Experimental investigation of the flow characteristics of jet pumps for zero flow-ratio conditions

Abstract

Experimental research was conducted on the performance curves and the cavity evolution for different flow and geometric parameters in jet pumps for zero flow ratio (ZFR) conditions. New pressure ratio, P_r, flow ratio, q_r, were used in place of the conventional performance parameters h, q, to characterize the jet pump flow performance. A super cavitation cavity in the jet pump was observed to fill most of the flow channel, which hindered further increases of the flow rate and increased q_r to one, thus, created a critical point on the new P_r - q ²_r curve. Before the critical point, P_r was proportional to q ²_r with a coefficient that was much more sensitive to the area ratio than the relative throat length and the diffusion angle. After the critical point, the flow rate reached its maximum, the limiting flow rate, which only depended on the total inlet pressure and the area ratio. The total inlet pressure was proportional to the square of the limiting flow rate with a flow coefficient that was only a quadratic function of the area ratio.