Effects of design variables on the performance of a centrifugal blower have been analyzed based on the three-dimensional flow analysis. Two design parameters defined the shape of a volute casing are introduced to enhance a blower performance. To analyze three-dimensional flow field in the centrifugal blower, general analysis code, CFX, is employed in the present work. SST turbulence model is employed to estimate the eddy viscosity. Boundary condition at the interference plane between rotational and stationary domains is applied by a stage method. Unstructured grids are used to represent a composite grid system including blade, casing and inlet guide.
In the present study, throughout the shape optimization of the centrifugal blower at the design flow condition, the blower efficiency and pressure are successfully increased by 0.5 and 1.6 percent compared to reference one. It is found that the casing height of design variables is more sensitive on the object function of efficiency compared to that of the casing width. And secondary flow due to velocity gradient and low velocity region increase pressure loss, leading to make low efficiency. Detailed flow field inside a centrifugal blower is also analyzed and compared.