Design, fabrication, and test of a microelectromechanical-system-based millinewton-level hydrazine thruster

The effects of both water and carbon dioxide vitiation on dual-mode scramjet (DMSJ) mode transition were investigated. The duct height and width were 1 and 1.5 in., respectively, and the isolator was 10 in. long, with an additional 0.5 in. prior to the leading edge of the ramp fuel injector. Three pressure distributions were measured while combusting for clean air, air vitiated with 9% H₂O, and air vitiated with both 9% H₂O and 4% CO₂, where all percentages are by mole. Downstream of the fuel injector was a series of reflected shocks and expansion fans that were generated by the ramp fuel injector. There was no combustion induced pressure rise upstream of the ramp fuel injector leading edge. The shock train also became shorter as the flow was increasingly vitiated. The DMSJ operated in the ram mode for the clean air case, the scram mode with an oblique precombustion shock train for the 9% H₂O case and in the scram mode with no precombustion shock train for the 9% H₂O and 4% CO₂ case.