Combustion noise investigation with multi-cylinder RCCI

Advanced combustion techniques have shown promise for achieving high thermal efficiency with simultaneous reductions in oxides of nitrogen (NO _x) and particulate matter (PM) emissions. Many advanced combustion studies have used some form of noise-related metric to constrain engine operation, whether it be cylinder pressure rise rate, combustion noise, or ringing intensity. As the development of advanced combustion techniques progresses towards production-viable concepts, combustion noise is anticipated to be of the upmost concern for consumer acceptability. This study compares the noise metrics of cylinder pressure rise rate with combustion noise as measured by an AVL combustion noise meter over a wide range of engine operation conditions with reactivity controlled compression ignition on a light-duty multi-cylinder diesel engine modified to allow for direct injection of diesel fuel and port fuel injection of gasoline. Key parameters affecting noise metrics are engine load, speed, and the amount of boost. The trade-offs between high efficiency, low NO_x emissions, and combustion noise were also explored. Additionally, the combustion noise algorithm integrated into the Drivven combustion analysis toolkit is compared to cylinder pressure rise rate and combustion noise as measured with a combustion noise meter. It is shown that the combustion noise of the multicylinder reactivity controlled compression ignition map can approach 100 dB while keeping the maximum pressure rise under 100 kPa/CAD.