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Shrouded Turbine in a Spinnaker under a Lifter
A spinnaker sail is used in downwind sailing and is practical to fly under
a lifter kite (or aerostat) as a variable drogue power element that also
contributes considerable lift. There is even an old trick of
spinnaker-flying whereby sailors fly out from their boat using the sail
like a kite.
A shrouded/ducted turbine set at the "belly-button" of a spinnaker sail
would have a greatly enhanced output due to the pressure differential
between the windward and leeward sides of the sail. In effect the sail
acts as an effective concentrator/diffuser structure, but its still just a
piece of cloth. Experimenting with this rig would help move forward the
debate of "rigid v. soft".
Spinnakers are launched with low actuation forces from tubes or sleeves
and doused by a recovery patch (and line) in the belly of the sail. This
process would stop and start the turbine under positive control. Trimming
the spinnaker's flight angle can tune the turbine output to its load. A
properly shrouded turbine would not foul with its spinnaker, and its
conductive line can be integrated into the recovery line.
Small used spinnakers are cheap and a small shrouded turbine is not hard
to cobble from scrap. This low-complexity concept could scale into the
megawatt range.
CoolIP
~Dave Santos 15October2011
AWE4481
Comment and development of this topic will be occurring here.
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- The following is different from what DaveS mentions above, but it is
involving lifter and huge sails. The inventor is concentrating on
hydrogen production. Method is in public domain.
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