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PHXcoach wrote:I posted a test to the test exchange http://scioly.org/wiki/index.php/2016_T ... Wind_Power. I am not sure if it was going in the correct direction since there aren't any other wind power tests posted so any thoughts / suggestions are welcome

I appreciated seeing the test you put up. I wrote a couple tests for local invitationals and struggled to write questions that were within the five subject areas given in the rules and that were also meaningful questions. I thought you did a pretty good job with this.

I did have a question about #2.

The questions asks:
What is the wind energy passing through a wind turbine with the following conditions? Turbine radius = 0.2m, Wind speed = 3 m/s, Air density = 1.23 kg/m^3 .

The answer given is:

0.5 A ρ v^3 = 0.5 * (2 * pi * 0.2) * 1.23 * 33 = 0.628 * 1.23 * 27 = 20.85588 W


It looks like the answer is solving for the Power available in the wind, rather than Energy? Am I misunderstanding some of the terminology?

Also, it seems that you used the formula for Circumference (2*pi*r) rather than Area (pi * r^2).

PHXcoach wrote: I think that using the 5cm tape on the table to align against the stand base may be incorrect. The rules require 5 cm from the blade assembly to the front of the fan grill. If the blade assembly sticks out in front of the CD a lot (e.g. a pin wheel design) then shouldn't the measurement be from the front of the blade to the fan grill rather than from the CD mounting point to the fan grill? (maybe I am guessing incorrectly as to how the 5cm tape was being used)

You are correct. This is just as a visual reference for the front of the blade assembly, not the base.

Full Power wrote:

PHXcoach wrote:I posted a test to the test exchange http://scioly.org/wiki/index.php/2016_T ... Wind_Power. I am not sure if it was going in the correct direction since there aren't any other wind power tests posted so any thoughts / suggestions are welcome

I did have a question about #2.

The questions asks:
What is the wind energy passing through a wind turbine with the following conditions? Turbine radius = 0.2m, Wind speed = 3 m/s, Air density = 1.23 kg/m^3 .

Also, it seems that you used the formula for Circumference (2*pi*r) rather than Area (pi * r^2).

Thanks - you are correct. The answer is in Watts so is a power. I fixed the wording and the answer key and uploaded them

PHXcoach wrote:

Full Power wrote:

PHXcoach wrote:I posted a test to the test exchange http://scioly.org/wiki/index.php/2016_T ... Wind_Power. I am not sure if it was going in the correct direction since there aren't any other wind power tests posted so any thoughts / suggestions are welcome

I did have a question about #2.

The questions asks:
What is the wind energy passing through a wind turbine with the following conditions? Turbine radius = 0.2m, Wind speed = 3 m/s, Air density = 1.23 kg/m^3 .

Also, it seems that you used the formula for Circumference (2*pi*r) rather than Area (pi * r^2).

Thanks - you are correct. The answer is in Watts so is a power. I fixed the wording and the answer key and uploaded them

Why is the name of this thread now invitational test???

You can change the subject when you're posting. If you reply to another post that changed the subject, then you will keep that subject. I didn't reply to one of those posts, so the topic is normal.

Would spoons be an acceptable blade design for the event? ( Out of our designs, the blade assembly with the spoons produced the most voltage at high and low speeds)

MariaK wrote:Would spoons be an acceptable blade design for the event? ( Out of our designs, the blade assembly with the spoons produced the most voltage at high and low speeds)

Yes, as long as they fit the size parameters. You'll probably want to look over the rules to be sure.

Want to see if anyone has seen different performance.
in the attach picture, the leading edge is the straight untapered side.
In all actual wind turbine, the blade rotate in the direction of leading edge. But in our design, we get better performance when blade rotate into the tapered edge.
I want to see how we can improve, but having it spin into the leading edge is not improving.

AGH wrong account again

soyuppy wrote:Want to see if anyone has seen different performance.
in the attach picture, the leading edge is the straight untapered side.
In all actual wind turbine, the blade rotate in the direction of leading edge. But in our design, we get better performance when blade rotate into the tapered edge.
I want to see how we can improve, but having it spin into the leading edge is not improving.

Actually, ours does the same thing... weird.