流体压缩性对发动机滑油通风系统流动特性的影响

Effects of Fluid Compressibility on Flow Characteristics of Aeroengine Lubrication Vent System

关键词:  滑油通风系统  可压缩性  马赫数  流量

Key words:  Lubrication vent system  Compressibility  Mach number  Mass flow rate

摘要:

为了研究流体压缩性对滑油通风系统流动特性的影响，通过在元件流动控制方程中引入气流马赫数，建立了考虑压缩性的元件计算模型。模型利用可压损失系数来建立元件进出口流动参数之间的关系，以确定进出口气流的马赫数。以发动机滑油通风系统为对象，进行验证计算，计算结果与试验结果非常接近，最大误差不超过4%。从元件、系统两个方面，通过计算深入分析流体压缩性的影响。结果表明:相比于不可压流动，马赫数较小时，空气流量差异很小；马赫数较大时，空气流量明显小于按照不可压流动计算的流量；对于单支路系统，出口Ma为1时可压流计算的空气流量约为不可压流的78%。应用该模型，进行通风系统的一维仿真分析，有利于较为全面地了解系统内气体流动状态和提高计算精度。

Abstract:

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.