题目：Turbocharger Rotor Unsteadiness and 1D Modelling
Bijie Yang is a research assistant at Imperial College London. He received his master degree from the Institute of Mechanics, Chinese Academy of Science in 2015. After that, he came to Imperial College London for PhD and joined the turbomachinery group. His research focuses on computational centrifugal rotor aerodynamics, particularly, flow separations, losses and unsteady effects due to engine reciprocating motion. He is also proficient in simulating multi-physical issues (including flow, heat transfer, electrochemical reaction and electromagnetic field).
Secondary flow structures in turbocharger rotors are particularly complex due to various time scales from engine reciprocating motions and scroll geometries. It is not appropriate to consider secondary flows as steady state in this scenario and the inertia of these structures must be understood. In the present work, the flow field evolution in a mixed flow turbine is investigated using three-dimensional unsteady computational fluid dynamics (CFD). Results show that the timescale of secondary flows in the rotor is found to be at the same order as the rotation period of the rotor. In addition, a newly developed 1D modelling which couples different time scales is introduced.