Numerical investigation of transverse jets through multiport injector arrays in supersonic crossflow

A three-dimensional numerical study has been performed of the effects of sonic gaseous hydrogen injection through multiple transverse injectors subjected to a supersonic crossflow. Solutions were obtained for a series of injection configurations in a Mach 4.0 crossflow, with a global equivalence ratio of phi = 0.5. Results indicate a different flow structure than for a typical single jet, with the development of two clearly defined wake vortices, including a stagnation point and reversed flow region immediately behind each downstream jet. While the overall penetration was reduced under the investigated conditions, significant improvements were observed when nondimensionalizing against the equivalent jet diameter for each modeled injector row. This was found to be the result of increased jet-to-freestream momentum ratio due to the subsonic flow regions between each injector. Further enhancements were also observed in terms of mixing performance for the multijet cases. Improvements of up to 5% in the overall mixing efficiency were experienced by using multiple jets due to increased mixant interface area and intermediate stirring through wake vortices between each injector. No improvement in far-field mixing was observed. Overall, it has been demonstrated that there are benefits to be gained through the injection of gaseous hydrogen from many small injectors rather than fewer large injectors.