Improvement in accuracy of engine cycle simulations by using a turbocharger prediction model instead of measured efficiency map. Issue 1 (May 2021) - Misono, Y
Abstract: In the downsizing concept, the turbocharger (T/C) is one of the key devices for improving thermal efficiency and exhaust emissions of internal combustion engines for automobiles. In order to maximize the supercharged engine performance, the size of the T/C applied for the given engine system has been optimized by using a 1-D engine cycle simulation. For this reason, T/C performance prediction model for engine cycle simulation is required to be accurate over a wide operating range. In the conventional T/C performance prediction model, the turbine performance was predicted by extrapolating from the efficiency map measured under steady flow. However, the accuracy of the extrapolation method is uncertain, and it has been pointed out that the prediction accuracy is low in the low load operations. In this study, a 1-D T/C model developed based on hydrodynamics and thermodynamics was used. Using the 1-D T/C model, a grid efficiency map over the entire operating range was calculated and the grid map was applied to 1-D engine cycle simulation. The accuracy of the T/C model was verified by comparing the experimentally measured efficiency under steady flow.