Theoretical, simulation and experimental investigation of 1D hybrid pressure distribution for internal gear motors and pumps

Abstract

Internal gear motor and pump is the typical rotating machine which operates in hybrid regime of lubrication. Calculation of the pressure distribution in the oil-lubrication film is the fundamental issue for determination of the upper and lower speed limit as well as analysis of the stability phenomenon of internal gear motor and pump. However, the simultaneously existence problem of hydrodynamic and hydrostatic pressure in case of hybrid regime is a challenge for calculation. This paper introduces an approach for calculation of 1D hybrid pressure distribution. The Reynolds equation with appropriate boundary condition is solved to obtain 2D hydrodynamic pressure distribution by using the finite difference method (FDM). The resistance network model (RNM) is used to predict the 1D hydrostatic pressure profile. Based on the hydrostatic and hydrodynamic pressure, the 1D total pressure profile can be retrieved. The CFD simulation has been performed to obtain the hydrostatic pressure profile and then compare to the hydrostatic pressure distribution by using RNM. A test rig has been designed to measure the oil-film pressure at five different points over the circumferential direction. Results pointed out that the numerical calculation agree well with the experimental results, particularly at high values of the working pressure.