A nonlinear, transient, single-cylinder diesel engine simulation for predictions of instantaneous engine speed and torque

A non-linear transient, single-cylinder diesel engine simulation has been d eveloped for predictions of instantaneous engine speed and torque. The foun dation of our model is a physically based, thermodynamic, steady-state dies el engine simulation (Assanis, D. N., and Heywood, J. B., 1986, "Developmen t and Use of a Computer Simulation of the Turbocompounded Diesel System for Engine Performance and Component Heat Transfer Studies," SAE Paper 860329) , which has been comprehensively validated for various engine designs. The transient extension of the parent model represents the diesel engine as a n on-linear, dynamic system. The instantaneous crank-shaft speed is determine d from the solution of the engine-external load dynamics equation, where th e engine torque is tracked on a crank-angle basis. Validation of the transi ent model during rapid engine acceleration shows that both the cyclic fluct uations in the instantaneous crank-shaft speed line and the overall engine response are in good agreement with experimental measurements. Predictions of sing le-cylinder engine starting reveals the importance of selecting the proper value of the engine moment of inertia in order to control the ampli tude of angular velocity fluctuations and ensure stable engine operation. I t is fin-ther shown that the variation in the inertial forces on the recipr ocating components with speed has a dramatic impact on the instantaneous to rque profile, and consequently on angular velocity fluctuations.