Inlets, exits, and cooling problems III : preliminary analysis of hypersonic ramjet cooling problems

摘要

One of the basic differences between flight at supersonic and hypersonic speeds lies in the temperatures encountered in these two flight regimes. At supersonic speeds, stagnation temperatures are sufficiently low so that internal components of ramjet engines upstream of the combustor do not have to be cooled. The hot parts of an engine (combustor and nozzle) can generally be film-cooled with ram air. At hypersonic speeds, temperatures may reach a high enough level to make the cooling of all internal components mandatory. Furthermore, since the ram air will also be hot, it cannot be used as a coolant. At sufficiently high speeds, therefore, all internal components of ramjet engines will have to be cooled either with an expendable coolant or regeneratively with the fuel; an alternative cooling scheme which transports the internally generated heat to the external surfaces, whence it can be radiated to the atmosphere, may also be feasible. This paper presents the results of preliminary calculations of the heat loads sustained by ramjet engines in hypersonic flight. The heat-sink capacity of several fuels is examined, and the heat load is compared to the available cooling capacity. (author)