An advanced analytical model is presented and used for a fundamental investigation of the response of highly rated turbocharged diesel engines. Details of many aspects of the model are presented, along with a discussion of certain limitations and their importance. The accuracy of the model is illustrated.
Factors influencing turbocharger response are discussed and the dominant ones selected for further analysis. The fuel control system of a highly rated engine usually consists of a device that limits maximum fuel delivery as a function of boost pressure. Changes in turbocharger match can be used to improve low-speed torque and reduce exhaust smoke. The importance of then re-optimizing the maximum fuel controller for transient as well as steady state conditions is illustrated, showing the trade-off between improved drive ability and exhaust smoke.
Turbocharger inertia also strongly influences response and can be reduced by design, material and diameter changes. However reducing turbine diameter alone causes an efficiency miss-match {with radial turbo machinery). The implications of the trade-off between specific speed, efficiency, diameter, inertia, matching and response are presented.