Calculation and analysis of fan inlet rain ingestion of a civil turbofan engine throughout the flight envelope

To evaluate the influence of rain ingestion on the performance of an aircraft engine, the amount of rain ingested into the engine should be determined first. In this paper, the effects of liquid water concentration profiles defined by China Civil Aviation Regulations, environment temperature, flight speed, engine power, and scoop factor on water ingestion of engine, combined the full power management schedules, the fan inlet water air ratio (WAR) throughout a civil turbofan engine's operating envelope at different thrust levels is calculated and analysed.The results at all power levels show that at any constant Mach number, fan inlet water air ratio increases with altitude until it peaks at 6 100 m. Above 6 100 m, WAR decreases with the increase of altitude. Furthermore, the higher the Mach number and the ambient temperature, the larger the WAR. For flight idle on a standard day, the maximum WAR can reach as high as 7.38%. The calculating and analyzing method presented in this paper can provide the inlet boundary condition for analysis of rain ingestion critical point in engine airworthiness compliance test. © 2017, Press of Chinese Journal of Aeronautics. All right reserved.