Pressure wave generating device

Abstract

The present application relates to the technical field of pressure wave generating device, and 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 liquid working medium, and the resonance tube is provided with a pressurizing port and a pressure wave output surface; the pressurizing port is used for being connected 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; the present application fills the liquid working medium with a small isothermal compression rate in the resonance tube, increases the output pressure amplitude, and does not need to use moving parts, so that the structure is simple, and the service life is long.

Description

Technical Field

[0001] This invention relates to the field of pressure wave generating equipment technology, and more particularly to a pressure wave generating device. Background Technology

[0002] Pressure wave generators have applications in many fields. For example, they are required to drive electrically driven regenerative refrigerators such as Stirling refrigerators, pulse tube refrigerators, and thermoacoustic refrigerators.

[0003] The existing pressure wave generator works by using the reciprocating motion of the piston in the cylinder to generate a pressure wave of a certain frequency. Because this pressure wave generator has moving parts, its structure is relatively complex, its reliability is low, and its pressure amplitude is small, making it difficult to meet the driving requirements of equipment with higher pressure amplitude. Summary of the Invention

[0004] The present invention provides a pressure wave generating device to solve or improve the problems of existing pressure wave generators having complex structures and small pressure amplitudes.

[0005] This invention provides a pressure wave generating device, comprising: a resonant tube, a thermoacoustic plate stack, a heater, and a cooler; the resonant tube is filled with a liquid working fluid, and the resonant tube is provided with a pressurization port and a pressure wave output surface, the pressurization port being used to connect to a pressurizing device; the thermoacoustic plate stack is disposed inside the resonant tube; the heater is disposed at one end of the thermoacoustic plate stack; and the cooler is disposed at the other end of the thermoacoustic plate stack.

[0006] According to the pressure wave generating device provided by the present invention, the liquid working medium includes any one of liquid sodium, mercury and propylene.

[0007] According to a pressure wave generating device provided by the present invention, the resonant tube includes a standing wave resonant tube; the heater, the thermoacoustic plate stack, and the cooler are arranged sequentially along the axial direction of the standing wave resonant tube, and the standing wave resonant tube has a first port and a second port facing away from each other along the axial direction of the standing wave resonant tube; 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 less 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 less than the distance between the cooler and the second port.

[0008] According to a pressure wave generating device provided by the present invention, the pressure port and the pressure wave output surface are disposed at the same end of the standing wave resonator along the axial direction of the standing wave resonator, or the pressure port and the pressure wave output surface are disposed at opposite ends of the standing wave resonator along the axial direction of the standing wave resonator.

[0009] According to a pressure wave generating device provided by the present invention, the resonant tube includes a traveling wave resonant tube; the traveling wave resonant tube is annular, the circumference of the traveling wave resonant tube is equal to one sound wave wavelength, and a phase tuning tube section is provided on the traveling wave resonant tube.

[0010] According to a pressure wave generating device provided by the present invention, the phase-tuning tube section includes a capacitive tube, the cross-sectional area of ​​which is larger than the cross-sectional area of ​​the traveling wave resonator tube, and the distance between the capacitive tube and the thermoacoustic plate stacked along the axial direction of the traveling wave resonator tube is equal to one-quarter of the wavelength of the sound wave.

[0011] According to a pressure wave generating device provided by the present invention, the phase-tuning 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 resonator tube, and the distance between the resistive tube and the thermoacoustic plate stacked along the axial direction of the traveling wave resonator tube is equal to half of the wavelength of the sound wave.

[0012] According to a pressure wave generating device provided by the present invention, the resonant tube includes a traveling-standing wave resonant tube; the traveling-standing wave resonant tube includes a first tube segment and a second tube segment, the first tube segment is annular, the second tube segment is linear, and the heater, the thermoacoustic plate stack and the cooler are disposed in the first tube segment.

[0013] According to a pressure wave generating device provided by the present invention, the thermoacoustic plate stack is provided with a plurality of flow channels, the plurality of flow channels are parallel to each other, and the flow channels extend along the axial direction of the resonant tube.

[0014] According to a pressure wave generating device provided by the present invention, the thermoacoustic plate stack comprises porous foam or stacked wire mesh.

[0015] The pressure wave generator provided by this invention uses a liquid as the working medium and utilizes the thermoacoustic effect to output a pressure wave at the pressure wave output surface. When a pressure wave needs to be generated, a pressurizing device pressurizes the resonant tube through a pressurizing port, thereby pressurizing the liquid working medium. The heater and cooler are turned on, thus forming a temperature gradient in the liquid working medium within the thermoacoustic plate stack. When the temperature gradient exceeds the oscillation critical value, the liquid working medium will oscillate, and the resulting pressure wave will be output from the pressure wave output surface. Compared to a gaseous working medium, the isothermal compressibility of the liquid working medium is much lower than that of the gaseous working medium. Therefore, under a certain acoustic power output, a much larger pressure amplitude can be obtained than that of a gaseous working medium, and the corresponding velocity amplitude is also much smaller. A sound power flow rate of tens of watts can be accompanied by a pressure amplitude of several megapascals, while existing pressure waves generated by moving parts are generally below 1 megapascal. Therefore, the pressure wave generator of this invention increases the pressure amplitude of the pressure wave, and does not require moving parts, has a simple structure, good maintenance-free operation, and long service life. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is one of the structural schematic diagrams of the pressure wave generating device provided by the present invention;

[0018] Figure 2 This is the second schematic diagram of the pressure wave generating device provided by the present invention;

[0019] Figure 3 This is the third schematic diagram of the pressure wave generating device provided by the present invention;

[0020] Figure 4 This is the fourth schematic diagram of the pressure wave generating device provided by the present invention;

[0021] Figure 5 This is the fifth schematic diagram of the pressure wave generating device provided by the present invention.

[0022] Figure label:

[0023] 1: Resonant tube; 11: Standing wave resonant tube; 12: Traveling wave resonant tube; 13: Traveling-standing wave resonant tube; 131: First tube segment; 132: Second tube segment; 2: Thermoacoustic plate stack; 3: Heater; 4: Cooler; 5: Pressurization port; 6: Pressure wave output surface; 71: Capacitive tube; 72: Resistive tube. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0025] In the description of the embodiments of the present invention, it should be noted that the terms "inner" and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] The following is combined Figure 1 This invention describes a pressure wave generating device.

[0027] like Figure 1 As shown in the figure, the pressure wave generating device shown in this embodiment includes: a resonant tube 1, a thermoacoustic plate stack 2, a heater 3, and a cooler 4.

[0028] The resonant tube 1 is filled with a liquid working medium. The resonant tube 1 is provided with a pressurization port 5 and a pressure wave output surface 6. The pressurization port 5 is used to connect to a pressurization device. The thermoacoustic plate stack 2 is located inside the resonant tube 1. The heater 3 is located at one end of the thermoacoustic plate stack 2, and the cooler 3 is located at the other end of the thermoacoustic plate stack 2.

[0029] Specifically, the pressure wave generating device shown in this embodiment uses a liquid as the working medium and utilizes the thermoacoustic effect to output a pressure wave at the pressure wave output surface 6. When a pressure wave needs to be generated, a pressurizing device pressurizes the resonant tube 1 through the pressurizing port 5, thereby pressurizing the liquid working medium. The heater 3 and the cooler 4 are turned on, thereby forming a temperature gradient in the liquid working medium within the thermoacoustic plate stack 2. When the temperature gradient exceeds the oscillation critical value, the liquid working medium will oscillate, and the resulting pressure wave is output from the pressure wave output surface 6. Compared with the gaseous working medium, the isothermal compressibility of the liquid working medium is much lower than that of the gaseous working medium. Therefore, under a certain acoustic power output, a much larger pressure amplitude can be obtained than that of the gaseous working medium. Correspondingly, the velocity amplitude is also much smaller than that of the gaseous working medium. A sound power flow rate of tens of watts can be accompanied by a pressure amplitude of several megapascals. In contrast, the pressure waves generated by existing moving parts are generally below 1 megapascal. Thus, the pressure wave generating device shown in this embodiment increases the pressure amplitude of the pressure wave, and does not require moving parts. It has a simple structure, good maintenance-free operation, and long service life.

[0030] It should be noted that the pressurization device can pressurize using either gas or liquid. When pressurizing using gas, gases such as nitrogen, helium, or argon that do not react with the liquid working medium can be introduced into the resonant tube 1. When pressurizing using liquid, a liquid of the same substance as the liquid working medium can be introduced into the resonant tube 1 to achieve pressurization. Alternatively, a liquid that does not react with the liquid working medium can be used to achieve pressurization. In this case, the liquid and the liquid working medium can be isolated by a non-corrosive elastic membrane.

[0031] The following explanation, using the formula for calculating acoustic power, explains the principle that, under a certain acoustic power output, a pressure amplitude much larger than that of a gaseous working medium can be obtained, while the corresponding velocity amplitude is also much smaller than that of a gaseous working medium.

[0032] The formula for calculating acoustic power is as follows:

[0033]

[0034] Where |P1| is the amplitude of the pressure fluctuation, |U1| is the amplitude of the volumetric flow rate fluctuation, the amplitude of the volumetric flow rate fluctuation is equal to the product of the velocity amplitude and the cross-sectional area, and θ is the phase difference between the pressure fluctuation and the volumetric flow rate fluctuation. θ can be kept basically constant in the thermoacoustic plate stack through structural design or phase adjustment device. It can be seen from the formula for calculating acoustic power that, under the condition of constant acoustic power, as the amplitude of the pressure fluctuation increases, the amplitude of the volumetric flow rate fluctuation decreases, and under the condition that the structure does not change, the velocity amplitude also decreases.

[0035] 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, which must satisfy T·β>0.1, where T is the temperature and β is the coefficient of thermal expansion. Since the compressibility of the liquid is very low, only a small amount of gas or liquid needs to be injected to make the pressure in the resonant tube 1 rise rapidly to the required average pressure. The thermoacoustic plate stack 2 is provided with multiple flow channels, which are parallel to each other and extend along the axial direction of the resonant tube. The flow channels are used to supply the flow of the liquid working medium. Alternatively, the thermoacoustic plate stack 2 can be a porous foam or a stacked wire mesh.

[0036] Furthermore, in practical use, the required average pressure should be slightly greater than twice the required pressure amplitude. If the average pressure is less than twice the required pressure amplitude, the liquid working fluid will generate negative pressure during the oscillation cycle, causing localized liquid evaporation and cavitation, leading to a deterioration in the performance of the pressure wave generator. For example, if a pressure amplitude of 4 MPa is required to be generated by this pressure wave generator, then the average pressure can be set to 8.5 MPa.

[0037] In some embodiments, such as Figure 1 As shown in the figure, the resonant tube 1 in this embodiment includes a standing wave resonant tube 11, which has a straight tube structure. The heater 3, thermoacoustic plate stack 2, and cooler 4 are arranged sequentially along the axial direction of the standing wave resonant tube 11. The standing wave resonant tube 11 has a first port and a second port that are opposite to each other along its axial direction. The heater 3, thermoacoustic plate stack 2, and cooler 4 are positioned close to either the first or second port. It is understood that it is necessary to avoid placing the heater 3, thermoacoustic plate stack 2, and cooler 4 in the middle of the standing wave resonant tube 11 to ensure the pressure wave... High-efficiency output; regardless of whether the heater 3, thermoacoustic plate stack 2, and cooler 4 are located near the first port or near the second port, the heater 3 is located closer to the port than the cooler 4. That is, when the heater 3, thermoacoustic plate stack 2, and cooler 4 are located near the first port, the distance between the heater 3 and the first port is less than the distance between the cooler 4 and the first port. When the heater 3, thermoacoustic plate stack 2, and cooler 4 are located near the second port, the distance between the heater 3 and the second port is less than the distance between the cooler 4 and the second port.

[0038] The positions of the pressurization port 5 and the pressure wave output surface 6 on the standing wave resonator tube 11 can be flexibly set according to actual needs.

[0039] In some embodiments, such as Figure 1As shown in the embodiment, the pressurization port 5 and the pressure wave output surface 6 are located at the same end of the standing wave resonator 11 along the axial direction of the standing wave resonator 11. Alternatively, the pressurization port 5 and the pressure wave output surface 6 are located at opposite ends of the standing wave resonator 11 along the axial direction of the standing wave resonator 11. In this case, the liquid working fluid is pressurized from one end of the standing wave resonator 11, and the pressure wave is output from the other end of the standing wave resonator 11.

[0040] Furthermore, such as Figure 1 As shown, with the pressurization port 5 and the pressure wave output surface 6 located at opposite ends of the standing wave resonator tube 11, the heater 3 is located on the side closer to the pressurization port 5, and the cooler 4 is located on the side closer to the pressure wave output surface 6, so that the temperature near the pressure wave output surface 6 is relatively low.

[0041] In some embodiments, such as Figure 1 As shown in the figure, the pressure wave output surface 6 shown in this embodiment is located at the end of the standing wave resonator 11 along the axial direction of the standing wave resonator 11, so the generated pressure wave is output along the axial direction of the standing wave resonator 11.

[0042] In some embodiments, the pressure wave output surface 6 is disposed on the tube wall of the standing wave resonator 1, and the generated pressure wave is output along the radial direction of the standing wave resonator 11.

[0043] In some embodiments, such as Figures 2 to 4 As shown, the resonant tube 1 in this embodiment includes a traveling wave resonant tube 12, which has a ring-shaped structure. The circumference of the traveling wave resonant tube 12 is equal to one sound wave wavelength, and a phase-tuning tube section is provided on the traveling wave resonant tube 12.

[0044] Specifically, the phase-adjusting pipe section is used to ensure the phase of the gas in the thermoacoustic plate stack 2, thereby ensuring the efficiency of thermoacoustic conversion.

[0045] The phase-adjusting tube section includes either a capacitive tube or a resistive tube; either a capacitive tube or a resistive tube can be used to adjust the phase of the gas.

[0046] In some embodiments, such as Figure 2 and Figure 3 As shown, the phase-tuning tube section in this embodiment includes a capacitive tube 71. The cross-sectional area of ​​the capacitive tube 71 is larger than that of the traveling wave resonator 12. The distance between the capacitive tube 71 and the thermoacoustic plate stack 2 along the axial direction of the traveling wave resonator 12 is equal to one-quarter of the wavelength of an acoustic 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 resonator 12. The capacitive tube 71 can be located as follows: Figure 2 The position on the right side of the center can also be located as follows: Figure 3 The position is on the left side of the center.

[0047] In some embodiments, such as Figure 4As shown, the phase-tuning tube section in this embodiment includes a resistive tube 72. The cross-sectional area of ​​the resistive tube 72 is smaller than that of the traveling wave resonator tube 12. The distance between the resistive tube 72 and the thermoacoustic plate stack 2 along the axial direction of the traveling wave resonator tube 12 is equal to half of the wavelength of an acoustic 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 resonator tube 12. The resistive tube 72 and the thermoacoustic plate stack 2 are arranged opposite to each other.

[0048] In some embodiments, such as Figure 5 As shown, the resonant tube 1 in this embodiment includes a traveling-standing wave resonant tube 13. The traveling-standing wave resonant 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 resonant tube 13 is equivalent to being composed of a traveling wave resonant tube 12 and a standing wave resonant tube 11. The heater 3, the thermoacoustic plate stack 2, and the cooler 4 are disposed in the first tube segment 131.

[0049] The pressurization port 5 can be set on the first pipe section 131, and the pressure wave output surface 6 can be set on the second pipe section 132.

[0050] In some embodiments, the cooler 4 shown in this embodiment uses water cooling, air cooling, or radiant cooling to achieve cooling.

[0051] The heating part of heater 3 and the cooling part of cooler 4 can be set inside resonant tube 1. Then the heating part and the cooling part will be in contact with the liquid working fluid. Therefore, the heating part and the cooling part should be constructed with materials that are resistant to liquid working fluid corrosion. Similarly, resonant tube 1 and thermoacoustic plate stack 2 should also be constructed with materials that are resistant to liquid working fluid corrosion.

[0052] In one embodiment, the liquid working medium used in the resonant 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, which is greater than the melting point of sodium, 98°C, and 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. Thus, a temperature gradient exceeding the oscillation critical value is established in the liquid working medium in the thermoacoustic plate stack 2, causing the liquid working medium to oscillate. Compared with traditional gas thermoacoustic engines, by using a liquid working medium with a certain compressibility, the isothermal compressibility of the liquid working medium is much lower than that of gas, thus a much larger pressure amplitude can be obtained than that of traditional gas thermoacoustic engines. During the research and development process, the applicant conducted experiments and calculations and found that when the heating power is 1000W, the acoustic power generated by this pressure wave generator 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 amplitude.

[0053] Furthermore, the applicant discovered through theoretical analysis that the frequency of the pressure wave depends on the characteristics of the liquid working fluid and the length of the resonant tube 1. Theoretically, the frequency range of the output pressure wave is between a few hertz and thousands of hertz.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A pressure wave generating device, characterized in that, include: A resonant tube, which is filled with a liquid working fluid, has a pressure port and a pressure wave output surface on it, and the pressure port is used to connect to a pressure device; Thermoacoustic plates are stacked inside the resonant tube; A heater, wherein the heater is disposed at one end of the thermoacoustic plate stack; A cooler is located 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 resonant tube includes a standing wave resonant tube; The heater, the thermoacoustic plate stack, and the cooler are arranged sequentially along the axial direction of the standing wave resonator. The standing wave resonator has a first port and a second port that are opposite to each other along the axial direction of the standing wave resonator. 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 positioned close to the first port, the distance between the heater and the first port is less than the distance between the cooler and the first port; When the heater, the thermoacoustic plate stack, and the cooler are positioned close to the second port, the distance between the heater and the second port is less than the distance between the cooler and the second port.

4. The pressure wave generating device according to claim 3, characterized in that, The pressurization port and the pressure wave output surface are located at the same end of the standing wave resonator along the axial direction of the standing wave resonator, or the pressurization port and the pressure wave output surface are located at opposite ends of the standing wave resonator along the axial direction of the standing wave resonator.

5. The pressure wave generating device according to claim 1, characterized in that, The resonant tube includes a traveling wave resonant tube; The traveling wave resonator is ring-shaped, and its circumference is equal to the wavelength of an acoustic wave. The traveling wave resonator is provided with a phase-tuning tube section.

6. The pressure wave generating device according to claim 5, characterized in that, The phase-tuning tube section includes a capacitive tube, the cross-sectional area of ​​which is larger than that of the traveling wave resonator tube, and the distance between the capacitive tube and the thermoacoustic plate stacked along the axial direction of the traveling wave resonator 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-tuning tube section includes a resistive tube, the cross-sectional area of ​​which is smaller than that of the traveling wave resonator tube, and the distance between the resistive tube and the thermoacoustic plate stacked along the axial direction of the traveling wave resonator tube is equal to half the wavelength of the sound wave.

8. The pressure wave generating device according to claim 1, characterized in that, The resonant tube includes a traveling-standing wave resonant tube; The traveling-standing wave resonator includes a first tube segment and a second tube segment. The first tube segment is annular, and the second tube segment is linear. The heater, the thermoacoustic plate stack, and the cooler are disposed within the first tube segment.

9. The pressure wave generating device according to claim 1, characterized in that, The thermoacoustic plate stack is provided with multiple flow channels, which are parallel to each other and extend along the axial direction of the resonant tube.

10. The pressure wave generating device according to claim 1, characterized in that, The thermoacoustic plate stack includes porous foam or stacked wire mesh.

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