Akihito Nagao

Prediction of ln-Cylinder Flow and Spray Formation Effects on Combustion in Direct Injection Diesel Engines

The study of the phenomena of in-cylinder flow, spray and combustion by measurement and calculation has been vigorously pursued, because thermal efficiency and emissions of the D.I. diesel engine are influenced by them. To investigate the effects of in-cylinder flow on spray and combustion, the D.I. diesel engine simulation model has been developed. This model is composed of in-cylinder flow, spray and combustion models. In the spray model, spray non-uniformity is considered, and physical and chemical processes are considered in the combustion model. The effects of swirl, number of nozzle holes, injection pressure and squish area on thermal efficiency and emissions have been investigated, and the existence of optimum values of these parameters against thermal efficiency have been predicted and these predictions have been verified by measurement.

Present Status and Future View of Rotary Engines

The fundamental mechanism of the rotary engine (RE) was invented by Dr. Felix Wankel who had carried out thorough investigations into the smoothness of centroid motions of moving parts. The RE has no reciprocating piston and valvetrain which are the sources of vibration and the obstructions to increased engine speed. The RE aspirates a larger amount of air per unit volume of engine package than the reciprocating piston engine does, because the charge flows continuously from an intake stroke chamber through an exhaust stroke chamber. Hence, the inherent features of RE are less vibration, compactness, light weight and high performance.