An Eiffel type wind tunnel operates by drawing air through a contraction, passing this air through a test section (a rectangular section of duct made of clear plastic, and then exhausting the air using a large axial fan. In the test section, it is important that the boundary layer be very thin at the end of the test section to provide a uniform velocity distribution. For the pictured wind tunnel below, the test section is square with the dimension of W = 457mm on each side & a length of L = 914 mm. Find the ratio of δ(x = L)/W for two cases: (a) incoming minimum velocity of 1 m/s & (b) incoming maximum velocity of 70 m/s. Assume air properties at 1 atm & 20°C.

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a Let S 1 be the boundary layer thickness for minimum velocity ... View the full answer