Exhaust measurements of NO, soot, and hydrocarbons were made on a 2340-cm3 displacement, single-cylinder diesel engine operated over a range of speed, fuel-air ratio, and timing. Modifications systematically tested include chamber shape (open and divided chamber, prechamber volume ratio, and compression ratio), air swirl, thermodynamic state of the intake charge (EGR, turbocharging, water injection, and air temperature), and fuel injection parameters (orifice size, rate of injection, cam shape, pilot injection).
Exhaust data suggest that the phenomena of air swirl, fuel spray, and diffusion flames are key elements in diesel combustion behavior. The sensitivity of emissions to time-dependent phenomena such as mixing rates, ignition, heat transfer, and burning rates is apparently connected to the extent to which heat release is delayed.