Wind Tunnel Familiarization Flashcards
machines for producing controlled stream of air flowing through tunnels of varying but controlled sizes
wind tunnels
enables us to study the effects of bodies moving through air or the resistance to moving air of manufactured models
wind tunnels
facilities (circular, elliptical or rectangular tunnels) in which the wind is produced by fans or by compressed air to study and measure the action of the air flow around a solid
wind tunnels
part of the circuit where the solid is studied
test section
The method of wind tunnel is based on the ________ enunciated by Isaac Newton in 1687.
principle of relativity
The object to be tested is ______ in the test section as to prevent the stream of air from moving the object.
fastened
the slow-moving layer of air adjacent to any wind-exposed body surface
boundary layer
world’s largest wind tunnel at the NASA Ames Research Center
Unitary Plan Wind Tunnel
Where is NASA’s Langley Research Center?
Hampton, Virginia
first to make use of the “Whirling Arm”
Benjamin Robins
this machine had an arm with a length of __ ft spun around by a falling weight acting on a pulley and spindle arrangement
whirling arm, 4
The whirling arm brought light as to how different shaped objects, when moving through air is affected differently by air resistance, or _____.
drag
What limited Benjamin Robins experiments regarding the whirling arm?
the speed the arm can reach
He wrote and published in 1759 a paper that addressed the relationship between pressure and velocity for objects moving in water and air.
John Smeaton
Smeaton created what equation
drag equation
Father of Aviation
George Cayley
Cayley’s whirling arm was ___ ft (1.5 m) long and attained top speeds of about _______ (3 to 6 m/s).
5, 10 to 20 ft/s
Two very important factors
that are related to flight identified by Cayley
lift and drag
In ______, an unpiloted glider was built and flew successfully based on test data gathered from Cayley’s whirling arm.
1804
became famous as the first man to launch himself into the air, fly, and land safely using a glider
Otto Lilienthal
Between 1866 and 1889, Lilienthal built several whirling arms, ranging from ______ (2 to 7 m) in diameter.
6.5 to 23 ft
What did Otto Lilienthal say?
“Sacrifices must be made.”
famous for his automatic machine gun creations
Hiram Stevens Maxim
Maxim used a huge whirling arm to test airfoils between 1872 to 1894 in his _________.
helicopter experiment
Maxim’s version of the whirling arm had a diameter of ____ with the arm boasting elaborate instrumentation to measure lift, drag, and relative air velocity.
64 ft
What can Maxim’s whirling arm measure?
lift, drag, relative air velocity
he built a large whirling arm, 60 ft in diameter, and was spun around by ___ engine
Samuel Langley, 10-hp
One of Langley’s experiments with the arm attained speeds up to ______.
100 mph
first individual to design a wind tunnel
Frank H. Wenham
When did Frank H. Wenham build a wind tunnel?
1871
How long was Wenham’s wind tunnel and what is its area?
12 ft, 18 sqi
In Wenham’s wind tunnel, what drove the air through a duct to the test section where the model was mounted?
steam-powered fan
Maximum velocity of air in Wenham’s wind tunnel
40 mph
Two varieties measured in Wenham’s tunnel
lift-to-drag ratio, effect of different aspect ratios
he began experimenting with lifting curved surfaces in the 1880s
Horatio Frederick Phillips
He tried to carry out tests similar to Wenham’s with his own wind tunnel
Horatio Frederick Phillips
he eliminated the problems associated with airflow fluctuation
that troubled Wenham by using a steam injection system to generate the airflow
Horatio Frederick Phillips
What did Phillips use to eliminate the problem associated with airflow fluctuation?
steam injection system
built a small wind tunnel at the foot
of the Eiffel Tower to study the effect of the wind on more precise fixed points
Gustave Eiffel
became an adversary of the Wrights in their legal battles
Dr. Albert Francis Zahm
In October 1901, their small wind tunnel was created.
Wright Brothers
first to make use of the “Whirling Arm”
Benjamin Robins
What is the Drag Equation?
D=CD(k)(S)(V^2)
Used huge whirling arm to test airfoils
Hiram Stevens Maxim
used huge whirling arm to test airfoils yet met frustrations and limitations
Samuel P. Langley
designed the world’s first wind tunnel
Francis Herbert Wenham
was unimpressed with Francis Wenham’s experiments thus creating his own wind tunnel
Horatio Frederick Phillips
Classification/Types of Wind Tunnel
Speed Regimes, Geometry
Types of Wind Tunnel under Geometry
open return, closed return, intermittent, continuous
Types of Wind Tunnel under Speed Regimes
sonic, subsonic, transonic, supersonic, hypersonic
Speed Regime (Sonic)
M = 1.0
Speed Regime (Subsonic)
0<M<1.0
Speed Regime (Transonic)
0.8<M<1.2
Speed Regime (Supersonic)
1.2<M<5.0
Speed Regime (Hypersonic)
M>5.0
These are wind tunnels used to test objects at low Mach numbers or speeds slower than the speed of sound and below sonic speed.
Subsonic
are wind tunnels used to study high-speed aerodynamic flows around aircraft and to investigate how these flows interact with the stores and other attachments carried and released from the wings and fuselage
transonic wind tunnels
An open circuit suction subsonic wind tunnel
TecQuipment Subsonic Wind Tunnel - AF1300
The only independently owned and operated wind tunnel in the United States; a continuous flow, variable density, closed-circuit facility with an 8 ft x 8 ft test section.
Calspan Transonic Wind Tunnel
Max Mach number of Calspan Transonic Wind Tunnel
1.30
Designed to conduct research, development, and acceptance testing of supersonic and hypersonic air-breathing propulsion systems
Glenn Research Center Supersonic Wind Tunnel
notable in this regime is the appearance of shock waves
supersonic
are very small regions in the gas where the gas properties change by a large amount
shockwaves
most are designed for intermittent instead of continuous operation
supersonic wind tunnels
these types of wind tunnels are used to test flight characteristics in a hypersonic region of Mach number 5 or more
hypersonic
other term for open return
Eiffel type
other term for closed return
Prandtl or Göttingen type
The open circuit arrangements, collect air upstream is accelerated in a contraction consisting of a conduit of convergent section; low construction cost; superior design for propulsion and smoke visualization; no accumulation of exhaust products in an open tunnel
open return or Eiffel type
its corners typically consist of 90 degree bends; air circulates continuously within the wind tunnel
close return or Prandtl or Göttingen type
To limit the pressure losses at the corners and avoid the formation of secondary re-circulating flows in a Close Return, the corners are usually equipped with ______.
guide vanes
make use of surging air flow at a particular set of intervals
intermittent
In this type of tunnel, the compressor continuously adds energy to the flow to allow the continuous air flow through the tunnel. As a result, the air is continuously heated.
Continuous
Elements of a Wind Tunnel
test section, contraction cone, diffuser, drive section
most delicate part of the tunnel
test section
part of the wind tunnel where the air flow accelerates
contraction cone
a divergent section between the test section and the suction fan located downstream of the tunnel
diffuser
drives the flow of air through the wind tunnel by producing an increase in pressure in the flow
drive section
determines how the working fluid is moved through the test section
drive section
