Miloš Polášek

New Approach to Turbocharger Optimization using 1-D Simulation Tools

The paper deals with the investigation of turbocharger optimization procedures using amended 1-D simulation tools. The proposed method uses scaled flow rate/effficiency maps for different sizes of a radial turbine together with a fictitious compressor map. The compressor pressure ratio/efficiency map depends on compressor circumference velocity only and predicts the both compressor specific power and achievable efficiency. At the first stage of optimization, it avoids the problems of reaching choking/surge limits. It enables the designer to find a suitable turbine type under realistic unsteady conditions (pressure pulses in exhaust manifold) concerning turbine flow area. Once the optimization of turbine/compressor impeller diameters is finished, the specific compressor map is selected. The proposed method provides the fast way to the best solution even for the case of a VGT turbine. Additional features have been developed for the representation of scaled turbine and compressor maps. They are based on application of versatile regression functions. No recalculation of normalized curves is needed. The method is presented for the model of a one-loop hot gas stand (steady performance compressor/turbine optimization) and for a modelled engine with different compressors. The potential of optimized turbocharger is evaluated at simulated typical operation points for a passenger car equipped with a 4-cylinder 2 dm engine.