散热损失对微推进器性能的影响

Influences of heat loss on micro thruster

微推进器尺寸小,散热损失对微推进器性能有较大影响。本文研究微推进器阵列燃烧室壁散热情况;分析热损失对单元发动机性能的影响;试验测量微型发动机推力,并与理论计算值对比分析。研究结果表明,对于微推进器阵列,燃烧室壁面处温度最高,热应力和热变形也最大;硅材料的室壁热应力以及热变形均比钢材料的小。微推进器喷管喉部散热损失最为严重。微推进器散热损失使喷管出口温度降低,出口速度减小,推力减小11%。对不同单元发动机实测推力值分析,发现各单元实测推力有差异,但都小于绝热理论计算推力;实测推力的平均值比散热损失计算值小。

The performance of micro thruster is influenced greatly by heat loss due to the small size of micro thruster. The heat loss of the combustion chamber wall in micro thruster array and the performance of unit engine affected by the heat loss were studied. Thrust produced by micro thruster was measured and compared with the theoretical value. The results indicate that temperature,thermal stress and thermal deformation are at their maximum on the surface of combustion chamber wall in micro thruster array. The thermal stress and thermal deformation of silicon wall are smaller than the steel ones. The heat loss at nozzle throat is the most serious. The heat loss makes temperature of nozzle outlet and exit velocity decrease,and the thrust is reduced by 11%. For different engine unit,the measured thrust is diverse,but it is smaller than the adiabatic thrust. What＇s more,mean of the measured thrust is smaller than the value obtained from the heat loss calculation.