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Destination Tomorrow - DT4 - Wind Tunnels

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Subido el 28 de mayo de 2007 por EducaMadrid

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NASA Destination Tomorrow Segment describing wind tunnels and how aircraft designers use them to understand airflow.

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Wind tunnels have been around for well over 100 years. 00:00:00
Now, even before powered flight had been achieved, aircraft designers like the Wright Brothers 00:00:08
used them to understand how air flowed over aircraft surfaces. 00:00:12
Wind tunnels come in many different sizes and can reach speeds from 1 mile per hour 00:00:15
to over 17,000 miles per hour. 00:00:19
Most are used for testing aircraft, but they've also been used for testing things like cars, 00:00:21
submarines, buildings, golf balls, and even wheelchairs. 00:00:25
Wind tunnels are fairly simple devices, but have you ever wondered how one works? 00:00:30
For some answers, I spoke with NASA Langley researcher Luther Jenkins to find out more. 00:00:35
Well, a wind tunnel is actually a simulator. 00:00:39
It allows us to simulate the conditions that an airplane or some other type of vehicle 00:00:41
is actually going to experience as it's operating. 00:00:46
So instead of building a full-size aircraft or a full-size car, 00:00:48
we actually build a small-scale model, testing the wind tunnel to see how it's going to perform. 00:00:53
And once we see that it has the performance characteristics that we desire, 00:00:57
then you may take it and start manufacturing it on a mass scale. 00:01:01
Anything that's going to be exposed to the air or has to travel through the air 00:01:05
can actually be tested in the wind tunnel to see how it will perform. 00:01:09
Earlier, you mentioned that wind tunnels come in different sizes, correct? 00:01:12
That's true. 00:01:15
Great. So how does that work? What, the bigger the fan, the faster the speed? 00:01:16
Wind tunnels come in all shapes and sizes, but they're actually just two types of tunnels. 00:01:21
One is an open-return wind tunnel, and the other one is a closed-return. 00:01:25
And what it describes is the way the air flows through. 00:01:28
In an open-return wind tunnel, the inlet, or the opening to the tunnel, 00:01:31
is open to the atmosphere or the environment, 00:01:35
and the exit, or where the air comes out, is open to the environment. 00:01:37
In between, what you have is your test section, where you actually put your model, your test article. 00:01:41
And then you have a diffuser, which actually causes the air to slow down a little bit before it hits the fan. 00:01:45
And then the fan is downstream, so it actually pulls the air or draws the air through the tunnel like a vacuum cleaner. 00:01:50
And then in your closed-return tunnels, those are a little bit more complicated 00:01:56
because the air flows continuously around the loop. 00:01:59
You have to have turning vanes in the corners to actually turn the air so it moves through nice and smoothly. 00:02:02
You have a fan, which is actually providing the air that goes through the tunnel. 00:02:07
And then you have your test section, just like in the open-return wind tunnel, 00:02:11
where you would place your model. 00:02:14
Now, all tunnels don't have fans. 00:02:16
Some use just air sources. 00:02:18
I mean, you can hook an air bottle up to the tunnel and turn it on, and the air flows through the tunnel. 00:02:20
Is air the only media that you can use in a wind tunnel? 00:02:24
No, actually, wind tunnels use a variety of media. 00:02:27
You can use air, you can use water, you can use nitrogen, you can use freon, you can use helium. 00:02:29
And all of these different gases are used to actually produce certain conditions 00:02:34
that the design or the aircraft is going to actually see when it flies. 00:02:39
All right, so why do we still need wind tunnels? 00:02:43
I mean, can't computers today do the simulation? 00:02:45
Well, computers can be used to do a lot of the simulation work. 00:02:47
But just like the Wright brothers, they would start off doing testing in the wind tunnel, 00:02:50
and they had to do it over and over and over again until they arrived at the final design. 00:02:54
Whereas now, a lot of that work could be done on the computer, 00:02:58
but you would still, once you come up with your final design, you want to test it in the wind tunnel 00:03:01
just to make sure that all of the things that you predicted with the computer occur in reality. 00:03:05
Sure. 00:03:11
A wind tunnel is a valuable tool for an engineer. 00:03:12
Every plane that flies, every car that travels along the road, every bus, every ship, 00:03:14
it's tested in a wind tunnel to make sure it's going to perform as designed. 00:03:19
And in that regard, we save time, we save money, and we also save a lot of lives. 00:03:23
So remember, the next time you ride in a plane, a car, or even hit a golf ball, 00:03:29
it was probably tested in a wind tunnel first. 00:03:33
I sure wish I had a wind tunnel behind me now. 00:03:36
Perfect. 00:03:39
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Idioma/s:
en
Niveles educativos:
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Autor/es:
NASA LaRC Office of Education
Subido por:
EducaMadrid
Licencia:
Reconocimiento - No comercial - Sin obra derivada
Visualizaciones:
438
Fecha:
28 de mayo de 2007 - 17:04
Visibilidad:
Público
Enlace Relacionado:
NASAs center for distance learning
Duración:
03′ 47″
Relación de aspecto:
4:3 Hasta 2009 fue el estándar utilizado en la televisión PAL; muchas pantallas de ordenador y televisores usan este estándar, erróneamente llamado cuadrado, cuando en la realidad es rectangular o wide.
Resolución:
480x360 píxeles
Tamaño:
21.99 MBytes

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