Turbochargers are widely used in Diesel engines as a
means of increasing the output power. Most of them are fitted with radial or
mixed flow turbines. In applications where high boost pressure is required,
radial turbines are replaced with mixed flow turbines with positive rotor
inlet blade angle so that they can achieve a maximum efficiency at a lower
value of blade speed to isentropic expansion velocity ratio than the usual
0.7 (for radial turbines). This study, performed with the ICEM and CFX
softwares of ANSYS, presents a numerical performance prediction of a mixed
flow turbine for a wide range of rotational speeds and pressure ratios. The
influence of the clearance between the rotor tip blades and the casing on
the turbine performances is also investigated. A simulation of the turbine
under pulsed inlet flow conditions is also presented.