衝擊噴流目前已廣泛的應用在工業用途上，最主要的原因在於它的高質量與能量傳遞特性，利用流體快速流動的特性，可帶走相當大的熱能。此外隨著不同之需求，單孔與多孔噴流衝擊移動平板之應用也越來越普及，因此如何調整噴流與衝擊平板之最佳角度與平板移動速度之關係，已成一重要課題。本文主要針對單雙孔噴流於傾斜移動平板之熱傳研究進行探討，以數值模擬的方式分析三維穩態之紊流流場。

　　本文的研究參數包含無因次化平板移動速度(Up = -0.1 ~ 0.1)，Up之定義為平板移動速度與入口流速之比值，平板之傾斜角(θ= 0° ~ 30°)，而傾斜角0°為垂直噴流。根據本文之結果顯示，平板的移動現象與傾斜角度對衝擊表面之Nu值有很大的影響。在單孔噴流部分，平板移動速度Up= 0.1時，熱傳效率較佳，當傾斜角度增加至30°時，其平均Nu值約下降3%，而在Up= -0.1時，熱傳效率較差，當傾斜角度增加至30°時，平均Nu值約下降16%，其原因為在上游處因相對速度過大而有渦流出現，此渦流會破壞壁面噴流區的形成，導致壁面熱傳效率的下降，而當傾斜角度增加時，渦流形成的現象也越明顯。而雙孔噴流部分，由於兩噴流互相干擾，在同質量流率的條件下，雙孔噴流之熱傳效率約比單孔噴流減少33%，但其熱傳分佈較單孔噴流均勻。在移動平板部分，當Up= 0.1時，傾斜角度增加至30°時，平均Nu值約增加1.5%，而在Up= -0.1時，傾斜角度增加至30°時，其平均Nu值約下降12%，其原因與單孔噴流相同，當傾斜角過大時，易有渦流現象產生，因而導致壁面熱傳值下降。

　　The impinging jet has been widely used in industrial applications, because of the high heat transfer characteristic. With the characteristic of rapid fluid flow, it can take considerable heat away. In addition, with different demands, the applications of impinging multi-jet on moving plate are becoming more and more common. Therefore, how to adjust the jet angle with different plate velocity has become an important issue. This study aims to investigate “heat transfer characteristics of single and double impinging jets on an obliquely moving plate” by analyzing three-dimensional turbulent flow numerically.

　　The parameters of the study include the normalized plate velocity (Up=plate velocity / jet velocity), ranging from -0.1 to 0.1, and the plate oblique angles θ, ranging from 0 ° to 30 °, with 0 ° being a vertical jet. The analysis reveals that the Nusselt number on the plate changes with different plate velocity. In single jet, at plate velocity Up=0.1, it has the best heat transfer efficiency. The average Nusselt number decrease 3% by oblique angle increasing to 30°. But at plate velocity Up= - 0.1, the average Nusselt number decrease 16% by oblique angle increasing to 30°. The reason of the changes is that the relative velocity increasing can help vortex generation in upstream region and cause Nusselt number dropped. About the double jets, because the two jets will disturb mutually, the heat transfer efficiency of single jet is much higher than double jets, but double jets have better heat transfer distribution on plate. At plate velocity Up=0.1. The average Nusselt number increase 1.5% when oblique angle increase to 30°. But at plate velocity Up= -0.1, the average Nusselt number decrease 12% when oblique angle increase to 30°. The reason is that the oblique angle increasing can help vortex generation and cause Nusselt number dropped.

1. Gardon, R. and Akfirat, J. C., The role of turbulence in determining the heat-transfer characteristics of impinging jets, International Journal of Heat Mass Transfer Vol. 8 (1965) pp. 1261-1272.
2. Gardon, R. and Akfirat, J. C., Heat transfer characteristics of impinging two-dimensional air jets, Journal of Heat Transfer Vol. 88 (1966) pp. 101-108.
3. Martin, H., Heat and mass transfer between impinging gas jets and solid surfaces, Advances in heat transfer Vol. 13 (1977) pp. 1-60.
4. Goldstein, R. J. and Behbahani, A. I., Impingement of a circular jet with and without cross flow, International Journal of Heat Mass Transfer Vol. 25 (1982) pp. 1377-1382.
5. Liu, X., Lienhard, J. H. and Lombara, J. S., Convective heat transfer by impingement of circular liquid jets, Journal of Heat Transfer Vol. 113 (1991) pp. 571-582.
6. Huang, L. and El-Genk, M. S., Heat transfer of an impinging jet on a flat surface, International Journal of Heat Mass Transfer Vol. 37 (1993) pp. 1915-1923.
7. Fitzgerald, J. A. and Garimella, S. V., Flow field effects on heat transfer in confined jet impingement, Journal of Heat Transfer Vol. 119 (1997) pp. 630-635.
8. Ma, C. F., Zhuang, Y., Lee, S. C. and Gomi, T., Impingement heat transfer and recovery effect with submerged jets of large prandtl number liquid - I. unconfined circular jets, International Journal of Heat Mass Transfer Vol. 40 (1997) pp. 1481-1490.
9. Ma, C. F., Zhuang, Y., Lee, S. C. and Gomi, T., Impingement heat transfer and recovery effect with submerged jets of large prandtl number liquid - II. Initially laminar confined slot jets, International Journal of Heat Mass Transfer Vol. 40 (1997) pp. 1491-1500.
10. Behnia, M., Parneix, S., Shabany, Y. and Durbin, P. A., Numerical study of turbulent heat transfer in confined and unconfined impinging jets, International Journal of Heat and Fluid Flow Vol. 20 (1999) pp. 1-9.
11. Chung, Y. M. and Luo, K. H., Unsteady heat transfer analysis of an impinging jet, Journal of Heat Transfer Vol. 124 (2002) pp. 1039-1048.
12. Zumbrunnen, D. A., Convective heat and mass transfer in the stagnation region of a laminar planar jet impinging on a moving surface, Journal of Heat Transfer Vol. 113 (1991) pp. 563-570.
13. Zumbrunnen, D. A., A laminar boundary layer model of heat transfer due to a nonuniform planer jet impinging on a moving plate, Wärme-Stoffübertr Vol. 27 (1992) pp. 311-319.
14. Chattopadhyay, H. and Saha, S. K., Simulation of laminar slot jets impinging on a moving surface, Journal of Heat Transfer Vol. 124 (2002) pp. 1049–1055.
15. Chattopadhyay, H. and Saha, S. K., Turbulent heat transfer from a slot jet impinging on a moving plate, International Journal of Heat and Fluid Flow Vol. 24 (2003) pp. 685-697.
16. Senter, J. and Solliec, C., Flow field analysis of a turbulent slot air jet impinging on a moving flat surface, International Journal of Heat and Fluid Flow Vol. 28 (2007) pp. 708-719.
17. Sharif, M. A. R. and Banerjee, A., Numerical analysis of heat transfer due to confined slot-jet impingement on a moving plate, Applied Thermal Engineering Vol. 29 (2009) pp. 532-540.
18. Goldstein, R. J. and Franchett, M. E., Heat transfer from a flat surface to an oblique impinging jet, Journal of Heat Transfer Vol. 110 (1988) pp. 84-90.
19. Seyedein, S. H., Hasan, M. and Mujumdar, A. S., Laminar flow and heat tranfer from multiple impinging slot jets with an inclined confinement surface, International Journal of Heat Mass Transfer Vol. 37 (1994) pp. 1867-1875.
20. Yang, Y. T. and Shyu, C. h., Numerical study of multiple impinging slot jets with an inclined confinement surface, Numerical Heat Transfer Vol. Part A 48 (1998) pp. 23-37.
21. Yan, X. and Saniei, N., Heat transfer from an obliquely impinging circular air jet to a flat plate, International Journal of Heat and Fluid Flow Vol. 18 (1997) pp. 591-599.
22. Abdel-Fattah, A., Numerical and experimental study of turbulent impinging twin-jet flow, Experimental Thermal and Fluid Science Vol. 31 (2007) pp. 1061-1072.
23. Launder, B. E. and Spalding, D. B., Mathematical Models of Turbulence, Academic, London Vol. (1974) pp. 90-100.
24. Doormaal, V., J.P. and Raithby, F. D., Enhancements of the SIMPLE Method predicting Incompressible fliud flows, Numerical heat Transfer Vol. 7 (1984) pp. 147-163.