结构参数设计对微喷管性能的影响

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。

Effects of structure parameter design on performance of micro-nozzle

The micro-nozzle is remarkably different from traditional macro-nozzle owing to its tiny size, large area-to-volume ratio, low Reynolds number, notable viscous influence and special fabrica-tion. The effects of different divergence half angles, area ratios and etching depths on thrust and specif-ic impulse of the micro-nozzle were studied with the numerical simulation method to investigate the in-fluence of structure parameters on micro-nozzle performance of vaporizing liquid micro-thruster. The re-sults indicate that the larger divergence half angle of the micro-nozzle is in favour of reduction of viscous loss;the best divergence half angle of the micro-nozzle is 30°, which exceeds that of the traditional macro-nozzle;larger area ratio can improve gas expansion coefficient, but it increases viscous loss due to the addition of divergence wall area; both the thrust and specific impulse increase at first with the growth of area ratio until a peak value at 14, where the micro-nozzle perform best and then they de-crease;increase of etching depth is beneficial to promote the performance of micro-nozzle.