Isentropic Compressor Efficiency Calculation Method for Small Gasoline Engine Turbocharger Using Supplier Performance Maps

A turbocharger efficiency performance map given by the supplier is calculated using adiabatic flow equations and nonadiabatic experimental data. The experimental data used for this calculation are measured in hot gas stand conditions which are not adiabatic and the efficiency calculation needs correction. This article presents a method to correct the isentropic efficiency of a compressor using the supplier maps and a heat transfer model applied on the compressor. Water is circulating in the central housing to cool the turbocharger and this water flow could be considered as insulation for heat transfer between the compressor and the turbine. The thermal effect of the turbine on the compressor is then neglected and the compressor heat flux is calculated and used to correct the isentropic efficiency calculation. The heat transfer is considered between the compressor and the surrounding environment and between the compressor and the central housing. Experimental adiabatic measurements are used to validate the model. Experimental tests are carried with different oil and water temperature combinations to test the accuracy of the heat transfer model with these different combinations.