Question

Air at 20°C (1 atm) is flowing over a 0.025-m diameter sphere with a velocity of 3.5 m/s. If the surface temperature of the sphere is constant at 80°C, determine the Reynolds number corresponding to the sphere, its average drag co-efficient, and the heat transfer rate from the sphere. The properties of air (1 atm) at the free stream temperature T_∞ = 20°C, ρ = 1.204 kg/m³, k = 0.02514 W/m∙K, μ = 1.825 × 10⁻⁵ kg/m∙s, and Pr = 0.7309. At the surface temperature T_s= 80°C: μ_s = 2.096 × 10⁻⁵ kg/m∙s. At the film temperature T_f = (80°C + 20°C)/2 = 50°C: ρ = 1.092 kg/m³ and v = 1.798 × 10⁻⁵ m²/s. (Round the Reynolds number to the nearest whole number and other answers to two decimal places.)

Answer 1