Experimental Study of Mixed Convection from Horizontal ‎Isothermal Elliptic Cylinders at Different Aspect Ratios

• Published in: Experimental heat transfer Vol. 33; no. 3; pp. 245 - 260
• Main Authors: Alnakeeb, Mohamed A., El-Maghlany, Wael M., Teamah, Mohamed A., Sorour, Medhat M.
• Format: Journal Article
• Language: English
• Published: Philadelphia Taylor & Francis 15-04-2020; Taylor & Francis Ltd
• Subjects: Angle of attack; Aspect ratio; axis ratio; Convection; Convective heat transfer; Cylinders; elliptic cylinder; Experimental; Fluid dynamics; Fluid flow; Heat transfer; mixed convection; Nusselt number; Richardson number; Viscosity
• ISSN: 0891-6152; 1521-0480
• DOI: 10.1080/08916152.2019.1625468

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 × 10
5
, 1.5 × 10
6
, and 2.1 × 10
6
, 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 Nu
avg
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.