On the Optimal Configuration of Three Cylinders in a Row Cooled by a Slot Jet of Air

The optimal positions of three circular cylinders, cooled by a slot jet of air, are investigated. The diameters of the three cylinders are the same, D = 10 mm, while the slot jet has an height of S = 5 mm. The first cylinder is set up at a distance, H, from the slot exit, H/S = 6, which is the optimum in a one cylinder configuration. The second cylinder is set up at a distance from the first one, L1, with L1/S = 4, which is the optimum when two cylinders are present. The optimal distance of the third cylinder from the second one is L2, such that L2/S = 4, and the mean heat transfer coefficient on the third cylinder is at the maximum value. Local heat transfer coefficients on the surface of the third cylinder varies with L2/S. Measurements of axial velocity and turbulence intensity, in the axial direction, accompany the heat transfer results.