JP4117489B2 - Fluid vibration or fluid noise suppression device for fluid machinery - Google Patents

Description

  The present invention relates to a fluid vibration or fluid noise suppression device for a fluid machine, and more particularly to a device for suppressing fluid vibration or fluid noise due to a thermoacoustic phenomenon, and more particularly to the fluid vibration or fluid noise found in a fluid machine. In addition, the present invention relates to a fluid vibration or fluid noise suppression device that can obtain the above suppression effect and can easily and automatically adjust the suppression effect according to the load of the fluid machine.

  In fluid machines that work on fluids or work on fluids, such as boilers, heat exchangers, pumps, gas turbines, steam turbines, air conditioners, duct pipes, fluid mixing Fluid vibration or fluid noise occurs due to a single fluid such as diffusion, density change, or phase change, or due to mutual interference such as collision between fluid and structure, vortex generation, heat exchange, etc. However, in some cases, they may develop due to the resonance structure inherent to the device. The causal relationships between fluid vibration, fluid noise, and resonance are diverse, and tend to become more complex as the mechanical device becomes larger and the load during operation increases. Some examples of these causal relationships are described in Non-Patent Document 1 and the like.

  Fluid vibration and fluid noise peculiar to fluid machinery can be attributed to interference between the fluid and the machine and structure and fluid motion itself, and it is said that measures are systematized compared to general mechanical vibration and mechanical noise. hard. Conventionally known countermeasures against fluid vibrations or fluid noises are roughly divided into two countermeasures: a countermeasure for the source and a countermeasure for the propagation path. One countermeasure for the source is to weaken the source of vibration and noise. Specifically, it is possible to suppress the structural vibration that is the cause by using a cushioning material or the like, or to change the operating conditions of the mechanical device to weaken the generation of vibration or noise. However, when the source of vibration or noise is very high temperature or due to vortices, it is difficult to take additional measures such as a buffer material. In addition, changing the operating conditions is undesirable because it may affect the main performance of the machine, and there is a problem that vibration and noise may occur in a wide operating range.

  Another countermeasure for the source is to suppress resonance or resonance. The requirement for resonance or resonance is that there is a source of vibration or noise, and that the environment surrounding the source must satisfy an acoustic condition corresponding to a period close to the fluctuation period. If the structure around the source is designed, the vibration or noise amplitude will not develop from a small value. However, when the structural design cannot be changed in order to ensure the device performance, or when the structure cannot be changed with the existing device, there is a problem that countermeasures must be taken on the premise of the presence of resonance or resonance. In addition, a structure designed to avoid resonance or resonance has a problem that resonance or resonance of another period can be generated.

  Providing an appropriate buffer mechanism is one of resonance or resonance countermeasures. However, since the buffer mechanism absorbs the amount of mechanical energy that exceeds the amount of mechanical energy generated by the vibration or noise source, in addition to the problem that the buffer mechanism becomes larger and larger in capacity, the great buffer effect is There is a problem of degrading the main performance of the mechanical device.

  On the other hand, as a countermeasure for the propagation path, first, a countermeasure when sound or vibration propagates through the pipe can be mentioned. For example, a sudden expansion section or branch pipe found in piping or the like changes the acoustic impedance of the noise propagation path and disturbs the propagation of noise. Therefore, the sudden expansion section or branch pipe section has an effect equivalent to sound absorption. The Furthermore, using a sound absorbing material in combination with the rapidly expanding portion or the inner surface of the pipe has an effect of increasing noise transmission loss. However, when there is a main flow in the pipe, there is a problem that the rapid expansion pipe causes a large pressure loss. Since the capacity of the branch pipe is constant, there is a problem that if the linearity is assumed, the suppression effect does not increase sufficiently depending on the state of growth of vibration or noise.

  Shielding is another countermeasure for the propagation path. Covering the sound source with a shielding plate for sound propagating from the source, and providing vibration absorbers at the pipe joints and fixed parts of the machine device for vibrations transmitted through the machine or piping. Shut off. However, since the sound insulating material is generally governed by the mass law, a relatively large-scale measure such as increasing the mass of the sound insulating material or multiplying the partition walls is necessary to provide a sound insulating effect. In addition, since unnecessary parts are sometimes shielded, there is a problem that countermeasure costs are required.

  Furthermore, as a countermeasure for the propagation path, vibration or noise having the same magnitude and opposite phase as the vibration or noise propagating from the source is generated from the artificial source, and the vibration or noise propagating by interfering with each other is generated. Active control methods to weaken have been proposed. However, in the active control method, the secondary sound is oscillated when the secondary sound is received by the input sensor, the upper limit of the applied frequency due to the performance limit of the signal processing device, the noise increase other than the position where the error sensor is located, There are problems such as the power limit of the secondary sound, noise in the presence of airflow, etc., and the cases that can be applied are limited. For example, it is extremely difficult to apply under high sound pressure conditions found in high-pressure compressors and high-temperature conditions found in boilers and combustors.

On the other hand, research on thermoacoustic generators has been actively conducted in recent years, and thermoacoustic generators are closed systems in which heat, acoustic energy, and gas pressure oscillations that generate sound by heat given from outside are converted into each other. There is a characteristic that can generate fluid vibration or fluid sound without having a movable part such as a diaphragm, and it is applied to thermoacoustic heat pumps, thermoacoustic refrigerators, Stirling engines, etc. However, a technical idea for suppressing fluid vibration or fluid noise in a fluid machine by a thermoacoustic phenomenon is not yet known. Conversely, thermoacoustic phenomena that inevitably occur in fluid machinery, for example, thermoacoustic vibrations often occur in the combustion chamber of a gas turbine, etc., resulting in the occurrence of pressure fluctuations and vortices in the combustion chamber. It is also known to cause malfunctions such as increased load and inhomogeneous combustion. For this reason, methods for reducing thermoacoustic vibration generated in these devices have also been proposed (see, for example, Patent Documents 4 and 5).
JP 2001-330330 A JP-T-2001-521125 JP 2000-088378 A Japanese Patent Laid-Open No. 10-068556 JP 2002-61521 A Japanese Patent Laid-Open No. 7-293858 Industrial Environment Management Association "Pollution Prevention Technology and Regulations Noise", Nippon Printing, (2002) GBSwift, "Thermo-acoustic Engines", Journal of Acoustic Society of America, 84-4, (1988), p1145 JWSRayleigh, "The Theory of Sound", Dover Pub., (1945) AAPutnam, "Combustion Driven Oscillation in Industry", Elesevier Pub., (1971)

Conventionally, various methods have been proposed to suppress fluid vibration and fluid noise in a fluid machine as described above. These conventional measures include the following (1) to (4). There are issues to be solved.
(1) The device must have a simple structure. It may not be applicable to a device with a complicated mechanism or a method that operates only under special conditions, depending on the constraints of the mechanical device to which countermeasures are taken. Become. If the vibration and noise suppression device has a simple structure without a special circuit board or sensor, it is meaningful that the manufacturing cost can be reduced and the maintenance inspection period can be extended. In addition, if it can be easily added to an existing machine, it is advantageous to avoid remodeling or performance deterioration of the machine as much as possible.
(2) Having an autonomous function Secondary sound sources found in noise active control devices require an external power supply, condition monitoring sensor, and wiring, so there are malfunctions and maintenance inspection items due to problems with these auxiliary devices. There are problems such as an increase. These problems can be solved if an external power supply is not required and the noise vibration suppression function can be automatically exhibited by using energy such as exhaust pressure and exhaust heat of the applied mechanical device. It is also desirable if the noise and vibration suppression function can be automatically stopped without the need for a special monitoring sensor or wiring when the output of the mechanical device is reduced or stopped.
(3) The effect can be automatically adjusted according to the load. Suppression of vibration and noise is sufficient if it is necessary and sufficient depending on the level of the source, and excessive reduction performance is rather cost-effective. There is a risk that it will become a large scale and the performance of the mechanical device will deteriorate. In general, the number of rotations and the amount of heat generated increase as the operating load of the mechanical device increases, so that vibration and noise tend to increase accordingly. On the contrary, the vibration noise may be significant only at the time of starting the mechanical device. Therefore, if the vibration suppression effect can be automatically adjusted according to the exhaust pressure and exhaust heat caused by the mechanical device when the operating state of the mechanical device reaches a certain condition, the machine under the operational condition that does not require vibration noise suppression. It is possible to reduce the performance degradation of the apparatus, and to save labor for monitoring and adjustment by the operator.
(4) Acting indirectly on the generation source Generally, in order to suppress these in a state where vibration and noise are developed, a corresponding energy is required. For example, active control of noise requires a secondary sound source having a sound power comparable to that of the sound source. The same applies to fluid-related vibrations and fluid-related noises. If the flow field, temperature field, and density field of the fluid are non-uniform, the fluid itself or the interference between it and the structure will be the source of the large amplitude fluid vibration. Or fluid noise is generated. Since once generated fluid vibration and fluid noise have a large energy in a wide range, it is necessary to install a device for directly reducing these vibrations, and to absorb and absorb vibration and absorb sound with a predetermined volume and dynamics. It is necessary to supply energy. On the other hand, in many cases, it is only necessary to use a reduction device having a relatively small capacity and power to suppress the occurrence of fluid vibration and fluid noise indirectly by acting on the cause of fluid vibration and fluid noise. For fluid-related vibrations and fluid-related noises caused by large velocity gradients and temperature gradients, for example, the mechanism that increases the mechanical energy related to vibrations and noises by acting on the steep parts of the velocity gradients and temperature gradients. If it can be destroyed, the energy required for the vibration and noise suppression device can be reduced.

  The present invention intends to solve the above-mentioned problems to be solved in the suppression of fluid vibration and fluid noise by utilizing the thermoacoustic phenomenon, and to solve the fluid vibration and fluid noise using the thermoacoustic phenomenon. An object is to provide a suppression device.

The fluid vibration or fluid noise suppression device of the present invention that solves the above problems is a device that suppresses fluid vibration and fluid noise of a fluid machine, and at least one end of the pipe is open at a high temperature side heat exchanger and a low temperature side heat exchange. A thermoacoustic generator is configured by installing a heat exchanger adjacent to the high temperature side heat exchanger, and the thermoacoustic generator is installed so that the open end of the pipe faces the fluid flow field of the fluid machine. A low temperature fluid is respectively introduced into the low temperature side heat exchanger to form a local temperature gradient between the high temperature side heat exchanger and the low temperature side heat exchanger, and the open end of the thermoacoustic generator By generating air column vibrations so that the particle velocity becomes an antinode, and acting on the fluid of the fluid flow field velocity gradient or temperature gradient steep part, to relax the fluid velocity gradient and temperature gradient, To suppress fluid vibration and fluid noise. Wherein the high-temperature side heat exchanger is characterized by being configured to introduce hot gases caused by the driving of the fluid machine.

  By installing a rectifying regenerator having a rectifying action and a heat accumulating effect in one direction between the high temperature side heat exchanger and the low temperature side heat exchanger, the fluid receives heat from the heat accumulator and the heat accumulator. The process of releasing heat is repeated to become a driving source for the fluid vibration. The tube of the thermoacoustic generator may be either a tube open at one end and a tube closed at both ends, or a tube open at both ends. In the case of a tube closed at one end and the other end, the low temperature side from the open end to the closed end in the center of the tube. Heat exchanger and high temperature side heat exchanger are arranged, and in the case of open pipes at both ends, the low temperature side heat exchanger and the high temperature side heat exchange from the open end to the center at each 1/4 position of the tube length from both open ends A container is arranged and configured. Moreover, various heat sources can be adopted as the heat source of the high temperature side heat exchanger according to the fluid machine, for example, a fine flame burner or an electric heater can be used. In the case of an electric heater, it is desirable to adjust the applied voltage according to the operating load. The tube of the thermoacoustic generator for generating the air column vibration can widen the frequency band of particle velocity fluctuations generated by using not only one but also a plurality of pipes having different lengths, and various fluid vibrations. Or it can respond to fluid noise suppression.

  The fluid vibration or fluid noise suppression device can be applied to suppression of combustion vibration occurring in a combustor such as a boiler or a gas turbine. In that case, the fluid flow field is the combustion chamber of the combustor, the open end of the tube is installed at a position where the temperature gradient near the combustion burner is steep, and the high temperature gas is externally supplied to the high temperature side heat exchanger. Introduce low-temperature fluid into the low-temperature side heat exchanger, generate air column vibrations in the pipe, cause particle velocity fluctuations at the open end, promote mixing of hot gas near the flame and unburned low-temperature gas, steep Reducing the temperature gradient can suppress the occurrence and growth of combustion vibration in the combustion chamber. In that case, it is desirable that the high temperature gas inside the combustor is adopted as the high temperature gas introduced into the high temperature side heat exchanger, and the unburned low temperature gas is introduced as the low temperature gas introduced into the low temperature side heat exchanger. Also, if the fluid introduced into the low temperature side heat exchanger is a low temperature gas or exhaust gas in the combustor, it functions because there is a temperature difference between high temperature (near the burner) and low temperature (exhaust gas, etc.) at the start, Combustion vibration at start-up can be suppressed, and the effect can be automatically adjusted according to the load. In addition, there is an advantage that fluid motion is promoted at start-up, and mixing in the combustor proceeds.

  In the fluid vibration or fluid noise suppression device, separation occurs immediately after the bent portion, such as a compressor immediately after the bent pipe, and a non-uniform flow flows into the rotor blades such as the impeller behind and causes failure and noise. It can be applied to the device. In that case, the fluid flow field is in a bent pipe of a fluid machine having a rotor blade immediately after the bent pipe, and the pipe that generates the air column vibration is located immediately before the bent portion of the bent pipe or the opening end faces the bent portion. It is installed in such a way that momentum transport is promoted at the bend by air column vibration, vortex generation at the bend is mitigated, and large-scale vortices are crushed to reduce vortex interference with downstream rotor blades. This is characterized by preventing vibration noise.

  Furthermore, the fluid vibration or fluid noise suppression device can be applied to a device having a nozzle that ejects fluid. In that case, the fluid flow field is a low-speed flow field in the vicinity of the nozzle that ejects high-speed gas, and the nozzle that generates the air column vibration is disposed near the nozzle end on the outer periphery of the nozzle, thereby causing the nozzle to vibrate due to air column vibration. Shock wave-related by preventing the generation of interference waves returning to the nozzle while promoting the mixing of the high-speed gas flow exhausted from the nozzle and the low-speed air flow along the nozzle periphery and converting the vortex generated from the nozzle end into a small-scale vortex Generation of noise and jet noise can be reduced.

  The tube for generating the air column vibration has a tube diameter that is sufficiently smaller than the flame of the combustion burner or the vortex dimension of the vortex generated from the nozzle end, and the period of the air column vibration is the burner flame vibration. It is desirable to set the tube length to be sufficiently shorter than the period or the vortex shedding period. In addition, by changing the cross-sectional shape of the tube or the cross-sectional area in the axial direction, or by providing a projection inside the tube to change the acoustic impedance, the air column vibration generation threshold can be adjusted according to the use conditions. Can demonstrate self-supporting function.

  The fluid vibration or fluid noise suppression device according to the present invention constitutes a tube-shaped thermoacoustic generator with one end open and the other end closed or both ends open, and can be formed in a simple and compact structure. Can be easily added. The device is composed only of a heat source, a heat storage rectifier, a heat exchanger, and a tube, and there are no moving parts and there are few failures. Therefore, the time and cost required for maintenance can be saved. In addition, since the device according to the present invention utilizes the high and low temperature difference caused by the operation of the mechanical device, it can operate independently without a sensor or a control device when it reaches a specific operation state (automatic ON-OFF function) ). Further, the adjustment can be made so that the operation is performed only in a state where the vibration and noise are remarkable and the operation is stopped under other conditions, so that the influence on the performance deterioration of the mechanical device is small.

  Furthermore, in the fluid vibration or fluid noise suppression device or method according to the present invention, the larger the local temperature difference, the greater the effects such as the magnitude of the particle velocity fluctuation that occurs. Therefore, the vibration or noise suppression effect can be automatically adjusted without a sensor or a control device for fluid vibration or fluid noise that occurs as the operating load of the mechanical device increases and the local temperature difference increases. Adaptive control function). Furthermore, the apparatus or method according to the present invention does not directly act on the vibration field or noise field formed by the mechanical device, but acts indirectly on the mechanism governing the generation of the vibration or noise of the source. In order to suppress vibration or noise generation, less power is required compared to the case of direct action. In addition, it is assumed that the required power is obtained from excess exhaust heat of the mechanical device, which also has an energy saving effect.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a basic form of a thermoacoustic generator used in a fluid vibration or fluid noise suppression device of the present invention, and FIG. 2 is a schematic diagram of its operation. The thermoacoustic generator 1 of this embodiment is a thermoacoustic generator with one end open and the other end closed. In the thermoacoustic generator, a heat exchanger as a high and low heat source is placed close to the inside of the pipe, and a rectifying regenerator having a rectifying action and a heat storage effect in one direction is placed between the heat exchangers. By forming a temperature gradient, there is a certain phase difference with respect to the fluid motion in the transfer of heat between the fluid passing through the rectifying regenerator and both the high and low heat sources, and the thermal energy from the heat source is fluid vibration or fluid It appears as mechanical energy called sound. The thermoacoustic generator 1 according to the present embodiment includes a heat-insulating tube portion 3 made of a heat insulating material at a central portion, and both ends of the thermoacoustic generating device 1 are formed of tube ends 2 and 5 that are closed at one end. Yes. A large number of heat storage plates 6 are filled in the heat insulating tube portion 3 in parallel with the tube axis direction to form a heat storage unit 7. In the heat accumulator 7, a large number of heat storage plates arranged in parallel have a structure like a rectifying grid, and fluid can freely pass therethrough. Wire meshes 8 and 9 constituting a heat exchanger are provided at both ends of the heat storage plate 6 (heat storage 7).
On the other hand, heat exchange pipes 10 and 11 are embedded in the pipe wall near the ends of the pipe main body parts 4 and 5 facing both ends of the heat insulation pipe part 3, and as shown in the drawing, for heat exchange on the closed end side. The pipe 10 is heated and the open-end heat exchange pipe 11 is used as a low-temperature fluid (for example, a refrigerant), and a coolant or a cooling gas flows to heat and cool the metal meshes 8 and 9 to a constant temperature. Accordingly, the wire mesh 8 constitutes a high temperature side heat exchanger, and the wire mesh 9 constitutes a low temperature side heat exchanger. The center of the heat insulating pipe part 3 is located at the center of the pipe length L of the pipe 2, that is, L / 2, and the metal meshes 8 and 9 are arranged symmetrically and close to the central part.

The heat exchanging pipe is not limited to the above-described configuration, and can be appropriately configured. For example, the heat exchanger only needs to have a structure that is uniformly present in the cross section of the tube but does not hinder the passage of gas. As described above, the mesh wire net 8 is fixed to the tube wall and the heat passing through the tube wall is fixed. A structure in which heat is exchanged from the exchanger may be used, or a thin tube may be arranged in a cross section of the tube in a mesh shape so that heat is exchanged with air passing through the tube through a hot gas and a cold fluid, respectively. . In any event, to transfer heat outside the high-temperature heat source in the tube a gas, the heat transfer path to abandon the outside of the cold heat source takes heat is established from tube gas, heat exchange into the tube gas tube cross section uniform And it must be generated in a very short section in the tube axis direction. It is desirable to install a heat accumulator that also functions as a rectifier as described above between the heat exchangers, but it is not necessary to install a heat accumulator as will be described later.

  The thermoacoustic generator 1 of the present embodiment is configured as described above, and the high-temperature gas and the low-temperature fluid exchange heat with the tube walls of the tube main body portions 4 and 5, respectively, and are made of high-temperature metal wires that are in contact with the heat storage plate 6. The side heat exchanger (high temperature side heat exchanger) 8 and the low temperature heat source (low temperature side heat exchanger) 9 are kept at a predetermined temperature. When the temperature difference between the high temperature gas and the low temperature fluid increases, a corresponding temperature difference of the wire mesh is generated, and a temperature gradient is generated in the heat accumulator 7 along the tube axis. When the air passing through the heat accumulator 7 periodically fluctuates in the tube axis direction, the heat flow fluctuation between the heat storage plate and the air in the region sandwiched between the heat storage plates and the air pressure fluctuation have a predetermined phase relationship, Part of the energy is converted into mechanical energy, causing a phenomenon in which pressure fluctuations increase with time. The pressure fluctuation forms an antinode of speed fluctuation at the open end and an antinode of pressure fluctuation at the closed end. When the temperature difference between the hot gas and the cold fluid decreases, the amount of heat transport from the high temperature heat source to the low temperature heat source decreases and the amount of mechanical energy generation also decreases. Vibration stops. When the temperature of the low temperature fluid is kept constant, air column vibrations are excited if the high temperature gas is heated, and when the high temperature gas is stopped, the air column vibrations gradually weaken and eventually stop. Thus, in order to generate the air column vibration excited in the tube, there is a predetermined threshold for the temperature difference between the high and low heat sources. Therefore, since it has an on / off function autonomously depending on the threshold value, as will be described in detail in the embodiments to be described later, a special sensor or arithmetic device follows a change in the fluid temperature introduced into the high temperature heat source and the low temperature heat source. Even without adding, the operating range of the device can be automatically adjusted. That is, an autonomous function that follows changes in the temperature of the fluid introduced into the high-temperature heat source and the low-temperature heat source can be exhibited. Therefore, if exhaust gas generated by driving a fluid machine or the like to which the device is applied is used as a fluid to be introduced into the heat source, the exhaust gas temperature differs depending on the load (output) of the fluid machine or the like. On the contrary, it does not operate at the time of starting but operates only at the steady state, or can be automatically operated according to the load.

2-6 is a schematic diagram for demonstrating in detail the said principle of operation of a thermoacoustic generator. Air column vibration in a thermoacoustic generator refers to fluid vibration caused by a high temperature or low temperature heat source instead of a vibration source. Although the heat source releases or absorbs a certain amount of heat in time internally, when the pressure change of the fluid surrounding the heat source and the heat flux change of the heat source surface have an appropriate phase relationship, fluid vibration is promoted, It is suppressed. FIG. 2 shows an example of a low-temperature heat source and a high-temperature heat source placed in one end open / closed end closed tube that excites the fundamental order, that is, the longest wavelength air column vibration. Although steep temperature gradient between the cold heat source and a high temperature heat source is formed, since here the heat accumulator 7 is installed, the fluid in sandwiched engagement cormorants thermal storage plate 6 adjacent area heat storage plate The process of receiving heat from 6 and the process of releasing heat to the heat storage plate are repeated to provide a driving source for fluid vibration.

  The mechanism for promoting or suppressing fluid vibration is roughly described as follows. FIG. 3 shows two sets of a low temperature heat source (low temperature side heat exchanger 9), a high temperature heat source (high temperature side heat exchanger 8), and a heat storage plate 6. Even in the state where no vibration is excited in the tube, there are minute fluctuations in pressure and particle velocity in the tube. The heat flux on the surface of the heat storage plate 6 also varies depending on the state of the fluid around the heat storage plate. The vicinity of the heat storage plate surface pole is the boundary layer vicinity region, and the temperature change rapidly occurs due to heat conduction from the surface of the heat storage plate 6. On the other hand, the central mainstream region that is some distance away from the surface of the heat storage plate is a main adiabatic propagation path of sound waves. Although heat transfer between this region and the region near the boundary layer is mainly due to heat conduction, the time required for diffusion is different from the above case and cannot be ignored. Therefore, there is a time delay for the temperature to be the same as that in the vicinity of the boundary layer, that is, the same temperature as the heat storage plate surface. Macroscopically, this means that the heat transfer between the main fluid occupying between the heat storage plates and the heat storage plate, that is, the heat flux, has a time lag or phase lag with respect to the fluid particle motion. means.

  If the particle velocity in the mainstream region is high on the high temperature heat source side, the low temperature side fluid enters the region between the heat storage plates 6, so the temperature distribution around the low temperature heat source, the high temperature heat source, and the heat storage plate changes as shown in FIG. However, compared to the steady temperature gradient, the temperature is gentle on the low temperature side and steep on the high temperature side, and a temperature distribution lower than the steady temperature distribution is formed as a whole. At this time, since the mainstream fluid temperature is lower than the surface temperature of the heat storage plate, a heat flux from the heat storage plate 6 to the fluid is generated. However, the heat flux is maximized with a time delay after the particle velocity of the mainstream fluid is maximized due to the phase delay.

  On the other hand, when the particle velocity in the mainstream region is large on the low temperature heat source side (when the direction toward the high temperature heat source is positive and large in the negative direction), the fluid on the high temperature side enters the region between the heat storage plates. The temperature distribution around the heat source, high-temperature heat source, and heat storage plate changes as shown in Fig. 5, and is steeper on the low temperature side and gentle on the high temperature side than the steady temperature gradient, and the overall temperature distribution is higher than the steady temperature distribution. Is done. At this time, since the mainstream fluid temperature becomes higher than the heat storage plate surface temperature, a heat flux from the fluid to the heat storage plate is generated. However, the heat flux is maximized with a time delay after the particle velocity of the mainstream fluid is maximized in the negative direction due to the phase delay.

  FIG. 6 shows the phase relationship between the elementary fluid velocity, the pressure, and the received heat flux of the main fluid in the region sandwiched between the heat storage plates 6. The standing wave of the lowest order formed in the tube with one end open and the other end is closed, considering that the particle velocity is advanced 90 degrees with respect to the pressure at a distance of half the tube length from the open end. It can be seen that the heat source is in phase within 90 degrees. At this time, when the fluid pressure is slightly higher than the steady pressure, the heat flux from the heat storage plate surface is slightly higher than the steady heat flux, and when the surrounding fluid pressure is slightly lower than the steady pressure, the heat flux from the heat storage plate surface The temporal relationship (hereinafter referred to as phase relationship) that the heat flux is slightly less than the steady heat flux is satisfied. That is, since the fluid sandwiched between the high and low heat sources, the heat storage plate, and the heat storage plate performs the same process as the internal combustion engine, the heat energy from the heat source appears as mechanical energy such as fluid vibration or fluid sound.

  The above is the case of a tube with one end open and the other end closed, but the thermoacoustic generator 20 composed of a tube with both ends open can also be used. FIG. 7 is a schematic diagram for explaining the operation when applied to the tube 21 having both ends open. Portions similar to those of the above-described embodiment are denoted by the same reference numerals, detailed description thereof is omitted, and only differences are described. Considering the lowest order mode in the open tube 21 at both ends, the center of the tube is an antinode of pressure and a node of speed. Therefore, a low-temperature heat source from the open end to the position of 1/4 of the tube length L toward the center from the open end. A heat source may be arranged in the order of (low temperature side heat exchanger) 22 and high temperature heat source (high temperature side heat exchanger) 23, and a heat accumulator 24 may be arranged therebetween. FIG. 7 is a schematic diagram (a) of the thermoacoustic generator 20 in which two sets of high and low heat sources are arranged at positions L / 4 and 3L / 4, and the heat flow rate fluctuation and air pressure received by the air at that time. The phase relationship of the fluctuation is shown in (b) and (c) corresponding to the positions of the high and low heat sources. FIG. 8 shows the lowest order mode of pressure fluctuation and speed fluctuation at that time. In the figure, a solid line 25 indicates pressure fluctuation, and a broken line 26 indicates heat flow speed fluctuation. In any case, since the phase difference between the heat flux fluctuation and the pressure fluctuation is within 90 degrees, a heat engine is formed and the air column vibration is excited. Even if it is arranged only on one side, the air column vibration is excited. By using a heat source, air column vibrations generated in the pipe can be actively suppressed.

  FIG. 9 shows a thermoacoustic generator 30 according to another embodiment. When the arrangement of the high and low heat sources is opposite to that in FIG. 2, that is, the high temperature heat source 32 and the low temperature heat source from the open end to the closed end of the tube 31. This is the case of arranging in the order of 33. In this state, the heat flux fluctuation when the air passing through the heat accumulator 34 vibrates in the tube axis direction is opposite to the phase described in FIGS. 6 and 7, and the phase relationship between the pressure fluctuation and the heat flux fluctuation is as shown in FIG. As shown in the figure, a heat cycle is constructed in which heat is taken away when the pressure is high and heat is supplied when the pressure is low. This is equivalent to taking heat away from work, resulting in a decrease in mechanical energy in the tube and suppression of air column vibration growth. FIG. 11A shows an arrangement of high and low heat sources for realizing this vibration suppression with both ends open pipes, and pressure fluctuation and heat flow fluctuation at positions L / 4 and 3L / 4 from the pipe end at that time. The phase relationship is shown in FIG.

  FIG. 12 shows a basic form of a thermoacoustic generator when no heat accumulator is provided between the high temperature heat source and the low temperature heat source. In the thermoacoustic generator 40 of this embodiment, a low-temperature heat source (heat exchanger) 42 and a high-temperature heat source (heat exchanger) 43 are adjacent to each other in the vicinity of the center of the tube 41 that is open at one end and the other end from the open end toward the closed end. Installed. Both heat sources have a structure that does not prevent the passage of gas while being uniformly present in the cross section of the tube, for example, a heat exchanger that passes through the tube wall with a mesh metal mesh fixed to the tube wall as shown in the figure The structure may be such that heat is transferred from or to the tube, or the thin tubes may be arranged in a cross section of the tube in a mesh shape to exchange heat with the air passing through the tubes through the hot gas and the cold fluid, respectively. A fine flame burner may be arranged on the high temperature heat source side. In any case, a heat transfer path is established in which heat from the external high-temperature heat source is transferred to the gas in the pipe, and heat is taken from the gas in the pipe and discarded to the external low-temperature heat source. It must be generated in a very short section in the pipe axis direction. The tube cross-sectional shape is arbitrary.

Hereinafter, an embodiment of a fluid vibration suppression device or a fluid noise suppression device that suppresses fluid vibration or fluid noise of a fluid machine using the thermoacoustic generator will be described in detail with reference to the drawings.
FIG. 13 shows an embodiment applied to suppress combustion vibration in a combustor. Of the combustion vibration generated in the combustor, the vibration due to thermal excitation is generated from the portion where the temperature gradient increases rapidly in the vicinity of the burner. Similar to the above-described heat column vibration generation principle, when the gas periodically fluctuates with pressure fluctuations in the temperature gradient portion near the burner, heat energy is supplied from a high-temperature heat source to form a heat engine. Reduce the action of the heat engine that is the combustion vibration source (specifically, reduce the heat flux, disturb the phase of the heat flux fluctuation relative to the pressure fluctuation, or weaken the correlation between the pressure fluctuation and the heat flux fluctuation) If so, it will lead to suppression of combustion vibration.
One way to reduce the heat flux from the combustion part is to moderate the temperature gradient. In order to moderate the temperature gradient, it is effective to promote the mixing of the relatively low temperature unburned gas upstream of the burner with the high temperature gas. By installing the opening of the tube of the thermoacoustic generator for exciting the air column vibration according to the present invention near the upstream of the burner, the particle velocity fluctuation of the opening accompanying the air column vibration promotes mixing around the temperature gradient portion. As a result of the increase in the heat transfer coefficient, it can be expected that the temperature gradient becomes gentle. By mixing the gas in the part where there is a temperature gradient, the effect of disturbing the correlation between the pressure fluctuation of the gas and the fluctuation of the heat receiving heat flux can be expected.

  As for the gas supplied to the heat exchanger of the heat source in the pipe, the vibration noise in response to the operation of the combustor itself by introducing the combustion gas on the high temperature side and the outside air or unburned gas in the combustor on the low temperature side. The suppression device will be activated and deactivated. That is, when unburned gas is introduced into the low-temperature side heat exchanger, the temperature difference between the high and low heat sources is large immediately after the combustor is started. growing. When the time after combustor startup elapses, the temperature inside the combustor rises due to heat conduction, etc., and the temperature of the unburned gas also rises. Stops. When the low temperature gas is selected in this way, if the combustion vibration is significant at the start, the suppression effect works only when the vibration occurs, and when the vibration is small, the suppression effect is lowered and the air column vibration itself does not adversely affect the combustion performance. There is a feature.

  The present embodiment is based on the above principle, and in order to suppress the emission of nitrogen oxides (NOx) in recent years, the combustor of the gas turbine performs uniform combustion using a very fine flame. In this case, a steep temperature gradient is formed between the vicinity of the burner and the upstream side. Due to this steep temperature gradient, combustion vibration corresponding to air column vibration is generated inside the combustor. In the present embodiment, in order to suppress the combustion vibration, the tube opening end of the thermoacoustic generator 47 is installed so as to be positioned near the fine flame 46, and as shown in FIG. For example, outside air or compressor bleed air is introduced into the heat exchanging portion 49 connected to the low temperature heat source, and combustion gas is introduced into the heat exchanging portion 50 connected to the high temperature heat source.

  With the above configuration, when the combustor 45 is started and the combustion temperature rises, the temperature difference between the high and low heat sources of the apparatus rises, and air column vibration grows in the pipe. Since air column vibration becomes an antinode of particle velocity at the opening, it is installed in the vicinity of the flame to promote the stirring of the low temperature gas upstream of the flame and the high temperature gas near the flame, and gradually reduce the temperature gradient near the flame. Can be expected. The stirring action has an action of weakening the heat flux by making the temperature gradient near the flame gentle, and an action of shifting the phase relation between the pressure fluctuation and the heat flux fluctuation from the phase relation acting as a heat engine. As a result, the temperature gradient portion in the vicinity of the flame hinders the function as a heat engine, the conversion from thermal energy to mechanical energy becomes insufficient, and the growth of combustion vibration is suppressed. Adding particle velocity fluctuations in the vicinity of the flame may lead to flame instability, but the device itself may have many thin tubes that do not cause flame instability, or many tubes with different tube lengths. As a result, combustion instability can be avoided by exciting a plurality of particle velocity fluctuations and acting only on the source of combustion oscillation.

The effect of stirring increases as the combustion gas temperature increases, that is, as the load on the combustor increases. As a result, a steep temperature gradient is relieved in the combustor compared to the case where no thermoacoustic generator is installed, and combustion vibration is suppressed. Therefore, according to the present embodiment, it is possible to effectively suppress the combustion vibration of the combustor and reduce NOx only by installing a thermoacoustic generator having a simple structure including a tube and a heat source. Moreover, since the shape of the combustor is hardly changed when the thermoacoustic generator is applied to the combustor, it can be easily applied to a conventional combustor.
The above description has been made by taking a combustor such as a gas turbine as an example, but the same effect can be applied to combustion vibration of a boiler, unstable combustion of a rocket combustor, and the like. In addition, to reduce rotating machine noise generated by interference with the wake and shock wave related noise generated from supersonic nozzles, the cause vortex is divided into a large number of small vortices, and separation by promoting momentum near the wall surface is performed. By preventing it, the noise source can be weakened and the noise generation can be suppressed.

  FIG. 14 shows a case where a bend is made in order to prevent the occurrence of a failure, noise, or a phenomenon that causes a reduction in lift due to a non-uniform flow flowing into an impeller behind the bend, such as a compressor or aircraft wing surface immediately after the bend. The Example which applied the thermoacoustic generator of this invention to the pipe part is shown. FIG. 14 is a schematic diagram in the case where an impeller 56 such as a compressor or a pump is installed immediately after the bent pipe 55. Since flow separation occurs immediately after the bent portion, uneven flow and separation vortex are behind. When an impeller 56 collides with the impeller 56, a large interference sound is generated. Therefore, in this embodiment, the thermoacoustic generator 57 of the present invention is arranged at the bent portion or immediately before it to generate thermoacoustic vibration according to the load of the mechanical device, thereby promoting the momentum transport of the peeling portion. To suppress the generation of vortices and uneven flow.

  The thermoacoustic generator 57 installs the illustrated opening, that is, the part that becomes the antinode of the particle velocity motion at the peeling position, introduces a low temperature fluid into the heat exchanger of the low temperature heat source 58 located on the opening side, The exhaust heat of the mechanical device was introduced into 59 heat exchangers to excite the air column vibration. At the position where the opening of the thermoacoustic generator faces the fluid flow field of the bent pipe, a perforated plate 60 or a flexible structure film is installed to excite the fluid. As described above, by installing the thermoacoustic generator at the bent portion of the bent tube or immediately before it, the air column vibration generated by the thermoacoustic generator vibrates the fluid, and the momentum where the velocity gradient of the flow field is large It has the effect of promoting transportation, preventing separation, and crushing large-scale vortices into fine vortices. Thereby, it is possible to suppress the generation of vibration noise due to the vortex and the non-uniform flow interfering with the impeller on the downstream side.

  As an application example of the above liquid embodiment, when applied to a rocket motor pump, when a combustion gas is introduced into a high-temperature heat source and liquid fuel is introduced into a low-temperature heat source, the temperature of the combustion gas is low at low loads, so the high-temperature heat source The temperature difference between the low-temperature heat source and the air column vibration is small, and no air column vibration occurs. Since the startability of the pump is important when the load is low, air column vibration is not necessary, so it is convenient that the thermoacoustic generator does not operate when the load is low. On the other hand, when the load is high, the combustion gas temperature rises, so the temperature difference between the low-temperature heat source and the high-temperature heat source becomes large, and air column vibration occurs. The operation of the thermoacoustic generator is advantageous in order to prevent the influence of the peeling because the flow rate is high at high loads and the influence of the peeling leads to damage of the impeller. As described above, in the present invention, by adopting the high-temperature heat source and the mechanical device to which the low-temperature heat source is applied, the thermoacoustic vibration is automatically or actively performed according to the load of the mechanical device without requiring a special control mechanism. Can be generated, and the momentum transport of the peeling portion can be promoted.

As another application example, it can be used to promote turbulent flow on the surface of the main wing during takeoff of an aircraft. Currently, a vortex generator or the like is used to promote turbulent flow on the surface of the main wing at takeoff, but turbulent flow promotion on the surface of the main wing is necessary at takeoff and not at cruising. Therefore, there is a demand for a turbulent flow promoting means on the surface of the main wing that is small and light and that automatically operates only during takeoff.
Therefore, if the thermoacoustic generator of the present invention is installed on the surface of the main wing in place of the current Vortex generator and the combustion gas or engine exhaust at the turbine inlet is introduced into the high-temperature heat source, the engine output becomes maximum at takeoff. Therefore, the turbine inlet temperature becomes maximum, the temperature difference between the high temperature heat source and the low temperature heat source is large, and air column vibration is generated in the thermoacoustic generator, which promotes turbulent flow on the surface of the main blade. On the other hand, during cruising, the temperature of the high-temperature heat source decreases, and the action of air column vibration can be stopped.

FIG. 15 shows an embodiment in which the thermoacoustic generator of the present invention is applied to a nozzle portion of a jet engine in order to reduce the noise of the jet engine.
Since the exhaust gas flow velocity from the nozzle of an aircraft jet engine is higher than the atmospheric flow velocity on the outer peripheral surface of the nozzle, the difference between the high-speed flow and the low-speed flow is large behind the nozzle, and the vortex is excited and jet noise occurs. In addition, if there is a shock wave behind, the vortex interferes with the shock wave to form a feedback circuit, generating a screech sound that is a high-frequency, sharp noise. In order to suppress the generation of the noise, in this embodiment, the thermoacoustic generator 65 is installed so that the opening faces the flow direction of the atmospheric flow field on the outer peripheral surface near the tip of the nozzle 66 of the jet engine. . That is, a low-temperature heat source 67 is provided on the opening side of the thermoacoustic generator, a high-temperature heat source 68 is provided on the closed side, exhaust gas is guided to the high-temperature heat source, and the opening becomes an antinode of particle velocity fluctuations to the low-temperature heat source. It is installed to excite the air column vibration.

In this way, air column vibrations generated by the thermoacoustic generator near the nozzles promote the mixing of the low-speed flow and the high-speed flow, so that the average speed can be reduced quickly and jet noise can be reduced. Further, the generated vortex can be made into a large number of small vortices, the interference with the shock wave can be weakened, and the shock wave related noise can be weakened by breaking the feedback circuit. And by using exhaust gas as a high-temperature heat source, unlike the conventional mixer, when the output is low during cruising, that is, when the action of the thermoacoustic generator is not required, it will not work naturally. There is no risk of pressure loss due to this.
In FIG. 15, the portion indicated by a broken line behind the nozzle in the lower half of the center line schematically represents the velocity distribution.
By providing the thermoacoustic generator near the nozzle as in the above embodiment, mixing of the low speed flow and the high speed flow is promoted, and as a result, the average exhaust speed is reduced, leading to a reduction in jet noise.

This embodiment is an embodiment applied to noise reduction of a duct having a branch pipe.
As shown in FIG. 16, when there is a branch pipe 71 whose end is closed and closed in the middle of the duct 70, the noise propagating in the duct from the upstream noise source is acoustic as viewed from the noise source. Since the impedance becomes zero, all the sound that propagates theoretically goes to the branch pipe, and no sound propagates downstream from the branch pipe. When the high and low heat sources are arranged at a position L / 2 from the entrance of the branch pipe having the length L, the following effects are produced.
1) When a heat source is placed in the order of a low-temperature heat source and a high-temperature heat source from the branch pipe inlet, standing wave column vibration with a wavelength of 4L is excited in the branch pipe, and the acoustic impedance at the branch pipe inlet becomes zero and Therefore, the sound absorption effect is increased as compared with the case where there is no heat source. In this case, the inner wall of the branch pipe may be covered with a sound absorbing material or provided with a mesh, a rough shape, a protrusion, or the like so as to promote friction loss and sound absorption.
2) When a heat source is placed in the order of a high-temperature heat source and a low-acoustic heat source from the branch pipe inlet, the standing wave column vibration with a wavelength of 4L excited inside the branch pipe absorbs mechanical energy as heat energy in the heat source near the heat source. Therefore, the excited vibration is attenuated. Since the acoustic impedance at the entrance of the branch pipe is still zero, the sound wave entering the branch pipe is absorbed by the heat source even when the standing wave is excited inside, so that the sound absorption effect is increased as compared to when there is no heat source.

  The present invention can suppress fluid vibration or fluid noise due to the thermoacoustic phenomenon, and simply install the thermoacoustic generator in the fluid flow field and remove the low-temperature heat source and the high-temperature heat source of the thermoacoustic generator from the mechanical device itself. It can be adopted, has a very simple configuration, can automatically adjust the suppression effect according to the load of the target mechanical device, can exhibit an autonomous function, and is a source of generation. Since it acts indirectly, it can be applied to various fluid machines such as boilers, heat exchangers, pumps, gas turbines, steam turbines, air conditioners, duct pipes, etc.

1 is a partial cross-sectional front schematic view of a thermoacoustic generator with one end open and one end closed according to an embodiment of the present invention. It is a schematic diagram of the action explanation. It is explanatory drawing of the heat transport between the high-low-temperature both heat sources and two sets of heat accumulators in a thermoacoustic generator. FIG. 4 is an explanatory diagram of fluid temperature distribution when the speed fluctuation is X> 0 in FIG. 3. FIG. 4 is an explanatory diagram of fluid temperature distribution when the speed fluctuation is X <0 in FIG. 3. FIG. 2 is a phase relationship diagram of pressure, velocity, and fluid heat receiving amount at X = L / 2 of the thermoacoustic generator shown in FIG. 1. (A) is a schematic cross-sectional view of a thermoacoustic generator having both ends open according to an embodiment of the present invention, and (b) and (c) are pressure, velocity, fluid receiving at X = L / 4 and X = 3L / 4. It is a phase relationship diagram of heat quantity. It is a basic mode figure of the pressure fluctuation and speed fluctuation which can be made in the pipe of the thermoacoustic generator shown in FIG. It is a cross-sectional schematic diagram of the thermoacoustic generator of one end opening and closing the other end which concerns on other embodiment of this invention. FIG. 10 is a phase relationship diagram of pressure, velocity, and fluid heat receiving amount at X = L / 2 of the thermoacoustic generator shown in FIG. 9. (A) is the cross-sectional schematic diagram of the thermoacoustic generator of both ends open which concerns on other embodiment of this invention, (b) and (c) are the pressure in this X = L / 4 and X = 3L / 4, speed, It is a phase relationship figure of fluid heat receiving amount. (A) is the cross-sectional front schematic diagram of the thermoacoustic generator of the one end open end closed which concerns on other embodiment of this invention, (b) is the AA sectional drawing. (A) is explanatory drawing of the vibration noise suppression apparatus which concerns on embodiment of this invention at the time of applying to the combustion vibration in a combustor, (b) is the enlarged view. It is explanatory drawing of the vibration noise suppression apparatus which concerns on other embodiment of this invention at the time of applying to the vibration noise suppression of the rotating member immediately after a bending pipe. It is explanatory drawing of the vibration noise suppression apparatus which concerns on other embodiment of this invention at the time of applying to the mixing jet noise suppression of a nozzle back flow. It is explanatory drawing of the vibration noise suppression apparatus which concerns on other embodiment of this invention at the time of applying to the performance improvement of the branch pipe in duct noise.

Explanation of symbols

1, 20, 30, 40, 47, 57, 65 Thermoacoustic generator 2, 21, 31, 41, 48 Tube 3 Heat insulation tube portion 4, 5 Tube body portion 6 Heat storage plate 7, 24 Heat storage device 8, 23, 32 , 50, 59, 68 High temperature heat source (high temperature side heat exchanger)
9, 22, 33, 42, 49, 58, 67 Low temperature heat source (low temperature side heat exchanger)
10, 11 Heat exchange piping 25 Pressure fluctuation 26 Speed fluctuation 45 Combustor 46 Fine flame 55 Curved pipe 56 Impeller 60 Perforated plate 70 Duct

Claims (7)

An apparatus for suppressing fluid vibration and fluid noise of a fluid machine, wherein a thermoacoustic generator is configured by installing a high temperature side heat exchanger and a low temperature side heat exchanger adjacent to each other in a pipe having at least one end opened. The thermoacoustic generator is installed so that the open end of the pipe faces the fluid flow field of the fluid machine, and a high temperature gas is introduced into the high temperature side heat exchanger and a low temperature fluid is introduced into the low temperature side heat exchanger, respectively. Forming a local temperature gradient between the high temperature side heat exchanger and the low temperature side heat exchanger, causing the thermoacoustic generator to generate air column vibrations so that the open end becomes an antinode of the particle velocity, is allowed to act on the fluid in the steep part of the velocity gradient or temperature gradient of the fluid flow field, by relaxing the velocity gradient or temperature gradient of the fluid, become so as to inhibit fluid vibration and fluid noise, the high-temperature-side heat The exchanger has a high temperature gas generated by driving the fluid machine. Fluid vibration or fluid noise control apparatus characterized by being configured to introduce.   The fluid vibration or fluid noise suppression device according to claim 1, wherein a rectifying regenerator having a rectifying action and a heat accumulating effect in one direction is installed between the high temperature side heat exchanger and the low temperature side heat exchanger.   The tube of the thermoacoustic generator is a tube that is open at one end and closed at the other end, and is arranged in the order of a low temperature side heat exchanger and a high temperature side heat exchanger from the open end toward the closed end in the center of the tube. 2. The fluid vibration or fluid noise suppression device according to 2.   The said pipe | tube is a both-ends open pipe, It arrange | positions in order of a low temperature side heat exchanger and a high temperature side heat exchanger from the open end toward the center at each 1/4 position of the pipe length from both open ends. 2. The fluid vibration or fluid noise suppression device according to 2. Wherein the fluid machine is a fluid machine having a combustor, wherein the fluid flow field, a combustion chamber of the combustor, the burner upstream near the open end of the pipe a temperature gradient in the vicinity of the combustion burner is steep position placed in, the combustor inside the hot gas to the hot-side heat exchanger, in any one of claims 1-4, characterized by introducing each non燃低warm gas or combustor exhaust gases to the low temperature side heat exchanger The fluid vibration or fluid noise suppression device described in 1. A fluid machine having a rotating blade to bend tube after the fluid machine, the fluid flow field, is said bend pipe, open the tube for generating the air column vibration in the bending portion before or bend of the bent pipe It is installed so that the end faces, the exhaust heat of the fluid machine is introduced into the high temperature side heat exchanger, and the low temperature fluid supplied to the fluid machine is introduced into the low temperature side heat exchanger. The fluid vibration or fluid noise suppression device according to any one of claims 1 to 4 . The fluid machine is a jet engine, the fluid flow field is a low-speed flow field in the vicinity of a nozzle that ejects a high-speed gas, and the pipe is disposed in the vicinity of the nozzle end on the outer periphery of the nozzle so that the open end faces ; claim 1-4 fluidic oscillator or fluid noise suppression device according to any one, characterized by introducing the exhaust gas ejected from the nozzle to the hot side heat exchanger.

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