Experimental Study on the Aerodynamic Characteristics of a Compact Multi-Stage Centrifugal Fan

Abstract

Large multi-stage compressors and blowers have been applied widely in the energy industry, such as oil and gas plants, for many years. In recent years, a compact blower with a high pressure difference and high flow rate (e.g., as the cooling system for a densely packed server) is anticipated with the development of miniaturization technology for machinery. Thus, this experimental study was conducted for the development of a novel compact multi-stage blower. The appropriate combinations of curved impellers and return vanes, which eliminate the swirling flow for a static pressure recovery and draw an operating fluid to the 2nd impeller from the 1st impeller, were investigated from the viewpoint of performance and efficiency. In addition, the velocity and pressure fluctuations of flow instabilities generated in the return vanes for a low flow rate were also investigated. The results indicated that the best combination of the impellers from the point of total efficiency, which was the backward-curved vane for the 1st impeller and the forward-curved vane for the 2nd impeller, in the case of present condition. In addition, flow instability in the return vanes circumferentially propagates with the cell structure.