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Posted: **Sun Jul 10, 2022 11:37 am**

: Experiments Have Been Conducted On Three Geometrically Similar Air Foils Since Airfoils Are Thin The Fluid Flow Over A 1 (93.85 KiB) Viewed 37 times

: Experiments Have Been Conducted On Three Geometrically Similar Air Foils Since Airfoils Are Thin The Fluid Flow Over A 2 (69.85 KiB) Viewed 37 times

Experiments have been conducted on three geometrically similar air-foils. Since airfoils are thin, the fluid flow over airfoils can be considered to be like flow over flat plate, i.e., the streamwise pressure drop can be neglected. Too, U₂ The width of airfoils (perpendicular to air stream) is 1.0 m. Neglect the curvature of airfoils in your calculations. The results obtained from experiments are shown below: Length, L (m) 1 Velocity, U Air temp., T Airfoil No. (m/s) (K) 1 10 300 2 5 300 3 10 300 Considering the results presented in the above table, answer the following questions: Air foil 0.2 0.5 Airfoil temp., Ts (K) 320 320 320 Friction force, F (N) 1 0.1 ??? 1- We know that Cf = C Rem in which Cf and Re, are the average friction coefficient and the Reynolds number, respectively. Moreover, C and m are two constant parameters. Find C and m. 2- Calculate the friction force imposed on airfoild No. 3. 3- Calculate the heat transfer rate between airfoil No. 1 and the air stream Note: Thermophysical properties of air is constant in all experiments. p = 1 kg.m-3 μ = 10-5 Pa.s k = 0.05 W.m-¹.K-1 Pr = 0.7
An infinite cylinder with ro = 3 cm is initially at the uniform temperature of T; = 10 °C. At this time, the cylinder is dropped into a bath of hot water at Too = 80 °C and convection heat transfer coefficient of h = 1500 W.m 2.K-¹. The thermal conductivity and diffusivity of cylinder are k = 0.6 W.m¹.K-¹ and a = 0.15 x 10-6 m². s-¹, respectively. A) Considering the lumped capacitance method: 1- Calculate the time required so that the temperature of the cylinder reaches 50 °C. 2- Calculate the total heat transfer from the cylinder after 1 minute. B) Considering the one-term approximation for exact solution (Fo> 0.2): 3- Calculate the time required so that the temperature of the center line of the cylinder reaches 50 °C. 4- Calculate the temperature of the surface of the cylinder when the center line temperature is 50 °C. C) Comparison: 5- What method (lumped or one-term approximation) is more accurate in this problem? Why?