Thermal recycling analysis in regenerative cooling channels based on liquid rocket engine cycles

• Published in: Applied thermal engineering 2024-11, Vol.256, p.124095, Article 124095
• Main Authors: Jun Jeon, Tae, Seon Park, Tae
• Format: Article
• Language: English
• Subjects: Flamelet analysis; Liquid rocket engine cycle; Regeneration heat; Regenerative cooling; Thermal recycling method; Thermal resistance method
• ISSN: 1359-4311
• DOI: 10.1016/j.applthermaleng.2024.124095

•A regenerative cooling analysis for considering multiple injectors and four rocket cycles is newly proposed.•The coolant condition after cooling is reassigned through the turbine or preburner to the inlet of the combustion chamber.•A non-uniform velocity profile based on each injector’s mass flow rate is implemented for the multi-injector effect.•The specific impulse increase of 1.5–2% due to the regenerative heat effect is identified. For rocket cycles involving electric pumps, gas generators, expanders, and staged combustion, a thermal recycling method is proposed to provide a more realistic simulation of regenerative cooling systems in liquid rocket engines. This method simulates a real situation where the outlet of the cooling channel is thermally recycled through the turbine or preburner to the inlet of the combustion chamber. Supercritical fluid properties are determined using the extended Redlich–Kwong (RK)–Peng–Robinson (PR) real-fluid equation of state. The axisymmetric reacting flows of a thrust chamber with regenerative cooling channels are simulated using the flamelet-based lookup table. To account for the multi-injector effect in the two-dimensional axisymmetric simulation, a non-uniform velocity distribution is implemented, utilizing exponential distributions of each injector’s mass flow rate. For the hot gas temperature, coolant temperature, and cooling mass flowrate, the thermal recycling method is comparatively analyzed with the thermal decoupling method. The regeneration effect of the heated fuel is explored by evaluating the inflow energy, reaction energy, wall heat transfer, and the exit kinetic energy conversion. The thermal recycling method is developed for regeneratively cooled rocket engines with the expander, gas generator, staged combustion, and electric-pump cycles. Through this numerical procedure, the thermal recycling method is successfully applied to a liquid oxygen/methane engine and NASA’s Crew Exploration Vehicle nozzle with two types of cooling. Based on the results of the four types of rocket cycles, it is confirmed that the specific impulse increases by 1.5–2% due to the regenerative heat effect.