Turbocharger Turbine Performance; a Sensitivity to the Boundary Conditions

Authors: Lim, S.M., Mihaescu, M.
Document Type: Conference
Pubstate: Published
Journal: 14th International Symposium on Unsteady Aerodynamics and Aeroelasticity of Turbomachines, ISUAAAT14, Stockholm,
Volume: I14-S14-1  
Year: 2015


Deviation of turbocharger’s performance under engine-like pulsating flow conditions from that estimated on a test rig under steady-flow conditions motivated this study. This numerical study aimed to look into the sensitivity of turbocharger turbine performance to different pulse profiles for the exhaust gases which are feeding the turbine through the exhaust manifold. Exhaust pulse profiles which are corresponding to an automotive engine working with wide open throttle and with divided exhaust period respectively, as well as corresponding to a test rig pulse generator were investigated by using Detached Eddy Simulations (DES) approach under adiabatic condition. The study found that the level of phase shift in mass from upstream to downstream in the turbine is different. Furthermore, rotor torque was found to be strongly affected by the pulse profile, considering the same injected mass flow per engine cycle. No direct correlation between rotor’s upstream total pressure loss and the rotor torque was observed. The instantaneous relative flow field under pulsating flow condition was found to be dissimilar qualitatively when compared with the corresponding non-pulsating flow condition. When compared with literatures, this study observed difference rotor behaviour in handling period with no flow. Also, different direction of phase shift in mass at rotor downstream was also observed, as compared with past study. These differences might suggest that the effects of pulsating flow to turbine performance is geometry dependence and further study is necessary to find the optimum matching of turbine and inflow pulse.