Comparative study of different layouts in the closed-Brayton-cycle-based segmented cooling thermal management system for scramjets

Abstract

The segmented cooling thermal management system based on the closed-Brayton-cycle (CBC) is an excellent technology for thermal protection and power generation of scramjets. In this paper, a comparative study is conducted to investigate the system performance under different supercritical carbon dioxide CBC layouts. A zero-dimensional thermodynamic model was established to analyze the effects of compressor inlet temperature (T1), turbine inlet temperature (T3), and compressor outlet pressure (p2) on fuel mass flow rate for cooling (mf) and net power (Pnet). A quasi-one-dimensional flow and heat transfer model was developed to study the cooling effectiveness. Results indicate that higher T3 and p2 reduce mf while increasing Pnet in the simple layout (SL) and simple recuperated layout (SRL). However, in the recompressing layout (RCL), the effects of T1, T3, and p2 on mf are more complex due to the split ratio. Moreover, RCL has the lowest maximum wall temperature among the three layouts. Finally, after optimization, RCL has the lowest mf about 0.332 kg/s, which is a 19.8 % reduction compared to the regenerative cooling system. Correspondingly, RCL achieves the highest Pnet, reaching 109.89 kW. In general, the recompressing layout is most suitable for the CBC-based segmented cooling thermal management system for scramjets.