Aerodynamic approach of a variable stator controllability for a small radial turbine

Abstract

A measurement campaign focused on volute outlet conditions and its effects on the variable stator controllability has been conducted on a radial turbine. Indeed, the use of a variable geometry system implies the continuous control of the stator opening to best match the throat section to engine operating conditions. The control of this section highly depends on the mechanic system clearances and the aerodynamic moment transmitted to the actuator. Those two parameters are related to the aerodynamic moment generated on the blades. A previous campaign has allowed simultaneous measurements of the moment on 3 blades thanks to strain gauges. The study described in this paper developed an integrated device for the simultaneous measurements of the 13 blades. This new system integrated to the central housing of the turbocharger reduces the manipulation on the instrumentation. The first part of results concerns the influence of the volute outlet conditions and its effects on the aerodynamic moment of all the blades. The second part deals with the influence of the moments on the controllability along the engine line.