Computational Analysis of Flow in a Turbocharger Turbine with Pulsating Inflow
Tezduyar, Tayfun E.
Master of Science
The turbine of an automobile turbocharger commonly operates under pulsating inflow, which leads to an undesired “hysteresis” performance. This study is to investigate this phenomenon by presenting a computational flow analysis that can capture the pulsating flow physics in a turbocharger turbine. We use a method of higher-order accuracy, and the key techniques include: (i) the Space–Time Variational Multiscale (ST-VMS) method, which is a stabilized formulation and a turbulence model, (ii) the ST Slip Interface (ST-SI) method, which maintains the solution quality near rotor surface, (iii) the Isogeometric Analysis (IGA), where we use NURBS basis functions in space and time, and (iv) weakly-imposed Dirichlet boundary conditions, which can give accurate mean flow solutions on a coarse mesh with unresolved boundary layers. The geometric model is from a realistic turbocharger turbine. The pulsating inflow conditions are taken from a 1D engine-cycle simulation. The computations are carried out with an incompressible-flow solver. The results show that the turbine is likely to operate far from nominal conditions under pulsating inflow, and geometric features such as exhaust manifold and vanes play a significant role in improving the performance. The techniques show a good potential for solving difficult turbomachinery problems.