First attempt to determine the critical inlet pressure for aircraft pumps with a numerical approach that considers vapor cavitation and air aeration

Critical inlet pressure (CIP) is a key parameter for ensuring the long life and steady operation of aircraft piston pumps. In the past, this parameter was determined through experimental methods that had drawbacks such as a long duration and narrow application range. To identify an alternate approach that can be substituted for the traditional approach, a numerical model for determining the CIP that considers the dynamic effects of the transient period is proposed in this paper. First, a dynamic model of the pressure-controlled piston pump was established in the form of differential equations based on the lumped parameter method. Next, the fluid model for vapor cavitation and air aeration was derived using homogeneous mixture theory with consideration of the effects of compressibility of both liquid and gaseous phases. Simulation investigation highlighted how the shaft speed, inlet pressure, and transient time influence the fluid properties inside the piston chamber, and a method for determining the CIP both for steady and transient conditions is presented. Finally, tests were conducted on an aircraft piston pump in open-circuit applications for verifying the applicability of the proposed numerical model.