This work is concerned with the prediction of the transient performance of two engine systems associated with high speed Diesel engines. These are an automotive turbocharged Diesel engine and a differential compound engine. The extension of a one dimensional analysis, to cover the transient mode of operation by allowing for component inertias, is described in detail. As a check on the validity of the simulation, a test rig for a turbocharged engine has been built and suitably instrumented. Details of this and the hydrostatic braking system are included. Two different simulations for the turbocharged engine are proposed to predict the transient characteristics of the engine. The first method treats the response between initial and final running conditions as a number of steady state operating points, while the second discriminates between the firing in each cylinder. On the whole accurate predictions were obtained although s me errors occurred mainly in conditions of excess fuelling. The simulations show that under transient conditions the compressor can often work at 'off- design' operating points and may sometimes surge or choke. Some suggestions are made for improving the overall performance of the system. The extension of the work to include the differential compound engine has proved the adaptability of the approach. Further, it has shown the ability of the compound engine to respond rapidly to a demand for a speed change, as the load does not have to be accelerated at the same speed as the engine. During an acceleration the compound engine displays an ability to recover quickly from low values of air to fuel ratio.
|Date of Award||1975|