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The methodology put forth in this paper stems from the premise that the primary reason for the generation of major pollutants by diesel engines, particulates and nitric oxides, is associated with over-reliance upon diffusion flames to carry out the process of combustion. Specific means are, therefore, proposed to inhibit their formation. This consists of refinements involving the use of either hollow cone spray injectors or air blast atomizers. Concomitantly, the process of combustion is staged by either regulating the rate of injection or employing a number of consecutively activated injectors per cylinder under a microprocessor command, while regions of high temperature peaks are distributed throughout the charge and kept at a relatively low level by exploiting the large scale vortex structure of turbulent pulsed jets combined with residual gas recirculation.

In principle, the thermodynamic and thermochemical processes evolve with time, irrespectively of their spatial orientation. They are, therefore, specified in terms of ordinary differential equations with respect to time as the only independent variable. This feature is well reflected in the literature by the so-called zero-dimensional models. Current demands of technological progress impose much stricter requirements upon the precision of such calculations than ever before. A methodology for catering to them is presented. Its application is illustrated by the performance analysis of a Renault engine, operated at full and part loads, with particular emphasis placed upon the formation of major combustion-generated pollutants, NOx and CO, in a premixed-charge engine.

The mandate of the President's Clean Car Initiative to produce a car engine that will more than double the mileage per gallon of fuel and simultaneously eliminate pollutant emissions poses an unprecedented challenge to automotive industry. It ought to be met, it is claimed, by radical improvements in the execution of the exothermic process of combustion. The conventional combustion process involves the mode of flame traversing the charge (FTC). In this process control over the exothermic process is, in effect, non-existent. The exothermic process should be executed instead by a microprocessor controlled fireball mode of combustion (FMC) - the epitome of direct injection stratified charge (DISC) engine, featuring late injection and stratified combustion using a pulsed combustion jet (PCJ) system.

Pulsed Jet Combustion (PJC) is introduced here as a key element for engines where the progress of combustion is interactively controlled by a microprocessor system. Practical realization of PJC presented here involves the use of an 18 mm plug containing a cavity, where a rich mixture is ignited by a conventional spark discharge, closed by a tip with a suitable orifice to form the effluent stream. Its performance is determined by tests carried out in a constant volume vessel, simulating the enclosure of a CFR engine at 60 CAD with compression ratio of 7:1, using propane/air mixtures at equivalence ratios of an order of 0.6, in comparison to that of a flame traversing the charge, a so-called FTC mode, upon ignition by standard spark discharge under identical geometrical and initial thermochemical conditions. The results demonstrate the superiority of PJC for executing the exothermic process of combustion in a lean burn engine.