The Study Of 3D Optimal Design Of Centrifugal Impeller Based On Velocity Distribution Control

Centrifugal impeller machinery is widely used in industries such as metallurgy, exploration, chemical engineering, aeronautics, power, vessels and civil engineering. With the growing significance of energy conservation, higher aerodynamic performance of centrifugal impellers has become the key to reduce energy consumption. This paper has developed the theories and methods of three dimensional blade optimization in which the influence of rotation, curvature and compressibility are taken into account.The optimization design method of centrifugal impellers focuses reducing internal flow losses through restraining the development of boundary layer, secondary flow and stratification effects. These flow effects are based on relative velocity distribution of impeller flow channel. Four parameters are selected to establish velocity distribution model, two parameters, which are the maximum reduction ratio and its location, are used in average relative velocity distribution; others, which are the maximum loading coefficient and its location, are used in relative velocity distribution on the suction side. The compressibility of gas is considered in the optimal design, which improved the reliability and accuracy of the design method. The best relative velocity distribution depends on whether the boundary layer is the thinnest. The calculation of the boundary layer took the rotation, curvature of the blades and compressibility of gas into consideration, which improved the accuracy of boundary layer calculation. The streamline curvature method is adopted to design blade.After accomplishing the optimization process, the internal flow of centrifugal impeller was stimulated through CFD method, the results show that the boundary layer development is restrained effectively, the boundary is thinner and the second flow is weaker. Overall, the jet-wake structure is weakened, therefore, the flow efficiency was increased.