Supersonic Combustion of a Scramjet Engine Using Hydrogen Fuel in Shock Tunnel

Experiments were carried out on a scaled model of scramjet engine with gaseous hydrogen as a fuel in a 1 m combustion-driven shock tunnel. The simulated enthalpy was 2.6 MJ/kg, at a freestream Mach number of 6.8 with varying stagnation pressures (110-190 bar), dynamic pressures (72-130 kPa), and equivalence ratio (0.24-1.16). Detailed studies were carried out to tailor the shock tunnel. Experiments were carried out with air and N-2 as the test gases with hydrogen (H-2) injection to bring out the difference between reactive and nonreactive cases. Pressure measurement along the centerline of the engine and heat flux (through temperature measurements) inside the combustor was carried. The occurrence of supersonic combustion was ascertained through pressure measurements where no upstream influence was seen ahead of the strut injector and the same was corroborated by heat flux measurements. The pressure rise due to supersonic combustion downstream of the fuel injection was nearly three times as compared with nonreactive case. For the current case, when the combustor inlet pressure (P-c) exceeds 1 bar, a sharp rise in the pressure signature was observed downstream of fuel injection, whereas no such marked trace was seen when P-c is below 1 bar.