Performance analysis and optimization of a novel S-CO2 closed-Brayton-cycle-based thermal management system for scramjets

Abstract

The thermal management system (TMS) based on closed-Brayton-cycle is a solution to solve the problems of thermal protection and electricity supply for long-endurance hypersonic vehicles. A novel TMS is proposed in this paper, and the system performance is simulated and analyzed based on a zero-dimensional thermodynamic cycle model and a quasi-one-dimensional heat transfer model. The results indicate that the heat transfer coefficients of the post-mixing method are significantly higher. As the split ratio of the bottom sub-cycle increases, net power first increases to a maximum value and then gradually decreases, but the fuel flow rate for cooling is the opposite. Moreover, the increase in turbine inlet temperature has a positive effect on both fuel flow rate and net power. The optimization results show that the minimum fuel flow rate for cooling is 0.3313 kg/s and net power reaches 162.37 kW when keeps wall temperature under the limit. Furthermore, if the maximum fuel temperature is 723 K, the fuel mass flow rate will further decrease to 0.2907 kg/s. This research provides a potential solution for enhancing the performance of the thermal management system for hypersonic vehicles powered by scramjets.