CN101264798A - Three-dimensional cavity resonance pulsation pressure and aerodynamic noise suppression device - Google Patents

Abstract

The invention relates to a three-dimensional cavity resonance pulsation pressure and aerodynamic noise suppression device in the technical field of flow control, comprising: an array groove, an actuating reed, a piezoelectric ceramic sheet, a mounting seat, a high-voltage power supply dedicated to piezoelectric ceramics, a dynamic A pressure sensor and a computer equipped with an A/D acquisition card. A dynamic pressure sensor is installed at the bottom of the cavity, and is connected with a computer equipped with an A/D acquisition card through a through hole at the bottom. An actuating reed is installed inside the groove of the array. The bottom of the reed is pasted with a piezoelectric ceramic sheet as an excitation element. The piezoelectric ceramic sheet is connected with a high-voltage power supply dedicated to the piezoelectric ceramic. Under the excitation of the control signal, the piezoelectric ceramic sheet produces stretching deformation, and drives the moving reed to vibrate, changing the oscillation frequency of the shear layer, breaking the resonance of the cavity, and suppressing the aerodynamic noise of the cavity. The invention has a wide range of adjustment, and realizes the precise control of the three-dimensional phased array of the cavity through the real-time feedback of the pulsating pressure of the cavity.

Description

Three-dimensional cavity resonance pulsation pressure and aerodynamic noise suppression device

technical field

The invention relates to an electromechanical device in the technical field of vibration and noise engineering, in particular to a device for suppressing three-dimensional cavity pulsating pressure and aerodynamic noise by using a distributed piezoelectric actuator.

Background technique

When the high-speed fluid flows through the cavity structure, due to the interaction between the shear layer at the mouth of the cavity and the flow in the cavity, a strong self-sustained oscillation phenomenon may occur, resulting in severe pressure, velocity and other pulsations, that is, the cavity self-sustained oscillation, and thus radiate Make a strong noise. Under the action of high-speed airflow, the cavity formed by the weapon compartment and ammunition compartment of a fighter jet will have a pulsating pressure level of more than 180dB; when the aircraft takes off and lands, the noise caused by the pulsating pressure of the landing gear compartment has become one of the main noises. one. In addition, the pulsating pressure of the cavity will cause the aircraft fuselage structure to bear additional unsteady loads, accelerate fatigue failure, and affect flight safety. This strong acoustic load can also damage the sensitivity of electronic devices and affect the service life of the aircraft. Cavity oscillation suppression technology is to take measures to reduce the pulsating pressure in the cavity and reduce aerodynamic noise.

The cavity self-sustained oscillation mechanism is complex, and typical cavity oscillations include the following features: the boundary layer separates at the cavity front, resulting in unstable fluctuations of the shear layer at the cavity opening. The undulating shear layer collides with the trailing edge of the cavity, generating a disturbance wave. The disturbance wave travels back to the cavity front where it interacts with the shear layer to form a feedback loop. The unstable shear layer contains a large number of shedding vortices from the front edge of the cavity, and the shedding frequency is related to the cavity structure size, incoming flow velocity, density and so on. When the geometric resonance frequency of the cavity is close to the shedding vortex frequency of the shear layer or its high-order resonance frequency, resonance will be formed in the cavity, resulting in a rapid increase in the noise in the cavity and the formation of cavity self-sustained oscillation. The core of cavity oscillation suppression is to break the self-sustained oscillation by destroying the feedback loop.

In the past, cavity oscillation and aerodynamic noise suppression devices were mostly static passive control devices. The main disadvantage of this type of device is that it can only suppress noise within a certain range of incoming flow velocity under design conditions; once the incoming flow velocity changes greatly, the oscillation suppression effect is very limited. In addition, this type of device generally consumes a lot of energy and has little practical application value. At the end of the 1990s and the beginning of this century, with the development of modern control technology, material technology, and information technology, through the active flow control method of injecting a small amount of energy locally into the fluid, the research on cavity suppression technology has been greatly promoted. Development of Oscillation Suppression Technology. Active flow control breaks through traditional technical barriers and can be used to improve the comfort and safety of aircraft. It has huge direct and potential economic and environmental benefits, and it also has a wide range of application values in military defense. A large number of studies at home and abroad have confirmed that the introduction of advanced active flow control in the cavity self-sustained oscillation has many advantages such as simple structure, low energy consumption, and high work efficiency.

Found through literature search to prior art, American patent Aircraft Cavity AcousticResonance Suppression System (authorized announcement number is US005699981). The inventive device mainly consists of a cylinder pure tone generator. This cylinder is arranged at the front edge of the cavity and is perpendicular to the direction of the incoming flow. When the incoming flow flows through the cylinder, it will generate flow around the cylinder and form a large number of shedding vortices. The shedding vortex of the cylinder has high frequency and small scale, and collides with the shear layer, resulting in the rapid dissipation of the shear layer vortex and the disappearance of the accelerated turbulent kinetic energy. Its shortcoming is that it is more sensitive to the flow conditions, and the change of the flow state of the incoming flow will affect its effect.

Contents of the invention

The purpose of the present invention is to address the deficiencies in the prior art, to provide a three-dimensional cavity resonance pulsation pressure and aerodynamic noise suppression device, so that it can suppress cavity resonance, reduce discrete noise and part of broadband noise at self-sustained oscillation frequency, and control aerodynamic noise sound pressure level. On the basis of maintaining the advantages of small volume, low energy consumption and fast response speed of the piezoelectric ceramic exciter, the present invention realizes large-scale arrangement through the distributed exciter array, and can comprehensively control cavity oscillation in three-dimensional space. The system can work in a wide range of incoming flow speeds, and its applicability is enhanced; it is smaller in size and has strong anti-interference performance, and can work stably under high flow rates and large loads, which enhances stability and reliability. In addition, through the real-time feedback of the sensor to the cavity noise, it is easy to realize the adaptive processing of the phased array in space and time.

The present invention is realized through the following technical solutions, and the present invention includes: arrayed grooves, actuating reeds, piezoelectric ceramic sheets, mounting bases, high-voltage power supplies dedicated to piezoelectric ceramics, dynamic pressure sensors, and A/D acquisition cards computer. The arrayed grooves are distributed on the plane of the incoming flow direction of the cavity. The dynamic pressure sensor is installed at the bottom of the cavity and is connected with a computer equipped with an A/D acquisition card. One end of the actuating reed is fixed on the mounting base, and the other end vibrates freely. The upper surface of the actuating reed is flush with the surface of the cavity in the incoming flow direction, and its vibration mode is designed through simulation. The bottom of the actuating reed is pasted with a piezoelectric ceramic sheet as an exciting element. The piezoelectric ceramic sheet driving power signal line is connected with the high-voltage power supply dedicated to the piezoelectric ceramic. For the convenience of installation, the actuating reed and piezoelectric ceramic sheet are installed on a mount. The bottom of the mounting seat is provided with a wire hole, which is connected to the bottom of the groove of the array, and the signal wire is connected to the piezoelectric ceramic sheet through the hole, so that the entire array is compact and easy to connect.

The arrayed grooves are spaced vertically and horizontally in an array on the plane of the incoming flow direction of the cavity.

The actuating reed is a metal elastic element installed inside the array groove.

The piezoelectric ceramic sheet is a square thin piece of piezoelectric ceramic material, attached to the bottom of the actuating reed, and connected with a dedicated high-voltage power supply for piezoelectric ceramics through a signal line.

The dynamic pressure sensor is an ordinary dynamic pressure sensor arranged along the bottom of the cavity, and its signal is amplified and collected and processed by the computer of the A/D acquisition card.

The mounting seat is a square piece with a hole at the bottom and a stepped shape at one end.

When in use, the computer collects and analyzes the dynamic pressure signal at the bottom of the cavity to obtain a frequency response curve. Through the comprehensive analysis of the signal on each sensor, the computer sends out corresponding vibration trigger signals to the piezoelectric ceramic sheets in the array, and after being amplified by the high-voltage power supply dedicated to piezoelectric ceramics, it is transmitted to the piezoelectric ceramic sheets. Under the action of current, the piezoelectric ceramic sheet produces expansion and contraction deformation, and drives the moving reed to vibrate, and then generates new disturbances at the front edge of the cavity, which controls the shear layer flow of the cavity and breaks the shear layer disturbance formed downstream. Acoustic feedback. When the incoming flow is disturbed, the computer adjusts the vibration frequency in real time according to the collected sensor signals to ensure the robustness of the system.

Compared with the existing aerodynamic noise suppression means, the device of the present invention has simple structure, fast response speed and low energy consumption; through the arrangement of the exciter, the bearing capacity of the exciter is improved, it can be used for high-speed airflow, and has high reliability ; By adjusting the arrangement of the vibrator, the control range is expanded; considering the inhomogeneity of the incoming flow and the three-dimensional characteristics of the cavity, it is easy to realize the phased array precise control of the three-dimensional flow in space. When the incoming flow is disturbed, the computer adjusts the vibration frequency in real time according to the sensor signal, which ensures the robustness of the system. Up to 30dB of noise can be suppressed.

Description of drawings

Fig. 1 is a schematic diagram of the structure of the present invention.

Detailed ways

The embodiments of the present invention are described in detail below in conjunction with the accompanying drawings: the present embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and processes are provided, but the protection scope of the present invention is not limited to the following implementations example.

As shown in Figure 1, this embodiment includes: arrayed groove 1, actuating reed 2, piezoelectric ceramic sheet 3, piezoelectric ceramic high-voltage power supply 4, computer 5 equipped with A/D acquisition card, dynamic pressure Sensor 6 and mount 7. The arrayed grooves 1 are distributed on the plane of the incoming flow direction of the cavity. One end of the actuating reed 2 is fixed on the mounting base 7, and the other end can vibrate freely. The upper surface of the actuating reed 2 is flush with the cavity surface in the incoming flow direction, and its vibration mode is designed through simulation. The upper surface of the piezoelectric ceramic sheet 3 is attached to the bottom of the actuating reed 2 , and the end is fixed on the mounting seat 7 . The mounting base 7 is fixed on the bottom of the array groove 1 with screws, and the piezoelectric ceramic sheet 3 is connected with the high-voltage power supply 4 dedicated to piezoelectric ceramics through a signal line. The dynamic pressure sensor 6 is installed along the bottom of the cavity, and is connected with the computer 5 equipped with an A/D acquisition card.

The arrayed grooves 1 are spaced vertically and horizontally in an array on the plane of the incoming flow direction of the cavity.

The actuating reed 2 is a metal elastic element installed inside the array groove 1 .

The piezoelectric ceramic sheet 3 is a square thin piece of piezoelectric ceramic material.

The high-voltage power supply 4 dedicated to piezoelectric ceramics is a dedicated high-voltage power supply for driving piezoelectric ceramic sheets.

The dynamic pressure sensors 6 are distributed and installed along the bottom of the cavity along the centerline, and their signals are amplified, collected and processed by a computer 5 equipped with an A/D acquisition card.

The mounting seat 7 is a bottom opening, and one end is a stepped square piece, which is fixed to the bottom of the array groove 1 with screws.

The actuating reed 2 is a metal elastic element, one end is fixed on the upper step surface of the mounting seat 7 , and the end of the piezoelectric ceramic sheet 3 is fixed on the lower step surface of the mounting seat 7 .

When working, the dynamic pressure sensor 6 at the bottom of the cavity receives the pulsating pressure signal and transmits it to the computer 5 through the acquisition card. The computer 5 analyzes the signals on each sensor, and then sends corresponding vibration trigger signals to the piezoelectric ceramic sheets 3 in the array, and transmits them to the piezoelectric ceramic sheets 3 after being amplified by the high-voltage power supply 4 dedicated to piezoelectric ceramics. The piezoelectric ceramic sheet 3 produces expansion and contraction deformation under the action of the current, and drives the moving reed 2 to vibrate, thereby generating new disturbances at the front edge of the cavity, controlling the flow of the shear layer in the cavity, and breaking the shear layer disturbance in the downstream Acoustic feedback formed. When the incoming flow is disturbed, the computer 5 adjusts the vibration frequency in real time according to the collected sensor signals to ensure the robustness of the system.

In operation, this embodiment is based on the cavity self-sustained oscillation and its flow control principle. The shear layer instability of the cavity flow makes the flow extremely sensitive to the disturbance in the initial stage, and has a strong nonlinear amplification effect on the initial disturbance. Inhibition has an important effect. In this embodiment, by analyzing the pulsating pressure signal at the bottom of the cavity, the excitation signal is output to control the vibration of the multi-layer actuating element, interfere with the boundary layer of the incoming flow at the front edge of the cavity, change the oscillation frequency of the shear layer, and break the resonance. The purpose of suppressing the aerodynamic noise of the cavity is achieved.

The noise closed-loop active control in this embodiment has low energy consumption and high work efficiency; it can adapt to a wide range of flow velocity changes; it is small in size, high in reliability and stable in performance.

Claims (7)

1. A three-dimensional cavity resonance pulsation pressure and aerodynamic noise suppression device, characterized in that it includes: array grooves (1), excitation reeds (2), piezoelectric ceramic sheets (3), piezoelectric ceramic dedicated High-voltage power supply (4), computer (5) equipped with A/D acquisition card, dynamic pressure sensor (6), mounting base (7), wherein: arrayed grooves (1) are distributed on the plane of the incoming flow direction of the cavity One end of the actuating reed (2) is fixed on the mounting base (7), and the other end vibrates freely. The upper surface of the actuating reed (2) is flush with the surface of the cavity in the incoming flow direction, and the piezoelectric ceramic sheet (3) The upper surface is attached to the bottom of the actuating reed (2), and the end is fixed on the mounting seat (7). The signal line of the piezoelectric ceramic sheet (3) is connected to the high-voltage power supply (4) dedicated to piezoelectric ceramics, and the mounting seat (7) is fixed on the bottom of the array groove (1), and the dynamic pressure sensor (6) is installed on the bottom of the cavity, and is connected with the computer (5) equipped with an A/D acquisition card. 2. The three-dimensional cavity resonance pulsation pressure and aerodynamic noise suppression device according to claim 1, characterized in that, the arrayed grooves (1) are distributed vertically and horizontally on the incoming flow surface in an array manner. 3. The three-dimensional cavity resonance pulsation pressure and aerodynamic noise suppression device according to claim 2, characterized in that the actuating reed (2) is a metal elastic element installed inside the array groove (1). 4. The three-dimensional cavity resonant pulsation pressure and aerodynamic noise suppression device according to claim 1, characterized in that the dynamic pressure sensors (6) are distributed and installed at the bottom of the cavity along the center line to measure the sound pressure signal in real time, which The signal is amplified, collected and processed by a computer (5) equipped with an A/D acquisition card. 5. The three-dimensional cavity resonance pulsation pressure and aerodynamic noise suppression device according to claim 1 or 4, characterized in that the computer (5) analyzes the signal of the dynamic pressure sensor (6) and passes it to the high-voltage power supply dedicated to piezoelectric ceramics (4) After amplification, the piezoelectric ceramic sheet (3) is triggered in real time. 6. The three-dimensional cavity resonance pulsation pressure and aerodynamic noise suppression device according to claim 1, characterized in that, the mounting seat (7) is a square piece with a hole at the bottom and a stepped shape at one end. 7. The three-dimensional cavity resonance pulsation pressure and aerodynamic noise suppression device according to claim 1 or 6, characterized in that the actuating reed (2) is a metal elastic element, and one end is fixed on the mounting seat (7). On the upper step surface, the end of the piezoelectric ceramic sheet (3) is fixed on the lower step surface of the mounting seat (7).

Images