A Study of Sirocco Fan with Eccentric Inlet Nozzle

本文介绍了一种带有偏心进气喷嘴的热风机的性能。针对多种叶轮和机匣，实验研究了进口喷嘴偏心位置对风机压力系数和内部流动的影响。结果表明，当偏心位置位于涡旋出口上游较远处时，压力系数明显高于无偏心时的压力系数。在这种偏心风扇中，形成了从叶轮出口到入口通过护罩间隙的循环流。由于循环流动阻挡了吸入气流进入叶轮进口，叶栅的有效流动区域变窄。因此，通过叶栅的流速增加，所做的功增加，因此风扇的总压力增加。当涡卷中的一些流体通过护罩间隙循环时，流入出口管道的剩余流体突然膨胀。因此，在涡旋中获得大的静压恢复。

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.