Study On The Effect Of Particle Characteristics On The Surface Deposition Of Turbine Blades

With the development of aviation industry,the air route of aircraft is gradually expanding.Different kinds of particles will be injected in the engines and cause certain deposition results.The characteristic parameters of particles have always been an important factor affecting the cumulative results of deposition.The changing particle size and chemical composition of particles will correspond to the different particle motion conditions and particle attribute parameters,resulting in different deposition morphology,corresponding to different damage degree and service life of the engine.It is an important content to study the effect of particle characteristic parameters on the deposition results.In order to find out the influence of particle characteristic parameters on the deposition of particles on the surface of turbine blades,it studies the influence of particle size distribution,chemical composition,density of particles and other parameters on the deposition by means of user-defined numerical simulation,which is based on the analysis of deposition particle parameters,particle deposition movement analysis,wax particle deposition experiment.The growth of particles deposition on the surface of turbine guide vane provide a theoretical basis for the future analysis of the impact of the injection of external particles in different environments on the replacement and maintenance of aeroengine.In the analysis of the parameters of the deposited particles,the basic characteristics of the deposited particles used in the research of particle deposition in the past 40 years are statistically analyzed.It is concluded that most of the particles that cause the deposition have the characteristics of high density(usually above 1500kg/m~3),small particle size(0-20?m),and high content of silicon aluminum oxide.Based on the concept of particle deposition movement period,the impact probability and adhesion probability of various particles are investigated from the four processes of particle transport,impact,adhesion and detachment.The results show that the influence of particle size on deposition is the most complex.Under the normal operation condition of engine,the particles with particle size larger than 12?m usually reflect the calculation results of more impact,less adhesion and more peeling,while the relatively small particles show higher adhesion probability in less impact;At the same time,the parameters such as chemical composition,particle density,and temperature or velocity of particles show a direct positive or negative correlation to particle deposition,and the influence mode is relatively single.The lower the silicon aluminum content of the particles,the higher the temperature of the particles,and the lower the velocity of impact particles,the easier the deposition is formed.In order to integrate the particle movement stages and reflect the unsteady results of particle deposition on the surface of turbine guide vanes,based on the combined adhesion model and detachment model,the unsteady numerical simulation scheme of turbine guide vanes is established by using the user-defined function of fluent.Meanwhile,in order to verify the accuracy of the model,the wax particle deposition experiment was carried out.The distribution of deposition is in good agreement with the results of dimensionless deposition thickness.Finally,according to the established deposition simulation scheme,the deposition process of particles on the turbine blade surface is simulated.On the one hand,it shows that the main position of particles deposition on the turbine guide vane surface is in the leading edge and pressure surface area of the blade.It also verifies that user-defined programs such as grid deformation can operate normally.On the other hand,it is revealed that the deposition accumulation rate of the leading edge is the highest.The characteristics of particle stripping,different mainstream and particle temperature,and different diameter particles have significant effects on the deposition.The influence law is consistent with the conclusion of the previous theoretical analysis in each particle characteristic parameter,which provides the initial data support for the quantitative study of the influence of particle characteristics on deposition.