Bi-directional turbines combined with rotary motors may be a feasible option for developing high power thermoacoustic generators with low cost. A general expression for the acoustic characteristics of the bi-directional turbine was proposed based on theoretical derivation, which was validated by computational fluid dynamics modeling of an impulse turbine with fixed guide vanes. The structure of the turbine was optimized primarily using steady flow with an efficiency of near 70% (the shaft power divided by the total energy consumed by the turbine). The turbine in the oscillating flow was treated in a lumped-parameter model to extract the acoustic impedance characteristics from the simulation results. The key acoustic impedance characteristic of the turbine was the resistance and inertance due to complex flow condition in the turbine, whereas the capacitance was treated as an adiabatic case because of the large-scale flow channel relative to the heat penetration depth. Correlations for the impedance were obtained from both theoretical predictions and numerical fittings. The good fit of the correlations shows that these characteristics are valid for describing the bi-directional turbine, providing the basis for optimization of the coupling between the thermoacoustic engine and the turbine using quasi-one-dimensional theory in the frequency domain.

双向涡轮机结合旋转电机可能是开发低成本高功率热声发电机的可行选择。在理论推导的基础上，提出了双向涡轮机声学特性的通用表达式，并通过固定导叶的脉冲涡轮机的流体动力学模型进行了验证。涡轮机的结构主要通过使用稳定流进行优化，效率接近70％（轴功率除以涡轮机消耗的总能量）。在集总参数模型中处理了涡流中的涡轮，以从模拟结果中提取出声阻抗特性。涡轮的关键声阻抗特性是由于涡轮中复杂的流动条件引起的阻力和惯性，而由于相对于热穿透深度的大型流道，将电容视为绝热情况。阻抗的相关性是从理论预测和数值拟合获得的。相关性的良好拟合表明，这些特性对于描述双向涡轮机是有效的，这为使用频域中的准一维理论优化热声发动机与涡轮之间的耦合提供了基础。