An interesting little Vertical-Axis ‘windmill’

[Michael GilliganParticipant @michaelgilligan61133]

One of several in the shopping-precinct in Flint

… it was going like the clappers !

MichaelG.

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[peter1972Participant @peter1972]

I used to live in a listed thatched property in an exposed location which is heated by electric storage heaters. Looking up its Energy Performance Certificate online, I see a wind turbine is recommended at a cost of £15,000 to £25,000 which would give a “typical yearly saving” of £725. Of course solar panels could not be fixed to the roof.

[Michael GilliganParticipant @michaelgilligan61133]

These appear to be a combination of the Darrieus and Savonius designs

MichaelG.

[BazyleParticipant @bazyle]

There is an interesting vertical axis in development that is just a column. As you know tall metal chimneys vibrate due to vortex shedding so have spiral ribs running up them that somehow alleviate this. However by encouraging the vibration, making it resonate instead of damping it the movement can be harnessed by a generator. The idea is to have lots of poles in a field looking like a fence and not interfering with crop growing or grazing. This is probably the only sort the National Parks parasites would let me have.

[FulmenParticipant @fulmen]

@Michael: Yup, looks like it. As I recall the Darrieus design isn’t self staring while savonius is.

I must admit I have a particular of love for the egg-beater turbines, I think they are gorgeous.

[Nigel Graham 2Participant @nigelgraham2]

The basic Savonius rotor used to be familiar outside garages, not powering anything but simply a spinning advertising-device for an oil company – Castrol, I think, from memory.

A third rotor, according to Wikipedia, is the Panemone; first known in Persia in the first few centuries CE. Although very inefficient by being simply flat blades on a vertical shaft, such machines drove grain-mills and simple irrigation-water lifters; so their builders deserve our respect as engineers.

 

Yet another is the Pantanemone (sounds as if from His Dark Materials!), invented sometime around the late-19C or early 20C, and, so (Hutton, p.13)* says, “on the continent”. Further reading suggests in France. Such wind-motors need be very large for their power…

The Pantanemone consists of two flat, semi-circular plates joined centrally and perpendicularly, the combination in turn at 45º on a horizontal shaft through the common centre. It is claimed to operate in any wind direction; but on the basic machine illustrated diagrammatically, there seemed no governor or any method for coping with over-high winds.

Two French examples cited drove reservoir pumps, the larger, at Villejuif, raising 15 000 litres of water 10m in 24h; in wind speeds of 5 to 6m/s.

The text gives this horsepower formula for the Pantanemone, which would seem to operate by triangle-of-forces reactions rather than impulse or aerofoil effects:

HP = {[Total sail area in sq. ft] X [Wind velocity in ft/s]^3 } / 1 200 000.

Which doesn’t sound much, and examining the drawing, it is hard to see how the driving force is not fighting the sail faces coming back into the wind.

E.g. 20ft dia sails (as if the pair were joined all along their common diameter) in 15f/s wind give 0.88HP.

We are not told the Villejuif wind-motor’s size, pump type and output purpose; but that quoted rate is only 625 litres or kg per hour; not much over 10 litre / minute. Assuming steady breeze throughout. Though evidently fine for the purpose, rather like the Hydraulic Ram that delivers but a drop per impulse but continuously – and for “free”.

The corresponding formula for the wind-turbine familiar from so many photographs of Australian farms, if designed properly (arithmetically, they are quite fussy), differs only by the denominator being 1 100 000.

 

*Hutton W.S. The Practical Engineer’s Handbook; Crosby, Lockwood & Son, 1911

[Michael GilliganParticipant @michaelgilligan61133]

I have no objection whatsoever to topic-creep [it’s one of the more enjoyable features of this forum] … but would just mention my use of the word ‘little’ in the title.

I will measure the pole next time I’m in Flint, but my guess [viewed from the car] is about 150-200mm diameter.

MichaelG.

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