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基于线性热声网络理论,推导了多级环形行波热声热机的起振条件式,并对无负载系统的起振及稳态特性进行数值模拟分析.重点研究了不同工质、充气压力、回热器丝网水力半径及热声芯级数对热声热机起振温度、自激振荡频率以及相应声功率和效率的影响.模拟结果表明:不同充气压力下均存在获得最低起振温差的最优丝网水力半径,且在最优值附近存在一个合适的选值范围,使起振温差随充气压力的增加而降低,充气压力对振荡频率的影响不大;起振温差和振荡频率均随热声热机级数的增加而减小,当回热器温差一定时,增加级数会降低单个热声芯产生的声功率和效率.在一定加热功率条件下,采用混合工质可以获得比氦气工质更低的起振温差,且能获得与氦气工质相当的高声功率,因此混合工质有利于降低热机系统的工作温度和低品位热能的利用.
Based on the theory of linear thermoacoustic network, the starting condition of multi-stage toroidal thermoacoustic thermoacoustic engine is deduced, and the numerical simulation of the start-up and steady-state characteristics of no-load system is carried out. The effects of different working fluids, The hydrodynamic radius of the regenerator screen and the number of thermoacoustic cores on the onset temperature of the thermoacoustic engine, the frequency of self-oscillation and the corresponding sound power and efficiency.The simulation results show that the lowest starting temperature difference exists under different inflation pressures The optimum hydraulic radius of the mesh, and in the vicinity of the optimal value there is a suitable range of options, so that the starting temperature difference decreases with the increase of inflation pressure, inflation pressure has little effect on the oscillation frequency; temperature difference between oscillation and oscillation frequency When the temperature difference of regenerator is constant, increasing the number of stages will reduce the sound power and efficiency of a single thermoacoustic core.Under a certain heating power, it is possible to obtain the ratio Helium working fluid has a lower start-up temperature difference and can obtain high acoustic power corresponding to helium working fluid. Therefore, the mixed working fluid helps to reduce the working temperature of the heat engine system and the utilization of low-grade heat energy.