Synthetic and jet fuels pyrolysis for cooling and combustion applications

Large heat load are encountered in hypersonic flight applications due to the high vehicle speed (over Mach 5, i.e. 5000 km h−1) and to the combustion heat release. If passive and ablative protections are a way to ensure the thermal management, the regenerative cooling is probably the most efficient one to enable the structures withstanding (notably for reusable structures). The present study is a part of COMPARER project (COntrol and Measure of PArameters in a REacting stReam) which aims at investigating the highly coupled phenomenon (heat and mass transfers, pyrolysis, combustion) in a cooling channel surrounding a SCRamjet combustion chamber and at proposing some parameters to enable the control of such a complex technology. In this paper, we present the comparative numerical pyrolysis study of some selected synthetic and jet fuels (heptane, decane, dodecane, kerosene surrogate). The fluid pyrolysis has been studied experimentally and the results of RESPIRE numerical simulation under lab and in-flight conditions are given with validation to provide a deep understanding of phenomenon. The impact of the density, of the critical parameters, of the viscosity and of the chemistry is investigated to analyze their effect on the cooling efficiency of the engine. That also enables to estimate properties which the best cooling fuel should have. Furthermore, a combustion study is conducted because the cooling fuel is the one that ensure the thrust. The RESPIRE code enables to conduct both coupled pyrolysis and combustion studies. A first approach of the dynamic regeneratively cooled SCRamjet is provided to get a large vision of the fuel nature impact on the system.