from the nozzle outlet, where D is the diameter of the nozzle outlet, and N vortex generators are evenly arranged in the circumferential direction of the nozzle; the vortex generator is a tetrahedron, including a curved mounting surface that fits the inner wall of the nozzle, two triangular side surfaces symmetrically distributed on the left and right, and an inclined third surface, and the angle α between the third surface and the vertical direction is between 14 - 20 degrees; a jet channel is arranged inside the vortex generator, a circular jet hole outlet is arranged at the center position of the third surface, a jet hole inlet is arranged on the mounting surface, and the direction of the jet channel is perpendicular to the third surface.

[0008] Further, 6 vortex generators are evenly arranged in the circumferential direction of the nozzle.

[0009] Further, the height of the vortex generator on the side close to the nozzle outlet is H, the height on the side far from the nozzle outlet is 1.4H, the length in the axial direction of the nozzle is 2H, and the width is 1.4H.

[0010] Further, the jet hole inlet is oval, the jet hole outlet is a regular circle, and the outlet diameter is 0.3H.

[0011] Further, a jet channel is arranged inside the vortex generator for injecting cold flow into the interior of the high-temperature and high-pressure gas main flow, and the cold flow is mixed with the main flow to change the flow field structure.

[0012] A noise reduction method for a vortex generator nozzle noise reduction device, where the high-temperature and high-pressure gas main flow jets out through the nozzle at a high speed, flows through the vortex generator arranged at the tail of the nozzle, and the high-temperature and high-pressure gas main flow flows along the directions of the two side surfaces of the vortex generator, and the original flow state that fits the nozzle surface is broken. During this process, the flow direction of this part of the gas is forced to change, and the originally uniform air flow begins to show differences in direction to generate turbulent vortices; subsequently, the gas with the changed flow direction meets and acts on the gas with the unchanged flow state; the cold flow is injected into the interior of the high-temperature and high-pressure gas main flow through the jet holes and is mixed with the gas main flow. Under the combined action of the vortex generator and the cold flow, the large-scale turbulent structure is transformed into a small-scale turbulent structure, thereby achieving the purpose of reducing noise.

[0013] The beneficial effects of the present invention are as follows:

[0014] The vortex generator proposed in the present invention is installed inside the nozzle. There are jet holes inside the vortex generator, and secondary air is injected into the high-temperature and high-pressure exhaust gas through the jet holes. The present invention can reduce the noise by about 3 decibels. The invention of this patent can be verified through numerical simulation and experiments. This patent describes based on the numerical simulation calculation results. The specific dimensions and positions should be determined by combining numerical simulation and simulation in actual applications. Description of the Drawings

[0015] Figure 1 is a schematic plan view of the vortex generator;

[0016] Figure 2 is a three-dimensional schematic diagram of the vortex generator;

[0017] Figure 3 is a front view of the vortex generator;

[0018] Figure 4 is a right view of the vortex generator;

[0019] Figure 5 is a schematic diagram of the installation position of the vortex generator inside the nozzle. Detailed Implementation Modes

[0020] The present invention will be further described below with reference to the drawings.

[0021] The present invention provides a Figures 1-5 shown vortex generator nozzle noise reduction device and noise reduction method. The nozzle noise reduction device includes a vortex generator body.

[0022] The high-temperature and high-pressure main gas flow sprays out through the nozzle at an extremely high speed, flowing through the vortex generator arranged at the tail of the nozzle. The vortex generator is installed at a position 0.2D - 0.3D (D is the diameter of the nozzle outlet) from the nozzle outlet, and a plurality of vortex generators are evenly arranged in the circumferential direction. The installation position of the vortex generator cannot be too far from the nozzle outlet, nor can it be too close to the nozzle outlet. When the installation position of the vortex generator is far from the nozzle outlet, the effect of the vortex generator on the main gas flow has recovered before the main flow has exited the nozzle, and the purpose of changing the flow state of the main gas flow to reduce the nozzle noise cannot be achieved. When the installation position of the vortex generator is too close to the nozzle outlet, the change in the flow state of the main gas flow by the vortex generator has not fully developed, and the main gas flow has already flowed out of the nozzle, and the purpose of changing the flow state of the main gas flow to reduce the nozzle noise cannot be achieved either. The inner surface of the nozzle presents a curved surface with a certain curvature, which is determined by the overall design of the nozzle and the gas flow characteristics. For this reason, the installation surface of the vortex generator is also designed as a curved surface with a corresponding curvature to perfectly fit the inner surface of the nozzle.

[0023] The eddy current generator consists of four surfaces. The overall shape of the eddy current generator is approximately a regular tetrahedron. Each of its surfaces is smooth and flat, with smooth lines, presenting a simple and regular geometric shape. The nozzle is a convergent structure. Therefore, the height of the eddy current generator near the nozzle outlet side is different from that far from the nozzle outlet side. The height near the nozzle outlet side is H, and the height far from the nozzle outlet side is 1.4H. The length along the axial direction of the nozzle is 2H, and the width is 1.4H. The eddy current generator is installed on the inner surface of the nozzle through the installation surface. When the eddy current generator is installed on the inner surface of the nozzle, the two side surfaces of the eddy current generator form a certain angle with the incoming flow direction of the high-temperature and high-pressure gas mainstream. The high-temperature and high-pressure gas mainstream flows along the directions of the two side surfaces of the eddy current generator. The two side surfaces of the eddy current generator are completely symmetrical and are triangular in shape. In the eddy current generator, its left and right side surfaces are the core areas for generating eddy currents. When the gas mainstream flows through the two side surfaces of the eddy current generator at an extremely high speed, due to the special shape and angle guidance of the side surfaces, the gas will flow along the directions of the two side surfaces, and the original flow state that adheres to the nozzle surface is broken. During this process, the flow direction of this part of the gas is forced to change, and the originally uniform air flow begins to show differences in direction, generating turbulent vortices. Subsequently, the gas with the changed flow direction meets and interacts with the gas whose flow state has not changed, converting the large-scale turbulent structure that generates low-frequency noise into a small-scale turbulent structure, thereby achieving the purpose of noise reduction. The shape of the third surface of the eddy current generator is also approximately triangular. The third surface of the eddy current generator is not perpendicular to the nozzle axis direction. The angle α between the third surface of the eddy current generator and the vertical direction is between 14° and 20°.

[0024] Another core component of the nozzle noise reduction device based on the eddy current generator is the jet channel installed inside the eddy current generator. The main function of the jet channel is to inject cold flow into the gas mainstream. By injecting the cold flow into the gas mainstream, the cold flow mixes with the mainstream and changes the flow field structure. The inlet position of the jet hole is on the installation surface of the eddy current generator. In order to fit the shape of the installation surface, the shape of the jet hole is not a regular circle but an ellipse, and the cold flow enters from the inlet of the jet hole. The outlet of the jet hole is located on the third surface of the eddy current generator. The direction of the jet channel is perpendicular to the third surface of the eddy current generator. The shape of the jet hole outlet is a regular circle. The center position of the jet hole outlet is at the center of the third surface of the eddy current generator, and the outlet diameter is 0.3H. The angle at which the cold flow is injected into the gas mainstream is related to α. In this invention, the installation position of the eddy current generator and the range of α are obtained through simulation. Within this range, better nozzle noise reduction effects can be achieved.

[0025] The third surface of the vortex generator has a certain angle with the main flow direction of the high-temperature and high-pressure combustion gas. Therefore, the cold flow is injected into the main flow of the combustion gas at a certain angle from the jet holes. The main flow direction of the combustion gas on the third surface of the vortex generator determines the angle at which the cold flow is injected into the main flow of the combustion gas. The angle at which the cold flow is injected into the main flow of the combustion gas is related to the degree to which the cold flow penetrates into the main flow of the combustion gas. The larger the angle, the deeper the cold flow can penetrate into the main flow. The cold flow is injected into the main flow of the combustion gas from the inlet of the jet holes and is mixed with the main flow of the combustion gas, further converting the large-scale turbulent structure into a small-scale turbulent structure, thereby further achieving the purpose of reducing the nozzle noise.

[0026] When performing the noise reduction simulation calculation of the vortex generator in the present invention, compared with the nozzle without the vortex generator, the noise of the nozzle with the added vortex generator is reduced by about 3 decibels.

[0027] In summary, the device of the present invention has a simple structure, can change the internal flow field of the nozzle, convert the large-scale turbulent structure into a small-scale turbulent structure, and achieve the purpose of reducing the nozzle noise.

[0028] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A noise reduction device for an eddy current generator nozzle, characterized in that: It includes a nozzle with a tapered structure and a vortex generator installed on the inner surface of the nozzle; the vortex generator is installed at a position 0.2D - 0.3D away from the nozzle outlet, where D is the nozzle outlet diameter, and N vortex generators are evenly arranged in the circumferential direction of the nozzle; the vortex generator is a tetrahedron, including a curved mounting surface that fits the inner wall of the nozzle, two triangular sides symmetrically distributed on the left and right, and an inclined third side, and the angle α between the third side and the vertical direction is between 14 - 20 degrees; a jet channel is arranged inside the vortex generator, a circular jet hole outlet is arranged at the center position of the third side, a jet hole inlet is arranged on the mounting surface, and the direction of the jet channel is perpendicular to the third side.

2. The noise reduction device for a vortex generator nozzle according to claim 1, wherein: Six vortex generators are evenly arranged in the circumferential direction of the nozzle.

3. The noise reduction device for an eddy current generator nozzle according to claim 1, characterized in that: The height of the vortex generator near the nozzle outlet side is H, the height of the side far from the nozzle outlet is 1.4H, the length in the axial direction of the nozzle is 2H, and the width is 1.4H.

4. The noise reduction device for an eddy current generator nozzle according to claim 1, wherein: The jet hole inlet is oval, the jet hole outlet is a regular circle, and the outlet diameter is 0.3H.

5. The noise reduction device for an eddy current generator nozzle according to claim 1, wherein: A jet channel is arranged inside the vortex generator to inject cold flow into the interior of the high-temperature and high-pressure gas mainstream, and the cold flow is mixed with the mainstream to change the flow field structure.

6. The noise reduction method of an eddy current generator nozzle noise reduction device according to any one of claims 1-5, characterized in that: The high-temperature and high-pressure gas mainstream is ejected through the nozzle at a high speed and flows through the vortex generators arranged at the tail of the nozzle. The high-temperature and high-pressure gas mainstream flows along the directions of the two sides of the vortex generator, and the original flow state that adheres to the nozzle surface is broken. During this process, the flow direction of this part of the gas is forced to change, and the originally uniform airflow begins to show differences in direction to generate turbulent vortices; subsequently, the gas with the changed flow direction meets and interacts with the gas whose flow state has not changed. The cold flow is injected into the interior of the high-temperature and high-pressure gas mainstream through the jet holes and is mixed with the gas mainstream. Under the combined action of the vortex generator and the cold flow, the large-scale turbulent structure is transformed into a small-scale turbulent structure, thereby achieving the purpose of reducing noise.

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