Proof-of-Principle Experiment of a Shock-Induced Combustion Ramjet

Abstract

By injecting and mixing the fuel upstream of the combustor and initiating the combustion of the fuel-air mixture by a shock wave in the combustor, shock-induced combustion ramjets offer the potential to drastically reduce the length and mass of scramjet propulsion systems. Based on extensive numerical gas dynamic and thermo-mechanical analysis, an axi-symmetric dual cone test object was designed and manufactured to demonstrate that it is possible to inject hydrogen into a high enthalpy supersonic air flow without causing premature ignition and subsequently induce combustion of this mixture by a strong oblique shock wave. The test object was instrumented with 16 thermocouples and a shadowgraph technique was used to visualize density changes in the flow field. A test series was executed in the TNO Free Jet Test Facility using the Mach 3.25 free jet nozzle in which the air flow stagnation temperature and the injected hydrogen mass flow rate was varied. Due to thermal expansion of the strut holding the test object, a small angle-of-attack was induced and resulted in different types of combustion occurring at the top and bottom sides of the test object. At the bottom, hydrogen was captured and subsequently burned in the boundary layer separation zone resulting in very high local heat loads. At the top side of the test object, shock-induced combustion occurred in the inviscid flow field only at a higher level of stagnation temperature with a peak heat load clearly downstream of the boundary layer separation zone. This experimental result is an important step in demonstrating the feasibility of a shock-induced combustion ramjet as a future hypersonic propulsion system.

Numerical Study on the Aerodynamic Heating Characteristics of the Cantilevered Injection System for Oblique Detonation Engine Inlets

“…Therefore, scholars are interested in fuel injection near the leading edge of the ODE inlet and its premixing with the incoming airflow under the premise of avoiding premature ignition, and some efforts have been made [3,[7][8][9][10][11]. In the simulations conducted by Sislian et al [7][8][9] for cantilevered ramp injection, well-premixed flow conditions were achieved, while premature ignition was prevented.…”

“…In the simulations conducted by Sislian et al [7][8][9] for cantilevered ramp injection, well-premixed flow conditions were achieved, while premature ignition was prevented. Veraar and Mayer [10] performed a proof-of-principle experiment, injecting hydrogen into a high enthalpy supersonic airflow by a double-wedge injector configuration. During their test, the mixture was burnt by a strong oblique shock wave, and premature ignition was avoided successfully.…”

Rayleigh–Taylor and Richtmyer–Meshkov instabilities: A journey through scales

“…Marble et al[333] suggested 2856 using shock-induced mixing associated with the RMI to 2857 accelerate the mixing process between a cylindrical column of Hydrogen fuel and the ambient air. In a typical scramjet configuration (or a Shcramjet: shock-induced combustion ramjet[533]), the fuel jet is supersonic and is intersected by an oblique stationary shock at every cross-section along its length. The authors of[333] applied thin body theory to show that the spatial development of the cross-section of the cylindrical jet is equivalent to the temporal development of a fuel jet that is processed by a moving shock wave.…”