Simulation of Pulsating Flow Unsteady Operation of a Turbocharger Radial Turbine 2008-01-0295
The aim of the current contribution is to develop a tool for the improvement of accuracy of turbocharger turbine simulation during matching of a turbocharger to an engine. The paper demonstrates the possibility of unsteady turbine simulation in pulsating flow caused by an internal combustion engine using the basic modules of generalized 1-D manifold solver with entities (pipes, channels) under centrifugal acceleration in general direction and under non-uniform angular speed, which has not yet been explored.
The developed model extrapolates steady operation turbine maps by this way. It uses 1-D model parameters identified from steady flow experiments. Unlike the lumped-parameter standard models of turbocharger turbines, the model takes into account complete 1-D features of a turbine flow path including arbitrary shape of turbine impeller vanes.
The turbine model calibration parameters (1-D averaged flow exit angles, loss coefficients, leakage coefficients, etc.) are identified by means of 1-D steady model (described in previous papers). The model was used in optimization code loop to find the set of 10 calibration parameters for the best fit of measured turbine efficiency and reduced flow rate.
Due to modular construction the model can be easily amended to very complicated geometries of twin scroll turbines, turbines with a WG ejector or an outlet diffuser casing, as well as future turbocharger turbines coupled closely to exhaust gas aftertreatment facilities. The model covering 1-D phenomena in a turbocharger turbine of general geometry under real operation conditions has not been used in such a scale yet.