Flows in Vaneless Radial Diffuser Operating at Low Flow Rates : 2nd Report, Flow Around Volute Tongue-Guide Vane and Improvement in Performance of Blower

摘要

The collapse and redevelopment of rotating stall cells around the volute tongue were experimentally observed in low flow rate regions in the vaneless radial diffuser. The suitably located angle of the tongue-guide vane was revealed by flow visualization and testing of a blower with the volute casing. Based on the observation of the flow patterns around the tongue-guide vane and measurements of velocities and pressures in the diffuser and in the exit of the blower, a method of improvement of the efficiency in a wide flow range was proposed in the design of radial blowers or pumps.