Investigation On Numerical Simulation And Inverse Design Method For Turbomachinery

With the improvement of computer performance,computational fluid dynamics(CFD)has developed rapidly,which plays an increasingly important role in the design of turbomachinery and flow field analysis.Especially in the blade aerodynamic design,CFD technology greatly reduces the dependence on experimental data,and becomes the main part of modern turbomachinery design system.With the support of CFD technology,a variety of direct optimization programs and inverse design methods have been developed at home and abroad.In this paper,based on the engineering application and the numerical solution of Navier-Stokes(N-S)equation,a set of general numerical solution program of threedimensional flow field is developed,which can meet the requirements of certain accuracy and solution speed.On this basis,the inverse design method of turbomachinery is developed.Then,the transonic compressor is taken as the main research object to test and study the developed direct and inverse program.The specific work includes the following contents:(1)A three-dimensional high-precision RANS numerical solver was developed for the complex internal viscous flow in transonic turbomachinery.Numerical experiments were carried out on Rotor67 compressor rotor.The results of two FVS scheme,namely Steger-Warming and Van Leer scheme were compared under different MUSCL interpolation methods.The results showed that the simulation effect of Van Leer scheme is better than that of Steger-Warming,and the simulation effect using primitive variables interpolation is better than that of flux interpolation,and the performance of Albada limiter is basically the same as of Hemker limiter.(2)The Rotor67 transonic compressor rotor was numerically simulated by using FVS scheme and AUSM + scheme combined with various limiters.The calculation results of these schemes were analyzed and compared with the experimental results.The results showed that AUSM + scheme has smaller numerical viscosity and higher simulation accuracy of boundary layer than FVS scheme.The Hemker limiter has the best overall performance.The viscous resolution of the Van Albada limiter is slightly lower than that of the Hemker limiter.The Minmod limiter has poor ability to capture the flow separation phenomenon.The Van leer limiter is easy to introduce the dispersion error.(3)An improved inverse design method for three-dimensional turbomachinery blades in viscous flow field is proposed.This method assumes that the camber line has a virtual moving speed.The virtual movement is calculated by the difference between the target load and the actual load,and is reasonably limited by the thickness of viscous sublayer.The camber line is smoothed by cubic B-spline interpolation,and the new blade profile is obtained by updated camber line and the given blade thickness.Verification results showed that the method can modify the blade profile according to the design intention.It has strong robustness,fast convergence speed,high degree of freedom of the blade,independent of the specific grid and solver,and has certain generality.(4)A full three-dimensional viscous inverse design method suitable for multi-row blade flow field was proposed and applied to the optimization design of an entire stage high-load axial compressor blade.The inverse problem method takes the load distribution as the optimization objective.The load distribution of the rotor blade can be adjusted reasonably according to the calculation results of the direct problem,so as to control the position and intensity of shock,optimize the aerodynamic parameter distribution on the blade surface and reduce the flow separation.At the same time,the inlet and outlet angle of the stator blade can be adjusted in real time according to the blade inlet flow angle,so that the rotor and stator blade rows can keep the best matching state and reduce flow losses.By inverse optimum design of the Stage 35 compressor stage,the isentropic efficiency was increased by 1.1%.The results show that the method can significantly improve the flow field distribution of the blade,optimize the matching state of the rotor and stator blade rows,and improve the efficiency of the compressor stage in the full operating range.