Investigation of the combustion noise of hydrogen piston engines

For hydrogen internal combustion engines (H 2 ICEs), the existing researches mainly focus on their thermodynamic aspects, while the engine acoustics are paid less attention. The objective of this research is to investigate the combustion noise characteristics of H 2 ICEs and find the biggest lever for combustion noise mitigation. Based on the data from previous thermodynamic measurements of various H 2 ICEs, the influences of different parameters for the combustion noise and knocking are studied with sensitivity analysis and machine learning based method. The results show that increasing Air–fuel equivalence ratio ( λ ), ignition delay and exhaust-gas recirculation rate (EGR) are acoustically beneficial, where λ is the most effective one with possible noise reduction up to 20 dB. Further, the comparison results between the H 2 ICEs and conventional engines indicates that the combustion noise of the H 2 ICE is kept at similar level as the respective gasoline variant if the H 2 ICE is operated withλ >2.