A Study of Sirocco Fan with Eccentric Inlet Nozzle

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This report describes the performance of a scirocco fan with eccentric inlet nozzle. The effects of the eccentric position of the inlet nozzle on the pressure coefficient and internal flow of the fan are experimentally investigated for many kinds of impellers and casings. It is found that, in case that the eccentric position is located far upstream of scroll exit, the pressure coefficient is considerably higher than that without eccentricirty. In this eccentric fan a circulating flow through shroud clearance from the impeller outlet to inlet is formed. As the circulating flow blocks the suction flow entering into impeller inlet, the effective flow region of the cascade is narrowed. Therefore the flow velocity through the cascades increases and the work done by it increases, so the total pressure of the fan increases. As some fluid in the scroll circulates through shroud clearance, the remaining fluid, which flows into an exit duct, suddenly expands. Therefore a large static pressure recovery is obtained in the scroll.