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Wind Tunnel Aerodynamics Activity
If so instructed by your teacher, print out a worksheet page for these problems.


Open the slides called Bernoulli's Equation (with text) and Wind Tunnel Aerodynamics (with text) and read the explanations of the relationships between air velocity, pressure, and density in a closed system of varying cross section like a wind tunnel.

 

Shown below is an image of a typical wind tunnel with three cross sections: A (test section), B (Fan Outlet) and C .

 
Image of Windtunnel Aerodynamics


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 two sections B and C are not adjustable. Give all answers to the nearest hundredth.

  1. 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.
    1. What is the cross-sectional area (A)? ________________
    2. What is the constant (V x A)? ________________
    3. What cross-sectional area (A) will I need to double the velocity? ________________
    4. What cross-sectional area ( A) will I need to decrease the velocity fourfold? ________________
    5. What would the velocity be if I changed the dimensions to 6 m high and 4 m wide?_____________________________
    6. What would the velocity be if I changed the dimensions to 5 m high and 5 m wide? _____________________________

     

  2. Assume that the wind tunnel test section (A) is triangular. Our initial velocity is still 10 m/sec.
    1. What is the formula for the area of a triangular cross-section? ________________
    2. The triangular test section has a base of 5 m and a height of 4 m. What is the Area (A)? _____________________________
    3. What is the constant (V x A)? _____________________________
    4. What cross-sectional area (A) will I need to double the velocity? _____________________________
    5. Give a base and height measurement which would result in the cross-sectional area in Problem 2d. _____________________________
    6. What would the velocity be if I changed the dimensions to a base of 8 m and a height of 10 m? _____________________________

     

  3. The fan exit section (B) is circular in shape. The initial velocity is again 10 m/sec.
    1. What is the formula for the area of a circular cross section? _____________________________
    2. The cross-sectional area of B is 20 sq. m. What is the radius? _____________________________
    3. What is the constant (V x A)? _____________________________
    4. If I rebuilt this section, what radius would be required to generate a velocity of 50 m/sec.? _____________________________

     

  4. 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.
    1. What is the constant (V x A)? _______________________________________
    2. What is the velocity at cross section C? _______________________________________
    3. What is the velocity at Test Section A? _______________________________________


Related Pages:
Standards
Worksheet
Lesson Index
Aerodynamics Index

 

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Editor: Tom Benson
NASA Official: Tom Benson
Last Updated: Thu, Jun 12 04:46:42 PM EDT 2014

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