化学激光器用文氏咀的临界背压比

建立了一套文氏咀临界背压比的测量系统，分别以氮气、氩气和氧气为工作介质，对两种加工工艺、不同规格文氏咀的临界背压比进行了测量，得到了各文氏咀对应不同工作介质的临界背压比，讨论了实验系统中第一个文氏咀的作用和温度对测量结果的影响。实验结果表明:设计合理、工艺合适的Laval喷管，临界背压比明显高于临界压力比，而且，比热容比越小，表面粗糙度等级越高，喉道直径越大，对应的临界背压比越大。

Experimental investigation on critical background-pressure ratioof Venturi for chemical laser

An experimental system for Venturi's critical background-pressure ratio(CPR) was set up, and a series of experiments was conducted with different mediums and Venturis. The function of the first Venturi in the experimental system and the effect of temperature on CPR were discussed. The results indicate that, the CPR of Venturis with reasonable design and suitable technics is obviously higher than critical pressure ratio. Moreover, smaller specific heat ratio, better surface roughness and larger throat diameter would result in higher CPR.