Using Turbocharger maps in gas exchange simulation and engine control units

Abstract

Characterisation of turbocharger performance is important in gas exchange simulation and engine control unit calibration. Compressor and turbine performance maps are measured on a hot-gas test bed. As a result their performance maps have a large dependence on heat transfer. Gas exchange simulation software assumes adiabatic compressor and turbine maps. The direct use of measured maps leads to defective simulation results. The power balance of compressor and turbine in steady state operation leads to limited turbine performance maps. The acceleration of compressor and turbine are not covered in those maps. In gas exchange simulation the performance maps are extrapolated to cover the entire range of operation. Simulations using the extrapolated maps do not correlate with empirical results. This paper presents methods for reconciling results derived from maps with those observed in the real world over the same extrapolated operating range. The methods use existing maps without additional information to construct performance maps relevant for operation on internal combustion engines. A recipe approach for the application to measured maps is developed and applied to examples. Compared to mathematical extrapolation, the presented methods yield empirically sound extrapolations and improve the quality of gas exchange simulation results.