喷水对风扇性能影响的数值研究

A Numerical Research of Effects of Water Ingestion

关键词:  风扇  液滴蒸发  两相流模型  平均流线法  水吸入

Key words:  Fan  Droplet evaporation  Two-phase flow model  Meanline code  Water ingestion

摘要:

为了获得潮湿环境对发动机性能的影响，开展了多级轴流风扇在来流含水情况下的性能研究。首先，基于液滴蒸发和冷凝相变过程，构建了解决气液两相间的热量与质量转化的两相流模型。该模型是由气相和液相的质量、动量和能量守恒方程及它们的状态方程组成。其次，在两相流模型的基础上，采用五阶龙格库塔法求解模型方程组，计算水相变过程对风扇性能的影响，并用平均流线法模拟气流通过风扇时的流动特性。最后通过耦合两种方法，分析喷水对风扇流量、压比和温比的影响。结果表明，喷水能提高风扇的进气流量和压比，最高分别可达到4.24%和2.51%，能使定子温比最大下降4.88%，转子温比先下降后升高。

Abstract:

In order to understand how moisture circumstances affect the engine performance，the research of the multistage fan performance，under the condition of the water ingestion in compression system，is conducted. A new two-phase flow model of the heat transfer and mass transfer has been formulated based on vaporization and condensation phase-change. The model solves the conservation equations of mass，momentum，and energy equations for both gas and liquid phase and ties the two together with the equation of states. It uses a 5th order Runge-Kutta solver for solving the governing equations numerically. The two-phase flow model primarily accounts for the heat transfer associated with the phase change of water and the meanline code uses gas properties to model the flow properties through a compression system. The two-phase flow model and the meanline code are loosely coupled to analysis the change of the mass flow，pressure ratio and temperature ratio with water ingestion. The results show that the mass flow and pressure ratio increased by 4.24% and 2.51% at most，respectively，the temperature ratio of stators is decreased by 4.88% at most，and the temperature ratio of rotors reduces initially then increases.