04-21-10, 07:38 AM | #11 | |
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Testing will show me the minimum wind speed required to meet the minimum power and voltage required to start a grid tie inverter. Information can be gathered to help me decide when I want the turbine to furl. I can then put the proper weighted tail fin on and test the furling with the test rig. With the test rig I don't need to wait for big wind to see if these blades are a good match for the generator, I can observe it under controlled wind speeds to be sure it performs safely and properly overall. Since there should be minimal wind on test day, I will use the truck speedometer for the as-tested wind speed. This is as good as I can do it without a good anenometer mounted up stream of the turbine. I have a cheap hand held wind speed meter, but I don't trust it's accuracy. |
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04-21-10, 07:50 AM | #12 |
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I forgot to explain the orientation of my test rig.
Researching test rigs I saw many ways of doing it. The ones mounted all the way out front seemed the best for clean wind. I couldn't think of a good temporary way to do that. I saw alote mounted with the rotor near the front of the cargo bed and above cab height. That seemed like a good way to go , except the air coming over the cab is going to mess with things. Then I started seeing other people testing with the rotors back near the tailgate and up high. I tried looking at the way the air travels over a truck, and it seems to me like the farther back the better as long as it's up high. So that's what I'm going to try. The vertical support will be up against the tailgate. It's not perfect, but I believe I can obtain useful data using this set-up. |
04-21-10, 08:52 AM | #13 |
Lex Parsimoniae
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I hope you have someone to help you take the data or do the driving.
Hopefully there aren't any low hanging limbs or wires to worry about, on your test route.. Maybe you can mount a camera in back of the cab, looking up towards the blades, maybe get some video of the action as the truck gets up to speed. Good luck and stay safe.. Rich |
04-22-10, 09:32 AM | #14 |
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With it mounted on your roof how are you going to brace the building to handle the wind load? a turbine prop is, from a load point of view seen as a solid disk or sail when the wind is hitting it, that can be alot of force.
Also the basic rule of 50 feet above anything within 500 feet treats the top of the roof as you would treat the ground level, just like if you put a turbine up in a forest you need to be 50 feet above the top of the tree line, otherwise you get turbulence and enough variation in wind speed that the machine will rip it's self appart, why? a 1mph difference in wind speed at 12mph is almost twice the force pushing on the blades, so if the top tip is seeing 12mph and the bottom tip is seeing 11mph that top tip, at 50 feet in the air this is not uncommon to see, at 10 feet in the air I can't say exactly what the difference is going to be but I'd like to see a video of it. |
04-22-10, 10:41 AM | #15 | ||
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I still need to finish bleeding my brake system before any testing can start.
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04-22-10, 10:48 AM | #16 | ||
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Last edited by jwxr7; 04-22-10 at 02:14 PM.. |
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04-22-10, 11:24 AM | #17 |
Lex Parsimoniae
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04-22-10, 02:15 PM | #18 |
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04-24-10, 05:03 PM | #19 |
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I trimmed the trees in the driveway and drove the route with a fiberglass pole that extended a few inches taller than the turbine would. There was good clearance on the road from what I could tell. I put the turbine on the test rig in the back of the truck this morning. It has been sprinkling all day, so I wrapped the head of the turbine in a plastic bag since it hasn't been weather proofed yet. It's been breezy so I haven't tried any testing while driving.
I have done a few preliminary tests. I aimed it into the breeze with no load (open circuit) and took a few voltage measurements against my handheld anenometer. It starts turning with a 5-6mph breeze. It reaches 12volts dc at 9-10mph. The highest wind I gathered data from was 12.5mph, where it put out 19volts dc. Keep in mind, these numbers give no real indication on power output. I didn't do any loaded testing since the winds were so sporadic. The grid tie inverters I've been most interested in, require 10.5 volts minimum and around 10 watts to start feeding the grid. I will try getting some driving numbers when conditions permit. |
04-25-10, 12:06 AM | #20 |
Lex Parsimoniae
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That's one neat looking test rig! Try not to speed!
Wind load can cause damage pretty quick. Once I had some 4'x8' paneling on a roof-rack, and only got up to about 30 mph when I hear this loud snap.. Then it was 4x6 panels... |
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