Effect of Inlet Pressure Fluctuation on the Unsteady Flow and Cavitation Characteristics of Water Hydraulic Reciprocating Plunger Pump with Check Valves

Cavitation is the main cause of vibration and mechanical failure in water hydraulic reciprocating plunger pump (WHRPP). Traditionally, it is believed that as long as the net positive suction head (NPSH) is ensured, cavitation in the plunger pump can be prevented to some extent. However, the negative peak value of the dynamic pressure wave at the pump inlet increases the possibility of cavitation in WHRPP with check valves. Based on multiphase flow and dynamic mesh technology, a full three-dimensional unsteady numerical model of valve and plunger cavity was established. The unsteady cavitation process under inlet pressure fluctuation was simulated, and the effects of inlet pressure fluctuation amplitude and frequency on the cavitation flow characteristics were obtained. The results show that the cavitation region is mainly located near the suction valve port and plunger surface. Under different amplitudes and frequencies, three cavitation stages are generated near the valve plate, namely opening cavitation, expansion cavitation, and jet cavitation. To some extent, increasing the amplitude of pulsation will increase the duration of cavitation during the expansion stage but will reduce the intensity of cavitation during the opening stage. The impact of pulsation frequency on cavitation is not monotonic, and the impact on different cavitation stages is also different. The cavitation intensity in the expansion cavitation stage and jet cavitation stage is related to the instantaneous value of inlet pressure.