Experimental investigation of the effects of injection strategies on cycle-to-cycle variations of a DISI engine fueled with ethanol and gasoline blend

In this study, the main objective of the work was to evaluate the injection strategies on the cycle-to-cycle variations of a turbocharged DISI engine fueled with ethanol and gasoline blend by using single injection (SI) and two-stagnation injection strategy (TSIS) modes, respectively. Two-stagnation injection strategy modes were adopted to control the first injection and the later second injection by changing the injection timing or the second fuel mass repartition. The cycle-to-cycle variations of the in-cylinder pressure, peak pressure and its location, maximum rate of pressure rise and its location, indicated mean effective pressure and combustion phasing were statistically analyzed and comprehensively compared with various injection strategies. Results showed that employing TSIS 3 mitigated the in-cylinder pressure fluctuation and concentrated the integral heat release compared with other injection strategies. Meanwhile, adopting TSIS 3 obtained the lowest COVPP (5.63%) and achieved the frequency distributions of peak pressure histograms in a relatively narrow range. Furthermore, the cycle-to-cycle variations of the 10-90% combustion duration were relatively small and less sensitive to change the injection strategy modes. Finally, employing TSIS 3 was proved to be the optimal injection strategy for achieving the lowest COVIMEP while obtaining the highest IMEP.