Study on the effect of variable valve timing and spark timing on the performance of the hydrogen-fueled engine with passive pre-chamber ignition under partial load conditions

•Passive pre-chamber internal flow characteristics, combustion, and energy conversion analysis.•Analysis of combustion and emission for TJI hydrogen engines at different conditions.•The effect of variable valve timing and spark timing on TJI hydrogen engines.•The spark timing has a relatively minor effect on the power output of the TJI hydrogen engine.•Variable valve timing can improve the power and reduce cycle-to-cycle variation.