ABSTRACT Mixed convective heat transfer from horizontal isothermal elliptic cylinder is experimentally studied. Three elliptic test cylinders with same perimeter and length are studied giving axis ratio (AR) equal 1, 0.709 and 0.496. The corresponding Gr for the three test sections is 9.8 × 105, 1.5 × 106, and 2.1 × 106, and Re varies from 111 to 1306. Consequently, the corresponding Ri is in range of 1 to 102. The angle of attack (ψ) is changed from 0° (assisting flow) to 180° (opposing flow) with an interval of 30°. New empirical correlation is obtained for the Nuavg as a function of the AR, Ri, and ψ. The experimental results are presented in the form of the average Nusselt number around the elliptic cylinder. It has been concluded that as the axis ratio decreases the averageNusselt number increases, in addition, increasing the angle of attack from 0° to 180° decreases the averageNusselt number considerably. New empirical correlations are obtained for the average Nusselt number as a function of the Richardson number and the attack angle.

中文翻译：

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不同纵横比水平等温椭圆圆柱混合对流的实验研究

摘要 实验研究了水平等温椭圆柱的混合对流传热。研究了三个具有相同周长和长度的椭圆测试圆柱体，轴比 (AR) 等于 1、0.709 和 0.496。三个测试段对应的 Gr 分别为 9.8 × 105、1.5 × 106 和 2.1 × 106，Re 从 111 到 1306 不等。因此，对应的 Ri 在 1 到 102 的范围内。 攻角（ψ）从 0°（助流）变为 180°（逆流），间隔 30°。作为 AR、Ri 和 ψ 的函数，Nuavg 获得了新的经验相关性。实验结果以椭圆圆柱周围的平均努塞尔数的形式表示。已经得出结论，随着轴比减小，平均努塞尔数增加，此外，将攻角从 0° 增加到 180° 会显着降低平均努塞尔数。对于作为理查森数和攻角的函数的平均努塞尔数获得了新的经验相关性。