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Cooling of Two Cylinders in a Row by a Slot Jet of Air
F. Gori and L. Bossi

The cooling of two cylinders in a row, by a slot jet flow of air, has been investigated experimentally. The slot has a height of S=5 mm. The cylinders diameter is D=10 mm. The first cylinder is set with the edge at a distance H, from the slot exit, equal to H/S=6. The edge of the second cylinder is at a distance L, from the edge of the first cylinder, variable from L/S=4 to L/S=8. The Reynolds number, based on the mean velocity at the outlet of the slot and the cylinder diameter, ranges from Re=4000 to Re=20000. The influence of the first cylinder on the second one is to decrease the heat transfer, just opposite to what has been observed in an uniform flow where the flow field is much larger than the cylinder diameter. The local Nusselt numbers on the two cylinders have been measured as a function of the Reynolds number, the angle from the impinging point and the distance between the edges of the two cylinders. A closed vortex region appears between the two cylinders for a distance L/S=4, depending on the Reynolds number. The positions of the two cylinders which allow to obtain the maximum heat transfer on each one is H/S=6 and L/S=4.

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