Use scale analysis to find an expression for 8/x and Nu for flow over a flat plate with a thin thermal boundary Layer. Find the expression 8/x = 4.92 Re** Consider the following NACA airfoils: 2412, 23012, 23021 a. For each of these airfoils, find the L/D ratio for angle of attack of 0, 4, 8 and 12 b. For each airfoil find the angle of maximum L/D and find the stall angle c. Find which airfoil will provide the maximum lift for any given geometry and flow conditions

In the experiment of high Reynolds number, an airfoil of width, W= 30 cm, and chord length, C = 24 cm is subjected to airflow at 1 atm and 5 °C as shown in Figure 2.1. The airfoil can be approximated as a flat plate. The total drag force acting on the airfoil is 40.2 N. The pressure drag acting on the airfoil is measured to be 39.9 N by using pressure sensors throughout the surface. Given, the drag coefficient of the airfoil is Cp = 0.04, the density and kinematic viscosity of air at 1 atm and 5 °C is 1.269 kg/m³ and 1.382 x 10$ m²/s, respectively. i. Determine the friction drag coefficient of the airfoil. ii. Verify that the boundary layer flow at the trailing edge is turbulent. V C Figure 2.1 The airflow on a streamlined body

You are designing an airfoil for a new hobby RC plane.  Because of your limited knowledge, you have mistakenly approximated your airfoil as an ellipse with a = 75mm and b = 12mm.  Here, “a” is the depth of your wing and “b” is the thickness.  Your plane travels through the air at approximately 20mph (8.9m/s).  As it does so, skin friction produces a drag-induced heat of 800W on your wind, of length 1m. Properties of Air: k = 0.025 W/mK, Pr = 0.72, v = 1.847 x 10−5, u = 16.84 x 10−6, p = 1.2 kg/m3, B = 1/Tf (ideal gas), TInfinity = 25oC a) What is the Reynold’s number?  Hint: “D” is taken to be the thickness for an elliptical crosssection. b) What is the Nusselt number? c) What is the convection coefficient? d) What is the average temperature of your wing?  Assume an ellipse perimeter of approximately 200mm.

You are designing an airfoil for a new hobby RC plane.  Because of your limited knowledge, you have mistakenly approximated your airfoil as an ellipse with a = 75mm and b = 12mm.  Here, “a” is the depth of your wing and “b” is the thickness.  Your plane travels through the air at approximately 20mph (8.9m/s).  As it does so, skin friction produces a drag-induced heat of 800W on your wind, of length 1m. Properties of Air: k = 0.025 W/mK, Pr = 0.72, v = 1.847 x 10−5, u = 16.84 x 10−6, p = 1.2 kg/m3, B = 1/Tf (ideal gas), TInfinity = 25oC a) What is the average temperature of your wing?  Assume an ellipse perimeter of approximately 200mm.