Method of Predicting Some Aspects of Performance of a Diesel Engine Using a Digital Computer

Abstract

While the design of diesel engines is necessarily based upon some estimate of the pressure and temperature conditions expected in the cylinder and in the air and exhaust manifolds, such estimates have usually been very approximate. The suitability of the design has to be proved, or improved, during a considerable programme of rigorous development As engines become more highly rated the value of more accurate early estimates of engine performance, as a guide to the designer, becomes more obvious. The paper describes a method of calculating this information by digital computer based on a fundamental approach to the processes involved. It is demonstrated that the cylinder pressures and temperatures, exhaust gas temperatures, fuel consumption, air flow, heat losses, piston and wall temperatures and engine output so calculated, correlate very well with experimental results Using this technique, different combinations of engine variables can be ‘tested’ by computation to reduce the range of engine tests necessary to develop the optimum design, and allow the designer and the development engineer to concentrate their practical experience and technical ‘know-how’ on the formidable problems of mechanical development and combustion improvement