Scioly.org

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.

I've helped test Wind Direction events. It seems like there are a lot of differences between the turbines that do well on the test stand and what a reliable, economical commercial wind turbine looks like.

Strong designs at the most recent test ranged from two blade designs out of curved plastic to three blade teardrop designs out of corrugated cardboard to plastic sheeting curved into a pinwheel design to two small teardrops mounted on a toilet paper roll. All of these designs spun very quickly.

One big difference between event designs and commercial wind turbines seems to be how three dimensional the blades are. Most of the designs I've seen work by having the air flow push on them, rather than by utilizing the effect of lift on a curved blade. I think you have to consider the fact that commercial wind turbines have a lower rotation rate and a much larger swept area. The test stand converts rotation to electricity right at the hub, not after the rotation has gone through a gearbox to create a higher electrical generation rotation speed.

That's a good point. I originally tried to use a lift design but it doesn't do as well as my drag design. I have 3 wide flat blades, each covering 1/6 of the area inside the 14 cm radius. They're tilted at an angle, of course. If I were to use 6 blades instead, I could cover the entire area. Would this increase the efficiency, having more surface area for the air to push?

FuzzyLogic wrote:That's a good point. I originally tried to use a lift design but it doesn't do as well as my drag design. I have 3 wide flat blades, each covering 1/6 of the area inside the 14 cm radius. They're tilted at an angle, of course. If I were to use 6 blades instead, I could cover the entire area. Would this increase the efficiency, having more surface area for the air to push?

That would also add a lot more weight and thus drag. Also, with six blades (even number), it is likely that you will notice some instability. I've noticed that three blades is typically the best, although that would depend on the rest of the design.

I think I'll try it anyway. My blades are made of balsa wood and tissue paper, so they're very light.

2009 "Physical Science Lab" (Only Div B) seems to have similar questions on wind power and generic power. If anyone has those old tests - do you mind uploading them?

2009 "Physical Science Lab" (Only Div B) seems to have similar questions on wind power and generic power. If anyone has those old tests - do you mind uploading them?

Does anyone know of any 20 cm or longer sphere type buckets out of type 5 plastic?

I built my own testing rig for this season out of a regular DC motor. Do you think I should be concerned about how the fact that this motor probably needs more torque in order to start moving might affect my rotor designs? If so, is it worth the outlay to get a real CD motor?

HandsFreeCookieDunk wrote:I built my own testing rig for this season out of a regular DC motor. Do you think I should be concerned about how the fact that this motor probably needs more torque in order to start moving might affect my rotor designs? If so, is it worth the outlay to get a real CD motor?

Sorry for this late response, but if you haven't already had your comp, I'd recommend getting a CD motor. We got ours for like $3 on Amazon.

dragon_fruit35 wrote:

HandsFreeCookieDunk wrote:I built my own testing rig for this season out of a regular DC motor. Do you think I should be concerned about how the fact that this motor probably needs more torque in order to start moving might affect my rotor designs? If so, is it worth the outlay to get a real CD motor?

Sorry for this late response, but if you haven't already had your comp, I'd recommend getting a CD motor. We got ours for like $3 on Amazon.

Eh, no worries, I was just curious if anyone thought there would be a significant difference. I wasn't really surprised by the lack of response being that it was states season.