Variable nozzle wake and clearance leakage of pulse turbocharging turbine

The wake and clearance flow of pulse turbocharging turbine variable nozzle were studied with CFD. Results show that, at low pulse pressure, the nozzle wake shakes severely and the effect of potential flow between the blades of nozzle-rotor is increased. At high pulse pressure, half of the rotor blade chord is influenced by the two nozzle wakes. Patterns of nozzle clearance leakage flow vary at different turbine inlet pressures, and the patterns at the shroud side and hub side are varied. Nozzle outlet flow angle and rotor inlet attacking angle are influenced by the nozzle clearance leakage flow. Nozzle outlet flow angle is sensitive to the variation of pulse pressure at low turbine stage inlet pressure. Rotor attacking angle becomes identical in the spanwise direction at high inlet pressure.