Improving turbocharged diesel engine transient response

During transient operation of a common rail turbocharged diesel, the engine response to a higher demand in speed or load could be regarded as an aggregate expression of the behavior of several engine subsystems that each follows certain dynamics along the path from one engine steady state point to another.;The present study proposes a system approach in engine simulation that is capable to detail transient processes at the level of engine subsystems and components during engine acceleration. A transient engine model based on the filling and emptying concept is developed in Simulink for the configuration of a modern multi-cylinder turbocharged diesel engine.;The model features look-up tables similar to ECU maps for the adaptive definition of injection timing and common rail set pressure, combustion characterization for multiple injections events, a turbocharger submodel with thermodynamics and dynamics calculation, detailed crankshaft dynamics analysis, detailed prediction of the components of instantaneous friction losses and power consumed to drive auxiliaries.;Original models have been created for the combustion description and turbocharger generic operation.;An original correlation has been developed for the power required to drive the common-rail high pressure fuel pump and its important contribution to the internal losses of the engine has been underlined.;Model is validated on a 2.5 liter, common-rail turbocharged and intercooled diesel engine. The engine is connected to an A/C dynamometer capable to operate controlled transients. Flexible electronic controls are used to modify the tuning parameters of the engine.;A good agreement has been found in between engine predictions and experimental evidence. It has been found that the model is capable to describe accurately the dependence of instantaneous fuel delivery rate to engine speed during acceleration and it predicts fairly well the various engine parameters during transient operation.;The model provides a detailed representation of processes that are followed by engine subsystems during a speed transient. As a result of the analysis, recommendations for the potential use of the model for improving transient performance are formulated.