Dynamics effect on combustion of a diesel pilot ignition hydrogen vibration combustor with nonlinear asymmetric motion

The hydrogen vibration combustion alternator (HVCA), utilizing diesel pilot ignition, represents a novel power system capable of reducing emissions while enhancing combustion efficiency. This study investigates the effects of varying spring stiffness on the dynamics and thermodynamics of the HVCA system. A system-level model was developed and validated with experimental data to explore the influence of spring stiffness changes on piston motion, mixing characteristics, and combustion performance. The results indicate that increasing spring stiffness from 70 kN/m to 78 kN/m led to an increase in maximum piston velocity from 12.4 m/s to 12.9 m/s. However, higher spring stiffness did not significantly improve the mixing of hydrogen and air, with the Sauter Mean Diameter (SMD) increasing from 4.2 m to 6.3 m, resulting in a 2.76% decrease in thermal efficiency. Additionally, NO emissions increased significantly under higher stiffness, while soot emissions decreased. The study also found that lower spring stiffness helped enhance cumulative heat release, reaching 573.6 J at 70 kN/m. This research reveals the critical impact of nonlinear dynamics and thermodynamic coupling on the diesel pilot ignition of hydrogen combustion, providing important insights for further optimizing combustion efficiency and emissions reduction.