Heat transfer effects on the performance of a radial turbine working under pulsatile flow conditions

Turbo charging of internal combustion in general and spark ignited engine in particular has become more common the last decay since it reduces fuel consumption and emissions. The turbine works under highly unsteady flow conditions, since the exhaust flow entering the turbine is pulsatile and turbulent with a varying strength of the axial and secondary flow components. Heat transfer from the fluid to the turbine housing is different for a pulsatile flow compared to a non-pulsatile flow. A numerical study with Large Eddy Simulation is applied to study the effects of heat transfer at the walls on the turbine performance working under pulsatile flow conditions. Two cases are considered, one with adiabatic walls and another with heat transfer at the walls. The flow field is assessed with focus on the differences between the two cases. The results show that difference in the shaft power is small, although the temperature distribution in the turbine is different for the two cases. The mechanisms for these differences in the flow field are assessed and discussed.
QC 20140829