Effects of fluid compressibility on flow characteristics of aeroengine lubrication vent system

In order to study the effects of the fluid compressibility on flow characteristics of lubrication vent system, by introducing Mach number in the governing equations, the calculation models of components were developed considering fluid compressibility. The relationships between the inlet and outlet flow parameters of components were obtained with the compressible loss coefficient in the model, and the inlet and outlet Mach number of the gas flow can be determined. Aimed at a kind of aeroengine lubrication vent system, the model was verified, and the results of the numerical simulation and tests were very close. The error is no more than 4%. Finally, by the calculation the effects of the fluid compressibility were analyzed further from two aspects, components and system. The results show that compared with the incompressible flow, the differences of air mass flow rate are small at low Mach number. However, at high Mach number the air flow rate in compressible flow is obviously smaller than that in incompressible flow. When the outflow Ma is 1, the air flow rate of system with single branch in compressible flow is about 78% of that in incompressible. The new model can be applied to the vent system one-dimensional simulation. It is helpful to understand the gas flow state comprehensively in the system and improve the computing accuracy.