The use of premixed , shock - induced combustion in the context of a hypervelocity , airbreathing vehicle requires effective injection and mixing of hydrogen fuel and air on the vehicle forebody . Three dimensional computational simulations of fuel injection and mixing from flush - wall and modified ramp and strut injectors are reported in this study . A well - established code , VULCAN , is used to conduct nonreacting , viscous , turbulent simulations on a flat plate at conditions relevant to a Mach 12 flight vehicle forebody . In comparing results of various fuel injection strategies , it is found that strut injection provides the greatest balance of performance between mixing efficiency and stream thrust potential .