The performance of a novel airfoil-based tube with dimples is numerically studied in the present work. The effect of Reynolds number Re, dimples number N, relative depth H/D, and cross-distribution angle α on flow and heat transfer characteristics are discussed for Re in the range between 7,753 and 21,736. The velocity contour, temperature contour, and local streamlines are also presented to get an insight into the heat transfer enhancement mechanisms. The results show that both the velocity magnitude and flow direction change, and fluid dynamic vortexes are generated around the dimples, which intensify the flow mixing and interrupt the boundary layer, resulting in a better heat transfer performance accompanied by a certain pressure loss compared with the plain tube. The Nusselt number Nu of the airfoil-based tube increases with the increase of dimples number, relative depth, and Reynolds numbers, but the effect of cross-distribution angle can be ignored. Under geometric parameters considered, the airfoil-based tube with N = 6, H/D = 0.1, α = 0° and Re = 7,753 can obtain the largest average PEC value 1.23. Further, the empirical formulas for Nusselt number Nu and friction factor f are fitted in terms of dimple number N, relative depth H/D, and Reynolds number Re, respectively, with the errors within ± 5%. It is found that the airfoil-based tube with dimples has a good comprehensive performance.

In response to the problems of high-temperature gas intrusion and ablation in the expansion slit between ceramic tiles under complex flow conditions in the floating-wall combustion chamber, as well as the issue of hooks exceeding their service temperature, numerical simulations and analysis were conducted for this paper. The study revealed the mechanisms of gas intrusion and sealing and proposed two evaluation metrics for evaluating the cooling effect: the maximum temperature of the hook and the proportion of high-temperature area on the sidewall of the tile. Furthermore, the CRITIC weighting method was used to analyze the weight of these metrics. Based on this, the spacing, radius, and length effects on sealing and cooling effectiveness were studied, and multi-parameter calculations and optimization were performed. The results showed that the degree of gas intrusion in the transverse slit was significantly higher than that in the longitudinal slit. In addition, the sealing method of the jet impingement could effectively cool the downstream of both the transverse and longitudinal slit. The spacing of the jet impingement holes had the greatest impact on the cooling effect, followed by the radius and length. Finally, when the spacing of the holes is 10 mm, the length is 18.125 mm, and the radius is 1.6 mm, the cooling effect is optimal, with the proportion of high-temperature area on the side wall of the tile being 20.86% and the highest temperature of the hook reaching 836.02 K.