Pump model for two-phase transient flow

A lumped-parameter model of a pump for transient two-phase flow conditions has been developed. This model is described by five variables: pressure, mixture enthalpy, vapor mass concentration, mixture flow rate, and angular velocity of the impeller. These variables are governed by four balance equations for mixture mass, mixture momentum, mixture energy, and angular momentum. The vapor mass concentration at the exit of the pump is computed from caloric equation of state. The mixture momentum equation is replaced by empirical, single- and two-phase homologous head curves, and an interpolating function based on inlet void fraction. The solutions of quasi-steady part of this model compare favorably with pump coast-down data. The transient model is applied to an exponentially decaying flow rate case