Home Store Project Ideas Project Guide Ask An Expert Blog Careers Teachers Parents Students

Wild Winds: Detecting Turbulence Around Structures

Difficulty
Time Required Short (2-5 days)
Prerequisites None
Material Availability Readily available
Cost Low ($20 - $50)
Safety Be sure not to put your fingers or any other objects inside the fan. Adult supervision is recommended.

Abstract

Watch out! It's Eddy Vortex, Superhero! He swirls, he tumbles, he churns up air and water! OK, maybe eddies and vortices aren't exactly superheroes, but they are powerful regions of air and water flow that you have to watch out for in some surprising places. Try out this science fair project to discover why, as well as where and how to find them.

Objective

To detect and measure the turbulent airflow around test structures.

Credits

Kristin Strong, Science Buddies

This science fair project was inspired by this resource: TPT. (2006). Whitewater Rafting by Rasheed, Kohner, Scotty, and JB. DragonflyTV, Twin Cities Public Television. Retrieved July 17, 2008, from http://pbskids.org/dragonflytv/show/whitewaterrafting.html

Cite This Page

MLA Style

Science Buddies Staff. "Wild Winds: Detecting Turbulence Around Structures" Science Buddies. Science Buddies, 10 Oct. 2014. Web. 25 Oct. 2014 <http://www.sciencebuddies.org/science-fair-projects/project_ideas/EnvEng_p029.shtml>

APA Style

Science Buddies Staff. (2014, October 10). Wild Winds: Detecting Turbulence Around Structures. Retrieved October 25, 2014 from http://www.sciencebuddies.org/science-fair-projects/project_ideas/EnvEng_p029.shtml

Share your story with Science Buddies!

I did this project I Did This Project! Please log in and let us know how things went.


Last edit date: 2014-10-10

Introduction

When you get a new piece of furniture, you have to figure out where to put it. You want your room to look nice, but at the same time, you want to make sure traffic can flow easily in and out of the room, and that the room functions as it was intended. For example, if the room is a play space, there must be enough room to spread out toys and games. If the room is a living space, seating must be arranged so people can easily talk to one another.

Environmental engineers—the people who decide where to place or site a wind generator—have a similar task. They want to avoid blocking views or creating noise pollution with the wind generators, and at the same time, they want the generators to function as well as they possibly can for the given location. They want this machine that changes the free energy found in wind forces into electrical power, to do the best job it can of making power, which requires consideration of factors like:

  • Cost
  • Aesthetics (beauty)
  • Zoning laws
  • Noise pollution
  • Wind speeds
  • Wind turbulence
  • Surrounding structures
  • Topography
  • Installation
  • Transportation
  • Wind generator type (horizontal-axis or vertical-axis)
  • Environmental conditions (extreme cold or heat)
  • Access to a power grid, and
  • Mechanical stresses.

For a wind generator to work effectively, it needs a location that has average winds of at least 10-13 miles per hour, or better, for over a year. A good location is also free from "bad winds" that can damage the wind generator, such as turbulent or chaotic winds that change quickly in force, speed, and direction.

The power the wind generator is able to produce increases by the cube of the wind speed. Cube means multiplying the wind speed by itself three times. Therefore, a small increase in wind speed results in a large increase in the power that the wind generator can produce. If you raise the wind generator up to as high as is allowed by building rules, you can take advantage of higher wind velocities. The trade-offs, though, are possible obstruction of views, difficulty in installation and transport, and mechanical stresses and fatigue from high winds, which can cause the wind generator to fail.

Watch DragonflyTV whitewater rafting video
Click here to watch a video of this investigation, produced by DragonflyTV and presented by pbskidsgo.org.

In this science fair project, you'll focus on two of the factors used in siting a wind generator: wind turbulence and surrounding structures. You might have heard the word turbulence before if you've flown on an airplane close to a storm. The pilot might have come on the intercom system and cautioned the passengers to remain seated and buckled because the plane was expected to experience some "rough air" or turbulence.

Turbulence is chaotic, random changes in the flow of a fluid or gas. An example is the behavior of smoke rising from a birthday candle, or the motion of frothy, white waves around the hull of a speedboat. Turbulence creates eddies (in the case of liquids, like water) or vortices (in the case of gases, like air). In eddies or vortices (which is the plural of vortex), the flow of the liquid or gas is reversed. An ideal place to spot an eddy in a river is on the downstream side of a rock or other obstacle in the river. If you want to see eddies on the downstream side of boulders, visit the DragonflyTV video on the right and join Rasheed, Kohner, Scotty, and JB as they go whitewater rafting.

Just as eddies occur on the downstream side of a rock in a river, vortices occur on the downwind side of a building or obstacle. This is why airplanes cannot take off too close together. Wake turbulence develops behind a plane as it takes off, which churns up the air downwind, making wind conditions too dangerous for the next plane, so air traffic controllers wait 2-3 minutes, depending on the size of the planes, before allowing the next one to take off. This gives time for the turbulence to disappear.

When siting wind generators, environmental engineers try to avoid placing generators downwind of structures or obstacles because of wind turbulence on the downwind side of the structure. Turbulent wind is not an efficient way to generate power and the violent, changing winds can also damage the wind generator. In this science fair project, you'll detect wind turbulence behind a structure by observing the motion of a streamer. You'll also determine how far away you need to be from the structure for the turbulence to die down.

Terms and Concepts

  • Environmental engineer
  • Site
  • Wind generator
  • Wind turbulence
  • Topography
  • Chaos
  • Cube
  • Velocity
  • Random
  • Eddy
  • Vortex
  • Downwind
  • Wake turbulence

Questions

  • Why is it important to avoid turbulence?
  • Where can you find turbulence?
  • How can you avoid turbulence?

Bibliography

This source discusses how to find the best location for placing small wind generators, as well as how structures and terrain influence winds:

This source describes and shows examples of vortices:

For help creating graphs, try this website:

Materials and Equipment

  • Streamer, such as party streamer, a piece of old cassette tape, or a strand of plastic tape from a pom-pom; streamer should be several inches long
  • Slender stick or pole, at least 2 feet long
  • Fan
  • Boxes (3 of equal size), approximately 6.5 inches x 5 inches x 2.5 inches; examples of this size are boxes of pasta or salt. The boxes don't have to be empty, but first ask your parents if it is OK to use the boxes if they are full.
  • Rocks, a few handfuls to use as weights if the boxes are empty
  • Measuring tape
  • Room that is free from drafts
  • Lab notebook

Share your story with Science Buddies!

I did this project I Did This Project! Please log in and let us know how things went.

Experimental Procedure

  1. Clear your room of as many obstacles as possible so you have a path that is free from furniture or other items, and that is several feet long and several feet wide.
  2. Tie the streamer onto the end of your stick.
  3. Place your fan at one end of the room, facing the path.
  4. Place one of the boxes upright, approximately 1-2 feet in front of the fan. If the box is empty, place rocks or other weights inside the box to keep it from blowing over.
  5. Turn the fan on high.
  6. Stand off to the side of the fan and box and dangle the streamer between the fan and the box. Look at the motion of the streamer. In which direction is it moving? Write down the streamer's behavior in your lab notebook.
  7. Again, stand off to the side of the fan and box so that your body does not affect the airflow. Now dangle the streamer on the downwind side of the box (meaning the side of the box not facing the fan). Look at the motion of the streamer. Which direction is it moving? Write down the streamer's behavior in your lab notebook.
  8. Stand off to the side of the fan and box again. Hold the streamer just below the top of the box on the downwind side, and slowly move the streamer away from the box and the fan observing the motion of the streamer.
    1. As shown below, turbulent wind will make the streamer flow backwards toward the box and the fan, or it will make the streamer move around chaotically in all directions.
    2. When the streamer changes direction and begins to flow only forward, away from the box and fan again, then stop moving away from the box and lower the streamer to the ground so you can take a measurement.
  9. Measure the distance from the downwind edge of the box to the streamer with the measuring tape, as shown in the figure below, and record your measurement in a data table in your lab notebook, like the one below.
Drawing of a fan blowing a box with straight arrows between the fan and the box and curved arrows progressively becoming straighter downwind of the box.

Figure 1. This drawing shows how to measure the turbulent flow distance.

  1. Repeat steps 8-9 two more times so that you have data from a total of three trials.
  2. Stack another box on top of the first box and repeat steps 5-10.
  3. Stack another box on top of the first two boxes and repeat steps 5-10.

Turbulent Flow Distance Data Chart

Height of Structure One Box High Two Boxes High Three Boxes High
Trial 1 Turbulent Flow Distance (inches)      
Trial 2 Turbulent Flow Distance (inches)      
Trial 3 Turbulent Flow Distance (inches)      
Average Turbulent Flow Distance (inches)      
  1. Calculate the average distance at which the turbulent flow ended for each of the structure heights and enter it into the data table.
  2. Plot the Height of the Structure on the x-axis and the Average Turbulent Flow Distance on the y-axis. You can make the line graph by hand or use a website like Create a Graph to make the graph on the computer and print it.
  3. As the height of the structure increased, did you have to get farther away from the box and fan before the turbulence died down? Is your plot linear (does it form a line)? Using your graph, can you predict how far you would need to be away from the structure to see the turbulence die down for a structure higher than three boxes, or a structure shorter than one box?

Share your story with Science Buddies!

I did this project I Did This Project! Please log in and let us know how things went.


Variations

  • Evaluate how high above the structure you need to be to avoid turbulence.
  • Investigate how air flows around more than one structure.
  • Investigate how turbulence changes as you move away from the center of a structure.

Share your story with Science Buddies!

I did this project I Did This Project! Please log in and let us know how things went.

Ask an Expert

The Ask an Expert Forum is intended to be a place where students can go to find answers to science questions that they have been unable to find using other resources. If you have specific questions about your science fair project or science fair, our team of volunteer scientists can help. Our Experts won't do the work for you, but they will make suggestions, offer guidance, and help you troubleshoot.

Ask an Expert

Related Links

If you like this project, you might enjoy exploring these related careers:

wind engineers readying wind turbine for testing

Wind Energy Engineer

Every day the Earth provides us with many sources of renewable energy to power our lifestyles. Wind energy is an example of a renewable energy because wind is a naturally replenished source. But how can energy be extracted efficiently from the wind? Sounds like a job for a wind energy engineer! The wind energy engineer works on modeling, designing, and building wind turbines and wind farms. These engineers are passionate about wind, renewable energy, and the environment, and they enjoy applying their math and science skills. Read more
female environmental engineer measuring streamflow

Environmental Engineer

Environmental engineers plan projects around their city or state—like municipal water systems, landfills, recycling centers, or sanitation facilities—that are essential to the health of the people who live there. Environmental engineers also work to minimize the impact of human developments, like new roads or dams, on environments and habitats, and they strive to improve the quality of our air, land, and water. Read more
Two technicians at work

Environmental Engineering Technician

Smog, car emissions, industry waste—unfortunately, pollution is a reality that humans have to deal with. However, we can all breathe a little easier with environmental engineering technicians on the job. These people test our water, air, and soil to help us find ways to lessen the impact of pollution. Read more
commercial pilots in cockpit

Pilot

Pilots fly airplanes, helicopters, and other aircraft to accomplish a variety of tasks. While the primary job of most pilots is to fly people and cargo from place to place, 20 percent of all pilots have more specialized jobs, like dropping fire retardant, seeds, or pesticides from the air, or helping law enforcement rescue and transport accident victims, and capture criminals. Pilots enjoy working and helping people in the "third dimension." Read more

Looking for more science fun?

Try one of our science activities for quick, anytime science explorations. The perfect thing to liven up a rainy day, school vacation, or moment of boredom.

Find an Activity