Numerical Assessment and Performance Maps Generation of a Turbocharger Attempted to Be Matched with an Automotive Engine

The present article aims to propose an efficient methodology to match aerodynamically a 1.5 L, three-cylinder downsized diesel engine with a suitable turbocharger (TC) to boost its performance based on a selection procedure and computational fluid dynamics (CFD) simulation. First, a radial turbine stage was sized and designed applying one-dimensional (1D) preliminary design in-house codes and then followed by a numerical simulation to investigate the flow fields and to predict its performance. Based on the simulation results, a global turbine performance map was generated. On the other hand, following a meticulous selection approach, a suitable TC compressor was chosen from a database. Therefore, performance maps of the designed turbine and the selected compressor were matched with the engine simulation model. From the findings, the engine equipped with the proposed compressor developed an operating area far from the instabilities limits over the entire speed range, with a maximum surge margin of 23.37% measured at the engine’s extreme conditions (full load and rated power). Additionally, the new turbocharged (TCed) engine exhibits remarkable improvement in terms of brake thermal efficiency, specific fuel consumption, compressor and turbine isentropic efficiencies at the engine rated power of about 5.41% (corresponding to an increase of 2.13 points), 5.14% (a decrease of 11 g/kW/hr), 4.07%, and 18.11%, respectively, compared to the original TCed engine. Furthermore, the measured brake power of the new TCed engine presented similar results as the original one, particularly at high engine speeds. Besides, maximum deviations of 7.31% and 0.45% were measured between the new and original TCed engines in terms of in-cylinder pressure and temperature, respectively, which guarantee the engine thermodynamic strength at the engine’s extreme conditions. Finally, the developed methodology reported satisfactory results in terms of the secure functioning and predicted performance of the engine, which can be considered as an important basis before initiating any detailed conception and/or further investigations such as vibration, mechanical stress, and heat transfer for fabrication purposes.