| In recent years,micro-gas turbines have occupied a very important position in energy,power and military industry because of their simple structure,easy installation,strong fuel adaptability,good environmental protection,flexible use,fast start-up and low maintenance cost.Therefore,the research and application of micro-gas turbines is one of the key research topics at present.However,turbines,as the key components of micro gas turbines,are mostly centripetal and axial flow turbines,while the research and application of centrifugal turbines are less.However,centripetal and axial flow turbines are incompatible in aerodynamics and geometry,whereas centrifugal turbines are opposite,and centrifugal turbines are aerodynamically and geometrically compatible in the flow process.Therefore,this paper takes the centrifugal turbine blade of micro gas turbine as the research object,and studies its aerodynamic characteristics.Firstly,three airfoils,RAE2822,BE10307 B and GOE531,are numerically simulated in infinite space.Using structured grid,k-w SST turbulence model and Coupled solution method,the effects of relative velocity and direction at the inlet of rotor blade,turbine rotating speed and blade installation angle on the aerodynamic characteristics of single blade are obtained.According to the calculation results of the three airfoils,it can be concluded that the aerodynamic characteristics of GOE531 airfoil are better,its lift-drag stability is better,and the turbine power and blade efficiency are greater.Based on the above analysis results,it can be concluded that the aerodynamic performance of GOE531 airfoil is better than that of the other two airfoils.In order to consider the influence of flow passage structure on aerodynamic characteristics of blades,numerical simulation of adjacent blades was carried out to monitor the intermediate blades.Firstly,the flow passage size corresponding to the best aerodynamic characteristics is selected when the number of blades is different.Then,the effects of the relative velocity and direction at the inlet of the rotor blade,the rotating speed of the turbine and the installation angle of the blade on the aerodynamic characteristics of the blade are obtained.The structure of centrifugal turbine runner has a significant effect on the aerodynamic characteristics of airfoil.The lift coefficient and blade efficiency decrease,while the drag coefficient changes slightly.The optimum operating conditions of centrifugal turbines are put forward.When the number of blades is 18,the aerodynamic characteristics of the blades are the best.The maximum lift-drag ratio is 5.27 and the maximum blade efficiency is 25.92%. |
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