The upstream flow condition effect on the premature unchoking phenomena of the sonic nozzles

Abstract

With the atmospheric air as the working fluid, the premature unchoking phenomena were investigated with 18 sets of critical flow Venturi nozzles under 8 types of upstream flow conditions. Unlike the available research, there were no clear relationship between the upstream flow condition and the flow rate fluctuation and flow rate recovery for the premature unchoking phenomena. However, the diverse and unsteady characteristics of the premature unchoking phenomena were shown. With the comparison of upstream flow conditions, the new disturbance might be resulted from the "improper" upstream flow condition, which might influence the intensity and the position of the shock in the diffuser section of CFVN, and finally resulted in the diverse and unsteady characteristics of premature unchoking phenomena.