Abstract: To meet the high-efficiency and uniform heat transfer requirements in the gas-suspended ultra-thin glass physical tempering heating furnace, a parametric design study on impinging jet arrays with return holes was conducted, particularly focusing on low jet heights. A three-dimensional numerical heat transfer model of high-temperature array jet impingement heat transfer was established, and the thermophysical properties of high-temperature gas were analyzed. Numerical simulations were conducted to investigate the effects of different design parameters on the transient heat transfer of impinging jets. Reynolds numbers (Re) ranging from 2000 to 10 000 were set. Under a certain mass flow rate, variations in the dimensionless reflux hole diameter (D1/D) from 1 to 3 and the dimensionless jet spacing (S/D) of 4, 5, and 7 were considered. Surface-averaged Nusselt number and temperature variation coefficient were used to illustrate the performance in terms of average heat transfer and uniformity. The results indicated that in the impinging jet array model with return holes at low jet heights, as Re varies from 2000 to 10 000, the surface average Nusselt number increased by 243.3%, and heat transfer uniformity improved by 90.9%. The diameter of the return holes had a significant effect on heat transfer. The ratio of the diameter of the return hole to the diameter of the jet hole (D1/D) increased from 1 to 3, and the average Nusselt number first increased and then decreased. When D1/D=2, the average heat transfer effect showed a turning point, and the average Nusselt number was always higher than that of the corresponding traditional array jet. A smaller return holes diameter led to a gradual reduction in the maximum velocity difference between the return holes and the jet holes, thus demonstrating excellent heat transfer uniformity. Additionally, reducing the ratio of jet holes spacing to diameter (S/D) improved heat transfer uniformity. At S/D=4 and D1/D=1, the heat transfer uniformity was maximally improved by 46.24% compared to the corresponding traditional array jet impingement. These research findings provide a theoretical foundation for the design and application of efficient impinging jet structures.

Key words: ultra-thin glass, impinging jet, return holes, average heat transfer, heat transfer uniformity

摘要： 针对气浮式超薄玻璃物理钢化加热炉内高效、均匀传热需求，开展低射流高度下带回流孔冲击射流阵列参数化设计研究。建立了三维高温阵列射流冲击传热数值模型，模拟研究了不同设计参数对射流冲击瞬态传热的影响。结果表明，在低射流高度下带回流孔的阵列射流模型中，当雷诺数从2000增加至10 000，表面平均努塞尔数增加了243.3%，传热均匀性提高了90.9%；回流孔直径对传热影响显著，回流孔与射流孔直径比值(D1/D)从1增至3，平均努塞尔数先增大后减小，在D1/D=2时，平均传热效果出现转折点，且始终获得了比对应的传统阵列射流更高的平均努塞尔数；回流孔直径越小，回流孔与射流孔处的最大流速差逐渐减小，从而表现出优秀的传热均匀性。此外，减小射流孔间距与直径比值(S/D)改善了传热均匀性，S/D=4和D1/D=1时，相对于相应的传统阵列射流，传热均匀性最大改善了46.24%。研究结果可为高效射流冲击结构设计及应用提供理论基础。

关键词: 超薄玻璃, 冲击射流, 回流孔, 平均传热, 传热均匀性