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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。
In order to study the influence of fluid compressibility on the flow characteristics of the lubricating oil ventilation system, an element calculation model considering the compressibility is established by introducing the Mach-number of gas flow in the element flow control equation. The model uses the pressure loss coefficient to establish the relationship between the inlet and outlet flow parameters of the component to determine the Mach number of the inlet and outlet airflow. Taking the engine lubricating oil ventilation system as an object, the verification calculation is carried out. The calculation result is very close to the test result, and the maximum error does not exceed 4%. From the aspects of components and system, the influence of fluid compressibility is analyzed through calculation. The results show that compared with incompressible flow, the difference of air flow rate is small when the Mach number is small; when the Mach number is larger, the air flow rate is obviously smaller than the flow rate calculated by incompressible flow; for the single-branch system, the outlet Ma is 1 Compressible flow is calculated as about 78% of incompressible air flow. The application of this model to the one-dimensional simulation of ventilation system is beneficial to a more comprehensive understanding of the gas flow in the system and to improve the calculation accuracy.