高焓膨胀管中压缩管最佳长度设计分析

中国空气动力研究与发展中心超高速所即将建成的高焓喷胀管采用自由活塞驱动,为了能够使该设备有效运行试验时间达到最长,需要对设备中的压缩管长度进行优化。针对压缩管中的自由活塞运动,本文通过数值求解单一组分和混合驱动气体条件下的活塞运动准一维常微分控制方程组,分析了不同试验设计参数和不同驱动气体介质对压缩管定压驱动时间的影响。采用数值解结合脊线(局部极值曲线)理论获得了定压驱动时间局部极值曲面,基于压缩管四种摩尔比例驱动气体(100%H2,85%H2+15%N2,100%He,85%He+15%Ar)和三组压缩比(λ=60,100,140)下的极值曲面,研究发现,定压驱动时间脊线高度随着压缩管的有效长度(初始活塞头部到压缩管末端膜片的距离)和内径之比L/D增加而增加。本文研究最终获得了给定参数条件下满足最长定压驱动时间要求的最佳压缩管长度。

Design and analysis of the optimal length for compression tube in the high enthalpy expansion tube

T he high enthalpy expansion tube facility being constructed in China Aerodynamics Research and Development Center will be driven by a free piston compression tube .The length of the compression tube needs to be optimized in order to make the effective test time as long as possible .T he influences of experimental parameters and various driver gases on the constant‐pressure time of compression tube were analyzed by numerically solving a set of piston motion model differential equations under the condi‐tions of a single and multi‐species driver gases .The numerical solution combined with the theory of bridge curve is used to construct a curve surface composed of local maximum values of constant‐pressure time in parameter space .The aforementioned curve surfaces from the cases including four kinds of driver gas (100% H2 ,85% H2 +15% N2 ,100% He ,85% He+15% Ar) and three set of volumetric compression ratios (λ= 60 ,100 ,140) showed that the altitude of bridge curve for constant‐pressure time increases with the ratio of effective length (namely ,the initial distance from front face of the piston to the diaphragm located at the terminal of compression tube ) of a compression tube to its internal diameter L/D .The optimal length of compression tube was obtained which satisfies the longest constant‐pressure time requirement .