Experimental Study Of Characteristic Parameters Of Thermoacoustic Core And Development Of High Frequency Miniature Thermoacoustic Experimental Devices

This research was supported by several science and project foundations which focused on the studies of high frequency thermoacoustic engine. Based on the analysis of characteristic and network parameters of thermoacoustic core, the characteristic time was used to evaluate the performance of thermoacoustic core in order to simplify the theory study method and instruct the engine design work. Through the design process and experimental performance test on the high frequency thermoacoustic refrigerator and its external excitation device, the optimizing experience could be achieved from theory and reality. The following were the main work:At first, basing on the analysis of parameter exciting principle, the network of the thermoacoustic core was conformed to a three-frequency parameter. The coupling of different frequencies was devoted to the energy gain and feedback. So it was the frequency who decided the ability and efficiency of the thermoacoustic effect in the engine. With the rising of the frequency, the size of the thermoacoustic engine would become smaller and smaller. The characteristic space and time dimensions were comparative with the time of system dynamic process. Then the relaxation time and frequency together could be used to scale the thermoacoustic effect. By the help of Professor Zuber's fractional scaling analysis, the characteristic time was proved to simplify the current theory research on thermoacoustic system effectively.Secondly, the thermoacoustic core was should be designed and chose correctly and effectively for its import role on the thermoacoustic effect. Since different thermoacoustic cores had different frequency properties, they had different frequency choices in the same resonator. Then by the experimental identification on the frequency characteristic of five kinds of thermoacoustic core coupled with the same resonator, the complex compliance and quality factor of these matrixes were experimentally analyzed respectively in the system of loudspeaker-driven thermoacoustic resonator (TAR). And the quality factor was then used to evaluate the performance of the thermoacoustic core to study the matching relationship with the resonator. Thirdly, the system identification method could help to analyze the complicated flow phenomena of gas whin the theromacoustic core. After setting up the network model of thermoacoustic core, the parameter identification skill was used to identify the network parameter of thermoacoustic core experimentally. The resistance, inertance and compliance were identified in two kinds of length resonator with and without temperature gradient and compared with the theory results to test and verify the feasibility of the system identificationFourthly, the high frequency made the size of thermoacoustic engine and external exiting device small without performance reduction. After consideration the requirement of thermoacoustic engine, a miniature moving magnet actuator was designed and made to drive a small thermoacoustic refrigerator. Two kinds of magnet configuration was designed and calculated for different application. The line of spring was improved and its static load was simulated and compared with the unimproved one. The concentricity of the whole engine was designed to be adjusted through the frame.At last, the shape of the resonator had some influences on the thermoacoustic engine. By simulating two kinds of cross section resonator, the performance of circular and flat tube was compared and analyzed. The result showed that the flat tube could improve the sound field in some degree. Furthermore, a high frequency thermoacoustic refrigerator was made to investigate experimentally its refrigeration performance and accumulate the miniature engine experience.