Numerical investigation on high temperature direct water injection characteristics within hydrogen/oxygen/argon premixed combustion process

Abstract

Hydrogen-fueled argon power cycle (H₂-APC) is a novel power system with high efficiency and zero emission by utilizing argon/oxygen mixture with high specific heat ratio as the working fluids. However, H₂-APC engines suffer from the challenge of knock suppression. Direct water injection (DWI) is an effective method to inhibit detonation. Spray morphology has a significant impact on the effectiveness of DWI and the study of spray characteristics in hydrogen/oxygen/argon premixed combustion atmosphere is critical. Based on a three-dimensional computational model built by the test bench data, this paper explores the DWI characteristics within hydrogen/oxygen/argon premixed combustion atmosphere and the effect of DWI on the combustion process. The results show that as the ambient temperature increases, the ambient density decreases and the SMD enlarges. The difference in spray morphology is small in the high-temperature and high-pressure environments after combustion. As the ambient pressure elevates, both the jet SMD and penetration reduce, and the evaporated mass improves. In addition, the majority of the water spray in contact with flame will evaporate rapidly due to the high temperature. Some of the liquid water on the outside of spray will evaporate owing to the heat, while the remaining portion will crack into OH reactive groups. The results can serve as an effective guide for the high efficiency operation scheme of H₂-APC engines.