CN118168182A - Pressure wave generator - Google Patents

Abstract

The invention relates to the technical field of pressure wave generating equipment, and provides a pressure wave generating device, which comprises: a resonator tube, a stack of thermoacoustic plates, a heater and a cooler; the resonance tube is filled with liquid working medium, and is provided with a pressurizing port and a pressure wave output surface, wherein the pressurizing port is used for being connected with pressurizing equipment; the thermoacoustic plate is overlapped in the resonance tube; the heater is arranged at one end of the thermoacoustic plate stack, and the cooler is arranged at the other end of the thermoacoustic plate stack; according to the invention, the liquid working medium with smaller isothermal compression rate is filled in the resonance tube, so that the output pressure amplitude is increased, a moving part is not required, the structure is simple, and the service life is long.

Description

Pressure wave generator

Technical Field

The present invention relates to the technical field of pressure wave generating equipment, and in particular to a pressure wave generating device.

Background technique

Pressure wave generators are used in many fields. For example, in electrically driven regenerative refrigerators such as Stirling refrigerators, pulse tube refrigerators and thermoacoustic refrigerators, pressure wave generators are required to drive them.

The working principle of the existing pressure wave generator is to use the reciprocating motion of the piston in the cylinder to generate pressure waves of a certain frequency. Since this pressure wave generator has moving parts, its structure is complex, its reliability is low, and its pressure amplitude is small, making it difficult to meet the driving requirements of equipment with higher pressure amplitudes.

Summary of the invention

The present invention provides a pressure wave generating device, which is used to solve or improve the problems of the existing pressure wave generator having a complex structure and a small pressure amplitude.

The present invention provides a pressure wave generating device, comprising: a resonance tube, a thermoacoustic plate stack, a heater and a cooler; the resonance tube is filled with a liquid working medium, and a pressurizing port and a pressure wave output surface are provided on the resonance tube, and the pressurizing port is used to connect with a pressurizing device; the thermoacoustic plate stack is arranged in the resonance tube; the heater is arranged at one end of the thermoacoustic plate stack; and the cooler is arranged at the other end of the thermoacoustic plate stack.

According to a pressure wave generating device provided by the present invention, the liquid working medium includes any one of liquid sodium, mercury and propylene.

According to a pressure wave generating device provided by the present invention, the resonance tube includes a standing wave resonance tube; the heater, the thermoacoustic plate stack and the cooler are arranged in sequence along the axial direction of the standing wave resonance tube, the standing wave resonance tube has a first port and a second port that are separated from each other along the axial direction of the standing wave resonance tube, and the heater, the thermoacoustic plate stack and the cooler are arranged close to the first port or the second port; when the heater, the thermoacoustic plate stack and the cooler are arranged close to the first port, the distance between the heater and the first port is smaller than the distance between the cooler and the first port; when the heater, the thermoacoustic plate stack and the cooler are arranged close to the second port, the distance between the heater and the second port is smaller than the distance between the cooler and the second port.

According to a pressure wave generating device provided by the present invention, the pressurizing port and the pressure wave output surface are arranged at the same end of the standing wave resonance tube along the axial direction of the standing wave resonance tube, or the pressurizing port and the pressure wave output surface are arranged at two ends of the standing wave resonance tube along the axial direction of the standing wave resonance tube.

According to a pressure wave generating device provided by the present invention, the resonance tube comprises a traveling wave resonance tube; the traveling wave resonance tube is ring-shaped, the circumference of the traveling wave resonance tube is equal to a sound wave wavelength, and a phase modulation tube section is provided on the traveling wave resonance tube.

According to a pressure wave generating device provided by the present invention, the phase adjustment tube section includes a capacitive tube, the cross-sectional area of the capacitive tube is larger than the cross-sectional area of the traveling wave resonance tube, and the distance between the capacitive tube and the thermoacoustic plate stack along the axial direction of the traveling wave resonance tube is equal to one quarter of the wavelength of the sound wave.

According to a pressure wave generating device provided by the present invention, the phase-adjusting tube section includes a resistive tube, the cross-sectional area of the resistive tube is smaller than the cross-sectional area of the traveling wave resonance tube, and the distance between the resistive tube and the thermoacoustic plate stack along the axial direction of the traveling wave resonance tube is equal to half of the wavelength of the sound wave.

According to a pressure wave generating device provided by the present invention, the resonance tube includes a traveling standing wave resonance tube; the traveling standing wave resonance tube includes a first tube segment and a second tube segment, the first tube segment is annular, and the second tube segment is linear, and the heater, the thermoacoustic plate stack and the cooler are arranged in the first tube segment.

According to a pressure wave generating device provided by the present invention, a plurality of flow channels are provided on the thermoacoustic plate stack, the plurality of flow channels are parallel to each other, and the flow channels extend along the axial direction of the resonance tube.

According to a pressure wave generating device provided by the present invention, the thermoacoustic plate stack comprises porous foam or stacked wire mesh.

The pressure wave generating device provided by the present invention uses liquid as the working fluid and realizes the output of pressure waves at the pressure wave output surface by utilizing the thermoacoustic effect. When it is necessary to generate pressure waves, the pressure-increasing device pressurizes the resonance tube through the pressurizing port, thereby pressurizing the liquid working fluid, and turning on the heater and the cooler, thereby forming a temperature gradient in the liquid working fluid in the thermoacoustic plate stack. When the temperature gradient exceeds the oscillation critical value, the liquid working fluid will oscillate, and the formed pressure wave is output from the pressure wave output surface. Compared with the gas working fluid, the isothermal compression rate of the liquid working fluid is much lower than that of the gas working fluid. Therefore, under a certain acoustic power output, a much larger pressure amplitude than that of the gas working fluid can be obtained, and correspondingly, the velocity amplitude is also much smaller than that of the gas working fluid. An acoustic power flow rate of tens of watts can be accompanied by a pressure amplitude of several megapascals, while the existing pressure waves generated by moving parts are generally below 1 megapascal. Therefore, the pressure wave generating device of the present invention improves the pressure amplitude of the pressure wave, and does not need to set moving parts, has a simple structure, good maintenance-free performance, and a long service life.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

FIG1 is a schematic diagram of the structure of a pressure wave generating device provided by the present invention;

FIG2 is a second schematic diagram of the structure of the pressure wave generating device provided by the present invention;

FIG3 is a third schematic diagram of the structure of the pressure wave generating device provided by the present invention;

FIG4 is a fourth schematic diagram of the structure of the pressure wave generating device provided by the present invention;

FIG. 5 is a fifth structural schematic diagram of the pressure wave generating device provided by the present invention.

Reference numerals:

1: resonance tube; 11: standing wave resonance tube; 12: travelling wave resonance tube; 13: travelling standing wave resonance tube; 131: first tube section; 132: second tube section; 2: thermoacoustic plate stack; 3: heater; 4: cooler; 5: pressurization port; 6: pressure wave output surface; 71: capacitive tube; 72: resistive tube.

Detailed ways

In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

In the description of the embodiments of the present invention, it should be noted that the terms "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

A pressure wave generating device provided by the present invention is described below in conjunction with FIG. 1 .

As shown in FIG. 1 , the pressure wave generating device shown in this embodiment includes: a resonance tube 1 , a thermoacoustic plate stack 2 , a heater 3 and a cooler 4 .

The resonance tube 1 is filled with liquid working medium, and a pressurizing port 5 and a pressure wave output surface 6 are provided on the resonance tube 1. The pressurizing port 5 is used to connect with a pressurizing device; the thermoacoustic plate stack 2 is arranged in the resonance tube 1; the heater 3 is arranged at one end of the thermoacoustic plate stack 2, and the cooler 3 is arranged at the other end of the thermoacoustic plate stack 2.

Specifically, the pressure wave generating device shown in the present embodiment uses liquid as the working fluid, and realizes the output of pressure waves at the pressure wave output surface 6 by utilizing the thermoacoustic effect; when it is necessary to generate pressure waves, the pressure-increasing device pressurizes the resonance tube 1 through the pressurizing port 5, thereby pressurizing the liquid working fluid, and the heater 3 and the cooler 4 are turned on, so that a temperature gradient is formed in the liquid working fluid in the thermoacoustic plate stack 2. When the temperature gradient exceeds the critical value of the oscillation, the liquid working fluid will oscillate, and the formed pressure wave is output from the pressure wave output surface 6; compared with the gas working fluid, the isothermal compressibility of the liquid working fluid is much lower than that of the gas working fluid, so under a certain acoustic power output, a much larger pressure amplitude can be obtained than that of the gas working fluid, and correspondingly, the velocity amplitude is also much smaller than that of the gas working fluid, and an acoustic power flow rate of tens of watts can be accompanied by a pressure amplitude of several MPa, while the existing pressure waves generated by moving parts are generally below 1 MPa. Therefore, the pressure wave generating device shown in the present embodiment improves the pressure amplitude of the pressure wave, and does not require the provision of moving parts, has a simple structure, good maintenance-free performance, and a long service life.

It should be noted that the pressurizing device can pressurize by gas or liquid. In the case of gas pressurization, nitrogen, helium or argon, etc., which do not react with the liquid working fluid, can be input into the resonance tube 1; in the case of liquid pressurization, a liquid of the same substance as the liquid working fluid can be input into the resonance tube 1 to achieve pressurization, or a liquid that does not react with the liquid working fluid can be used to achieve pressurization. At this time, the liquid and the liquid working fluid can be isolated by an elastic membrane that is not easily corroded.

The following is an explanation of the principle that under a certain acoustic power output, a pressure amplitude much larger than that of a gas working fluid can be obtained, and correspondingly a velocity amplitude much smaller than that of a gas working fluid is obtained, in combination with the calculation formula of acoustic power.

The calculation formula of sound power is as follows:

Among them, |P ₁ | is the amplitude of pressure fluctuation, |U ₁ | is the amplitude of volume flow rate fluctuation, the amplitude of volume flow rate fluctuation is equal to the product of velocity amplitude and cross-sectional area, θ is the phase difference between pressure fluctuation and volume flow rate fluctuation, and θ can be kept basically unchanged in the thermoacoustic plate stack through structural design or phase modulation device. It can be seen from the calculation formula of acoustic work that when the acoustic work is constant, the amplitude of pressure fluctuation increases and the amplitude of volume flow rate fluctuation decreases. Under the condition that the structure does not change, the velocity amplitude also decreases.

The liquid working medium shown in this embodiment includes any one of liquid sodium, mercury or propylene. The liquid working medium should have a certain compressibility in the working state, and must satisfy T·β>0.1, where T is the temperature and β is the thermal expansion coefficient. Since the compressibility of the liquid is very low, only a small amount of gas or liquid needs to be injected to quickly increase the pressure in the resonance tube 1 to the required average pressure. A plurality of flow channels are provided on the thermoacoustic plate stack 2, and the plurality of flow channels are parallel to each other. The flow channels extend along the axial direction of the resonance tube, and the flow channels are used for the flow of the liquid working medium. Alternatively, the thermoacoustic plate stack 2 is a porous foam or a stacked wire mesh.

Furthermore, in actual use, the required average pressure should be slightly greater than twice the required pressure amplitude. If the average pressure is lower than twice the required pressure amplitude, negative pressure will be generated in the liquid working medium during the oscillation period, causing local evaporation of the liquid, and then cavitation will occur, resulting in deterioration of the performance of the pressure wave generating device. For example, if a pressure amplitude of 4 MPa is required to be generated by the pressure wave generating device, the average pressure can be set to 8.5 MPa.

In some embodiments, as shown in FIG. 1 , the resonance tube 1 shown in this embodiment includes a standing wave resonance tube 11, and the structure of the standing wave resonance tube 11 is in the form of a straight tube; the heater 3, the thermoacoustic plate stack 2 and the cooler 4 are sequentially arranged along the axial direction of the standing wave resonance tube 11, and the standing wave resonance tube 11 has a first port and a second port that are separated from each other along the axial direction of the standing wave resonance tube 11, and the heater 3, the thermoacoustic plate stack 2 and the cooler 4 are arranged close to the first port or the second port. It can be understood that it is necessary to avoid arranging the heater 3, the thermoacoustic plate stack 2 and the cooler 4 in the middle of the standing wave resonance tube 11, so as to prevent the heater 3, the thermoacoustic plate stack 2 and the cooler 4 from being arranged in the middle of the standing wave resonance tube 11. Ensure efficient output of pressure waves; no matter the heater 3, the thermoacoustic plate stack 2 and the cooler 4 are arranged close to the first port or close to the second port, the heater 3 is arranged at a position closer to the port relative to the cooler 4, that is, when the heater 3, the thermoacoustic plate stack 2 and the cooler 4 are arranged close to the first port, the distance between the heater 3 and the first port is smaller than the distance between the cooler 4 and the first port; when the heater 3, the thermoacoustic plate stack 2 and the cooler 4 are arranged close to the second port, the distance between the heater 3 and the second port is smaller than the distance between the cooler 4 and the second port.

The positions of the pressurizing port 5 and the pressure wave output surface 6 on the standing wave resonance tube 11 can be flexibly set according to actual needs.

In some embodiments, as shown in FIG. 1 , the pressurizing port 5 and the pressure wave output surface 6 shown in this embodiment are arranged at the same end of the standing wave resonance tube 11 along the axial direction of the standing wave resonance tube 11, or the pressurizing port 5 and the pressure wave output surface 6 are arranged at both ends of the standing wave resonance tube 11 along the axis of the standing wave resonance tube 11. At this time, the liquid working medium is pressurized from one end of the standing wave resonance tube 11, and the pressure wave is output from the other end of the standing wave resonance tube 11.

Further, as shown in Figure 1, when the pressurization port 5 and the pressure wave output surface 6 are respectively arranged at the two ends of the standing wave resonance tube 11, the heater 3 is located on the side close to the pressurization port 5, and the cooler 4 is located on the side close to the pressure wave output surface 6, so that the temperature close to the pressure wave output surface 6 is relatively low.

In some embodiments, as shown in Figure 1, the pressure wave output surface 6 shown in this embodiment is arranged at the end of the standing wave resonance tube 11 along the axial direction of the standing wave resonance tube 11, and the generated pressure wave is output along the axial direction of the standing wave resonance tube 11.

In some embodiments, the pressure wave output surface 6 is disposed on the tube wall of the standing wave resonance tube 1 , and the generated pressure wave is output along the radial direction of the standing wave resonance tube 11 .

In some embodiments, as shown in Figures 2 to 4, the resonance tube 1 shown in this embodiment includes a traveling wave resonance tube 12, and the structure of the traveling wave resonance tube 12 is annular; the circumference of the traveling wave resonance tube 12 is equal to one sound wave wavelength, and a phase modulation tube section is provided on the traveling wave resonance tube 12.

Specifically, the phase adjustment pipe section is used to ensure the phase of the gas in the thermoacoustic plate stack 2, thereby ensuring the efficiency of the thermoacoustic conversion.

The phase adjustment tube section includes a capacitive tube or a resistive tube, that is, any one of the capacitive tube and the resistive tube can be used to adjust the phase of the gas.

In some embodiments, as shown in Figures 2 and 3, the phase-adjusting tube section shown in this embodiment includes a capacitive tube 71, the cross-sectional area of the capacitive tube 71 is larger than the cross-sectional area of the traveling wave resonance tube 12, and the distance between the capacitive tube 71 and the thermoacoustic plate stack 2 along the axial direction of the traveling wave resonance tube 12 is equal to one quarter of the wavelength of a sound wave, that is, the distance between the capacitive tube 71 and the thermoacoustic plate stack 2 is equal to one quarter of the circumference of the traveling wave resonance tube 12, and the capacitive tube 71 can be located either on the right side as shown in Figure 2 or on the left side as shown in Figure 3.

In some embodiments, as shown in FIG. 4 , the phase-adjusting tube section shown in this embodiment includes a resistive tube 72, the cross-sectional area of the resistive tube 72 is smaller than the cross-sectional area of the traveling wave resonance tube 12, and the distance between the resistive tube 72 and the thermoacoustic plate stack 2 along the axial direction of the traveling wave resonance tube 12 is equal to half of the wavelength of a sound wave, that is, the distance between the resistive tube 72 and the thermoacoustic plate stack 2 is equal to half of the circumference of the traveling wave resonance tube 12, and the resistive tube 72 and the thermoacoustic plate stack 2 are arranged opposite to each other.

In some embodiments, as shown in Figure 5, the resonance tube 1 shown in this embodiment includes a traveling standing wave resonance tube 13, and the traveling standing wave resonance tube 13 includes a first tube segment 131 and a second tube segment 132. The first tube segment 131 is annular, and the second tube segment 132 is linear, that is, the traveling standing wave resonance tube 13 is equivalent to being composed of a traveling wave resonance tube 12 and a standing wave resonance tube 11, and the heater 3, the thermoacoustic plate stack 2 and the cooler 4 are arranged in the first tube segment 131.

The pressurizing port 5 may be disposed on the first pipe section 131 , and the pressure wave output surface 6 may be disposed on the second pipe section 132 .

In some embodiments, the cooler 4 shown in this embodiment uses water cooling, air cooling or radiation cooling to achieve cooling.

The heating part of the heater 3 and the cooling part of the cooler 4 can be arranged in the resonance tube 1, and the heating part and the cooling part will be in contact with the liquid working medium. Therefore, the heating part and the cooling part should be constructed of materials resistant to corrosion by the liquid working medium. Similarly, the resonance tube 1 and the thermoacoustic plate stack 2 should also be constructed of materials resistant to corrosion by the liquid working medium.

In one embodiment, the liquid working fluid used in the resonance tube 1 is liquid sodium, the cooling temperature of the cooler 4 is 110°C, that is, the cold end temperature of the thermoacoustic plate stack 2 is 110°C, and the cold end temperature is greater than the melting point temperature of sodium 98°C. The heating temperature of the heater 3 is 480°C, that is, the hot end temperature of the thermoacoustic plate stack 2 is 480°C, thereby establishing a temperature gradient exceeding the critical value of oscillation in the liquid working fluid in the thermoacoustic plate stack 2, so that the liquid working fluid will oscillate. Compared with traditional gas thermoacoustic engines, by adopting a liquid working fluid with a certain compressibility, the isothermal compression rate of the liquid working fluid is much lower than that of the gas, so that a much larger pressure amplitude than that of traditional gas thermoacoustic engines can be obtained. During the research and development process, the applicant conducted experiments and calculations and found that when the heating power is 1000W, the sound power generated by the pressure wave generating device can reach tens of watts, and the pressure amplitude at the pressure wave output surface 6 can reach more than 6 MPa, which can meet the driving requirements of equipment with higher pressure amplitudes.

Furthermore, the applicant discovered through theoretical analysis that the frequency of the pressure wave depends on the characteristics of the liquid working medium and the length of the resonance tube 1. In theory, the frequency range of the output pressure wave is between a few hertz and thousands of hertz.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1. A pressure wave generating device, comprising: A resonance tube, wherein the resonance tube is filled with a liquid working medium, and a pressurizing port and a pressure wave output surface are provided on the resonance tube, wherein the pressurizing port is used to be connected to a pressurizing device; A thermoacoustic plate stack, wherein the thermoacoustic plate stack is arranged in the resonance tube; a heater, the heater being disposed at one end of the thermoacoustic plate stack; A cooler is arranged at the other end of the thermoacoustic plate stack. 2. The pressure wave generating device according to claim 1, characterized in that: The liquid working medium includes any one of liquid sodium, mercury and propylene. 3. The pressure wave generating device according to claim 1, characterized in that: The resonance tube comprises a standing wave resonance tube; The heater, the thermoacoustic plate stack and the cooler are sequentially arranged along the axial direction of the standing wave resonance tube, the standing wave resonance tube has a first port and a second port that are separated from each other along the axial direction of the standing wave resonance tube, and the heater, the thermoacoustic plate stack and the cooler are arranged close to the first port or the second port; In the case where the heater, the thermoacoustic plate stack and the cooler are arranged close to the first port, the distance between the heater and the first port is smaller than the distance between the cooler and the first port; In a case where the heater, the thermoacoustic plate stack, and the cooler are disposed close to the second port, a distance between the heater and the second port is smaller than a distance between the cooler and the second port. 4. The pressure wave generating device according to claim 3, characterized in that: The pressurizing port and the pressure wave output surface are arranged at the same end of the standing wave resonance tube along the axial direction of the standing wave resonance tube, or the pressurizing port and the pressure wave output surface are arranged at two ends of the standing wave resonance tube along the axial direction of the standing wave resonance tube. 5. The pressure wave generating device according to claim 1, characterized in that: The resonant tube comprises a traveling wave resonant tube; The traveling wave resonance tube is ring-shaped, the circumference of the traveling wave resonance tube is equal to a sound wave wavelength, and a phase modulation tube section is provided on the traveling wave resonance tube. 6. The pressure wave generating device according to claim 5, characterized in that: The phase-adjusting tube section includes a capacitive tube, the cross-sectional area of the capacitive tube is larger than the cross-sectional area of the traveling wave resonance tube, and the distance between the capacitive tube and the thermoacoustic plate stack along the axial direction of the traveling wave resonance tube is equal to one quarter of the wavelength of the sound wave. 7. The pressure wave generating device according to claim 5, characterized in that: The phase-adjusting tube section includes a resistive tube, the cross-sectional area of the resistive tube is smaller than the cross-sectional area of the traveling wave resonance tube, and the distance between the resistive tube and the thermoacoustic plate stack along the axial direction of the traveling wave resonance tube is equal to half of the wavelength of the sound wave. 8. The pressure wave generating device according to claim 1, characterized in that: The resonance tube comprises a traveling standing wave resonance tube; The traveling standing wave resonance tube comprises a first tube section and a second tube section, the first tube section is annular, the second tube section is linear, and the heater, the thermoacoustic plate stack and the cooler are arranged in the first tube section. 9. The pressure wave generating device according to claim 1, characterized in that: A plurality of flow channels are arranged on the thermoacoustic plate stack, the plurality of flow channels are parallel to each other, and the flow channels extend along the axial direction of the resonance tube. 10. The pressure wave generating device according to claim 1, characterized in that: The thermoacoustic panel stack comprises porous foam or stacked wire mesh.