Your blade calc is great piece of software although, I’m confused about some measurements and must ask about it:
1. When you say radius, do you mean radius of one blade or whole turbine?
2. When I put these parameters:
It says that blade in its root must be 2.562 m wide?! Is this some kind of error in calculations or what? Or i mismatched or misunderstood something? Is the width of the wing, right? If so, it would be strange if the wing length of 2.1 meters is 2.5 meters wide at the base?? Then it's a tent, not a wing of wind generator :)
Question 5: Answer
The radius is the distance from the center outwards. For example, if the blade radius is 4.2 m, one blade is 4.2 m. The overall diameter (distance across) is 8.4 m. If the theoretical chord size is about 2.5 m at the root, this is almost impossible to build.
This is a THEORETICAL size for if you wanted to continue the shape all the way to the middle of the wing. Most blades don't do this and neither do we. We use the chord sizes generated by the software from the tip to as close as possible to the hub, but when they get too large (or too close to the center) we taper the wing back in size to fit onto the hub. This way we have a shape as close as possible to the theoretical for most of the blade except for the distance closest to the center. We have to make the center part of the wing smaller for convenience and this is the same with almost all wind turbine blades.
Thank you for sharing your design for the 500 W turbine. I am very interested in building similar. I plan to build the blades first and would be very grateful if you could answer the following;
1. Our average wind speed is 11knts (20km/hr), would a T.S.R of 8 be okay?
2. Approx what would start up speed be?
3. How noisy are these blades as live in a suburban setting?
I am hoping to have tail furling before blade noise gets to loud.
To answer your question, the blades will spin at 20 km/h but the output will be very low (~50 W). Real power begins to be generated at 30 km/h and the blades begin to generate thrust. T.S.R. of 8 is OK but no higher, try to match the blade TSR to the generator RPM. The blades shown are not noisy even at 50 km/h and cannot really be heard above the noise of wind through trees and other objects
Question 6: Answer
Question 7: Answer
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TSR = 6
Blades = 3
Efficiency = 0.35
Wind speed = 14.4 km/h
Blade length = 4.2 m
Can you help us design a turbine that is efficient and safe to meet the requirements of EN 61400?
The structural requirements are specific to your location. You may need to follow a procedure given in the standards documentation and verify the physical strength: WG8 Full Scale Structural Testing of Rotor Blades for WTGS: (from "http://www.awea.org/standards/iec_stds.html")