Aerodynamic Optimization Design Of Fan Blades

Higher efficiency is always the goal of multistage axial flow fan. For a highly loaded fan rotor, high Mach number and strong shock ware at inlet of the tip will increase the difficulty of design. It can greatly reduce the dependence on designers' professional knowledge and experience when using the automatic optimization design platform of the laboratory. Because a number of individuals of the genetic algorithm will carry on enormous multistage calculation, this paper will grope for the three dimensional optimization method of a single rotor in multistage environment when taking into account the environmental matching characteristics, and ultimately improve the efficiency of two-stage fan. Another main task of this paper is to design a fan rotor whose performance is better than the first-stage rotor of a two-stage fan referring to it.In this paper,first, we had carried on numerical simulation and analyzed its flow characteristics through the analysis of flow field. Then, for the optimization design of the first-stage single rotor, through the study of three kinds of schemes, we had found the flow field of the third scheme is agreement with the first rotor in two-stage environment. So this paper had adopted the third scheme and used numerical optimization method combined with the direct problem calculation including stacking line, meridian plane, profiles and chord length along radial direction. Numerical optimization uses parallel genetic algorithm based on intranet. After optimized design for this rotor, guaranteeing the mass flow and total pressure ratio the approximate same as the original, the efficiency of single fan rotor is improved by about one percentage and the efficiency of the two-stage fan is improved by more than 0.5 percentage at design point. Through the optimization, the desired effect has been achieved.Next, this paper had designed one rotor autonomously with reference to the above rotor, including the initial design and the optimization design. For the initial design, quasi three dimensional blade design software of laboratory had been adopted, based on S1/S2 two stream surfaces as the basic idea, which can realize the design process from through-flow design to two-dimensional profile design/optimization to three-dimensional blade stack. 2-D profile at 10%?50%?90% had been designed referring to the result of through-flow calculation, because of high Mach number of transonic rotor at tip, two profile of 2D at 90% span had been designed using the supersonic profile of 2D which had been applied to the supersonic compressor successfully. After the 3-D calculation of the two rotors which use the above two profile respectively, the result shows that the rotor B that used the supersonic profile can effectively reduce Ma before shock wave and control the separation of boundary layer after shock wave. Last, this paper had carried on optimization design on the two original design fans rotors respectively. Through 3-D optimization, the efficiency of rotor A had been improved by more than 2 percentage and about 1 percentage for rotor B, meanwhile the mass flow and total pressure ratio are closer to design value.