Exhaust Flow Pulsation Effect on Radial Turbine Performance

Authors

J. Fjällman - Department of Mechanics, CCGEx, KTH Royal Institute of Technology, Sweden
M. Mihaescu - Department of Mechanics, CCGEx, KTH Royal Institute of Technology, Sweden
L. Fuchs - Department of Mechanics, CCGEx, KTH Royal Institute of Technology, Sweden

Abstract

In the current vehicle manufacturing world the chase for a better fuel economy and better driveability is in high gear. One way of doing so is to investigate and optimize the turbocharger. In this paper the flow in a radial turbine of a passenger car turbocharger has been analysed by Large Eddy Simulations. The current simulations have investigated the effects of changing the inlet pulse frequency and inlet pulse shape on turbine’s performance parameters (e.g. ef- ficiency, shaft power, pressure distributions). Three different engine speeds and two different pulse shapes were chosen to be compared and analysed. With the total mass flow per pulse being constant for all cases there is a clear dependence of both pulse shape and frequency when it comes to e.g. wheel momentum. Higher frequency increases the peak momentum more than the minimum level. A reduction in pulse duration also increases peak momentum more than the minimum.