Discharge Coefficients of Critical Venturi Nozzles for CO2 and SF6

Abstract

The discharge coefficients of critical Venturi nozzles were measured for CO2 and SF6 on the Reynolds number range from 3×103 to 2×105. The results showed that the measured discharge coefficients for both gases were about 2 percent larger than the theoretical estimation based on the assumption of isentropic flow of a perfect gas and this large deviation could not be reduced even by introducing real gas effects. The experimental results also showed that the large deviation for CO2 could be explained through the assumption of a nonequilibrium flow at the throat. On the other hand, the reason of the deviation observed for SF6 has not been clear yet, but one possible explanation would be the inadequate estimation of the boundary layer at the throat because the theory is based on the laminar boundary layer of a perfect gas. [S0098-2202(00)02004-6]