ABSTRACT

Heat transfer over a heated plate positioned normal to the horizontal circular impinging jet is investigated experimentally. The area average and local heat transfer characteristics over a large plate impinged by jet of air are investigated for Reynolds numbers ranging from 10,000 to 45,000, with jet-to-plate distances of 3–20 d for a maximum range of 0 ≤ r/d ≤ 44. The experiment is carried out for two jet diameters of 5.88 mm and 11.5 mm on a plate of 600 × 300 mm² impinged by a jet. The infrared (IR) thermal imaging method is used to find the temperature distribution over the heated plate. The combined heat transfer investigation of both local and area average gives a proper insight of the cooling phenomenon of the jet at any location over the plate. The investigation is effective in identifying areas with a greater rate of heat transfer. At various locations, the Nusselt number growth with increasing mass flow rate is studied. The area average heat transfer is discovered to be the highest at z/d = 3 for all Reynolds numbers in the A1 (0 < r/d < 2.17) region. However, for z/d = 6 and r/d = 0, the local Nusselt number is reported to be the highest. Reduction in area average heat transfer is reported in area A3, i.e., r/d = 6.5, and beyond this area, the profile of Nusselt number practically converges.

摘要

通过实验研究了垂直于水平圆形冲击射流定位的加热板的传热。研究了雷诺数在 10,000 到 45,000 之间，射流到板的距离为 3-20 d，最大范围为 0 ≤ r/d 时，空气射流撞击大板的面积平均和局部传热特性≤ 44。实验是在600×300 mm ²的板上对5.88 mm和11.5 mm两种射流直径进行的被喷气机撞击。红外 (IR) 热成像方法用于查找加热板上的温度分布。结合局部和区域平均的传热研究可以正确了解板上方任何位置的射流冷却现象。该调查可有效识别传热率较高的区域。在不同的位置，研究了努塞尔数随着质量流量的增加而增长。发现对于 A1 (0 < r/d < 2.17) 区域中的所有雷诺数，面积平均传热在 z/d = 3 时最高。然而，对于 z/d = 6 和 r/d = 0，据报道局部努塞尔数最高。在区域 A3 中报告了面积平均热传递的减少，即 r/d = 6.5，并且在该区域之外，努塞尔数的分布实际上收敛了。