Laminar forced convection heat transfer from isothermal cylinders with active ends and different aspect ratios in axial air flows

Abstract

In this article a semi-analytical approach is employed to obtain dimensionless heat transfer correlations for forced convection from isothermal circular cylinders with active ends and different aspect ratios \( (l/d \le 8) \) in laminar axial air flows. Then, using the present results and previous works, the modeling is extended to higher aspect ratios \( (l/d \ge 8) \)) as long as the entire flow field remains completely laminar. Validations of the present work are done not only with the available data on drag coefficients but with previous works for long cylinders with inactive ends and long spheroids. Two general correlations are also developed for a rough estimate of forced convection heat transfer from isothermal cylinders with active ends and arbitrary aspect ratios in the range of \( \frac{1}{2} \le \frac{l}{d} \le 8 \) and \( l/d \ge 8 \).