The Effect of Angle-of-Attack on Heat Transfer Characteristics of a Single Drop-Shaped Tube


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An experimental and numerical investigation has been conducted to clarify the effect of angle of attack on heat transfer characteristics around a single drop-shaped tube. The Reynolds number for the flow was varied from 21.8 x103 to 42.3 x103. Twelve flow an-gles of attack (θ=0°~50° and 130°~180°) were considered. The results of the drop-shaped tube were compared with those of a circular tube having the same equivalent diameter. Three methods of thermal evaluation criteria were discussed. Correlations for the average Nusselt number and the effectiveness for the drop-shaped tube in terms of Reynolds number, Prandtl number, and the angle of attack were obtained. The results indicated that the drop-shaped tube at θ=50° enhances the heat transfer considerably. The best effec-tiveness values were achieved at θ= 0°, and 180°, which were about 8.16–8.67, and 6.43–8.08 times, respectively, greater than those obtained for the circular tube. The highest val-ues of the area goodness factor were occurred at θ = 170°, which were higher than those obtained for the circular tube by about 437–677%. In addition, the drop-shaped tube con-tributes greatly to energy conservation.

Drop-shaped tube, circular tube, angle of attack, heat transfer coefficient, Nusselt number, effectiveness, efficiency, area goodness factor, CFD.

DOI: http://doi.org/10.33257/PhChGD.22.5.960


Volume 22, issue 5, 2021 year


Влияние угла атаки на характеристики теплообмена при обтекании одиночной каплевидной трубы

В данной работе проводится экспериментальное и численное исследование тепло-обмена одиночных труб круглой и каплевидной формы. Работа выполнена в диапа-зоне чисел Рейнольдса Re = (21,8 ~ 42,3)  103 и для двенадцати углов атаки капле-видной трубы (θ = 0° ~ 180°). Представлено распределение локального коэффициента теплоотдачи на поверхности трубы. Представлены три метода для оценки тепловых характеристик каплевидной трубы. Результаты настоящего исследования показыва-ют, что каплевидная труба при θ = 50° значительно улучшает теплоотдачу. Наилуч-шие значения теплогидродинамической эффективности были достигнуты при θ = 0° и 180° (примерно в 8,16–8,67 и 6,43–8,08 раз, соответственно, больше, чем для круглой трубы). Наибольшие значения компактности были получены при θ = 170° (выше, чем полученные для круглой трубы примерно на 437–677%). Получены уравнения для расчета среднего числа Нуссельта и теплогидродинамической эф-фективности, для каплевидных труб, в зависимости от чисел Рейнольдса и угла атаки.

каплевидная труба, круглая труба, угол атаки, коэффициент теплоотдачи, число Нуссельта, эффективность, компактность, численное исследование.

DOI: http://doi.org/10.33257/PhChGD.22.5.960


Volume 22, issue 5, 2021 year




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