EXPERIMENTAL STUDY ON THE PERFORMANCE OF A VARIABLE GEOMETRY MIXED FLOW TURBINE FOR AUTOMOTIVE TURBOCHARGER

This paper investigates a variable geometry (VG) mixed-flow turbine with a novel, purposely designed pivoting nozzle vane ring. The nozzle vane ring was matched to the 3-dimensional aspect of the mixed-flow rotor leading edge. The VG mixed-flow turbine has been evaluated experimentally, in steady and unsteady conditions. The VG turbine shows higher efficiency and swallowing capacity at various vane angle settings compared to an equivalent nozzleless turbine. But the VG turbine unsteady performance was found to deviate substantially from the quasi-steady assumption, compared to a nozzleless turbine. The VG stator with the new unique vane design is expected to further enhance the mixed-flow turbine benefits in term of engine-turbocharger matching and transient performance.