Numerical Analysis Of Film Cooling Of Turbine Blade Based On Fluid-structure Interaction

One of the important methods to improve the performance of aero-engine is to increase the gas temperature at turbine inlet.As turbine blades cannot withstand rising temperatures in front of the turbine,cooling techniques must be adopted,and film cooling is an important cooling techniques.Due to the limitations of theoretical analysis and experimental research,numerical simulation is the main choice to study the film cooling characteristics of turbine blades.Existing studies have not systematically studied the effects of the techniques of mesh generations,inflow conditions,turbulence models,and near-wall treatment of the turbulence models on film cooling.In this paper,the effect of the above factors on the film cooling characteristics was studied systematically with film cooling of the flat plates.Based on the results of the film cooling of the flat plate,the effects of different blowing ratios were studied on the film cooling characteristics of the turbine blade.The fluid-solid coupling interactions of the turbine blade with different blowing ratios were then investigated.First of all,for the simulations of film cooling of the flat plates,by consideration of the balance between calculation accuracy and efficiency,the realizable k-?model with non-equilibrium wall function was chose as the simulation model of film cooling based on the results of the different turbulence models.When the blowing ratio was relatively low,the calculation results were almost unaffected byy_pm^?10??y_jm^?10?,and grid-independent solutions obtained with the value ofy_pm^?10??y_jm^?10?in the range of both the loglayer and the viscous sublayer regions of the turbulent boundary layer.When the blowing ratio became larger,the simulation results were significantly affected by y_pm^?10??y_jm^?10?.The value ofy_pm^?10?at different positions of the flat plate influenced the calculating results differently.The influence of y^?10?on the cooling efficiency was small when it was far from the downstream of the jet holes,and the y^?10?near the jet holes had a great influence on the cooling efficiency.C hanges of y_pm^?10??y_jm^?10?in the transitional and logarithmic zone in the turbulent boundary layer affected the strength of the kidney-shaped vortex and the detachment and reattachment of the jet.The increase iny_pm^?10??y_jm^?10?caused detachment zone to extend downstream.In addition,changes iny_pm^?10??y_jm^?10?varied the strength of the kidney-shaped vortex and altered distribution of the cold air,resulting in greater changes of the cooling efficiency.Secondly,for the calculations of the film cooling of the turbine blade,at the downstream of the suction side and the pressure side,when the blow ratio was low,the coverage of cooling films increased faster with the increase of the blow ratio,and the increase of the coverage decreases as the blow ratio increased.At the high blow ratios,the cooling film efficiency downstream of the pressure side spread uniformly.On the pressure and the suction sides,with the increase of the blow ratio,the cold air deviated from the blade surface gradually,resulting in the decreasing of the cooling efficiency downstream of the jet hole s.At the same time,the increase of the blow ratio enhanced the momentum of the jet,and the cold air gradually accumulated in the direction on the top of the blade,causing the coverage of the cold air to shrink along the height of the blade.In addition,the effect of the leading edge of the holes on the suction side and downstream of the pressure side varied with the blow ratio.When the blow ratio was low,the cold air from the front edge of the holes accumulated toward the top of the blade,so that the coverage of the cold air at the suction side and the downstream of the pressure side were significantly larger than that on the blade root,however,the difference decreased at the high blow ratio.Thirdly,for the fluid-solid interactions of film cooling of the turbine blade,compared with the distribution of cooling efficiency of the insulation wall of the turbine blade,the cooling efficiency distributions of the coupled simulations were more uniform in the spanwise direction at the turbine blade,and the difference of the cooling efficiency between the holes and near the centerline of the holes became smaller.Therefore,the fluid-solid interaction models should be performed in order to simulation of film cooling of the turbine blades accurately.The influence of heat transfer of the solid part of the turbine blade on the flowfields mainly focused on the area close to the solid wall of the turbine blade.At last,summarizations and conclusions were conducted,and the directions of further research were indicated in this paper.