Numerical investigation of hydrogen strut injections into supersonic airflows

The influence of different injector geometries on the mixing behavior of planar supersonic jets is investigated. Hydrogen is injected in the flow direction through the blunt end of a strut. Different lip thicknesses at the injector end induce different extents of recirculation zones. Additionally, changes are caused within the shock-wave/expansion fan pattern at the injector exit that have an important influence on loss in total pressure. The accuracy of the used numerical scheme is demonstrated for one injector geometry by comparison with experimental data. Based on this configuration, modifications in lip thickness and injection Mach number are investigated numerically and are assessed using several calculated performance parameters. Results show that the chosen lip thickness has a much stronger influence on loss in total pressure than moderate modifications in injector length and height. For the very thin hydrogen jets that were investigated, the mixing efficiency is nearly independent on injector lip thickness.