Combustion, Cryogenic Combustion and Sprays

• CRYOGENIC COMBUSTION

In the aerospace field, the research activities regarded the combustion phenomena in liquid-propellant rocket engines. The combustion occurs at operating conditions well above of the thermodynamic critical points of the fluid where reactants properties show liquid-like densities, gas-like diffusivity, and pressure-dependent solubility. Actually, there is a great interest in the development of reusable liquid rocket engines that operates with methane and liquid oxygen as propellants. In the carried-out numerical study of LOX/CH4 jet flames, the choice of the combustion model is a critical point: it should be accurate in the phenomena description but it should also characterized by a low computational cost. Different combustion models were used as the Eddy-dissipation finite-rate approach based on Arrhenius chemical kinetics, the equilibrium mixture fraction model (PDF) and the Steady State Flamelet approaches. Different chemical kinetics schemes were used, as the Skeletal mechanism and the Jones- Lindstedt mechanism, that permit to limit the number of reactions and species but taking into account also the intermediate species in the flame. Finally, an Eulerian (i.e., single phase) methodology by using both ideal gas and real gas equation of state was used as well as a discrete phase approach that uses an Eulerian description of the gas phase and Lagrangian equations for the dilute spray.

• CARBON NANOTUBES

As part of the activity "Controlled ignition of a fuel mixture by ignition of carbon nanotubes", an innovative system (PTI) for the ignition of combustible mixtures is being studied. This system is based on the exposure of carbon nanotubes and/or nanostructured metal transition oxides to a low energy light source, comparable to the flash of a camera. Tests already carried out on air and methane, or hydrogen, or LPG or gasoline mixtures have demonstrated a combustion efficiency higher that observed triggering combustion with the classic spark plug (SI).

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