JP2023028062A - Thermoacoustic system and connection method for thermoacoustic engine - Google Patents

Abstract

To provide, for a thermoacoustic system in which a thermoacoustic engine and another engine are connected to each other, a technique for easily and reliably matching the acoustic impedances of connecting surfaces of the two engines.SOLUTION: In a thermoacoustic system 100 in which a first engine 10 that is a thermoacoustic engine and a second engine 20 that receives supply of acoustic energy are connected: the second engine 20 includes a receiving portion 22 that receives the acoustic energy supplied from the first engine 10 by a receiving surface C3p and generates predetermined thrust Fp; the pressure amplitude P2p of a second connection surface C2p and the pressure amplitude P3p of the receiving surface C3p are the same; and at least one of the area A1 of a first connection surface C1 and the area A2p of the second connection surface C2p is determined so that the predetermined thrust Fp is generated at the receiving portion 22 and the acoustic impedance Z1 of the first connection surface C1 matches with the acoustic impedance Z2p of the second connection surface C2p.SELECTED DRAWING: Figure 1

Description

The present invention relates to a thermoacoustic system in which a thermoacoustic engine that supplies acoustic energy and another engine that receives acoustic energy are connected, and a connection method for connecting the thermoacoustic engine to another engine.

A phenomenon in which sound waves are generated by a thermal factor is known as a thermoacoustic phenomenon. An example of a thermoacoustic phenomenon will be described with reference to FIG. In the following, for convenience of explanation, a small mass of gas is defined. This is a mass larger than gas molecules, and is hereinafter referred to as "gas particle Q".

Suppose now that the gas particle Q in the narrow tube is displaced in the +X direction while being compressed. Since the velocity of the gas particles Q is relatively high during the displacement, no heat is exchanged with the tube wall W. Therefore, the change at this time is adiabatic, and the temperature of the gas particle Q rises.

At the point A where the displacement in the +X direction is maximum, the velocity of the gas particles Q is relatively small, so heat is exchanged with the tube wall W. When the temperature of the tube wall W in the vicinity of the point A is higher than the temperature of the gas particles Q, heat flows into the gas particles Q from the tube wall W. That is, the gas particles Q are given heat.

Next, assume that the gas particle Q is displaced in the -X direction while being expanded. The change at this time is also adiabatic, and the temperature of the gas particles Q decreases.

At point B where the displacement in the −X direction is maximum, heat exchange with the tube wall W takes place. When the temperature of the tube wall W in the vicinity of the point B is lower than the temperature of the gas particles Q, heat flows from the gas particles Q to the tube wall W. That is, heat is taken from the gas particles Q.

When the above cycle is repeated, the amplitude of the gas particles Q gradually increases and becomes unstable, generating large pressure fluctuations (sound waves). Thus, acoustic waves are generated from thermal agents when specific relationships are formed between the phases of vibration and the phases of heating and cooling.

As one of the heat engines using this thermoacoustic phenomenon, a thermoacoustic engine (also called a thermoacoustic engine) that generates acoustic energy by inputting thermal energy is known. A configuration example of a thermoacoustic engine will be described with reference to FIG.

The thermoacoustic engine 9 shown here has a loop tube 91 for generating sound waves and a resonance tube 92 for propagating the sound waves generated here. A heat accumulator 93 having a structure in which a large number of thin tubes are bundled is provided in the middle of the loop tube 91 . A high temperature side heat exchanger (heater) 94 is provided on one side of the heat accumulator 93, and a low temperature side heat exchanger (cooler) 95 is provided on the other side.

In such a configuration, when a temperature gradient exceeding a predetermined threshold value is formed at both ends of the heat accumulator 93 by the heat exchangers 94 and 95, the thermoacoustic phenomenon causes the fluid (actuating A self-excited vibration of the fluid) is generated, and a sound wave is generated in the loop tube 91 . That is, thermal energy is converted into acoustic energy. At this time, a standing wave and a traveling wave are mixedly generated in the resonance tube 92, and due to the traveling wave component, the wave from the base end of the resonance tube 92 (the connection end with the loop tube 91) to the tip end C is generated. Towards ₁ , acoustic energy is transported.

In order to take out the acoustic energy generated by the thermoacoustic engine 9, another engine (hereinafter also referred to as “load engine”) 90 that receives the supply of acoustic energy is connected to the tip _C1 of the resonance tube 92 to generate heat. I need to build a sound system. For example, there is known a thermoacoustic system (thermoacoustic power generation system) in which a generator is connected to the thermoacoustic engine 9 to convert acoustic energy into electric power (see Patent Document 1).

By the way, in a thermoacoustic system in which the thermoacoustic engine 9 and the load engine 90 are connected, the acoustic impedance of the surface (connection surface) _C1 of the thermoacoustic engine 9 connected to the load engine 90 and the thermoacoustic impedance of the load engine 90 If the acoustic impedance of the connection surface C ₂ connected to the engine 9 is deviated, the acoustic energy generated by the thermoacoustic engine 9 cannot be extracted by the load engine 90 . That is, in order to appropriately transmit acoustic energy from the thermoacoustic engine 9 to the load engine 90, the acoustic impedance of the connection surface C1 on the thermoacoustic engine ₉ side and the acoustic impedance of the connection surface _C2 on the load engine 90 side must be must match (consistent). However, in this specification, the phrase “acoustic impedances match” between two connection surfaces means not only the case where the acoustic impedances of both connection surfaces completely match, but also the case where acoustic energy is sufficiently transmitted through both connection surfaces. It also includes cases where the difference in acoustic impedance between the connection surfaces is small.

However, the acoustic impedance of the connection surfaces C ₁ and C ₂ of the engines 9 and 90 is a value determined by a complex combination of various specifications of the engines 9 and 90, and the connection surface C of the thermoacoustic engine 9 ₁ and the acoustic impedance of the connection surface _C2 of the load engine 90 are very unlikely to match naturally (that is, without any adjustment). Therefore, some adjustment must be made to match the acoustic impedances of the connecting surfaces C ₁ and C ₂ of each engine 9 and 90 .

For example, Non-Patent Document 1 proposes a technique for matching the acoustic impedance of each connection surface of a thermoacoustic engine and a linear generator connected thereto. Here, the acoustic impedance of the connection surface on the thermoacoustic engine side depends on the length L of the resonance tube and the set temperature T on the high temperature side of the heat accumulator, and the acoustic impedance of the connection surface on the linear generator side depends on the external Focusing on the dependence on the resistance value Z, a combination (L, T, Z) that matches the acoustic impedances of both connection surfaces is specified through experiments. Change the length L of the resonance tube and the set temperature T on the high temperature side of the heat accumulator, which are the specifications of the thermoacoustic engine, and the external resistance value Z, which is the specification of the linear generator, to specified values. By doing so, it is possible to match the acoustic impedances of both connection surfaces.

Japanese Patent No. 6233835

"Basics of thermoacoustic power generation" Shinya Hasegawa Journal of the Japan Institute of Energy 92(11), 1111-1116, 2013-11-20

According to the technique of Non-Patent Document 1, the acoustic impedance of the connection surface on the thermoacoustic engine side and the connection surface on the linear generator side can be matched. However, in order to do so, it is necessary to find a combination (L, T, Z) that matches the acoustic impedances of both connection surfaces, which requires considerable experimentation. Therefore, the designer's workload is heavy. Moreover, such a combination (L, T, Z) does not always exist, and there are cases in which such a combination (L, T, Z) cannot be found even if an experiment is conducted. Furthermore, when the external resistance value Z changes, the power generation efficiency of the linear generator also changes, so there is a possibility that the power generation efficiency will decrease by adopting the external resistance value Z that can match the acoustic impedance. be.

The present invention has been made to solve the above problems, and in a thermoacoustic system in which a thermoacoustic engine and another engine are connected, the acoustic impedances of the connecting surfaces of the two engines can be easily and reliably matched. The aim is to provide technology that enables

In order to achieve this object, the present invention takes the following means.

That is, in the present invention, a first engine, which is a thermoacoustic engine that supplies acoustic energy, and a second engine that receives the supply of acoustic energy, are connected to a first connecting surface of the first engine and a first connecting surface of the second engine. A thermoacoustic system connected via two connecting surfaces, wherein the second engine comprises a receiving part that receives acoustic energy supplied from the first engine on the receiving surface and generates a predetermined thrust, The pressure amplitude of the second connection surface and the pressure amplitude of the receiving surface are the same, the predetermined thrust is generated at the receiving portion, and the acoustic impedance of the first connection surface and the acoustic impedance of the second connection surface are the same. At least one of the area of the first connection surface and the area of the second connection surface is determined so as to match the acoustic impedance.

However, "the acoustic impedances of two connection surfaces match" does not only mean that the acoustic impedances of each connection surface completely match, This includes cases where the difference in acoustic impedance between surfaces is small. That is, when acoustic energy is sufficiently transmitted through both connection surfaces, it is considered that the acoustic impedances of both connection surfaces are the same.

Moreover, the phrase "the pressure amplitudes of the two surfaces are the same" includes not only the case where the pressure amplitudes of the two surfaces are completely the same, but also the case where the difference between the pressure amplitudes of the two surfaces is sufficiently small. For example, if the separation between the two surfaces is negligibly small compared to the wavelength of the sound wave, the pressure amplitude difference between the two surfaces will be sufficiently small that the pressure amplitudes can be considered the same.

The acoustic impedance of each connection surface of the first engine and the second engine is a value defined by various specifications of the engine. , matching the acoustic impedance of both connection surfaces. Therefore, it is possible to easily and reliably match the acoustic impedances of the connecting surfaces of both engines.

Preferably, the thermoacoustic system is characterized in that the receiving part comprises a piston.

According to this configuration, it is possible to stably generate a predetermined thrust.

Preferably, in the thermoacoustic system, the area of the first connection surface is A ₁ , the pressure amplitude of the first connection surface is P ₁ , the flow velocity at the first connection surface is V ₁ , and the second connection is When the surface area is A _2p , the flow velocity at the second connection surface is V _2p , and the predetermined thrust is F _p , the area of the second connection surface is
A _2p = (A ₁ V ₁ F _p /P ₁ V _2p ) ^1/2
characterized by being determined by

According to this configuration, the area of the second connection surface is easily determined such that a predetermined thrust is generated in the receiving portion and the acoustic impedances of the first connection surface and the second connection surface can be matched. can do.

Preferably, the thermoacoustic system is characterized in that the receiving part comprises a diaphragm.

According to this configuration, it is possible to stably generate a predetermined thrust.

Preferably, in the thermoacoustic system, the area of the first connection surface is A ₁ , the pressure amplitude of the first connection surface is P ₁ , the flow velocity at the first connection surface is V ₁ , and the second connection is When the surface area is A _2d , the flow velocity at the second connection surface is V _2d , and the predetermined thrust force is F _d , the area of the second connection surface is
A _2d = [(3/2)(A ₁ V ₁ F _d /P ₁ V _2d )] ^1/2
characterized by being determined by

According to this configuration, the area of the second connection surface is easily determined such that a predetermined thrust is generated in the receiving portion and the acoustic impedances of the first connection surface and the second connection surface can be matched. can do.

In another aspect, the present invention includes a first engine that is a thermoacoustic engine that supplies acoustic energy, and a second engine that includes a receiving portion that receives the acoustic energy with a receiving surface and generates a predetermined thrust. , a connection method for connecting via a first connection surface of the first engine and a second connection surface of the second engine, wherein the pressure amplitude of the second connection surface and the pressure amplitude of the receiving surface are the same. a step of defining the second connection surface and the receiving surface, the predetermined thrust being generated at the receiving portion, and the acoustic impedance of the first connection surface and the acoustic impedance of the second connection surface determining at least one of the area of the first connection surface and the area of the second connection surface so that It is characterized by having

According to this configuration, by adjusting the area of at least one of the connection surfaces of the first engine and the second engine, the acoustic impedances of both connection surfaces are matched. Therefore, it is possible to easily and reliably match the acoustic impedances of the connecting surfaces of both engines.

According to the present invention, in a thermoacoustic system in which a thermoacoustic engine and another engine are connected, it is possible to easily and reliably match the acoustic impedances of the connecting surfaces of the two engines.

1 is a diagram schematically showing a thermoacoustic system according to an embodiment; FIG. FIG. 4 is an enlarged view showing the vicinity of the connecting portion between the first engine and the second engine; FIG. 4 is a diagram showing the flow of processing related to a connection method for connecting a first engine and a second engine; The figure which shows typically the thermoacoustic system which concerns on a 2nd modification. FIG. 4 is an enlarged view showing the vicinity of the connecting portion between the first engine and the second engine; FIG. 4 is a diagram for explaining the difference between the case where the receiving portion is configured by a piston and the case where the receiving portion is configured by a diaphragm; The figure which shows the connection part which concerns on another modification. The figure which shows the connection part which concerns on another modification. A diagram for explaining a thermoacoustic phenomenon. The figure which shows typically the thermoacoustic system based on a prior art example.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<1. Configuration of thermoacoustic system>
A configuration of a thermoacoustic system 100 according to an embodiment will be described with reference to FIG. FIG. 1 is a diagram schematically showing a thermoacoustic system 100. As shown in FIG.

A thermoacoustic system 100 has a configuration in which a first engine 10, which is a thermoacoustic engine that supplies acoustic energy, and a second engine 20 that receives supply of acoustic energy are connected.

(first agency)
The first engine 10 is a thermoacoustic engine that generates acoustic energy by inputting thermal energy, and includes a loop tube 11 that generates sound waves, a resonance tube 12 that propagates the generated sound waves, a heat storage device 13 that amplifies the acoustic energy, A pair of heat exchangers (a high-temperature side heat exchanger 14 and a low-temperature side heat exchanger 15) that forms a temperature gradient at both ends of the heat accumulator 13 is provided.

The loop tube 11 is a cylindrical tube that is bent into a rectangular frame shape and closed in a loop shape. Specifically, the loop tube 11 includes four tube portions 11a, 11b, 11c, and 11d extending linearly, and the first tube portion 11a and the second tube portion 11b are arranged at approximately 90 degrees. The second pipe portion 11b and the third pipe portion 11c are connected to each other at the ends while forming an angle of approximately 90 degrees, and the third pipe portion 11c and the fourth pipe portion 11d are connected to each other at approximately 90 degrees. The fourth pipe portion 11d and the first pipe portion 11a are connected to each other at their ends while forming a 90-degree angle.

The resonance tube 12 is a straight cylindrical tube, and one end surface of the loop tube 11 is bent at any bent portion (in the illustrated example, the portion where the first tube portion 11a and the fourth tube portion 11d are connected). Connected. The other end surface of the resonance tube 12 constitutes a connection surface (first connection surface) _C1 that is connected to the second engine 20 . That is, the first engine 10 is connected at the first connection surface _C1 to a second connection surface _C2p of the second engine 20 (see FIG. 2).

The insides of the loop tube 11 and the resonance tube 12 are filled with working fluid. The working fluid can be anything. For example, various gases such as air, nitrogen gas, helium gas, argon gas, mixtures thereof, and the like may be used as the working fluid.

The heat accumulator 13 is a structure having a structure in which countless thin tubes are bundled, and is also called a stack. Specifically, the heat accumulator 13 is, for example, a honeycomb structure made of ceramics, etc., stainless mesh (for example, a structure in which a large number of stainless steel mesh thin plates are laminated at a fine pitch), porous ceramics, wire mesh, metal It can be composed of an object in which fibers are woven in the form of a non-woven fabric, or the like.

The heat accumulator 13 is provided in the middle of the loop pipe 11 (the first pipeline portion 11a in the illustrated example). However, the heat accumulator 13 is in a posture such that the pipe line direction of the thin tube is parallel to the pipe line direction of the loop pipe 11 (that is, the pipe line direction of the first pipe line portion 11a) at the position where the heat accumulator 13 is provided. provided in

The high temperature side heat exchanger 14 is provided on the loop tube 11 so as to be adjacent to one end of the heat accumulator 13 . The high temperature side heat exchanger 14 is a heat exchanger (heater) for heating, and supplies heat to one end of the heat accumulator 13 to heat the end to a predetermined set temperature (high temperature side set temperature). heat up.

The low temperature side heat exchanger 15 is provided on the loop pipe 11 so as to be adjacent to the other end of the heat accumulator 13 . The low temperature side heat exchanger 15 is a heat exchanger (cooler) for cooling, and releases heat from the other end of the heat accumulator 13 to bring the end to a predetermined set temperature (low temperature side set temperature). Cooling.

In the first engine 10 having such a configuration, the high temperature side heat exchanger 14 provided on one end side of the heat accumulator 13 heats the one end side to the high temperature side set temperature, and the other end side of the heat accumulator 13 The provided low temperature side heat exchanger 15 cools the other end side to the low temperature side set temperature, and when a predetermined temperature gradient is formed at both ends of the heat accumulator 13, a thermoacoustic phenomenon causes the heat accumulator 13 A self-excited vibration of the working fluid is generated inside the narrow tube, and a sound wave is generated in the loop tube 11 . At this time, the heat accumulator 13 plays a role of accelerating the destabilization of the working fluid and amplifying the acoustic energy. When sound waves are generated in the loop tube 11 , sound waves are also generated in the resonance tube 12 . At this time, a standing wave and a traveling wave are mixedly generated in the resonance tube 12, and the acoustic energy generated in the loop tube 11 is transferred to one end side of the resonance tube 12 (connected to the loop tube 11) by the traveling wave component. ) to the other end side (that is, the first connecting surface _C1 side).

(Second institution)
The second engine 20 is a load engine that receives acoustic energy generated by the first engine 10, which is a thermoacoustic engine. In this embodiment, the second engine 20 is assumed to be a generator that converts acoustic energy into electrical power. That is, the thermoacoustic system 100 according to this embodiment is a thermoacoustic power generation system that outputs acoustic energy generated by the first engine 10 as electric power.

The second engine 20 is a linear generator, and includes a connecting pipe 21, a receiving portion 22, a power generating portion 23, a connecting portion 24, and the like.

The connecting pipe 21 is a straight cylindrical pipe. One end surface of the connecting pipe 21 constitutes a connecting surface (second connecting surface) _C2p that is connected to the first engine 10 . That is, the second engine 20 is connected to the first connection surface C1 of the first engine 10 at the second connection surface _C2p (see FIG. 2) _. On the other hand, the other end surface of the connecting pipe 21 is connected to one end surface of the accommodating portion 230 that accommodates the power generation portion 23 .

The receiving portion 22 is a member that receives acoustic energy supplied from the first engine 10 and generates a predetermined thrust, and is accommodated in the connecting pipe 21 . In this embodiment, the receiving part 22 is constituted by a piston 221 . The piston 221 is a cylindrical member and is arranged coaxially within the connecting tube 21 . The circular end face of the piston 221 is substantially congruent with the cross-section of the connection pipe 21 . In other words, the peripheral surface of the piston 221 is sufficiently close to the inner wall of the connection tube 21 and is opposed to the inner wall of the connection tube 21, so that sufficient airtightness is maintained between the two. On the other hand, the peripheral surface of piston 221 receives almost no frictional resistance from the inner wall of connecting pipe 21 . Therefore, the piston 221 can smoothly move back and forth along the pipeline direction of the connecting tube 21 .

The end face of the piston 221 on the side of the second connecting surface _C2p constitutes a receiving surface _C3p that receives acoustic energy (oscillating flow) propagating from the second connecting surface _C2p side. That is, the piston 221 receives acoustic energy propagating from the second connection surface _C2p side at the receiving surface _C3p , and vibrates (reciprocates) along the conduit direction of the connection pipe 21 with thrust. .

The power generation unit 23 includes a mover (oscillator) 231 and a cylindrical stator 232 that surrounds the outer peripheral surface of the mover 231 . The mover 231 is provided with a permanent magnet (not shown), and the stator 232 is wound with coil windings (not shown).

The connecting portion 24 is a rod-shaped member that connects the piston 221 and the mover 231, and has one end connected to the end surface of the piston 221 (the end surface opposite to the receiving surface _C3p ) and the other end connected to the mover 231. be done. The mover 231 is supported at a position coaxial with the piston 221 by being connected to the piston 221 via the connecting portion 24 . Therefore, when the piston 221 vibrates by receiving acoustic energy, the mover 231 vibrates synchronously. That is, the mover 231 vibrates with respect to the stator 232 . Then, magnetic flux fluctuation occurs, and an electromotive force is generated in the windings wound around the stator 232 .

<2. Operation of thermoacoustic system>
As described above, the thermoacoustic system 100 according to this embodiment is a thermoacoustic power generation system including a generator as a load engine. The manner in which the thermoacoustic system 100 generates power will be described with continued reference to FIG.

When the thermoacoustic system 100 generates electricity, the high temperature side heat exchanger 14 provided at one end of the heat accumulator 13 heats the one end to the high temperature set temperature, and the other end of the heat accumulator 13 The provided low temperature side heat exchanger 15 cools the other end side to the low temperature side set temperature.

As described above, when a predetermined temperature gradient is formed across both ends of the heat accumulator 13, the thermoacoustic phenomenon causes self-excited vibration of the working fluid inside the narrow tubes of the heat accumulator 13, and along with this, the loop tube Sound waves are generated in 11 and resonance tube 12 . At this time, a standing wave and a traveling wave are mixedly generated in the resonance tube 12, and the acoustic energy generated in the loop tube 11 is transferred from one end side of the resonance tube 12 to the other end side (first is transported to the connecting surface _C1 side).

A second connection surface _C2p of the second engine ₂₀ is connected to the first connection surface C1. As will be described later, in this thermoacoustic system 100, the area of the second connection surface C2p is defined so that the acoustic impedance of the first connection _{surface C1} and the acoustic impedance of the second connection surface _C2p match. ing. Therefore, the acoustic energy (oscillating flow) propagating through the resonance pipe 12 is transported into the connection pipe 21 via the first connection surface _C1 and the second connection surface _C2p , and is transferred to the receiving portion provided here. 22 (specifically, piston ₂₂₁ ).

The piston 221 vibrates with a predetermined thrust by receiving acoustic energy at the receiving surface _C3p . Vibration of the piston 221 is transmitted to the mover 231 via the connecting portion 24 , and the mover 231 vibrates with respect to the stator 232 . As a result, magnetic flux fluctuations occur and an electromotive force is generated in the windings. That is, it generates electricity.

<3. Configuration of Connection Portion>
As described above, in the thermoacoustic system 100, the first engine 10 and the second engine 20 are connected via the first connection surface C1 of the first engine ₁₀ and the second connection surface _C2p of the second engine 20. However, in order to transmit the acoustic energy generated by the first engine 10 to the second engine 20, the acoustic impedance of the first connection surface _C1 and the acoustic impedance of the second connection surface _C2p must match. need to be However, as described above, the term “acoustic impedance matches” here means not only the case where the acoustic impedances of the connection surfaces C ₁ and C _2p are completely matched, but also the case where both connection surfaces C ₁ and C _2p are completely matched. A case in which the difference in acoustic impedance between the connection surfaces C ₁ and C _2p is small enough to sufficiently transmit acoustic energy through the connection surfaces C 1 and C 2p is also included.

In this thermoacoustic system 100, the acoustic impedances of _the connection surfaces _C1 and _C2p are matched by using the area of the second connection surface C2p as a parameter for adjustment. A manner of determining the area of the second connection surface C _2p that can match the acoustic impedances of the connection surfaces C ₁ and C _2p will be described with reference to FIG. FIG. 2 is an enlarged view showing the vicinity of the connecting portion of the two engines 10 and 20. FIG. 2(a) shows the state before connection, and FIG. 2(b) shows the state after connection. It is shown.

Now, let the area of the first connection surface _C1 be " _A1 ", the flow velocity at the first connection surface _C1 be " _V1 ", and the pressure amplitude (sound pressure) of the first connection surface _C1 be " _P1 ". do. Further, the area of the second connection surface C _2p is “A _2p ”, the flow velocity at the second connection surface C _2p is “V _2p ”, and the pressure amplitude of the second connection surface C _2p is “P _2p ”. The area of the receiving surface C _3p is "A _3p ", the flow velocity at the receiving surface C _3p is "V _3p ", and the pressure amplitude of the receiving surface C _3p is "P _3p ". However, the term "flow velocity" as used herein refers to the velocity component of particles (particles forming the working fluid) along the normal direction of the target surface.

Acoustic impedance is the pressure amplitude divided by the volumetric flow rate (volumetric flow velocity). The volumetric flow rate of the first connecting surface _C1 is a value obtained by multiplying the area _A1 by the flow velocity _V1 . Similarly, the volume flow rate of the second connecting surface C _2p is the product of the area A _2p and the flow velocity V _2p . Therefore, the acoustic impedance _Z1 of the first connection surface _C1 is given by the following (Equation 1). Also, the acoustic impedance Z _2p of the second connection surface C _2p is given by the following (Equation 2).
Z ₁ =P ₁ /A ₁ V ₁ (Formula 1)
Z _2p =P _2p /A _2p V _2p (Formula 2)

On the other hand, between the pressure amplitude _P3p of the receiving surface _C3p and the thrust force _Fp generated in the receiving portion 22, the following relationship (Equation 3) is established.
P _3p =F _p /A _3p (Formula 3)
Basically, the magnitude of the electric power generated by the second engine 20 corresponds to the thrust _Fp generated by the receiving portion 22 . That is, once the target power to be generated by the second engine 20 is determined, the thrust _Fp to be generated by the receiving portion 22 is defined accordingly.

Here, in this thermoacoustic system 100, the area A _2p of the second connection surface C _2p and the area A _3p of the receiving surface C _3p are the same (A _2p =A _3p ). However, the two surfaces C _2p and C _3p “have the same area” means not only the case where the areas A _2p and A _3p of the two surfaces C _2p and C _3p are completely the same, but also the case where the two surfaces C It also includes the case where the difference between the areas A _2p and A _3p of _2p and C _3p is sufficiently small.

Furthermore, in this thermoacoustic system 100, the pressure amplitude P _2p of the second connection surface C _2p and the pressure amplitude P _3p of the receiving surface C _3p are the same (P _2p =P _3p ). However, "the pressure amplitudes of the two surfaces C _2p and C _3p are the same" does not only mean that the pressure amplitudes P _2p and P _3p of the two surfaces C _2p and C _3p are completely the same, This includes the case where the difference between the pressure amplitudes P _2p and P _3p on the surfaces C _2p and C _3p is sufficiently small. For example, when the distance d between the two surfaces C _2p and C _3p is negligibly small compared to the wavelength of the sound wave, the difference between the pressure amplitudes P _2p and P _3p between the two surfaces C _2p and C _3p is sufficient. , and the pressure amplitudes P _2p and P _3p can be considered the same. Therefore, here, the position where the second connecting surface _C2p is sufficiently close to the receiving surface C3p (specifically, the separation distance d between the receiving surface _C3p and the receiving surface _C3p is not propagated from the first engine 10). position such that it is negligibly small compared to the wavelength of the incoming sound wave).

Therefore, in this thermoacoustic system 100, the following (Formula 3') is established from the above (Formula 3).
P _2p =F _p /A _2p (Formula 3')

Then, the acoustic impedance Z _2p of the second connection surface C _2p represented by the above (Formula 2) is represented by the following (Formula 2').
Z _2p = F _p /A _2p ² V _2p (formula 2')

From (Equation 1) and (Equation 2′), in order to match the acoustic impedance Z ₁ of the first connection surface C ₁ and the acoustic impedance Z _2p of the second connection surface C _2p , the following (Equation 4) It suffices if the relationship of
P ₁ /A ₁ V ₁ =F _p /A _2p ² V _2p (Formula 4)

The following (Equation 5) is obtained by arranging the above (Equation 4) with respect to the area A _2p of the second connection surface C _2p .
A _2p = (A ₁ V ₁ F _p /P ₁ V _2p ) ^1/2 (Formula 5)

In this thermoacoustic system 100, the area _A2p of the second connection surface _C2p is set to the value determined by the above (Equation 5). Thereby, the acoustic impedance _Z1 of the first connection surface _C1 and the acoustic impedance _Z2p of the second connection surface _C2p can be matched. Further, in this thermoacoustic system 100, the area _A2p and pressure amplitude _P2p of the second connection surface _C2p are matched with the area _A3p and pressure amplitude _P3p of the receiving surface _C3p , respectively. Therefore, it is possible to match the acoustic impedances Z ₁ and Z _2p while ensuring that a predetermined thrust F _p is generated in the receiving portion 22 (that is, without affecting the electric power generated in the second engine 20). can.

In general, the acoustic impedance _Z1 of the first connecting surface _C1 of the first engine 10, which is a thermoacoustic engine, depends on the length L of the resonance tube 12. As shown in FIG. The acoustic impedance _Z1 also depends on the high temperature side set temperature T of the heat accumulator 13, and the acoustic impedance _Z1 decreases as the high temperature side set temperature T increases. Now, in a certain first engine (target first engine) 10, when the length L of the resonance tube 12 is about "3.1 (m)", the high temperature side set temperature T is set to about "300 (°C)". Assume that the acoustic impedance _Z1 of the first connection surface _C1 is approximately "600 (Ns/m)".

On the other hand, the acoustic impedance _Z2p of the second connection surface _C2p of the second engine 20, which is a linear generator, depends on the external resistance value Z. This external resistance value Z is also a value that defines the power generation efficiency of the linear generator. Now, in a certain second engine (target second engine) 20, when the external resistance value Z is set such that the necessary power generation efficiency can be obtained, the acoustic impedance Z _2p of the second connection surface C _2p is " 300 to 400 (Ns/m)”.

When these target engines 10 and 20 are connected as they are, the acoustic impedances Z ₁ and Z _2p of the connection surfaces C ₁ and C _2p are greatly different from each other. It cannot be retrieved by the second engine 20. For example, by changing the high-temperature side set temperature T in the target first engine 10, one idea is to reduce the acoustic impedance _Z1 of the first connection surface _C1 to about "300 to 400 (Ns/m)". It is conceivable, but in this case, the temperature must be set considerably higher than the initial high temperature side set temperature T, and a large-sized heat exchanger or the like is required.

In such a case, the above-described measures (that is, using the area A _2p of the second connection surface C _2p as an adjustment parameter to match the acoustic impedances Z ₁ and Z _2p of the connection surfaces C ₁ and C _2p is very effective. For example, in the case of the target engines 10 and 20 described above, only by changing the diameter of the second connection surface _C2p to, for example, about 2/3 of the diameter of the first connection surface _C1 , the acoustic wave of the first connection surface _C1 can be reduced. The impedance _Z1 and the acoustic impedance _Z2p of the second connection surface _C2p can be sufficiently matched. In this case, there is no need to change the set temperature T on the high temperature side, so a large heat exchanger or the like is not required. Also, since the external resistance value Z is not changed, the power generation efficiency of the target second engine 20 is not lowered.

<4. Connection method>
Next, a connection method for connecting the first engine 10 and the second engine 20 will be described with reference to FIG. 3 in addition to FIGS. FIG. 3 is a diagram showing the flow of processing related to the connection method.

(Step S1)
In connecting the first engine 10 and the second engine 20, first, the area A _2p of the second connecting surface C _2p and the area A _3p of the receiving surface C _3p are the same (A _2p =A _3p ), and , defining the second connecting surface C _2p and the receiving surface C _3p such that the pressure amplitude P _2p on the second connecting surface C _2p and the pressure amplitude P _3p on the receiving surface C _3p are the same (P _2p =P _3p ) do.

(Step S2)
Subsequently, _a predetermined thrust force _Fp is generated in the receiving portion 22, and the second connection surface _C1 and the second connection surface C2p are adjusted so that the acoustic impedance _Z1 of the first connection surface C1 and the acoustic impedance _Z2p of the second connection surface C2p match. Determine the area A _2p of the connecting surface C _2p . Specifically, first, the area A ₁ of the first connection surface C ₁ , the flow velocity V ₁ , the pressure amplitude P ₁ , and the flow velocity V _2p of the second connection surface C _2p are identified by measurement experiments, theoretical calculations, etc. do. Further, the thrust force _Fp to be generated by the receiving portion 22 is specified from the specifications of the second engine 20 and the like. Then, the identified values A ₁ , V ₁ , P ₁ , V _2p , and F _p are substituted into the above (Equation 5) to determine the area A _2p of the second connection surface C _2p .

(Step S3)
Subsequently, the first connection surface _C1 and the second connection surface _C2p are connected. The area _A2p of the second connection surface _C2p determined in step S2 does not necessarily match the area _A1 of the first connection surface _C1 . If the areas A ₁ and A _2p do not match, a brim-shaped flange component G (FIG. 2(b)) is interposed to fill the difference between the areas A ₁ and A _2p , and the connection surfaces C _{1 and} A 2p C _2p should be connected. Although the figure shows a case where the area _A2p of the second connection surface _C2p is smaller than the area _A1 of the first connection surface _C1 , it goes without saying that the area _A2p of the second connection surface C2p _2p may be larger than the area _A1 of the first connection surface _C1 .

Through the steps S1 to S3 described above, the first engine 10 and the second engine 20 are connected, and the thermoacoustic system 100 is constructed.

<5. Effect>
In the above embodiment, the first engine 10, which is a thermoacoustic engine that supplies acoustic energy, and the second engine 20 that receives the supply of acoustic energy are connected to the first connecting surface _C1 of the first engine 10 and the second engine. The thermoacoustic system 100 connected via the second connecting surface _C2p of the second engine 20 receives the acoustic energy supplied from the first engine 10 at the receiving surface _C3p and generates a predetermined thrust F. The pressure amplitude _P2p of the second connecting surface _C2p and the pressure amplitude _P3p of the receiving surface _C3p are the same, and a predetermined thrust force _Fp is generated in the receiving portion 22 _. and the area A1 of the first connection surface _C1 and the area _A1 of the second connection surface _C2p so that the acoustic impedance _Z1 of the first connection surface _C1 and the acoustic impedance _Z2p of the second connection surface _C2p match. At least one of the areas A _2p of is determined.

The acoustic impedances Z ₁ and Z _2p of the connection surfaces of the first engine 10 and the second engine 20 are values defined by various specifications of the engine. By adjusting the areas A ₁ and A _2p of C ₁ and C _2p , the acoustic impedances _{Z 1 and} Z _2p of both connection surfaces C 1 and C _2p are matched. Therefore, the acoustic impedances Z ₁ and Z _2p of the connection surfaces C ₁ and C _2p of both engines 10 and 20 can be easily and reliably matched. In the above _{configuration} , when using the areas A _{1 and A 2p of} the connection _surfaces C ₁ and C _2p as adjustment parameters, Since the area A _3p and the pressure amplitude P _3p are matched, the acoustic impedances Z ₁ and Z _2p can be matched while ensuring that the receiving portion 22 generates a predetermined thrust force _Fp .

Further, in the thermoacoustic system 100 according to the above embodiment, the receiving part 22 includes the piston 221 .

According to this configuration, it is possible to stably generate a predetermined thrust.

Further, in the thermoacoustic system 100 according to the above embodiment, the area of the first connection surface _C1 is _A1 , the pressure amplitude of the first connection surface _C1 is _P1 , and the flow velocity at the first connection surface _C1 is V ₁ , the area of the second connection surface C _2p is A _2p , the flow velocity at the second connection surface C _2p is V _2p , and the predetermined thrust is F _p , then the area A _2p of the second connection surface C _2p is ,
A _2p = (A ₁ V ₁ F _p /P ₁ V _2p ) ^1/2
determined by

According to this configuration, a predetermined thrust force _Fp is generated in the receiving portion 22, and the acoustic impedances _Z1 and _Z2p of the first connection surface _C1 and the second connection surface _C2p can be matched. , the area A _2p of the second connection surface can be easily determined.

In the above embodiment, the first engine 10, which is a thermoacoustic engine that supplies acoustic energy, and the second engine that includes the receiving portion 22 that receives the acoustic energy on the receiving surface _C3p and generates a predetermined thrust _Fp . 20 via the first connection surface _C1 of the first engine 10 and the second connection surface _C2p of the second engine 20, wherein the pressure amplitude _P2p of the second connection surface _C2p and _A step of defining the second connection surface _C2p and the receiving surface C3p so that the pressure amplitude _P3p of the receiving surface _C3p is the same (step S1), and a predetermined thrust force _Fp is generated in the receiving portion 22. and the area A1 of the first connection surface _C1 and the area _A1 of the second connection surface _C2p so that the acoustic impedance _Z1 of the first connection surface _C1 and the acoustic impedance _Z2p of the second connection surface _C2p match. (step S2) of determining at least one of the areas A _2p of , and connecting the first connection surface C ₁ and the second connection surface C _2p (step S3).

According to this configuration, by adjusting the area A 1 , A _2p of at least one of the connection surfaces C ₁ , C _2p of the first engine 10 and the second engine 20, the acoustic impedance of both connection surfaces C ₁ , C _{2p is} Z ₁ and Z _2p are matched. Therefore, the acoustic impedances Z ₁ and Z _2p of the connection surfaces C ₁ and C _2p of both engines 10 and 20 can be easily and reliably matched. In the above _{configuration} , when using the areas A _{1 and A 2p of} the connection _surfaces C ₁ and C _2p as adjustment parameters, Since the area A _3p and the pressure amplitude P _3p are matched, the acoustic impedances Z ₁ and Z _2p can be matched while ensuring that the receiving portion 22 generates a predetermined thrust force _Fp .

<6. Variation>
<6-1. First modification>
In the above embodiment, the area A _2p of the second connection surface C _2p is used as an adjustment parameter, and by setting this area to the value determined by the above (Equation 5), the acoustic impedance of the first connection surface C ₁ Although _Z1 and the acoustic impedance _Z2p of the second connection surface _C2p are made to match, the area _A1 of the first connection surface _C1 may be used as an adjustment parameter.

For example, when the above (Formula 4) is rearranged with respect to the area _A1 of the first connection surface _C1 , the following (Formula 6) is obtained.
A ₁ =A _2p ² V _2p P ₁ /V ₁ F _p (Formula 6)

By setting the area _A1 of the first connection surface _C1 to a value determined by the above (Equation 6), it is possible to ensure that a predetermined thrust force _Fp is generated in the receiving portion 22 as in the above embodiment. Both acoustic impedances Z ₁ and Z _2p can be made to match each other.

Also, both the area _A1 of the first connection surface _C1 and the area _A2p of the second connection surface _C2p may be used as adjustment parameters. In this case, each of the areas A ₁ and A _2p should be set to a value that satisfies the above (Equation 4).

<6-2. Second modification>
In the thermoacoustic system 100 according to the above embodiment, the receiving part 22 is configured by the piston 221, but the configuration of the receiving part 22 is not limited to this. For example, in the thermoacoustic system 100, the receiving part 22 may be configured by a diaphragm.

<6-2-1. Configuration of thermoacoustic system>
A configuration of a thermoacoustic system 100d including a receiving portion 22d composed of a diaphragm 222 will be described with reference to FIGS. 4 and 5. FIG. FIG. 4 is a diagram schematically showing the thermoacoustic system 100d. 5A and 5B are enlarged views showing the vicinity of the connection portion between the first engine 10 and the second engine 20d. FIG. 5(a) shows the state before connection, and FIG. 5(b) shows the state after connection. Each state is indicated. In the following, only points that are different from the above embodiment will be described, and descriptions of points that are the same will be omitted. Also, the same elements as in the above embodiment are denoted by the same reference numerals.

The thermoacoustic system 100d has a configuration in which a first engine 10, which is a thermoacoustic engine, and a second engine 20d, which is a load engine, are connected, like the thermoacoustic system 100 according to the above embodiment. The first engine 10 has the same configuration as the first engine 10 included in the thermoacoustic system 100 according to the above embodiment. On the other hand, the second engine 20d has substantially the same configuration as the second engine 20 included in the thermoacoustic system 100 according to the above embodiment, but the receiving portion 22d is configured by a diaphragm 222 instead of the piston 221. There is a difference.

The diaphragm 222 is a thin film made of an elastically deformable material (for example, a rubber film made of natural rubber) and stretched inside the connection pipe 21 . That is, the diaphragm 222 has a circular shape that is substantially congruent with the cross section of the connecting pipe 21, and is airtightly connected to the inner wall of the connecting pipe 21 over its entire circumference.

The surface of the diaphragm 222 on the side of the second connection surface _C2d constitutes a receiving surface _C3d that receives acoustic energy propagating from the second connection surface _C2d side. That is, the diaphragm 222 receives acoustic energy propagating from the second connecting surface _C2d side at the receiving surface _C3d , and repeats periodic deformation with thrust. Specifically, the diaphragm 222 has a planar shape parallel to the cross section of the connecting pipe 21 (a shape indicated by a solid line in FIG. 5) and a semi-elliptical shape bulging in the direction of the connecting pipe 21 (two points in FIG. 5). The shape shown by the dashed line) is periodically deformed.

The connecting portion 24d is a rod-shaped member that connects the diaphragm 222 and the mover 231, and is connected to the central portion of the diaphragm 222 at one end and to the mover 231 at the other end. The mover 231 is connected to the diaphragm 222 via the connecting portion 24d and is supported at a position coaxial with the axis passing through the center of the diaphragm 222 . Therefore, when the diaphragm 222 is periodically deformed by receiving acoustic energy and the central portion vibrates in the axial direction, the mover 231 vibrates synchronously. That is, the mover 231 vibrates with respect to the stator 232 . Then, magnetic flux fluctuation occurs, and an electromotive force is generated in the windings wound around the stator 232 .

<6-2-2. Mode of Determining Area of Second Connection Surface _C2d >
Similarly to the thermoacoustic system 100, the thermoacoustic system 100d uses the area of the second connection surface _C2d as an adjustment parameter to match the acoustic impedances of the connection surfaces _C1 and _C2d . . Continuing with FIG. 5, a manner of determining the area of the second connection surface _{C2d such that the acoustic impedances of the respective connection surfaces C1, C2d can be} matched will be described.

In the following, the area, flow velocity, and pressure amplitude of the first connecting surface C ₁ are respectively "A ₁ ,""V ₁ ," and "P ₁ ," as in the above embodiment. On the other hand, the area, flow velocity, and pressure amplitude of the second connection surface C _2d are defined as "A _2d ", "V _2d ", and "P _2d ", respectively. Also, the area of the receiving surface _C3d , the flow velocity, and the pressure amplitude are defined as " _A3d ", " _V3d ", and " _P3d ", respectively.

Note that in this thermoacoustic system 100d as well as the acoustic system 100 according to the above embodiment, the area _A2d of the second connection surface _C2d and the area _A3d of the receiving surface _C3d are assumed to be the same ( _A2d = _A3d ). Also, the pressure amplitude P _2d of the second connecting surface C _2d and the pressure amplitude P _3d of the receiving surface C _3d are the same (P _2d =P _3d ).

As mentioned above, acoustic impedance is the pressure amplitude divided by the volumetric flow rate. The volumetric flow rate _U1 of the first connecting surface _C1 is a value obtained by multiplying the area A1 by the flow velocity _V1 , and the acoustic impedance _Z1 of _the first connecting surface _C1 is given by the above (equation 1).
Z ₁ =P ₁ /U ₁ =P ₁ /A ₁ V ₁ (Formula 1)

On the other hand, _the volume flow rate U _2d of _the second connecting surface C _2d is equal to the volume flow rate U _3d of the receiving surface C _2d . formula, etc.), it is represented by the following (Equation 21d).
U _3d = (2/3) A _3d V _3d (formula 21d)

From the above (Equation 21d), the volume flow rate U _2d at the second connection surface C _2d is represented by the following (Equation 21d').
U _2d = (2/3) A _2d V _2d (equation 21d')

Therefore, the acoustic impedance _Z2d of the second connection surface _C2d is given by the following (equation 2d).
_Z2d = _P2d / _U2d = (3/2) _P2d / _{A2d V2d} (formula 2d)

On the other hand, similarly to the acoustic _system 100 according to the above embodiment, also in this thermoacoustic system _100d , the following ₍ The relationship of formula 3d) is established. Furthermore, from (Equation 3d), the following relationship (Equation 3d') is established.
P _3d =F _d /A _3d (Equation 3d)
P _2d = F _d /A _2d (Formula 3d')

Then, the acoustic impedance _Z2d of the second connection surface _C2d represented by the above (formula 2d) is represented by the following (formula 2d').
Z _2d = (3/2) F _d /A _2d ² V _2d (Formula 2d')

From (Equation 1) and (Equation 2d′), in order to match the acoustic impedance Z ₁ of the first connection surface C ₁ with the acoustic impedance Z _2d of the second connection surface C _2d , the following (Equation 4d) It suffices if the relationship of
P ₁ /A ₁ V ₁ =(3/2)F _d /A _2d ² V _2d (Formula 4d)

The following (Equation 5d) is obtained by arranging the above (Equation 4d) with respect to the area A _2d of the second connection surface C _2d .
A _2d = [(3/2)(A ₁ V ₁ F _d /P ₁ V _2d )] ^1/2 (equation 5d)

In the thermoacoustic system 100d according to this modification, the area _A2d of the second connection surface _C2d is set to the value determined by the above (Equation 5d). Thereby, the acoustic impedance _Z1 of the first connection surface _C1 and the acoustic impedance _Z2d of the second connection surface _C2d can be matched. Further, in the thermoacoustic system 100d according to this modification, as in the acoustic system 100 according to the above-described embodiment, the area _A2d and pressure amplitude _P2d of the second connection surface _C2d and the area _A3d of the receiving surface _C3d and the pressure amplitude _P3d are respectively matched. Therefore, it is possible to match the acoustic impedances Z ₁ and Z _2d while ensuring that the predetermined thrust _Fd is generated at the receiving portion 22d.

Needless to say, the area A1 of the first _connection surface _C1 may be determined using the above (Equation 4d) arranged with respect to the area _A1 of the first connection surface _C1 . That is, by using the area _A1 of the first connection surface _C1 as an adjustment parameter, the acoustic impedances of the connection surfaces _C1 and _C2d may be matched.

<6-3. Third modification>
The thermoacoustic system according to the third modification has the same configuration as the thermoacoustic system 100d according to the second modification (see FIGS. 4 and 5). Also in the thermoacoustic system according to this modification, the acoustic impedances of the connection surfaces _C1 and _C2d are matched by _using the area of the second connection surface C2d as a parameter for adjustment.

As described in the above embodiment, the appropriate area A _2p of the second connection surface C _2p (that is, matching the acoustic impedances of the connection surfaces C ₁ and C _2p ) when the receiving portion 22 is composed of the piston 221 The area A _2p ) of the second connection surface C _2p ), which can be determined from (Equation 5) above, can be determined. In this modified example, the difference between the case where the receiving portion 22 is configured by the piston 221 and the case where the receiving portion 22d is configured by the diaphragm 222 is taken into consideration, and by modifying this (Equation 5), the receiving portion 22d A formula for determining the appropriate area A _2d of the second connecting surface C _2d when is constituted by the diaphragm 222 is derived. A manner of deriving such a formula will be described below with reference to FIG. 6 in addition to FIG. 6A and 6B are diagrams for explaining the difference between the case where the receiving portion 22 is configured by the piston 221 and the case where the receiving portion 22d is configured by the diaphragm 222. FIG.

In the following, the area, flow velocity, and pressure amplitude of the second connection surface (hereinafter also referred to as “piston second connection surface”) C _2p when the receiving portion 22 is composed of the piston 221 are respectively expressed as “A _2p ”. , “V _2p ”, and “P _2p ”. Further, the thrust force generated in the receiving portion 22 in this case is assumed to be " _Fp ". On the other hand, the area, flow velocity, and pressure amplitude of the second connection surface (hereinafter also referred to as “diaphragm second connection surface”) C _2d when the receiving portion 22d is composed of the diaphragm 222 are “A _2d ” and “ V _2d ” and “P _2d ”. Further, the thrust force generated in the receiving portion 22d in this case is assumed to be "F _d ".

Here, it is assumed that the configuration of the receiving portion is changed from the piston 221 to the diaphragm 222 without changing the first engine 10 . Therefore, the condition is that the flow velocity V _2p of the piston second connecting surface C _2p and the flow velocity V _2d of the diaphragm second connecting surface C _2d be the same (V _2p =V _2d ). It is also a condition that the pressure amplitude _P2p of the piston second connection surface _C2p and _the pressure amplitude _P2d of the diaphragm second connection surface C2d are the same ( _P2p = _P2d ).

Also in this modification, the area _A2d of the diaphragm second connecting surface _C2d and the area _A3d of the receiving surface _C3d are the same ( _A2d = _A3d ). Further, the pressure amplitude P _2d of the diaphragm second connecting surface C _2d and the pressure amplitude P _3d of the receiving surface C _3d are the same (P _2d =P _3d ).

First, the relationship between the area _A2p of the piston second connecting surface _C2p and the area _A2d of the diaphragm second connecting surface _C2d will be examined.

The volumetric flow rate _U2p at the piston second connecting surface _C2p is a value obtained by multiplying the area _A2p by the flow velocity _V2p , and is expressed by the following (Equation 71).
U _2p = A _2p V _2p (equation 71)

On the other hand, the volumetric flow rate _U2d at the diaphragm second connection surface _C2d is represented by the following (Equation 72) (see the above (Equation 21d')).
U _2d = (2/3) A _2d V _2d (equation 72)

As described above, the flow velocity V _2p at the piston second connecting surface C _2p and the flow velocity V _2d at the diaphragm second connecting surface C _2d are the same (V _2p =V _2d ). Therefore, when the volumetric flow rate _U2p of the piston second connecting surface _C2p and the volumetric flow rate _U2d of the diaphragm second connecting surface _C2d match, the _{area A2p} of the piston second connecting surface C2p and the diaphragm second The following (Equation 73) is established between the area A _2d of the connection surface C _2d .
A _2p = (2/3) A _2d (equation 73)
That is, if this (Equation 73) holds, the volumetric flow rate _U2p of the piston second connecting surface _C2p and the volumetric flow rate _U2d of the diaphragm second connecting surface _C2d can be matched.

Next, the relationship between the thrust force _Fp generated at the receiving portion 22 composed of the piston 221 and the thrust force _Fd generated at the receiving portion 22d composed of the diaphragm 222 will be examined.

As described above, the relationship represented by the following (Equation 81) is established among the thrust force F _p generated in the receiving portion 22, the area A _2p of the piston second connection surface C _2p , and the pressure amplitude P _2p . (See (Formula 3′) above).
P _2p =F _p /A _2p (Equation 81)

Further, the relationship represented by the following (Equation 82) is established among the thrust force F _d generated in the receiving portion 22d, the area A _2d of the diaphragm second connection surface C _2d , and the pressure amplitude P _2d ( (see Equation 3d') above).
_P2d = _Fd / _A2d (Equation 82)

Here, since the pressure amplitude _P2p of the piston second connection surface _C2p and the pressure amplitude _P2d of the diaphragm second connection surface _C2d are equal, the following (Equation 83) is established.
F _p /A _2p =F _d /A _2d (Equation 83)

Furthermore, when the relationship of the above (formula 73) holds, the above (formula 83) is expressed as the following (formula 83').
F _d =(3/2) F _p (Formula 83′)

As described above, the area A2p of _the piston second connection surface _C2d that can match the acoustic impedance _Z1 of _the first connection surface C1 and the acoustic impedance _Z2p of the piston second connection surface _C2p is It is given by the following (Equation 91) (see (Equation 5) above).
A _2p = (A ₁ V ₁ F _p /P ₁ V _2p ) ^1/2 (equation 91)

By substituting the above (formula 73) and the above (formula 83') into this (formula 91), respectively, and applying the relationship "V _2p =V _2d ", the following (Formula 92) is obtained.
(2/3) A _2d = ((2/3) A ₁ V ₁ F _d /P ₁ V _2d ) ^1/2 (equation 92)

The following (Expression 93) is obtained by arranging the above (Expression 92) with respect to the area A _2d of the diaphragm second connection surface C _2d .
A _2d = [(3/2)(A ₁ V ₁ F _d /P ₁ V _2d )] ^1/2 (equation 93)

In the thermoacoustic system according to this modification, each value of the area _A2d of the second connection surface _C2d and the thrust force _Fd generated by the receiving portion 22d is defined so that the above (Equation 93) is satisfied. do. That is, in this modification, the acoustic impedance _Z2d of the second connection surface C2d is adjusted by using one or both of the two parameters of _the area _A2d and the thrust force _Fd as adjustment parameters. Thereby, the acoustic impedance _Z1 of the first connection surface _C1 and the acoustic impedance _Z2d of the second connection surface _C2d can be matched.

Needless to say, the area A1 _of the first connection surface _C1 may be determined by using the above (Equation 91) arranged with respect to the area _A1 of the first connection surface _C1 . That is, by using the area _A1 of the first connection surface _C1 as an adjustment parameter, the acoustic impedances of the connection surfaces _C1 and _C2d may be matched.

<6-4. Other Modifications>
In the above embodiment, when the area _A1 of _the first _connection surface _C1 and the area _A2p of the second connection surface _C2p do not match, the brim-shaped The flange component G (FIG. 2(b)) is interposed to connect both connecting surfaces C ₁ and C _2p , but for example, as shown in FIG. The connecting surfaces C ₁ and C _2p may be connected by interposing a tubular member Ga that expands and contracts between the connecting surfaces C ₁ and C _2p . According to this configuration, it is possible to reduce piping loss at the connecting portion. However, in this case, the distance t between the connecting surfaces C ₁ and C _2p is sufficiently short (that is, it is negligibly small compared to the wavelength of the sound wave). Preferably the length is sufficiently short.

Further, as shown in FIG. 8, for example, the connection pipe 21 and the resonance pipe 12 are configured to have the same diameter that matches the larger one of the areas A ₁ and A _2p of the connection surfaces C ₁ and C _2p . For example, a cylindrical inner tube Gb having an outer diameter corresponding to the area _A1 and an inner diameter corresponding to the area _A2p is inserted into the connecting tube 21, and then the connecting tube 21 and the resonance tube 12 are connected. good too. However, in this case, the receiving part 22 is also arranged inside the inner intubation tube Gb. Needless to say, if the area _A1 of the first connecting surface _C1 is smaller than the area _A2p of the second connecting surface _C2p , an inner intubation tube whose outer diameter corresponds to the area _A2p and whose inner diameter corresponds to the area _A1 Gb should be inserted into the resonance tube 12 .

In the above embodiment, the area _{A2p of} the second connection surface _C2p or the area _A1 of the first connection surface C1 is determined using (Equation 5) or (Equation 6), so that the first connection surface The acoustic impedance Z ₁ of C ₁ and the acoustic impedance Z _2p of the second connection surface C _2p are made to match, but the areas A ₁ and A _2p that match both acoustic impedances Z ₁ and Z _2p are determined. The mode is not limited to this, and may be determined from experiments, for example. The same applies to the second and third modifications.

In the above embodiment, the pressure amplitudes P _2p and P _3p of the two surfaces C _2p and C _3p are the same by defining the second connection surface C _2p at a position sufficiently close to the receiving surface C _3p . However, for example, by defining the second connection surface C _2p at a position where the separation distance d from the receiving surface C _3p is an integral multiple of the wavelength, the pressure amplitude of the two surfaces C _2p and C _3p P _2p and P _3p may be the same. In order to extract the maximum amount of acoustic energy propagating from the first engine 10, the receiving surface _C3p and the second connecting surface _C2p should be located at positions corresponding to the antinodes of the sound waves. It is also preferable to adjust the length of the connecting pipe 21 and the like.

In the above embodiment, the area A _2p of the second connection surface C _2p and the area A _3p of the receiving surface C 3p are the same, but these areas A _2p and _{A 3p do} not necessarily have to be the same. do not have. However, it is considered that _the smaller the difference between the two _{, the higher} the accuracy of impedance matching. , preferably the difference between them is sufficiently small. The same applies to the second and third modifications.

In the second modification described above, the diaphragm 222 stretched inside the connecting pipe 21 has a planar shape (a planar shape parallel to the cross section of the connecting pipe 21) in a natural state in which it does not receive acoustic energy. 222 may have a cone shape that decreases in diameter along the direction of the connecting pipe 21 in a natural state. However, when _a diaphragm having such a _shape is adopted, the cone It is necessary to add an appropriate modification to (Equation 5d) in consideration of the mode of deformation that occurs in the shape of the diaphragm.

The configuration of the first engine 10 is not limited to that illustrated in the above embodiment. For example, the shape of the loop tube 11 may be straight, U-shaped, or the like. Further, for example, a plurality of heat accumulators are provided in the middle of the resonance tube 12, and a pair of heat exchangers (that is, a high temperature side heat exchanger and a low temperature side heat exchanger) for forming a temperature gradient at both ends of each heat accumulator. heat exchanger) may be provided. With this configuration, the traveling wave propagating through the resonance tube 12 can be amplified to increase the acoustic energy.

The configuration of the second engine 20 is also not limited to that illustrated in the above embodiment. For example, the power generation section 23 of the second engine 20 may be of any type as long as it can convert vibrational energy into electrical energy. For example, in the above-described embodiment, the power generating section 23 is an inner movable type in which the mover 231 is arranged inside the stator 232 , but an outer movable type in which the mover 231 is arranged outside the stator 232 It may be of a movable type.

In the above embodiment, the second engine 20 connected to the first engine 10 is a linear generator, but various other generators may be used as the second engine. Specifically, for example, an impulse turbine or the like may be used as the second engine.

Furthermore, in the above embodiment, the second engine 20 connected to the first engine 10, which is a thermoacoustic engine, is a generator, but the second engine connected to the first engine 10 is a generator. It is not limited. For example, the second engine may be a piezoelectric element, a thermoacoustic heat pump, a thermoacoustic engine, or the like.

Other configurations can also be modified in various ways without departing from the gist of the present invention.

10 first engine 11 loop tube 12 resonance tube 13 heat accumulator 14 high temperature side heat exchanger 15 low temperature side heat exchanger 20 second engine 21 connection pipe 22, 22d receiving portion 221 piston 222 diaphragm 23 power generation portion 24, 24d connecting portion C ₁ First connection surface Z ₁ Acoustic impedance of first connection surface C _2p , C _2d Second connection surface Z _2p , Z _2d Acoustic impedance of second connection surface C _3p , C _3d Receiving surface 100, 100d

Claims (6)

A first engine, which is a thermoacoustic engine that supplies acoustic energy, and a second engine that receives the supply of acoustic energy are connected via a first connection surface of the first engine and a second connection surface of the second engine. A connected thermoacoustic system comprising:
The second engine comprises a receiving part that receives acoustic energy supplied from the first engine with a receiving surface and generates a predetermined thrust,
the pressure amplitude of the second connecting surface and the pressure amplitude of the receiving surface are the same;
The area of the first connection surface and the second connection are such that the predetermined thrust is generated in the receiving portion and the acoustic impedance of the first connection surface and the acoustic impedance of the second connection surface match. at least one of the areas of the faces is determined,
A thermoacoustic system characterized by: A thermoacoustic system according to claim 1,
wherein the receiving portion comprises a piston;
A thermoacoustic system characterized by: A thermoacoustic system according to claim 2,
A ₁ is the area of the first connection surface, P ₁ is the pressure amplitude of the first connection surface, V ₁ is the flow velocity at the first connection surface, A _2p is the area of the second connection surface, and the second connection When the flow velocity at the surface is V _2p and the predetermined thrust is F _p ,
The area of the second connection surface is
A _2p = (A ₁ V ₁ F _p /P ₁ V _2p ) ^1/2
A thermoacoustic system characterized by being determined by: A thermoacoustic system according to claim 1,
wherein the receiving part comprises a diaphragm,
A thermoacoustic system characterized by: A thermoacoustic system according to claim 4,
A ₁ is the area of the first connection surface, P ₁ is the pressure amplitude of the first connection surface, V ₁ is the flow velocity at the first connection surface, A _2d is the area of the second connection surface, and the second connection When the surface flow velocity is V _2d and the predetermined thrust is F _d ,
The area of the second connection surface is
A _2d = [(3/2)(A ₁ V ₁ F _d /P ₁ V _2d )] ^1/2
A thermoacoustic system characterized by being determined by: A first engine, which is a thermoacoustic engine that supplies acoustic energy, and a second engine, which is provided with a receiving part that receives the acoustic energy with a receiving surface and generates a predetermined thrust, are connected to the first connecting surface of the first engine and the A connection method for connecting via a second connection surface of the second engine,
defining the second connecting surface and the receiving surface such that the pressure amplitude of the second connecting surface and the receiving surface are the same;
The area of the first connection surface and the second connection are such that the predetermined thrust is generated in the receiving portion and the acoustic impedance of the first connection surface and the acoustic impedance of the second connection surface match. determining at least one of the areas of the faces;
connecting the first connection surface and the second connection surface;
A method for connecting a thermoacoustic engine, comprising:

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