Measurements for fuel reforming for scramjet thermal management and combustion optimization : 2009 status of the COMPARER project

Grégory Abraham (1, 2) , Nicolas Gascoin (3) , Stephane Bernard (1, 2) , Philippe Gillard (2) , Marc Bouchez (4) , Julien Bertrand (4) , Bruno Le Naour (4)

1 LEES - Laboratoire Énergétique Explosions Structures [1998-2007]
2 PRISME - Laboratoire Pluridisciplinaire de Recherche en Ingénierie des Systèmes, Mécanique et Energétique
3 Univ. Orléans, PRISME, CE
4 MBDA-F - MBDA

Hypersonic flight is expected to be achieved with dual-mode-Ramjet (Ramjet under Mach 6 and Scramjet beyond) because of its high specific impulse and its capability to be reusable (especially interesting for space transportation)1, but one of the main issues at these flight conditions is the thermal management of the engine and the vehicle. Different cooling strategies have been evaluated by MBDA-France (calculations, material tests). Metallic panels have been tested as CMC composite ones (C/SiC for instance)2, which seem to be promising. But even CMC materials could not withstand such large heat loads (for example, total temperature of external air reaches 2000 K at Mach 7 and combustion add more energy as the inner part of the engine cannot be radiatively cooled). Consequently an active cooling system has to be used but not a dedicated one because it would increase the vehicle weight. Furthermore, another issue occurs under theses flight conditions. The time allocated to mix the injected fuel with inlet air, to ignite the combustion and to complete it before the chamber outlet is about 1 ms. These two points lead to the so-called "regenerative cooling" solution : using the fuel to cool down the engine's wall and then burning it in the engine. The fuel is injected in a composite channel (which surrounds the engine) near the outlet of the combustion chamber, it flows to the injection on the opposite way of the burned gases. For "moderate" hypersonic flight Mach numbers (below Mach 8), a heavy hydrocarbon fuel is often chosen here because of its high density compared to cryogenic fuels (800 kg.m-3 instead of 70/80 kg.m-3 for cryogenic hydrogen, with a specific impulse of liquid hydrocarbon halved)3. When heated and pyrolysed, it produces lighter hydrocarbons species that are considered as more energetic and easier to ignite. This point allows responding to rapid phenomenon in the combustion chamber.

Domaines: Chimie analytique; Milieux fluides et réactifs

Grégory Abraham, Nicolas Gascoin, Stephane Bernard, Philippe Gillard, Marc Bouchez, et al.. Measurements for fuel reforming for scramjet thermal management and combustion optimization : 2009 status of the COMPARER project. 16th AIAA/DLR/DGLR International Space Planes and Hypersonic Systems and Technologies Conference, Oct 2009, France. pp.7373. ⟨hal-00641628⟩