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以抛物形点聚焦激光推进器模型为研究对象,数值模拟了脉冲重复频率在2~50Hz范围内吸气式多脉冲纳秒激光推进的流场演变过程,分析了脉冲数目和重复频率对推进性能的影响。结果表明:随着脉冲数目的增加,喷管内气体密度减小、温度升高,导致平均冲量耦合系数下降,但纳秒脉冲激光作用获得的平均冲量耦合系数明显高于微秒脉冲激光;相同脉冲数目条件下,随着脉冲重复频率的增大,流场恢复时间缩短,使得流场状态不能及时恢复,导致平均冲量耦合系数下降,其中脉冲重复频率f≥10 Hz时的下降趋势明显大于f≤10 Hz。
Taking the parabolic point-focused laser thruster model as the research object, the numerical simulation of the evolution of the flow field of the aspirated multi-pulse nanosecond laser with pulse repetition frequency in the range of 2 ~ 50Hz was carried out. The influence of pulse number and repetition frequency on the propulsion performance Impact. The results show that with the increase of the number of pulses, the gas density in the nozzle decreases and the temperature increases, which leads to the decrease of the average impulse coupling coefficient. However, the average impulse coupling coefficient obtained by the nanosecond pulse laser is obviously higher than that of the microsecond pulse laser. With the increase of pulse repetition frequency, the recovery time of flow field is shortened, which makes the state of flow field unable to recover in time, resulting in the decrease of coupling coefficient of average impulse. The declining trend of pulse repetition frequency f≥10 Hz is obviously larger than f≤ 10 Hz.