Numerical simulation of the optimal spacing for a radial finned tube cooled by a rectangular jet. I – Average thermal results.

The present work investigates the average heat transfer on a finned cylinder cooled by a rectangular jet of height H . The diameter of the external cylinder, without fins, is D and the cylinder to slot ratio D / H is equal to 1. Numerical simulations are carried on with two turbulent models, RNG k – ɛ and SST k – ω . The jet flow can be characterized by the Reynolds number, defined with the diameter of the external cylinder without fins, D , or with the hydraulic diameter of the rectangular slot, D hydr ≈ 2 H . Two turbulent flows are investigated at Re D = 7100, or Re D hydr = 13,200, and at Re D = 19,700, or Re D hydr = 36,700. The main goal of the paper is to evaluate the optimal spacing, s , between the fins, and the optimal slot-to-cylinder distance, S / H , which maximize the average heat transfer on the finned cylinder. The optimization process is performed for a pitch of 3 mm and at a given value of the fin volume. The numerical simulations show that an optimal configuration is obtained when the ratio s / l of the spacing, s , to fin height, l , is maximum, and the cylinder is set at the slot-to-cylinder distance, S / H = 3. [ABSTRACT FROM AUTHOR]