In: Mechanical Engineering
An airfoil profile to be used on a wind turbine blade is tested in a wind tunnel. The prototype (full-scale) airfoil section has a chord length of 2m and moves at 50 m/s relative to the wind, the wind tunnel model has a chord length of 0.4m. The temperature for the model test is the same as for prototype operation.
(a) What criterion should be used to obtain dynamic similarity in the experiment? (Write out the criterion in an equation.) (b) What velocity should the wind tunnel be operated at to have dynamic similarity for the scale model? (assuming tests at atmospheric pressure.) (c) The wind tunnel available for this test can only be operated at 100 m/s, but it can also be pressurized. What pressure should be used in the wind tunnel to have dynamic similarity? (Assume the air behaves like an ideal gas.)