An experimental assessment of the effects of stator vane clearance on an automotive turbocharger turbine

Experimental tests have been conducted on a radial turbine looking at three different stator vane positions equating to a minimum, 25% and maximum MFR condition. Separate tests have been performed investigating performance with either hub side or shroud side stator vane clearance. Through the experimental tests and CFD simulations it was found that better performance was achieved when operating with hub side tip clearance on the stator vanes. CFD revealed that the stator vane tip leakage flow modified the inlet flow angle at rotor inlet. The flow angle moved to more negative values of incidence.