Search Results

Cycle-to-cycle variations in the pressure evolution within the cylinder of a spark ignition engine has long been recognized as a phenomenon of considerable importance. In this work, use of tools borrowed to the nonlinear dynamical system theory to investigate the time evolution of the cylinder pressure is explored. By computing a divergence rate between different pressure cycles versus crank angle, four phases during the combustion cycle are exhibited. These four phases may be identified with the four common phases evidenced by burn rate calculations [1]. Starting from phase portraits and using Poincaré sections, we also study correlations between peak pressures, IMEP and the durations from ignition to appearance of a flame kernel.

The performance of a four-valve engine operating with combustion in all cylinders has been determined in terms of indicated mean-effective pressure, drivability and concentrations of unburned hydrocarbon in the exhaust gases with a stoichiometric mixture of gasoline and air and four injectors including two with air assist. In addition, size and velocity characteristics of the fuel sprays were measured with a phase-Doppler velocimeter outside and inside the engine. With operation at a steady rotational speed of 1200 rpm, the indicated mean- effective cylinder pressure and its covariance were found to be nearly constant with the initiation of injection from 150 to 600 degrees of crank angle after top-dead-centre of intake.