Effect of Variable Nozzle Vane Profile on Radial Turbine Performance for Automotive Turbochargers

Abstract

As a radial turbine applied to automotive turbochargers, a variable flow capacity turbine becomes very important to satisfy demands of less fuel consumption and emissions, recently. Especially, a variable nozzle, which can control a turbine wheel inflow velocity, is an indispensable component for diesel engines both of passenger and commercial vehicles in order to achieve high boosting and low pressure loss at engine low end to rated power operations.

In order to improve a variable nozzle turbine performance, the author clarified a relation between a nozzle passage profile and a turbine performance. About four different nozzle vane profiles, CFD calculations and turbine performance tests were conducted and it was revealed that nozzle passage length and inlet to outlet area ratio have a large influence to pressure loss coefficient of a variable nozzle and a turbine efficiency.