| During the operation of an aero engine,suspended particles such as haze and salt in the air will be sucked into the engine connotation,and these particles will adhere to the compressor blades and walls to form fouling.Fouling of pneumatic components will reduce the working efficiency of the engine.As a result,the fuel consumption of the engine will increase,and in severe cases,it will cause surge,engine air stop and other faults.The online cleaning of aero-engine is an effective method to remove fouling.However,domestic scholars have rarely studied the mechanism of fouling removal,and have a shallow understanding of the characteristics of the cleaning flow field boundary layer.The experimental parameters of the cleaning flow field optimization parameters are verified.Therefore,the boundary layer characteristics of engine cleaning flow field are studied in this paper,and the parameters of cleaning flow field optimization are verified experimentallyIn this paper,the compressor flow channel model is obtained based on reverse scanning.The finite element software is used to divide the mesh.The Euler method is used to numerically study the flow field of the compressor blade cleaning.The influence of different cleaning process parameters on the characteristics of the flow field boundary layer is analyzed.A mechanics model for cleaning flow field and scouring of scale particles on the blade surface was established,and the effect of the cleaning process parameters on the blade cleaning effect was verified by an engine blade cleaning test bench.The thesis mainly carried out the following tasks:(1)Analyze the forces received by the scale particles in the cleaning flow field,construct a scale particle scouring mechanical model,and establish a particle critical fluid velocity model to predict the removal of scale particles.(2)The first-stage compressor blades and stationary blades of the CFM56-7B engine were obtained through the model of reverse scanning,and the first-stage cleaning flow channel model of the engine was established.Analyze of different grid,the control equation and turbulence model selection of cleaning flow field numerical simulation the influence of the precision and accuracy,and turbulence model selection,and select the mesh,governing equations,and turbulence models that are suitable for wing cleaning conditions.(3)Using single particle kinematics analysis method,the cleaning liquid droplet kinematics equation is constructed with the cleaning liquid droplet as the research object.In the case of engine cleaning flow field,the movement characteristics of the droplet in the fan flow field were analyzed under the conditions of different droplet diameter,droplet velocity,initial incident angle,and initial position.The numerical study of the cleaning flow field of compressor blades was performed,and the effects of different degrees of fouling and cold rotation speed on the boundary layer thickness,shape factor and wall shear force of the cleaning flow field were analyzed.It was found that increasing fouling will increase wall shear stress and improve cold rotation speed can enhance the cleaning liquid transport capacity.By optimizing the cleaning parameters,the best jet parameters and cold rotation speed are obtained.(4)By setting up the engine test bench of online cleaning,the cleaning effect of different cleaning process parameters was judged by weighing method.Combined with the scale particle scouring mechanics model,the cleaning process parameters are optimized to improve the engine online washing effect. |
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