A method for measuring the convective heat transfer from spheres has been proposed. A 20 m diameter copper sphere with an embedded electrical heater is to be suspended in a wind tunnel. A thermocouple inside the sphere measures the sphere surface temperature. The sphere is supported in the tunnel by a type 304 stainless steel tube 5 mm outside diameter 3 mm inside diameter and 20 cm long. The steel tube is attached to the wind tunnel wall in such a way that no heat is transferred through the wall. For this experiment, examine the magnitude of the correction that must be applied to the sphere heater power to account for conduction along the support tube. The air temperature is 20?C and the desired range of Reynolds numbers is 103 to 105.GIVENA heater copper sphere supported by a steel tube in a wind tunnelSphere diameter (Ds) = 20 mm = 0.02 mTube diametersOutside (Dto) = 5 mm = 0.005 mInside (Dti) = 3 mm = 0.003 mTube length (L) = 20 cm = 0.2 mThere is no heat transfer between the tube and the wallAir temperature (T??) = 20?CReynolds number range: 103 ASSUMPTIONSSteady stateContact resistance between the sphere and the tube is negligibleThe effect of the boundary layer near the wind tunnel wall on the heat transfer from the tube isnegligible

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Alr T-= 20°C D,= 20 mm 10° < Re, < 100 Tube: Dio -5 mm Dy-3 mm L- 20 cm