This thesis presents the description and evaluation of two modelling techniques for the simulation of steady-state and transient response of a Diesel engine in single or two-stage turbocharged form on a digital computer. The simulation models are set up by assembling the sub-models of the individual components which represent their steady-state performance characteristics by means of the FORTRAN IV language. Two linking techniques viz. iterative and integrative, are used to solve the appropriate steady-state and/or dynamic equations. In order to investigate the effect of compression ratio on engine performance and generally to check the validity of the models, a series of steady-state and transient tests on the single and two-stage builds of the Leyland 520 Diesel engine fitted with low compression ratio pistons are carried out. Furthermore, the transient response of the engine in its single-stage and two-stage forms to a large fuel step, recorded by a PDP 8L on-line computer as data acquisition system, are compared. Finally, the performance potential of the Perkins T6.354.4 EEC Diesel engine is assessed by a theoretical investigation into the effect of turbine variable geometry schemes on performance of the turbocharged engine. Both nozzleless casings - with or without wastegating - and nozzled turbine casings are simulated to find a satisfactory solution to meet the operating requirements of high torque back up at high B.M.E.P. levels.
|Date of Award||1979|