Dimensioning of automated regenerative cooling: Setting of high-end experiment

International audienceRegenerative cooling is a hot topic as it contributes to energy saving and energy conversion, for example within high speed propulsion or chemical plants frameworks. Considering the use of this technology in fuel-cooled hypersonic structures, the propellant duality in terms of functions (coolant and fuel) makes the thermal and combustion management to be quite challenging. Dynamics of the system must be studied in order to develop regulation and control strategies which should be performed with a response time lower than the lowest characteristic time found in supersonic combustion ramjet, i.e. about 1 ms. The present work aims at setting experiments at lab scale by simplifying the additional difficulty of supersonic flow. A combustion chamber is dimensioned with similitude rules in terms of heat flux density, conversion rate, chemical compositions, dynamics. Computational Fluid Dynamics and analytical calculations are developed to dimension the experimental bench. Instead of using trial-error approach when setting up an experiment, this prediction work ensures having appropriate regulation dynamics for latter model and control developments. It has been found that a pyrolysis rate up to 100% can be obtained using ethylene as fuel at 50 bar and 1200 K and with a residence time of about 100 s. Combustion with air (adiabatic flame temperature up to 2400 K) will provide the required heat flux density. The operating range in terms of fuel pressure (10-50 bar), of fuel mass flow rates (50-100 mg s-1) and of equivalence ratio (0.8 to 1.0) have been certified