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21st Feb 2010
Winds, Wings, Whale Fins and Wind Power
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How can we make the most of the wind? In this week's Naked Scientists, we find out how Humpback whales have inspired a new, more efficient design for turbine blades and stall-resistant aeroplane wings and how an inflatable wind generator flies like a kite to extract energy from high altitude winds anywhere in the world. We also hear how a specially-designed wind generator has helped Antarctic-based scientists save 30 thousand litres of diesel. Plus, a simple programme to cut child deaths in the developing world by 30 percent, a new technique for keeping tabs on tumours and a sugar-based solution for keeping virus vaccines fresh without fridges...
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News
Researchers funded by the US National Institutes of Health and the Bill and Melinda Gates Foundation have discovered that a short training course can help to cut the rate of stillbirths by more than 30 per cent in developing countries...
Scientists have discovered a new, much more sensitive way to detect cancers and follow their response to therapy as well as monitor patients for signs of relapse...
Researchers in Australia have managed to use cotton thread and sewing needles to stitch together a “lab-on-a-chip” – technology that could one day be used for cheap diagnostic tests for medicine...
Scientists have discovered that cells use the biochemical equivalent of a chemical dimmer switch to control their metabolism.
Questions

Is the use of bumps on turbine blades similar to putting dimples on golfballs?
We posed this question to Professor Frank Fish from Westchester University...
It has similarities, but there are distinct differences. What a golf ball does by having the dimples on it is to turbulise the air over the surface of the golf ball. So normally air will move in nice, even layers over a surface, and that’s what we call laminar flow. The trouble with laminar flow is it’s not very stable. You can't maintain it at very high speeds or with very large entities. And so, by having the dimples that turbulises the flow over the golf ball, which means that the flow will continue over more of the surface, and as a result, there’s less resistance, and the ball travels further when it’s hit. With the tubercles, or these bumps along the leading edge, what they do is they do create a different flow regime, but not necessarily turbulising the flow. What they do is they produce large swirling masses of flow, what are called vortices. And these vortices interact over parts of the wing to actually help to speed up the flow over say, the bump itself and keep that flow attached over the entire surface of the wing, so that you don't stall out.

Why is it colder at higher altitudes?
Well, the reason, Dennis, is if you think about it, the distance between the Earth and Sun is a very long way. It's a hundred million miles or so. And therefore, the distance between the Earth's surface and the top of Everest at 29,000 feet is a tiny fraction of the total distance to the Sun. In the grans scheme of things it's a trivial change in the actual distance. So that isn't why the temperature changes and therefore it isn't hotter.
The reason it's actually colder is because as you go up in the atmosphere is that the Earth's atmosphere feels less pressure the higher up you go. So as the gas in the atmosphere rises it feels less pressure, which makes it expand.
When the gas expands it does some work. And and if it's doing work, it must be losing some energy; and if it loses energy, its temperature must drop because we define temperature as the average energy of the particles.
Therefore, if the energy of the particles is lower, the temperature must be lower. That's why, at altitude, the temperature appears to fall.
In space, outside the earth's atmosphere, if you're facing the Sun, you can actually fry. That's why space suits are specially designed in order to keep people from getting too hot in the sunny bits but also prevent them from becoming too cold in the non-sunny bits.

Can whale fin dimples be used on aeroplanes?
We posed this question to Professor Frank Fish from Westchester University...
The quick answer is yes. What it allows us to do is to make the wing and the aeroplane safer because you can operate at higher angles and really go beyond where a plane wing would normally stall. As a result, you don't need all the mechanics and extra control surfaces that you find on aeroplane wings. You can eliminate those and all the heavy components that go with it. That makes it more economical for a plane to fly because now, you've lightened the plane, this makes it easier to get off the ground, and to fly along. And this way, you can either make it cheaper to fly or you could actually take your wing and add more fuel in there, the result being that you can extend the range of the plane. You won't have to make as many stops. So, this is potentially beneficial to airplanes as much as windmills or any other lifting surface.
Kitchen Science
Make your own model weather system in a bowl of water.
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Interviews
Matt Cottingham explains how undetanding the structure of the resurrection plant could help us create live vaccines that are able to withstand hot climates...
Professor Frank Fish explains how a sculpture of a humpback whale triggered a whole new design for wind turbines...
Meera Senthilingam explores how wind turbines can be designed to withstand the cold temperatures of Antarctica in order to reduce the consumption of diesel fuel at research stations...
Pierre Rivard explains how inflatable wind trubines could help us harness the great winds we see at high altitudes...
It's been 10 years since Dr Chris and Dr Kat first appeared on the radio! Listen back to some clips of that first show to see how much they've changed...
QotW
I've read that painting rooftops white can help to cool cities. So does ploughing away the snow warm the earth up and add to global warming?
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