Flow resistance characteristics of hydrocarbon fuel at supercritical pressure under various heat fluxes in regenerative cooling channel with micro-ribs

Abstract

Flow distribution of hydrocarbon fuel in regenerative cooling channels is vital for the performance and safety of thermal protection system for scramjet engines. The spatially non-uniform distribution of heat flux at super-high speed (>Mach 6) brings great complexities on flow distribution inside cooling channels. In order to weaken the flow mail-distribution and enhance the adaptability of cooling system to various thermal environments, basic flow resistance characteristics of hydrocarbon fuel flow at supercritical pressure are numerically studied under various heat fluxes. Besides, the regulation patterns of micro-rib on flow resistance of hydrocarbon fuel are also explored. Results show that with incremental heat flux, flow resistance of hydrocarbon fuel in regenerative cooling channels not only shows different trends but also varies in large ranges in different temperature regions. Besides, the flow resistance of hydrocarbon fuel is intensively sensitive to heat flux, especially in trans-critical and supercritical temperature regions and thermal cracking regions. As a useful heat transfer enhancement structure, micro-rib shows extraordinary potential to both eliminate the nonlinearity and reduce the sensitivity of flow resistance to various heating conditions. Two main reasons accounting for this are: Wall shear stress on heated interface is significantly reduced by micro-ribs especially in supercritical and trans-critical temperature regions and thermal cracking regions. Also, enhanced turbulent energy consumption in channel central increases to a limited level even though heat flux is changed up to 5 times. The results provide an innovative perspective that those heat transfer enhancement structures could also be used to regulate flow distribution in parallel cooling channels.