Oscillations of Laval Nozzle Flow with Condensation : Part 1, On the Range of Oscillations and their Frequencies

Abstract

In the case of moist air or steam rapidly expanding in a Laval nozzle and condensation occurring in a supersonic section of the flow, if the heat released by the condensation exceeds a certain quantity, the flow becomes unstable and a periodic flow oscillation occurs. In the present paper, the flow oscillation has been examined experimentally in the case of rapid expansion of moist air, using a Ludwieg tube with a downstream diaphragm. As the result, the effects of the initial relative humidity of moist air and the configuration of the nozzle on the frequency of the periodic flow have been clarified. Furthermore, the relation between the incipient relative humidity in the supply condition at which the flow becomes unstable and the configuration of the nozzle has been presented.