Effects of diffuser shapes of critical nozzles on critical back pressure ration in the low reynolds unmber range

摘要

The behavior of the critical back pressure rato was investigated for three different diffuser shapes of ISO type toroidal throat Venturi Nozzles in the t heoretical Reynolds number range from 40 to 10000 for nitrogen gas. The results showed that a longer diffuser increases the critical back pressure ratio for theoretical Reynolds numbers between 200 and 4000, and that the larger angle diffuser increases it for theoretical Reynolds numbers between 80 and 10000. However, the effects of the diffuser length and the diffuser angle are lost for lower theoretical Reynolds numbers than 80, and furthermore the longer diffuser works badly for the critical back pressure ratio for higher theoretical Reynolds numbers than 4000 and neither does the diffuser angle work for higher theoretical Reynolds numbers than 1000.