In previous study of optimum meridian profile of impeller and guide-vane, almost all design parameters included in the specific speed and blade number are variable design parameters in optimum process. As the result, optimum specific speed and blade number were obtained. In the calculation, loss calculation consists of blade-to-blade diffusion loss and axial-symmetrical annular wall friction loss. The calculation result without annular friction loss head isn’t affected by normal diameter and rotational speed. In consideration of diffusion loss and annular friction loss, the result of calculation is affected by normal diameter and rotational speed. In this case study, normal diameter and rotational speed are also variable design parameters. The normal diameter is mid span impeller outlet diameter. So, normal velocity is peripheral velocity of mid span impeller outlet. The initial normal diameter is 100mm and the initial rotational speed is 1000min−1. And then, design parameters and all specification become variable. As there isn’t constant design parameter in this case study, there is no restriction in optimum process. As there is no restriction in optimum process, the best one optimum meridian profile can be obtained. In one case, the object function contains the efficiency and suction specific speed. In the other case, the object function contains the only efficiency. As the result, the optimum meridian profile of impeller and guide-vane can be obtained in each case.

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