Particle Erosion Inside Particle Separator And Particle Deposition Characteristics Of Turbine Blade As Well As Its Influences

When the gas turbine engines operate in the dusty or polluted atmosphere environment,they are seriously subjected to the risk of sand ingestion.Particulate inflow can lead to the erosion phenomenon in the intake particle separator,causing the reduction of separation efficiency of the particle separator.The particles with very fine size are difficult to be separated and thus enter into the engine main passage,causing the particle deposition or obstruction in the turbine blade.The particle deposition or obstruction in the turbine blade will lead to a change in the cooling characteristics of the turbine blades,which can have a serious impact on the reliability of the turbine blade cooling structure.Accroding to the above research background,the current study aims at the illustration of the erosion and deposition characteristics of the particulate flow.The gas-particle two-phase flow model,as well as the particle erosion and deposition models are built up for the numerical simulations.By using these models,a series of numerical simulatons are made to iluustrate the particle erosion inside particle separator as well as particle deposition inside turbine blade.Simultanously,an experimental and numerical study is also made to anylaze the influence of film cooling blockage on the cooling performance.The main contents of the current research contains mainly five parts.(1)Particle erosion characteristics inside an inertial particle separatorA two-dimensional numerical simulation is conducted to investigate the particle erosion phenomena in an inertial particle separator.The gas-solid two-phase flow field is solved by the uncompressible Reynolds-averaged Navier-Stokes equations and the Eulerian-Lagrangian approach respectively.User-defined subroutines are linked with FLUENT to calculate the erosion rate by using an empirical erosion model.Both the tangential cutting wear and normal deforming wear are taken into considerations.It is illustrated that the tangential cutting wear is the dominated mechanism in the particle erosion process inside the inertial particle separator.The most remarkable zone suffering severe erosion occurs on the upstream side of the inner wall bump as well as the sectional outer wall corresponding to the inner wall bump.As the inlet velocity increases,the erosive damage becomes seriously.In relative to the zero-attack inflow case,the positive inflow attack weakens the particle erosion on the upstream side of the inner wall bump but makes the erosion wider and deeply on the outer wall.The negative inflow attack aggravates the particle erosion on both the inner wall and outer wall.(2)Particle deposition characteristics on the turbine blade surfaceA numerical study is performed on the movement and deposition of dilute particles inside a two-dimensional turbine cascade,focusing on the effects of particle diameter and incidence angle on particle deposition characteristics.Based on the EI-Batsh deposition model including particle sticking/rebounding and particle detachment,the study links user definition functions with FLUENT to predict particle deposition.A comparison of the numerical results with existing experimental data shows that the present numerical model is valid.The research results show that for d<1?m particles,deposition mainly occurs on the central area and trailing edge of the blade pressure surface.But for the d=3?m and 5?m Particles,particle deposition mainly occurs on the leading edge and trailing edge of the blade pressure surface.The flow attack angle has important influence on particle deposition distribution.(3)Particle deposition characteristics inside typical cooling structures of the turbine bladeAcoording to the cooling structural features of turbine blades,some typical cooling structures including film-cooled wall,ribbed-wall with or without film holes,and impingement-film double walls are selected for individual investigation.For the film-cooled wall,main concerns are the effects of particle diameter and film jet blowing ratio on the particle deposition characteristics.The research results show that the deposition area is mainly ocurred upstream the fim cooling hole and the local region between adjacent film cooling holes under the suction of kidney vortices.Related to the convensional cylindrical hole,the conveging slot weakens the particle deposition on the film-cooled wall.For the ribbed-wall,the effects of particle diameter on the impact angle and impact normal velocity of particles on the ribbed-surface and rib surface,as well as the particle deposition characteristics inside the ribbed-wall duct are analyzed.The results show that the upstream region of the first rib and the front surface of the rib are most susceptible to particle deposition.The effect of particle size and the relative position between film hole and the rib on particle motion and deposition characteristics are also studied.For the impingement-film double walls,the effect of particle size and the relative position between impinging hole and film hole on particle motion and deposition characteristics are mainly studied.It is revealed that the presence of impinging wall is useful for weakening the paiticle deposition inside the film cooling holes.(4)Effect of paitial blockage inside the film cooling holesAn experimental investigation is carried out to study the effects of in-hole partial blockage on the film cooling effectiveness at the suction and pressure sides of a blade.Specific pyramid-shaped elements are used to simulate partial blockages inside the film hole.Experiments are performed for some typical blockage positions,blocking ratios and blowing ratios.In addition,a numerical computation is also performed on the simulation of flow fields to reveal the influence mechanism of in-hole blockage on the film cooling performances.The results indicats that the in-hole blockage changes the way the coolant flows inside film-hole and affects the interaction between the coolant jet and primary flow,tightly dependent on the deposited position,blocking ratio and blowing ratio.In general,the leading-inlet blockage seems to have little impaction on film cooling effectiveness.The leading-exit blockage produces an improvement of film cooling effectiveness under the situation where the blocking ratio is less than 0.5.While for the in-hole blockages deposited at other positions,the film cooling effectiveness is confirmed to be generally deteriorated as the increase of blocking ratio,especially for the lateral-exit blockage case.The influence of in-hole blockage on the film cooling effectiveness behaves more significantly under high blowing ratios.(5)Effect of paitial blockage inside the film cooling holes under typical operating parameters.A numerical investigation is performed to reveal the effects of partial blockage inside film holes on overall cooling effectiveness of an integrate impingement-fin-film cooling configuration on the blade leading edge and pressure side,mainly focusing on the effects of blockage position and blockage ratio.The results show that the overall cooling effectiveness are all increased gradually with the increase of blowing ratio,either for the no-blockage film holes or the partial blockage cases.Under low blowing ratio,the partial blockage located at the trailing edge of film-hole exit decreases weakly the overall cooling effectiveness whereas the other blockage positions including the leading edge of film-hole inlet and leading edge of film-hole exit decrease the overall cooling effectiveness significantly in relative to the no-blockage baseline case.Under high blowing ratio,the partial blockage located at the leading edge of film-hole exit could mitigate the kidney vortices due to mainstream-coolant jet interaction and thus plays a role on improving weakly the overall cooling effectiveness sometimes.Whereas the partial blockages located at the leading edge of film-hole inlet and trailing edge of film-hole exit result in the reduction of overall cooling effectiveness to some extent.In generally,the blockage ratio has a complicated influence on the overall cooling effectiveness due to the tightly dependent of the internal heat transfer enhancement and external film coverage for an integrate impingement-fin-film cooling configuration.