Study On Rain Injection Performance Of Turboshaft Engine Compression Component

Modern aero-engines are capable of all-weather flight,ensuring stability and safety in inclement weather.At present,there is little research on the rain absorption performance of turboshaft engine.According to the previous experiments and researches,the motion form of water droplets is the key factor affecting the performance of aeroengine.Unlike the typical jet propulsion engine,rain enters the air-inlet system of the turboshaft engine first,rather than touching the compressor blade directly.Modern helicopters mostly adopt the integrated particle separator with simple structure and high efficiency as air-inlet system.The behavior of droplets directly affect the intake conditions of the compressor and further affects the working state of the compression system.Therefore,it has great significance to study the water injection performance of the turboshaft engine,in order to guarantee the helicopter possess all-weather flight ability.Firstly,according to the aerodynamic and structural design scheme of particle separator,establish the rain injection experiment platform.Combined with the non-contact optical measurement method,the rain absorption characteristics of the particle separator test pieces were tested.It was observed that liquid droplets form the liquid film on the wall in the rain injection experiment.The results show that with the increase of rainfall absorption the flow loss in the main channel of the separator increases,and the influence of non-uniform rain injection on total pressure distribution at the outlet is in the low degreeSecondly,based on euler-Lagrange theory,using CFX calculation software simulate the rain injection process of the separator under test conditions,and analyze the calculation errors combining the experimental phenomena and the test results.Considering air shear force and particle momentum force and other factors,a calculation model of water film was established,and the equivalent roughness of wall surface was converted according to the liquid film wave theory,solve the flow field of separator under wet surface condition further.Considering the water film on the surface,wall boundary layer thickness increases,the flow losses in the main channel increases and complies with the experiment result more.A reliable numerical simulate method was provided for the study of turboshaft engines rain injection performance.Finally,analyze the variation of rain injection performance of the compression component with the particle separator,which estimate the motion form of raindrops by Sommerfeld number.It is found that the relative velocity of particles is the key factor affecting the broken degree and the behavior of raindrops impacting the surface.The diameter of low-velocity raindrops decrease greatly,then form the water film on the surface,the flow losses near the wall increases,the Mach number reduces.The high-speed raindrops splash in secondary droplets.With the rain injection amount increases,the viscous force between air and particle increases,while the liquid film changes little,the specific work of compression increases by about 2.3%.There are significant differences in the distribution of the flow field along the span direction of each blades at different particle speed.The efficiency of the compressor reduce and perform worse at lower particle relative velocity,and the margin decreases by 2.28%.The performance of the first stage is more sensitive to rain injection than the second stage,and the compress capability is further weakened at low rotating speed,the maximum efficiency decreased by 4.07%.