Method Research For Aerodynamic Optimization Design Of Compressor Blade

With the continuous improvement of the ability of CFD numerical simulation, a multidisciplinary aerodynamic optimization design method which is formed by combining numerical optimization theory with CFD method is getting more and more extensive research and application. Presented in this paper is a strategy of combination of CFD method, three-dimensional blade parametric design method and different optimization methods to establish a fully three-dimensional aerodynamic optimization design system suitable for turbomachinery blade. The system includes two kinds of optimization methods: one is the fast and efficient optimization method based on experimental design and response surface model; the other is the global and automatic optimization method based on genetic algorithm. Both of them can achieve the optimization objective to reduce loss and improve efficiency. Then on the basis of advantages and disadvantages of the two kinds of optimization methods and the difference of optimization results, the problem that for different requirements the turbomachinery aerodynamic optimization design should choose which kind of appropriate optimization method is discussed in this paper. Specifically, the main work is as follows:Firstly, the CFD calculation model of fully implicit coupled solution method, k- epsilon turbulence model, and the finite volume method based on finite element solving three-dimensional N-S equations is adopted for the flow field numerical simulation of NASA Rotor 37 blade. The comparison with experimental data is carried out and the validity of the calculation model is verified. All the above work lays a sound foundation for the following aerodynamic optimization.Secondly, cubic B spline curves are used for the parametric modeling of 3D blade. Through regulation of the vertical coordinate size of the spline curve main control points, the objective to make the blade profile to obtain the greatest change in reasonable range with fewer control parameters can be achieved. This part of work paves the way for the following aerodynamic optimization.Thirdly, to overcome the problem of large computational overhead of turbomachinery aerodynamic optimization, a fast and efficient optimization design system based on the response surface approximation model is proposed. The optimization of original blade which is analyzed previously through numerical simulation is then accomplished. The main objective of the optimization is to maximize the isentropic efficiency while constraining the mass flow rate and the total pressure ratio. A detailed analysis of all aspects of aerodynamic performance improvement of original and optimized blade is carried on. The optimization system advantages of low computational cost and disadvantages that the number of design variables cannot be too much are discussed afterwards.Lastly, considering the restriction of response surface method on the number of design variables, a global and automatic optimization design system based on genetic algorithm is set up. Through comparison with the response surface method optimization results, the different scope of application of the two optimization methods is analyzed, and the advantages that genetic algorithm can basically get global optimal solution and disadvantages of large amount of calculation is then studied.