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As part of a comprehensive simulation of a prototype locomotive propulsion system, a detailed model has been developed that predicts the dynamic response of an experimental two-stroke, turbocharged and intercooled diesel engine. Engine fueling and brake torque are computed from regression equations derived from an extensive data base. Corrections are applied to the calculated steady-state torque to account for dynamic deviations of in-cylinder trapped air-fuel ratio from the steady-state value. The engine simulation accurately represents the operation of the turbocharger, which is gear-driven at low turbocharger speeds, and freewheels through an overrunning clutch when exhaust energy accelerates the turbocharger beyond its geared speed. Engine fueling level, i.e., rack, is determined from a dynamic simulation of an electrohydraulic governor, which responds to the difference between the desired and the actual engine speeds. The governor representation includes: (1) finite rate of change of engine set speed; (2) load regulator feedback for control of applied engine loads; and (3) fuel limiting under conditions of excessively high load demand. The fundamentals of the engine/governor model are given in the paper along with examples that emphasize the dynamic operation of these particular components.

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A combustion model has been developed for a direct-injected diesel engine fueled with coal-water slurry mixture (CWM) and assisted by diesel pilot injection. The model combines the unique heat and mass transport and chemical kinetic processes of CWM combustion with the normal in-cylinder processes of a diesel engine. It includes a two-stage evaporation submodel for the drying of the CWM droplet, a global kinetic submodel for devolatilization, and a char combustion submodel describing surface gasification by oxygen, carbon dioxide, and water vapor. The combustion volume is discretized into multiple zones, each of whose individual thermochemistry is determined by in-situ equilibrium calculations. This provides an accurate determination of the boundary conditions for the CWM droplet combustion submodels and the gas phase heat release. A CWM fuel jet development, entrainment, and mixing submodel is used to calculate the mass of unburned air in each of the burned zones. A separate submodel of diesel pilot fuel combustion is incorporated into the overall model, as it has been found that pilot fuel is required to achieve satisfactory combustion under many operating conditions. The combustion model is integrated with an advanced engine design analysis code. The integrated model can be used as a tool for exploration of the effects of fuel characteristics, fuel injection parameters, and engine design variables on engine performance, and in the assessment of the effects of component design modifications on the overall efficiency of the engine and the degree of coal burnout achieved.