Experimental Study on Flow in VGS Nozzle of Radial Turbine

(Effects of Nozzle Vane Clearance Position)

Abstract

In this study, the effects of vane clearance position in VGS (variable geometry system) nozzle on the flow field at the inlet of turbine impeller of turbocharger were investigated experimentally at two nozzle opening conditions by using 5-hole Pitot tube. The effect of the existence of clearance pin was also examined. The experimental results clarified that the influence of leakage flow through the clearance obviously appeared in the case that vane clearance is arranged only at hub side by closing nozzle opening condition, and consequently the associated loss generation was increased and eventually the uniformity of the circumferential distributions of loss and flow angle at the downstream of nozzle was deteriorated. On the other hand, the influence of clearance pin became remarkable by opening nozzle opening condition.