T-Vawt Test Results

[Jacob Rojas]

Hey guys I finally finished some tests / data logging of my new design and have piled everything in to a .ppt I have to give to a few investors. The part that struck me odd was that I technically created a Vawt and I was still able to see an increase in efficiency by 2.7 times between 4.8ms and 7.8ms wind which is where supposedly vawts hit their limit and level out. Maybe you guys can give some insight. Here is the link (https://drive.google.com/file/d/1ZS4foHKfXpfAb2icOKggF7YT_pxEMern/view?usp=drivesdk) for the .PDF

[Rob Beckers]

Hi Jacob,

Part of the problem is that you're measuring Voltage, not power. When you do mention power it's the rated power of the dump load resistors (4x 100W), that doesn't mean you're loading up the turbine with 400W, it would depend on the Voltage over those resistors.

Some of your measurements are unloaded Voltage; unfortunately those are meaningless (if you're making a wind turbine, they could be great for yard-art!). About the only thing you can tell from unloaded Voltage is "it's spinning".

The measurements with the dump load resistor show a maximum of 8.25V (at 6.6 m/s wind). If that's going into a 200 Ohm resistor your turbine is producing a grand total of 0.34 Watt!!

There is no mention of the turbine dimensions, so it's impossible to verify efficiency numbers. However, I can tell you with near certainty you're not getting anywhere near the reported 6%.

Checking your Web site, I don't see any mention of dimensions anywhere, nor at what wind speed "rated power" is reached (ie. mention of a 1.5kW wind turbine is great, but if it will never produce more than a Watt it's fairly meaningless). The Youtube video gives me a rough idea of dimensions of your test model, looks about 1 meter high, by roughly 40 cm width(?). Going with that, the theoretical energy in 6.6 m/s wind and an area of 0.4 m^2 would be 70.0 Watt. Your output is 0.34 Watt. That makes for an efficiency of 0.5%...

Unfortunately the confusion of units continues, with "6+ Volt" being called "DC current" (current is measured in Amp, not Volt, and they have very different meanings).

That confusion runs like a red thread through your Web site; nowhere is a power curve to be found, or energy production. Those would actually convey meaningful information.

By the way, you do realize there is no useful power in very low wind speeds, right? A startup wind speed of 1 m/s doesn't actually mean anything (the wind of a 0.4 m^2 area would carry a whopping 0.25W total power)...

Not to toot my own horn, but it may be helpful to read an article I wrote about small wind turbines: https://www.solacity.com/small-wind-turbine-truth/

Much work to be done...

-RoB-

[Jacob Rojas]

Rob,

As always thanks for the response. The one blade on this turbine is 285mm wide x 980mm tall. The generator is a 1.5kw 220ac rectified full wave to dc. I'll have more information on the generator on Monday as far as when it hits it's peak rpm however from my understanding it is 220ac converted is 24vdc. Is it correct to assume 8.25vdc is around 28% of max of the 1.5kw or 480 watts?