Wall treatment effects on the heat transfer in a radial turbine turbocharge

Abstract

Contradicting results about heat transfer effects on the performance of turbine turbocharger motivated this study. It was aimed to assess the effects that the wall treatment in a numerical sense has on the performance of a radial turbine of automotive turbocharger operating under a continuous flow condition. Adiabatic and non-adiabatic conditions were analyzed by using Unsteady Reynolds Averaged Navier-Stokes (URANS), Large Eddy Simulations (LES) and Detached Eddy Simulations (DES) approaches. When considering heat transfer, heat transfer loss at various locations is highly dependent on the near-wall modelling approach employed. Development of thermal boundary layer in the upstream region of turbine affects how the gas is convected in the downstream components, such as the scroll and the rotor. As long as the deviation in predicting thermal boundary layer does not affect the prediction of gas temperature at the inlet and outlet of the rotor, the difference in turbine power prediction by different near-wall modelling approaches was found to be small.