Inter-chamber leakage flow through the transition contacts in epitrochoid generated star and ring hydrostatic units

Abstract

The current study examines the impact of tooth clearance on the flow performance at the location of transition contact of the internal positive displacement trochoidal gear pump. The aim is to enhance the volumetric efficiency, which is caused by internal leakage due to tooth clearance. Two clearance models, that is, form closed and interference (forced closed) models of the pump help to elucidate the leakage phenomenon through which optimal volumetric efficiency can be achieved. Finite element investigation comprises the static structural analysis followed by 3D CFD analysis carried out for the study. The CFD model includes the contact deformations of external trochoidal gear due to the application of maximum pressure, which increases the inter-chamber leakage. Fluid velocity and pressure inside the pump have been predicated to understand the flow dynamics inside the pump. The simulation results were matched to theoretical values, and this shows a very excellent match. The volumetric efficiency of 89% with less than 1 gm/s of leakage has been achieved at a speed of 2500 rpm. Moreover, the simulation results show an increase in discharge flow with the interference model. Further, an empirical relation is established between volumetric efficiency, fluid density, and rotor speed using partial least square regression analysis.