FLAME TORNADO

By Jennifer Ng and Lauren Helton

 

Table of Contents

Statement of the Problem

Background and Review of Literature

Hypothesis

Procedure

Photo of Lab Set-Up

Raw Data  and Calculations

Photo Data

Speed of Rotation vs. Flame Height Graph

Data Analysis and Conclusion

Evaluation

Bibliography

Return to research

J: Hey now! Look for more! This one is in an easy spot.. but now you know you are looking for them... have fun. (by the way... Aaron Pride thinks that people are like slinkys... they don't serve any real purpose, but when one falls down the stairs you just have to laugh!) Boy I am going to miss that kid. Gotta love the hardcore pessimism... 

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Statement of the Problem

The purpose of this investigation is to find the relationship between the number of revolutions per second of the plate and the height of the flame on that plate.  

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 Background and Review of Literature

 Convection currents are defined as "The process whereby heat is transferred by the movement of molecules from one place to another" (Giancoli 1998). The air above a heat source, such as the flame in our experiment, expands and rises. As it starts to cool, it falls back down to this heat source only to be heated again, creating a cycle. The process of convection currents is essential to the formation of tornadoes.

The lifting of warm surface air can occur anywhere there is sufficient heat, such as when the surface air heats up during the day, or again, a flame. The air above his heat source expands and begins to rise. In order for a tornado to be created, the updraft from the warm air must rotate. Air rising from the ground in the tornado vortex creates low air pressure near the ground, which air rushes inward to fill. As air rushes into the vortex, its pressure lowers, which cools the air (Williams 2003). Rapidly increasing wind speed and the changing wind direction are both factors of increased height, and cause the updraft inside the storm to rotate cyclonically. As air rushes toward the low-pressure area, the rotational wind speeds increase and vertical stretching occurs due to angular momentum principles (Twister).

The concepts involved in wind tornadoes apply to flame tornadoes as well, created by spinning a flame attached to a plate or disc. In fact, as was recently discovered, flame naturally takes a spiral shape as the plate begins to slowly spin. In an experiment involving flame on a slowly rotating disk, scientists found the flame because consistently spiral shaped, and moved around the disk surface in the opposite direction from the disk's rotation (Nayagam and Walker 2000).    

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Hypothesis

The number of revolutions per second of the plate is directly related to the height of the flame on that plate.

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Procedure

  1. Get materials:
    1. Turntable
    2. Thick rubber band (size depends on turn table)
    3. Motor
    4. Power supply
    5. Epoxy glue
    6. 2 Tuna cans (wrappers removed)
    7. Pencil
    8. Chicken wire (61.5 cm tall)
    9. Wire
    10. Duct Tape
    11. Rag
    12. Scissors
    13. Lamp Oil
    14. Matches
    15. Strobe Light
    16. Flashlight
    17. Meter Stick
    18. Wet paper towel or can
    19. Digital Camera
    20. Fire extinguisher (safety precaution)
    21. Safe environment away from flammable surfaces to work in
  2. Preliminary Set-up
    1. Turntable

                                                               i.      Replace motor with a faster motor (as the original turn table motor will not reach the velocity necessary for this experiment)

                                                             ii.      If the turn table belt is damaged or there is no belt (as in our case), replace it with the thick rubber band

    1. Place a tuna can face down in the center of the turntable

                                                               i.      Test the alignment by tracing the outline of the can onto the turntable with a pencil. Remove the can and adjust the position accordingly with reference to the center pole in the center of the turntable. 

    1. Tape the second tuna can on top of the first, bottom to bottom.
    2. Cut square strips from the rag, place them inside the tuna can and press them in firmly.
    3. Pour lamp oil onto the rags until they are damped. Make sure not to fill the can with too much lamp oil as it may spill during the experiment.
    4. Form the chicken wire into a cylinder with a diameter of 21 centimeters.
    5. Use a long piece of wire to tie the chicken wire together, especially around the seams.
    6. Place the chicken wire cylinder around the tuna cans (make sure it is centered)
    7. Tape both sides of the chicken wire to hold it in place.
  1. Collecting Data
    1. Count the dots on the edge of the turntable. Using tape, mark every tenth dot.
    2. Turn off the lights.
    3. Set the voltage to 3.75
    4. Using the strobe light, adjust the speed of the flash until the tape marks appear to be standing still.

                                                               i.      Record the flash per minute

                                                             ii.      To make sure the data is correct, set the strobe light speed twice as fast as the recorded setting. Exactly 2 times more dots should come into view, appearing to be standing still as before.

                                                            iii.      *              *              *              *

                                                           iv.      *      *      *      *      *      *      *

                                                             v.      Repeat for all voltage settings

    1. Turn on lights
    2. Tape a lighted match to the end on the meter stick
    3. Using the meter stick, reach into the chicken wire cylinder and light the rags in the tuna can.
    4. Remove the meter stick
    5. Set the voltage to 3.75
    6. Hold meter stick as close as possible to the spinning cylinder. Make sure that the 0 centimeter mark is on the bottom, touching the turntable.
    7. Take over six pictures with a high speed camera
    8. Repeat for all voltages.
  1. Clean Up
    1. Tape a wet paper towel onto the meter stick, stick it into the chicken wire cylinder and smother the flames
    2. Another effective way is to tape a can onto the meter stick, bottom down, and smother the flames that way.

        Oh boy! Isn't this fun? Get ready for FLAME!!!!

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Photo Data

Speed of Rotation vs. Flame Height Graph

Excel Version of this Graph (chart 2)

Whaahooooo! 

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Didn't you like the FLAME pictures? Go ahead... look at them again in their MASSIVE COOLNESS!

Data Analysis and Conclusion

     By looking at the raw data, we can see that indeed, there is a correlation between an increase in velocity and the height of the flame. As the number of revolutions per second increases, I found that the height of the flame tornado would increase as well, in an almost linear relationship. The only uncertainty involved in the procedure is regarding the actual measurement itself of the flame. The measurement is quite accurate, as they were read from the photos I took, and so the only real uncertainty in height comes from the fact that it was difficult to hold the meter stick close to the base of the turntable, resulting in an uncertainty of ± 1 cm. The equation for the line of best fit is y = 17.905x + 24.313, and the coefficient of determination is .96, which is incredibly close to 1. I chose to graph the average heights from each trial, simply for clarity. When looking at the graph of the average heights, the direct relationship is easily visible.
     There are a few things immediately apparent in the raw data that look wrong, but in fact are easily explained by the way our setup works. First, it can be seen that there is a gap in the recorded voltages between 0 and 3.75. This is because the turntable began spinning at 3.75 volts, and not before. It is also evident from this data that the height of a flame varies dramatically, even when sitting still.  This "flickering" caused a fairly large range of heights for each velocity, resulting in data points as much as 36 centimeters apart, which can be found in the flame heights for 2.382 rev/sec. However, even with this range of heights, an upward trend is still obvious.
     Similar to the findings of Nayagam and Walker, when looking down at the flame, a twisting shape can be seen. This supports the background information regarding the formation of a vortex caused by spinning, and the lifting of this flame into a tornado fits with the ideas regarding convection currents in a regular tornado. So, in examining previous research, along with my own, and analyzing the upward, linear trend in the data, I feel I can safely conclude that my hypothesis is correct.  

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Evaluation

       Although this experiment was fairly accurate, there are a few limitations.
     First of all, it would have been nice to test the results at even higher velocities, but the apparatus wasn't stable enough. At 2.382 rev/sec the cylinder begins rocking back and forth, and when I tried to push it up to 2.721 rev/sec, the cylinder rocked violently and even flew off once, so this was not a very safe thing to pursue. However, the relationship is visible even at the lower velocities, so this is not a very big problem.
     Second, when I conducted trials at different times, the flame would be either higher or lower than the previous average height. The most likely reason for this was that the amount of fuel used was not controlled very well. I poured enough lamp oil to soak the rag, but I did not measure out a specific amount, which probably would have been a good thing to do to ensure accuracy.
     Third, somehow when I was taking pictures of the flame for analysis, I took more at some heights than others, even though I had intended to take the same number of trials at each velocity. So to make it more accurate, I could have taken an equal number of trials for each data point, and taking more data would always be a good thing, since the flame height is highly variable.

     Also, there were times where the meter stick was not exactly vertical and perpendicular to the floor. In some of the pictures I took you can see the meter stick tilting slightly. This tilt could have affected the data, as the measurements would be slightly inaccurate.
     Finally, I had difficulty finding accurate data points using the strobe light for obtaining the correct number of flashes per minute.  Even though I used tape to mark every tenth dot to make it easier for me to see, the tape pieces were not uniform and it was difficult to see it "standing still" under the light. Therefore it was also difficult, when we doubled the number of flashes per minute, to see if the number of tapes doubled as well, since that would have proven that the number of flashes per minute was accurate. I attempted several trials of this and it looked correct, but using uniform markers, such as circular stickers for example, would have made this step much easier.
     Despite these three limitations, I feel that enough trial points were taken to reasonably prove that the hypothesis is in fact correct, even though it might not be perfectly accurate. Repeating this experiment and taking these limitations into account, which I had not foreseen originally, would certainly improve the quality of the data to some extent.

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Bibliography

* Something you should know before getting excited by the flame and deciding to do this project... THERE IS NOT VERY MUCH INFORMATION ON FLAME TORNADOES! BEWARE! Basically... the stuff you see here is all you got. We even went to Portland State University's library to find information. It turned out to be a complete waste of time as: 1. hardly any information available 2. the information there was WAY TOO TECHNICAL, even for us crazy IB students. You only need general knowledge for this project.

1. Fire on Spinning Disk. Focus. 27 October 2003. http://focus.aps.org/story/v5/st2

This site was not especially helpful. It does show, however, that fire will spiral while on a spinning disk... aka the turntable.

2. Giancoli, Douglas. Physics, Princlples with Applications.

     New Jersey: Prentice-Hall, 1998.

Just in case you couldn't tell, this is our Physics textbook. It had information on convection currents.

3. Twister. Int’l Man of MISTery. 27 October 2003 http://windfall.evsc.virginia.edu/~class/Jeremy/torn2.htm

Do not be deceived. Although this is not about FLAME tornadoes, the information in this site still applies. It is helpful especially in regards to the formation of the tornado. (gotta love the crazy visual aids)

4. Vortices. Membrane. 27 October 2003. http://ygraine.membrane.com/enterhtml/live/Time/vortintr.html

 This site has formulas and such about vortices. (::cough cough:: we really didn't use this... much...)

5. Weather. USA Today. 27 October 2003.

        http://www.usatoday.com/weather/resources/basics/2003-05-05-basics-tornadoes_x.htm

This site talks in greater detail about the formation of tornadoes than the other tornado site. Again this was about regular wind tornados but the information there can be applied to FLAME tornados. This was the most helpful site we found in regards to our project.  (I REPEAT... THE MOST HELPFUL... LOOK HERE)

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J: Okay... now, I am not the one who knows source coding... so I am going to do it the old fashion way... mwa ha ha ha ha! 

J: By the by, this was made by Jennifer Ng and Lauren Helton... Team Extraordinaire! (Way cooler name than team sausage... they don't even have secret messages on their website... and they are not cool enough to be capitalized) te he he he he!

J: ...now... I am not sure that you all noticed... but the hyperlinks are the colors of light!!! YAY

(okay... remember.. blue, red, green... that's right)

sorry... Jen (that would be me...) is a little too happy about making this website... Shini (known to you all as Lauren) is laughing though, so it's okay... 

::claps hands in excitement::