Question

3. Flows ove result in the formation of vortices in the downstream wake. These structures are shed much like that which is seen for circular cylinders and the frequency of shedding is important in the understanding of the flow field. This is particularly important for micro UAV's as they affect the flight characteristics of these small vehicles. To determine the shedding frequency, f, of the wake, researchers decide to run a model test with a 1/10 scale model wing in a water n of the water speed, u, the chord length of the airfoil, c, the angle of attack, α, the density of the water, p, and the viscosity of the water, H. At full scale, 110 m/s, -1.2 m and, a-0.089 radians (10°) (a) (10 pts) Find the non-dimensional groups associated with the problem. Use c, u, and pas the repeating variables. (b)(10 pts) What should the parameters a, c, and u be for model test. (c) (5 pts) If the frequency measured in the water tunnel is 75 1/s, estimate the frequency for the full-scale wing. (d) (5 points) If the proposed speed for the model test is too fast, what could you do to match the II terms and reduce the flow speed at the same time? Show how yo proposed solution reduce the flow speed. ur

Answer 1