In automotive turbochargers, the adequate and careful aerodynamic design of radial turbine scroll and nozzle guide vanes is one of the most critical issues for turbocharger designers. In this paper, three-dimensional numerical simulations were performed with a commercial CFD code "Fluent" to estimate distortion effects caused by the turbine scrolls and nozzles. This paper deals with the numerical simulations of two representative types of radial turbine scrolls; "symmetrical type" and "overhung type", coupled with Variable Geometry System (VGS) turbine nozzle. In the case of the symmetrical scroll, the discharge flow from the scroll was quite circumferentially symmetric at the nozzle mid-plane. On the other hand, in the case of the overhung scroll, the flow into the nozzle vanes was highly distorted both in the axial and in the circumferential directions near the shroud and near the tongue. It was confirmed that apparently higher distortion still remained in comparison with the symmetrical scroll case.
展开▼
