Characterizations of Cyclic Combustion Variations in RCCI Engine Using Multifractal Detrended Fluctuations Analysis

This study experimentally investigated the cyclic variations and partial burn in reactivity-controlled compression ignition (RCCI) engines. Multifractal Detrended Fluctuations Analysis (MFDFA) is employed for the purpose of describing cyclic variations and partial burn. The experiments are carried out on a modified diesel engine. Diesel is injected directly into the cylinder, whereas petrol is introduced into the inlet manifold via the port-injection system to facilitate RCCI combustion. This study explores the influence of the gasoline/diesel premixing ratio \(\left( {r_{p} } \right)\) on combustion stability and partial burn. It was found that the cyclic variations in CA10, CA50, and COVIMEP increased with \(r_{p}\) . Results indicate that the percentage of misfiring cycles increased from 36.4% to 83.1% when \(r_{p}\) increased from 40 to 50%. MFDFA analysis shows that total heat release (THR) time series becomes anti-persistent and its degree of multifractality decreases with \(r_{p}\) . The multifractal analysis also shows that THR, CA10, and CA50 have large fluctuations at smaller scales, and these fluctuations are persistent in nature, while smaller fluctuations at large scales are anti-persistent in nature.