Direct Numerical Simulation of Combined Heat and Power IC Engine Combustion and Wall Heat Transfer with Hydrogen/Methane Blends

DNS of flame-wall interactions have been performed in a simplified geometry capturing key aspects of a turbulent pre-chamber jet impinging on a piston cylinder wall. The DNSs were conducted for different hydrogen/methane blends at engine pressure conditions. The DNS data were used to assess the normalized quenching heat fluxes (mean and maximum) to the piston wall and to understand the underlying mechanisms that drive increased heat flux with H2-rich fuels. The DNS datasets are used to assess and improve low-dimensional heat transfer models and their empirical scaling. Consistent with earlier flame stretch results for hydrogen/air flames by Rieth et al. 2023 and Schneider et al. 2025, the normalized mean wall heat flux is found to be linearly correlated with the Peclet (Pe) and Zel'dovich (Ze) numbers if the wall temperature matches the reactant temperature. The Peclet number represents the ratio of the maximum diffusive to convective flux of hydrogen in a reference unstretched one-dimensional laminar premixed flame, whereas the Zel'dovich number is a normalized activation energy. Whereas Pe is correlated with the intensity of differential diffusion in a flame, the Zel'dovich number measures a flame's reactivity. Additional dependencies of the wall heat flux will also be discussed.