The influence of asymmetric truncated ribs on flow and heat transfer of supercritical aviation kerosene in a rectangular curved cooling channel

Abstract

Coke deposition and heat transfer deterioration in curved cooling channels have drawn increasing attention. In this work, the influence of asymmetric truncated micro-ribs on flow and heat transfer in a curved cooling channel is numerically investigated. Three-dimensional numerical model is established for the reacting flow of aviation kerosene, RP-3 in both the smooth and ribbed cooling channels. The results show that compared with the non-ribbed and the top heated wall-ribbed channels, the bottom heated wall-ribbed channel renders lower temperature and less coke deposition on the top wall with more uniform temperature field in the channel. Heat transfer deterioration at the top heated wall is significantly improved in the bottom heated wall-ribbed channel. As rib number of the bottom heated wall-ribbed channel increases from 0 to 18, the velocity of the secondary flow in curved channel increases by 68.7 %, heat transfer coefficient of the top wall rises by 50.6 % while coke deposition on top wall is reduced by 34.9 %, respectively. With the height of ribs in the bottom heated wall-ribbed channel increasing from 0 mm to 0.4 mm, temperature and coke deposition on the top heated wall decreases by up to 300 K and 59.26 %, respectively. Meanwhile, heat transfer coefficient at the top wall increases by as much as 69.23 %. The interaction between vortex structures and the micro-ribs enhances heat near the heating wall surface. Additionally, coke formation is inhibited due to enhanced secondary flow in the ribbed channel. However, pressure drop of the cooling channel rises rapidly with the increase of height and number of ribs. Considering both the overall thermal performance and flow resistance of the cooling channel, the bottom heated wall-ribbed curved channel with rib number of 9 and rib height of 0.2 mm is recommended in the present study.