Heat transfer performance of hydrocarbon fuels inside regenerative cooling channel using simple-cubic trusses

Regenerative cooling is a promising method for cooling aircraft engine combustion chambers, and the convective heat transfer effectiveness within cooling channels needs further improvement with the increase of cooling demands. This paper applies a novel Simple Cubic truss (SC-truss) structure based on additive manufacturing technology to regenerative cooling channels to address the issue of thermal stratification. Numerical simulations are performed to investigate the complicated flow, heat transfer, thermal cracking, and surface coking characteristics of hydrocarbon fuels in different structured channels. The results demonstrate that the SC-truss channel can significantly enhance heat transfer performance by increasing turbulent kinetic energy and promoting turbulent mixing. Comparing to smooth channels, the peak wall temperature is reduced by 16.4 %, 25.5 %, 32.3 % and 33.5 % under heat flux of 0.5 MW/m², 1 MW/m², 1.5 MW/m², and 2 MW/m² respectively, by SC-truss structures. The enhanced turbulent kinetic energy and mixing effects associated with the truss structure significantly reduce the thermal stratification effect, leading to more uniform distribution of the surface temperature and improved thermal cracking conversion rate, as well as reduced surface coking effect. Examples show that the maximum coking rate on the inner wall surface is decreased by 76.5 % and 81.2 % at the heat flux of 1 MW/m² and 1.5 MW/m², respectively. Further analysis reveals that reducing the truss spacing or increasing the truss structure length could increase the convective heat transfer further, i.e., up to 240 % increase in heat transfer coefficient can be achieve for optimized structures.