Performance cycle analysis of an open cooling cycle for a scramjet

In a conventional regeneratively cooled scramjet, fuel directly enters the combustor after cooling. It is proposed in this article that high-temperature and high-pressure fuel out of the first cooling passage can be used for secondary cooling after expanding through the turbine and transferring enthalpy from fuel to work. A fuel heat sink (cooling capacity) is thus repeatedly used to indirectly increase the fuel heat sink. Instead of carrying excess fuel for cooling or looking for any new coolant, the fuel flow for cooling is reduced, and fuel onboard is adequate to satisfy the cooling requirement for the whole hypersonic vehicle. First are defined cooling and expansion and, second, cooling an open cooling cycle (OCC) for the scramjet. This article provides a brief description of the assessment of the performance potential and scientific feasibility of a scramjet with OCC using fundamental thermodynamic principles. The results show that OCC yields higher performance gain over regenerative cooling, because of the increase in the fuel heat sink and additional power output.