Numerical And Experimental Study On Compressor Performance On Rain Droplets Distribution Form

The ability to operate safely in bad weather is essential for aero engines.Rain is one of the important threats affecting engine stability and performance parameters.When a large amount of rainwater is injected into an aeroengine,which will seriously affect the performance of every components of the aeroengine,and in severe cases,the aeroengine will stall,surge or even stall.As one of the important parts of aero engines,the compressor bears the brunt of the impact of rain.In the actual situation,the characteristic distribution of rainwater at the inlet of the compressor is uneven,which causes the inlet distortion of the compressor and affect the compressor characteristic parameters.Therefore,the numerical simulation and experimental measurement is used to analyze the compressor characteristics and internal flow field changes under different rain droplets distribution forms.Firstly,in this paper,based on the CFD software,the Eulerian-Lagrangian gas-liquid two-phase flow equation is established to analyze influence mechanism of different rain distribution forms on compressor characteristics and flow field,considering droplet evaporation,wall impact and aerodynamic crushing processes.The numerical results show that the performance of the compressor is decreased by the ingestion of rain water.In addition to the case that rain water is swallowed by the inlet near the blade tip,different raindrop distribution forms at the inlet can reduce the surge margin of the compressor to a certain extent and narrow the stable working range.Intake of rainwater near the tip of the blade causes less impact on compressor characteristics,which increases the flow loss at the tip of stator blades.The inlet near the blade root absorbs rain,which greatly reduces the compressor performance,and deviates the flow Angle at the root position of the static blade.Intake of rainwater near the root of the blade increases the Angle of attack at the inlet of the static blade root,which causes the separation of the static blade corner area.Compared with the uniform rain ingestion condition,the water ingestion by the inlet near the blade tip has less influence on the compressor performance,and the rain increases the flow loss of the stator blade tip under this condition.Compared with the uniform swallowing condition,the water swallowed by the inlet near the blade root has a great influence on the compressor performance which causes large deviation of flow Angle,resulting in too large Angle of attack,which promots the separation of stator blade corner area and increases flow loss.With the increase of massflow of rain ingestion,the decrease degree of this condition to compressor performance and stability is further enlarged.Secondly,a compressor rain ingestion test platform was set up to study the influence of different rain characteristic forms on compressor performance and characteristic distribution of inlet flow field.The research shows that rain ingestion reduced the efficiency of the compressor and the stable working range.For the condition of less rain ingestion mass fraction and smaller particle diameter,evaporative cooling of rain droplets can improve the pressure ratio and surge margin of the compressor to a certain extent,while increase the mass fraction of rain ingestion and the size of particle diameter,so that the pressure ratio and surge margin decreases significantly,which is lower than dry compression.The total pressure distortion of the compressor inlet is caused by non-uniform rain ingestion,and with the increase of rain ingestion mass fraction and particle diameter size,the total pressure distortion increased.Finally,the experimental results provide boundary conditions for numerical calculation of rain ingestion of the whole compressor model.The results show that the numerical simulation results have the same variation trend as the experimental results.The non-uniform rain ingestion condition at the inlet causes different degrees of total pressure distortion and total temperature distortion at each inlet of the compressor.The uneven distribution of rain increases the flow loss and leads to the increase of inlet static entropy,which deteriorates the performance of the compressor.