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+ Contact Glenn         Wind Tunnel Aerodynamics Answers The wind tunnel test section (A), as in some operating wind tunnels, can be resized by moving the walls, ceiling and or floor to give a different cross-sectional area. The other 2 sections B and C are not adjustable. Give all answers to the nearest hundredth. The measured velocity in the rectangular test section (A) is 10 m/sec. The initial dimensions of the test section are 3 m high and 4 m wide. What is the cross-sectional area (A)?12 m2 What is the constant (V x A)? 120 m3/sec. What cross-sectional area (A) will I need to double the Velocity? 6 m2 What cross-sectional area (A) will I need to decrease the Velocity fourfold? 48 m2 What would the Velocity be if I changed the dimensions to 6 m high and 4 m wide? 5 m/sec. What would the Velocity be if I changed the dimensions to 5 m high and 5 m wide? 4.8 m/sec.   Assume that the wind tunnel test section (A) is triangular. Our initial velocity is still 10 m/sec. What is the formula for the area of a triangular cross-section? A = 1/2 bh The triangular test section has a base of 5 m and a height of 4 m. What is the Area(A)? 10 m2 What is the constant (V x A)? 100 m3/sec. What cross-sectional area (A) will I need to double the velocity? 5 m2 Give a base and height measurement which would result in the cross-sectional area in 2d. b/h = 2/5, 1/10, 2.5/4 etc. What would the velocity be if I changed the dimensions to a base of 8 m and a height of 10 m? 2.5 m/sec.   The fan exit section (B) is circular in shape. The initial velocity is again 10 m/sec. What is the formula for the area of a circular cross-section? A = IIr2 The cross-sectional area of B is 20 sq. m. What is the radius? 2.52 m What is the constant (V x A)? 200 m3/sec. If I rebuilt this section, what radius would be required to generate a velocity of 50 m/sec.? 1.13 m   The cross-sectional areas of Test Section (A), Fan Exit Section (B), and Section C are 20, 60 and 100 m respectively. The velocity at B, the Fan Exit Section, is 50 m/sec. What is the constant (V x A)? 3000 m3/sec. What is the Velocity at cross section C? 30 m/sec. What is the Velocity at Test Section A? 150 m/sec.

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