Experimental investigation of intake and leakage performance for a shrouded radial turbine in the compressed air energy storage system

Abstract

The collector and the shrouded impeller are employed as the intake unit and the rotor respectively in the shrouded radial turbine which is applied to the high-pressure stage as a power generation device in the compressed air energy storage (CAES) system. In comparison to the volute and the tip clearance, the aerodynamic performance of the collector and the shroud cavity is less well understood in shrouded radial turbines. In the present work, the aerodynamic nonuniformity of the collector and leakage characteristics of the shroud cavity were experimentally tested and discussed. It is found that there exist several local high-pressure regions near the bottom (from 90° to 135° and from 225° to 270° in the clockwise direction) in the collector, and the flow congestion may occur in these regions. Both the magnitude and the location of high pressure could be changed as the rotating speed is adjusted. The throttling of labyrinth seals is enhanced when the rotating speed or the expansion ratio rises, and the maximum reduction rate of the cavity leakage is over 20%. At the impeller exit, losses have been enhanced and the outflow angle has been reduced at the region above 0.6 normalized spanwise due to the mixing between the leakage and the main flow.