Influence of Oxygenated Fuel and Compression Ratio on Engine Vibration and Noise: A Review

Abstract

This review investigates the influence of oxygenated fuel blends and compression ratio (CR) on engine vibration and noise, focusing on experimental studies involving biodiesel and alcohol-based fuels. A consistent trend is observed across various engine configurations—single, four, and six cylinders, where biodiesel blends such as B20 and B40 significantly reduce vibration and noise compared to pure diesel. For instance, experiments show a reduction in average vibration by 1.23%, 2.34%, and 3.54% at engine speeds between 1200–2400 rpm. Moreover, the compression ratio positively correlates with vibration levels; higher CR values (up to 20:1) intensify fluctuations and resonance frequencies, notably around 90 kHz in several test scenarios. Jatropha Methyl Ester (JME) and Karanja biodiesel mixtures exhibit distinct combustion characteristics that influence noise signatures and oscillation behaviour. Advanced diagnostic methods using accelerometers reveal that optimal combustion stages can be precisely monitored with a high correlation coefficient (R² = 0.97), especially in low-displacement engines. Additives like hydrogen further mitigate vibration by lowering transmitted energy to pistons. The findings underscore the potential of renewable biofuels in achieving better NVH (Noise, Vibration, Harshness) performance while highlighting the necessity for engine-specific fuel optimization strategies. This comprehensive synthesis contributes to the future design of low-emission and quieter internal combustion engines compatible with biodiesel blends.