Investigation On Full-3D Inverse Optimization Design Method For Turbomachinery Blade

This paper investigated turbomachinery problems regarding the engineering applications. Full-3D inverse optimization design method for turbomachinary blade was studied based on numerical solver of N-S (Navier-Stokes) equations. Computer programs of direct problem for flowfield and inverse problem for blade design were developed, and investigation on optimization of transonic rotor in axial fan/compressor was carried out.In terms of flowfield calculation within blade passage, it adopted N-S equations and Sparlart-Allmaras turbulence model in cylindrical coordinate, MUSCL scheme and LU-SGS implicit solver. The H-type grid was used for the computational domain, which was convenient for re-generating new grid of modified blade in inverse optimization design process.During debugging and validation of the direct program, the flowfield simulation results were compared with the experimental data of Rotor67and Rotor37respectively. Five kinds of discretization form limiters and inlet turbulence viscosity of boundary condition were discussed to evaluate their effects on numerical calculation. The results indicated:the program of direct problem could capture major characteristics such as shock wave and boundary layer separation well. The computer program could satisfy accuracy requirements of engineering applications.In the inverse problem, static pressure on blade surface was specified for obtaining the corresponding blade profile. It was assumed there was a virtual velocity of grid node on blade surface. Then, the blade geometry was modified by the difference between surface pressure and target pressure of the Original balde and temporary blades during iterative procedure. Methodologies of the inverse problem were introduced in detail, which included the set of inverse problem, blade profile modifying and smoothing method, grid re-generating method etc. The inverse design program was validated by the returning tests, in which the stator blade was made thinner and the rotor blade was thickened initially. The convergence solutions of new blade profiles were in good agreement with the target pressure well.Based on the research of typical internal flow mechanism of transonic rotor, the principle of partitional optimization and specific implement steps were proposed according to the flow constructure, losses, and stability of flowfield at different blade span sections. It was to adjust the loading distribution at flow direction and part static pressure gradient on blade surface to weaken separation in boundary layer near suction surface of subsonic area, and intensity and position of shock and interference with boundary layer of supersonic aera.The principle of partitional optimization was applied to optimize part and all span of Rotor67. The thesis analyzed the influences of controlling discipline of static pressure, loading distribution and their effects to performance, flowfield details, and outlet parameters in respect of subsonic and supersonic area. The calculation time of inverse optimization design was2times of that of direct problem. The optimized blade reduced flow separation and shock wave losses. The adiabatic efficiency was increased by0.6%at near design point in the case of the same row interface parameters of. The block massflow was increased by0.5%at design speed. The above results revealed the effectiveness of the inverse optimization design method.