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Optimal Camber for Dual-Mode (Motor/Generator)
Rotors
This is an old topic on this Forum, but its a
good time to update it-
Its known that optimal rotor airfoil camber reverses between AWES
motor/generator modes, and that two sets of solutions exist, but at added
cost and complexity-
One general method is a reversible camber blade that warps chord-wise or
uses slats and flaps. This could be a mix of active servo mechanism and
passive compliance. High passive compliance is revolutionary for
engineered turbines, but could be quite simple and cheap* (tuna fin
model).
The other known solution is a finely profiled fixed-camber variable pitch
blade that "tacks" its incidence between modes. A reversed helical-pitch
elastic warping* is required, with a full rotor rotation reversal.
Conventional transmissions can drive this sort of action by differential
gearing and clutching, but this is high-cost high-complexity mechanism, of
marginal "bleeding edge" value. It may pay in "perfected" versions,
especially with the added power management advantages of multi-gearing. A
key is maintaining the motor/generator in smooth unidirectional operation
by precise clutching and gearing, to buffer rotor churn between modes.
* Aero-turbine blades are evolving to have a tough compliant
(fiber-reinforced) rubbery consistency, much like tire construction.
CoolIP*
~Dave Santos 7Jan2012 AWES5322
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