Experimental investigation on critical background-pressure ratio of 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.