Experimental investigation on the effect air–fuel ratio on cycle-to-cycle variations of SI combustion and performance parameters,

摘要: In this paper we analyze the cycle-to-cycle fluctuations of peak pressure pmax and peak pressure angle αpmax in a fourcylinder spark ignition engine. We examine the experimental time series of pmax and αpmax for four different equivalence ratio. Using standard statistical techniques such as return maps and Standard Deviation we show that depending equivalence ratio, there are significant differences in the fluctuations of pmax and αpmax. To evaluate the cycle-to-cycle fluctuations of SI combustion parameters, Standard Deviation (σ) of every parameter were calculated for every engine operating condition. Finally, we explain how the information on both pmax and αpmax can be used to develop optimal strategies for controlling the combustion process and improving engine performance. The results showed that ϕ= 0.9 is enough to do accurate calculation of the average pressure cycle at various operation conditions of the engine.