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 crosssectional
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 crosssectional area (A)?12
m^{2}
 What is the
constant (V x A)? 120 m^{3}/sec.
 What crosssectional
area (A) will I need to double the Velocity?
6 m^{2}
 What crosssectional
area (A) will I need to decrease the Velocity fourfold? 48
m^{2}
 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 crosssection?
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 m^{2}
 What is the
constant (V x A)? 100 m^{3}/sec.
 What crosssectional
area (A) will I need to double the velocity? 5
m^{2}
 Give a base
and height measurement which would result in the crosssectional
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 crosssection? A
= IIr^{2}
 The crosssectional
area of B is 20 sq. m. What is the radius? 2.52
m
 What is the
constant (V x A)? 200 m^{3}/sec.
 If I rebuilt
this section, what radius would be required to generate a velocity
of 50 m/sec.? 1.13 m
 The crosssectional
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 m^{3}/sec.
 What is the
Velocity at cross section C? 30 m/sec.
 What is the
Velocity at Test Section A? 150 m/sec.
