Studies on injection and mixing characteristics of high pressure hydrogen and oxygen jet in argon atmosphere

Ar-circulated hydrogen engine replaces atmospheric nitrogen with Ar so as to increase engine efficiency and avoid NOx forming. Due to the differences in gas molecular weight of injection gas and ambient gas, two injection strategies were proposed for this engine. This study aims at measuring the characteristics of non-reactive H2 and O2 jets in Ar atmosphere by Schlieren method. The experimental results demonstrate that the increase of injection pressure or the decrease of ambient pressure leads to an increase of penetration. Jet penetration length of O2 is slightly lower than H2 by 0-6%. The dispersion angle of gas jet increases slightly with the increase of injection pressure and ambient pressure. Under all the experimental pressure boundary conditions, the dispersion angles of H2 jets are between 31° and 36° and the dispersion angles of O2 jets are between 22° and 28°. The entrainment rate of gas jet increases with the increase of injection pressure, ambient pressure and injection time. Jet entrainment rate of O2 is 2.43-2.98 times that of H2 jet because of the lower volume flow rate of O2 jet. H2 jet entrains more total argon volume for its higher penetration and dispersion angle. The actual engine prefers to use the hydrogen injection strategy.