Wind Tunnel

Have you ever thought about why cars, planes, or boats are shaped the way they are? Or even why air pressure is different when walking between tall buildings on different buildings. Well, some of this may be due to testing of the wind tunnel. According to the F1 dictionary it states, “Wind tunnel is a structure used for studying the interaction between solid or gel bodies and airstreams.” Meaning, engineers place a model to study how the shape of the model interacts with the air stream. Making note of whether it is not stable, redirecting air in another direction, or anything of that sort. In other words, aerodynamics. 

To understand why something came into existence you need to know what happened before it came to life. Before the wind tunnel was invented in 1764, English mathematician Benjamin Robin invented the whirling arm. This was a machine that held the object on an arm and spun it around in circles like if it was on a carousel. The objective of this invention is to push the object through the air to find out how it interacts and see what changes needed to be made for the first airplane. It was 5 feet tall so only small models of what they were tested were on it. What made the studies unhelpful was the reports weren’t helpful since the arm did not move the object fast enough. Also, the arm was moving as well as the wind speed so it could change and it wasn’t easy to determine the velocity of the object and wind speed.

Figure 1  

Nasa / Centennial of flight

Figure 2

Gary Bradshaw / Centennial of flight

 Frank H. Wenham (1824 – 1908) wanted to change this and solve the problem. He was a self-taught British engineer and a council member of the Aeronautical Society of Great Britain who had various ideas just like the wind tunnel. He was the first person to design it. The fan was 12 feet long and 18 inches squared with a steam-powered fan that was able to blow a wind speed of approximately 40 MPH. It provided an unsteady Windstream which helped with accurate measurements that would simulate what was impossible before. Over time the wind tunnel has become bigger and used in many facilities. Currently, NASA owns the biggest wind tunnel in the world in California at the Ames Research center. It is about 1,400ft long and 180ft high. Able to 

test airplanes over 100ft.

Figure 3

NASA Ames / NASA

Wind tunnels have been not only Used in airplanes but now used to study the design of buildings and how it will affect a city such as NYC with skyscrapers. Also, it has been more used in sports involving aerodynamics. 

Instead of using Benjamin Robin’s method which proved to not be as reliable. We have now found a way to have the object be stationary in one place. Let’s say you got a pencil and you made a ninja star out of paper and placed it on the pencil. Now you blow into it and what does it do? It spins. Sometimes not all the time depending on how much air you are blowing towards the paper. This is the same case with the wind tunnel but instead, nothing is moving unless it is something with wheels then only the wheels move. The main components of what makes up the wind tunnel are the fan, the test section, flow straightener, and contraction section.

Figure 4 

Glenn Research Center / NASA

 With the fan blowing air just like your regular 99 cents fan would do with its drive motor. The test section would hold the model you want to study on how it interacts with the wind at different speeds. A flow straightener sometimes called the honeycomb does what it’s called. It makes sure the air doesn’t take a different direction and flows smoothly just like an ocean current. Now the contraction section is the most important part of the wind tunnel. Yes, even though without the fan, there wouldn’t be a wind in the tunnel. But the contraction section is what controls the velocity of the wind towards the test section while reducing turbulence (disrupts airflow) and other things that will try to interrupt the test. 

As you were reading my paper you will come to the understanding that the wind tunnel is mostly used for planes, spaceships too, vehicles but also structures. It is not just buildings either, bridges as well. How do you think we are still able to cross long bridges at high wind speeds without having the bridge move a lot? Many people use the wind tunnel. Athletes whose sports involve aerodynamics so that goes from motorsports to skiing, to bobsledding, to sailing. Any sport that deals with wind and air at high speeds. But architects also use the wind tunnel to help them understand how they should design a building or how their building would affect the surrounding area.

Figure 5   

On The Apex / Car Throttle    

Figure 6

Roy Dennon / Structure Magazine

Have you ever noticed how on one street the wind speeds are calm but if you walk 2 blocks over you start to notice how the wind speeds picked up and you were almost blown off your feet? In a report from Fox news they wrote, “The wind tunnel effect in New York City is a situation where the air is being converted into a very small space and that leads to stronger winds,” said Steven DiMartino, a meteorologist, and the owner of NYNJPA Weather. “It’s the same process as if you take a hose for water and press down a little bit and that water comes out a little faster.” (Fox News) This goes to show that, with smaller areas for air to pass through, more air pressure would be used by nature to squeeze through just to get passed. If you go to downtown NYC, you might see certain buildings looking different than others. Some have a missing piece in them whether it is on top, in the middle, or on the bottom. It is to help the air move more freely and not be squeezed between different buildings. As I said before bridges have a higher risk with wind velocity since it is more of a flexible structure and may sometimes stretch for miles. Don’t believe me there’s a bridge in China that spans about 102.4 miles out. There are various ways they are tested in the wind tunnel but they all measure the Aerodynamic stability of the bridge at different angles and different wind speeds. 

The world has advanced so much with the help of the wind tunnel. The next time you see a car with a big wing in the back, a big splitter in the front, or just looks like a straight arrow of some sort. It is to improve the aerodynamics of it so it sticks to the ground. And who knows what the future holds for us we can have a different wind tunnel to where we can actually fly out to space like science fiction movies such as Star Wars.

References

Rumerman, Judy. The First Wind Tunnels, 2003, www.centennialofflight.net/essay/Evolution_of_Technology/first_wind_tunnels/Tech34.htm. 

Dunbar, Brian. “Sometimes Size DOES Matter: 25 Years with the Largest Wind Tunnel in the World.” NASA, NASA, 6 June 2013, www.nasa.gov/centers/ames/news/features/2012/nfac-25.html. 

Hall, Nancy. “Wind Tunnel Parts.” NASA, NASA, 5 May 2015, www.grc.nasa.gov/www/k-12/airplane/tunpart.html. 

Buddies, Science. “How to Build and Use a Subsonic Wind Tunnel.” Science Buddies, Science Buddies, 10 Jan. 2020, www.sciencebuddies.org/science-fair-projects/references/how-to-build-a-wind-tunnel. 

Seas, NIck. Wind Tunnel, 14 Jan. 2021, www.formula1-dictionary.net/wind_tunnel.html. 

B.Eng., Roy Denoon. “Wind Tunnel Testing for Tall Buildings.” STRUCTURE Magazine, June 2018, www.structuremag.org/?p=13256. 

Apex, On The. “4 Reasons Why Wind Tunnel Testing Is so Important to Race Car Aerodynamic Development.” Car Throttle, 2016, www.carthrottle.com/post/n43v9xq/. 

New York, FOX 5. “Why New York’s Architecture Creates Wind Tunnels.” FOX 5 New York, FOX 5 New York, 21 Oct. 2019, www.fox5ny.com/news/why-new-yorks-architecture-creates-wind-tunnels.