Impact of wall heat transfer modelling in large-eddy simulation of hydrogen knocking combustion

Abstract

This study assesses the performance of four wall heat transfer models in large-eddy simulations to simulate hydrogen knock in a cooperative research fuel engine. These models include Angelberger, Han and Reitz, O’Rourke and Amsden, and the GruMO-UniMORE. Simulations predict cycles with pressure out of the experimental range in some cases, especially under high knock intensity, with observable developing detonation. The Han and Reitz model is found to be the most suitable model for simulating knocking conditions, considering its performance and simplicity. This model is then used to investigate the wall heat transfer mechanism under knocking conditions. The results show that thermal boundary layers within the cylinder are disturbed through different mechanisms, contributing to auto-ignition close to the knockmeter cavity. The interaction between auto-ignition-induced pressure oscillations and the thermal boundary layer significantly increases the heat transfer rate during end-gas auto-ignition.