Investigation of hydrogen detonation in a spark-ignition engine using large eddy simulations

Hydrogen detonation is investigated using Large Eddy Simulations (LES) in a Cooperative Fuel Research (CFR) engine at compression ratios (CR) of 8.5, 10 and 12. It is shown that the blast theory can explain detonation development in this engine, particularly at high CR, where detonation cells form due to detonation spot interactions. The crosspoints at detonation cell tips amplify pressure fluctuations up to 21 MPa and cause localised heat losses up to about 1 GW/m 2 . Results show that increased CR intensifies knock due to higher unburned mass fraction (UMF) at the auto-ignition time, with hydrogen detonation being more sensitive to UMF than hydrocarbon fuels. Auto-ignition dynamics characterised by timing, location, and number of spots drive cyclic variability, causing up to 80% Maximum Amplitude of Pressure Oscillations (MAPO) difference between cycles. This is the first LES study of hydrogen superknock in a CFR engine, offering critical insights for hydrogen engine development. • Hydrogen spark-ignition engine detonation is studied using Large Eddy Simulations. • The hydrogen blast theory explains detonation development in engines. • Detonative wave crosspoints feature extremely large pressure fluctuations. • The amount of unburnt mass significantly affects knock intensity. • Detonation drives up to 80% variation in maximum pressure between cycles.