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微喷管设计加工方法不同于常规尺寸喷管,具有小尺寸、大面积-体积比的特点,内部流动雷诺数低,粘性力影响显著。为研究结构参数设计对蒸发液体微推力器喷管性能的影响,利用三维数值模拟方法研究不同扩张半角、面积比以及刻蚀深度对微喷管推力、比冲的影响。结果显示,增加微喷管扩张半角有利于降低粘性损失,最优扩张半角为30°,其数值大于常规尺寸喷管。增加面积比可以提高气体膨胀程度,但与之同时增加的壁面面积会增加粘性损失,推力、比冲先随面积比增加而增加,面积比为14时达到峰值,随后下降。增加刻蚀深度有利于减小扩张段壁面面积,提高微喷管性能。
Micro nozzle design and processing method is different from the conventional nozzle size, with small size, large area - volume ratio, the internal flow Reynolds number is low, viscous force significant impact. In order to study the influence of structural parameter design on the nozzle performance of evaporative liquid micro thrusters, the effects of different expansion half angles, area ratio and etching depth on the thrust and specific impulse of the micro-nozzle were studied by three-dimensional numerical simulation. The results show that increasing the micro-nozzle expansion half-angle is conducive to reducing the viscosity loss, the optimum expansion angle is 30 °, the value is larger than the conventional nozzle. Increasing the area ratio can increase the degree of gas expansion, but at the same time increasing the wall area will increase the viscosity loss. The thrust and specific impulse increase with the increase of area ratio. The area ratio reaches the peak at 14 and then decreases. Increasing the etching depth is helpful to reduce the wall area of the expansion section and improve the performance of the micro-nozzle.