I just noticed a pattern.
Doing 120 Things in 20 years has taught me a few things about myself. One is that whenever I need to discuss aerodynamics, my medium of choice gravitates toward crayons and my seemingly limitless ream of old dot matrix printer paper rather than animation or 3D design tools. Interestingly this was my preferred media for everything when I was a five year old.
I have no idea what that means.
A modern wind turbine blade has a few improvements over the old water pumping windmills. It's blades don't just get moved out of the way by the wind, the blades interact with the wind in a much more amazing way.
Yep, that's right, to the sky.
A fast modern jet might have a shape, and angle of attack more like "B"
*Do not use these crayon drawings to build a modern, high speed jet. It's possible they may have not been as rigorously tested as they should be.
If we put the bi-plane wing on the jet, it would slow the thing down too much, and would geneate hilarious flight antics, and many spilled coffees. If we put the jet wing on the bi-plane we would have a funny shaped, propeller powered car, with wing looking things sticking out the sides. It would never get off the ground, because at bi-plane speeds, it would never generate enough lift.
Point "A" travels only about a quarter of the distance point "B" travels.
If both point "A" and "B" do one revolution, but point "B" travels 4 times the distance, then point "B" must travel a stack faster.
What all this means is that as the turbine is spinning, Point "A" sees the windspeed of the day, PLUS the extra speed it sees because the turbine is spinning. Point "B" sees the windspeed of the day, PLUS AN ABSURD EXTRA SPEED, seen because the windmill is spinning.
This extra windspeed that different points on a blade see, is called "apparent wind". As far as point "B" is concerned the wind speed might feel like 6 times the windspeed someone not standing on the blade might feel. Now, interestingly, we need to take this apparent wind speed into account if we want to use "lift" to power our wind turbine. If we present a blade so that the bottom is flat and point it into the wind, it will lift. If one end of the blade is attached to the centre hub of a wind turbine, it will lift, and rotate. But now the thing is rotating, there is some apparent wind. This means that the wind is no longer hitting the blade from the right angle. It's now hitting more from the top down. We have to rotate the blade so that its interacting with the APPARENT windspeed not the windspeed of the day. Because the blades will be rotating quite fast, most of the wind will present itself almost on the plane of rotation, so we adjust the blades so they are flatter to the direction of spin. I need a model to show this better.
"Why are you telling us this?" I hear you ask.
It turns out very clever people in lab-coats use all this stuff to design really efficient blades.
An ideal blade would be like a bi-plane wing at the centre, where the apparent wind speed is slowest, a jet wing at the tip, where the apparent wind is fastest, and everything else in between.
The more accurately we set all these varying angles the better our wind turbine will work. But we can also get a turbine to work inefficiently. It's up to us. I'll find some nice comfortable spot in between once I've explored a few different ways to go about making a set of blades.
And a model. I'll make a model.
Things so far...
Animation (5) Aquaponics (338) Bread (15) Cheese (14) cooking (49) electronics (57) Epic adventurer (20) Escargot (2) Fire (6) Fraudster (1) Handmade fishing lures (31) Home made preserves (11) Making smoked foods (11) Mold making (7) Movie watcher and critic (2) Photography (17) PVC (36) Snail farming (6) Solar hot water (26) Solar photovoltaic panels (7) Stirling Engines (11) Thinking (48) Vermiculture (1) Wind energy (25)
The bell siphon was a clever thing for someone to design, and as such you feel a bit of that "clever" rub off onto you when you m...
You see CHIFT PIST a lot in the aquaponics forums and it means "constant height in fish tank, pump in sump tank". And its a very g...
A "bell siphon" is a device that automates the flooding and draining of an aquaponics grow bed, even though the pump is adding wa...
Painting lures is easier if you don't know how. I don't, so I'm already well on my way. I started by owning a printer. That ...
A while ago I tried to make a fish fed fish feeder design that would allow the fish to feed themselves. I think It's made. I say &q...
Apparently, marron come in two varieties. Hairy and not so hairy. Cherax cainii (smooth) and Cherax tenuimanus, or Margret River marron (hai...
In aquaponics, one issue that can effect your success rate is the pH of your water. pH is a measure of water's (or soil's or whateve...
With a little practice its possible to make a screw. If you bend your wire into an eyelet, its possible to make a screw in eyelet. The use...
I had an idea, but now I'm not sure it was mine after all. But here it is anyway. I need to get solids out of the water for the NFT, ...
This post is a follow up to the " handmade fishing lures how to get most out of your printer " post describing my way to colour ha...