高速来流发动机射流预冷及压气机湿压缩特性一体化分析方法

Integrated Analysis Approach of Injection Precooling and Compressor Wet Compression Characteristics of Jet-Engine under High Speed Inflow Condition

关键词:  射流预冷  跨声速压气机  气液两相流  湿压缩  数值模拟

Key words:  Injection precooling  Transonic compressor  Gas-liquid two-phase flow  Wet compression  Numerical simulation

摘要:

为了研究高空高速来流条件下发动机射流预冷及压气机湿压缩特性，针对发动机进气道部分和压气机部分的气液两相流动过程分别建立相应的计算模型，发展了一体化分析方法。对于进气道喷水后的气液两相流动，采用基于微元段思想的气动效应-蒸发冷却修正两步法建立一维计算模型；对于压气机湿压缩过程，采用基于CFD技术的欧拉-拉格朗日方法对气液两相流动进行建模。利用所建立的一体化分析方法，考虑真实高空高速来流条件，同时保证发动机在喷水前后具有等换算转速调节规律，对发动机射流预冷及压气机湿压缩特性进行分析。结果表明：射流预冷能够显著降低高马赫数来流下的压气机进气温度，使得相同最高物理转速下压气机换算转速提高，使压气机具有更好的气动性能；若液滴在进入压气机前蒸发完全，混入工质中的过量水蒸汽会降低压气机的无量纲转速，使得同换算转速下压气机压比较不喷水时降低；小粒径液滴更快的蒸发作用有助于对高温气流的快速降温，当液滴粒径为3μm和喷湿量为10%时，压气机进气温度较喷水前降低247.13K，同换算转速下物理转速仅为不喷水时的76%。

Abstract:

In order to study the characteristics of jet-engine injection precooling and compressor wet compression under high altitude and high speed inflow condition， the present paper establishs the corresponding calculation models， respectively， for the gas-liquid two phase flow processes in the inlet duct and the compressor section， and develops an integrated analysis approach. For the gas-liquid two-phase flow after the injection in the inlet duct， a one-dimensional model is established by using a two-step approach with aerodynamic effect - evaporative correction based on the idea of infinitesimal method. For the compressor wet compression process， Euler-Lagrange method based on CFD technology is adopted to model the gas-liquid two-phase flow. Considering the real high altitude and high speed inflow conditions， the characteristics of injection precooling and wet compression of the engine are analyzed by the established method， meanwhile the equal corrected speed regulation of the engine before and after the injection is guaranteed. The results show that the injection precooling can significantly reduce the inlet temperature of the compressor under high Mach number inflow condition， so that the corrected speed of the compressor can be increased under the same maximum physical rotation speed which makes the compressor achieve better performance. If the liquid droplets evaporate completely before entering the compressor， the extra water vapor mixed into the working medium will lower the dimensionless speed of the compressor， so that the compressor pressure rise is lower than that of the non-water injection case at the same corrected speed. The faster evaporation of small-size droplets can help to rapidly cool the high-temperature gas flow. When the particle size of the droplets is 3μm and the water to air ratio is 10%， the air inlet temperature of the compressor is reduced by 247.13K， and the physical rotation speed is only 76% of that of the non-water injection case at the same corrected speed.