Strength Analysis And Structual Optimization For Turbocharger Turbine Blade Of A Locomotive Internal Combustion Engine

As engine power and economic performance requirements continue to increase and emissions regulations become more stringent,the use of turbochargers is expanding.As an important part of the turbocharger,the turbine is in direct contact with high-temperature,highpressure and high-speed gas for a long time.It is subjected to centrifugal load,aerodynamic load and temperature load.The working environment is very harsh,and the load will inevitably cause a certain impact on the turbine blade.Turbine reliability work is the basis for the turbocharger to effectively play its role,so the analysis of the strength of the turbine blade is necessary.Based on the fluid-solid coupling analysis method,the stress-strain distribution of the turbine blade under the simultaneous action of aerodynamic load,temperature load and centrifugal load is analyzed.After Turbogrid meshed the flow area,CFX was used to obtain the temperature and pressure distribution of the turbine blade surface during stable operation under full load conditions.The thermal stress analysis of the turbine blade is then carried out,and the turbine blade surface temperature calculated by the flow simulation is input as a boundary condition to obtain the thermal stress distribution of the entire turbine blade.The above analysis results and centrifugal load are loaded onto the turbine blades,and the strength analysis is performed together with the wheel disc to obtain the stress and strain distribution of the turbine blades.The stress concentration mainly occurs in the area of the fir-tree root.The maximum equivalent stress value of the turbine blade is 629 MPa,which occurs between the fourth tooth of mortise and tenon.Therefore,the fir-tree root structure of the turbine end is optimized.After the parametric structure,five design variables are selected to obtain the influence of different parameters on the maximum equivalent stress of the turbine.The orthogonal experiment method was used to compare the influence level of each factor.The five-factor five-level orthogonal experiment table was used to carry out the simulation calculation of 25 groups.The orthogonal design method was used to establish the optimal design scheme.Compared with the original scheme,the turbine blade was the largest.The equivalent stress is reduced by 11%.The turbine was subjected to an over-rotation crack test to verify its over-rotation ability.When the speed was loaded to 49056r/min,the turbine blades burst.Finally,a modal experiment is performed on the turbine blades to measure the natural frequencies of the turbine blades.And establish a finite element model,compare the experimental values and modal calculation results,the error is within 5%.At the same time,different centrifugal loads are applied to the turbine blades,and the natural frequencies of the turbine blades at different rotational speeds are analyzed.Through the above experiments and calculation results,the turbine resonance is analyzed.When the supercharger rotates at 23,072 r/min,27,125 r/min and 28,263 r/min,the turbine blades are prone to resonance.These three speeds should be avoided in the supercharger matching work.