A Passive Delayed Stall Propulsor for Enhanced Thrust and Reduced Noise

"The Navy has reached the limit of propulsor system development based on conventional steady state aerodynamic theories. Further advances only appear possible through the innovative application of unsteady lift concepts like those found in biological formsof flight. Continuum Dynamics, Inc. (C.D.I.) proposes the innovative application of unsteady lift enhancement through delayed stall, to increase the lift on rotor blades without adding mechanical complexity. Our concept increases propeller performance byharnessing unsteady vortical structures, resulting in either increased thrust or a reduction in propeller rotational speed. Advantages of the proposed concept include: (1) it is a completely passive and robust, with no on-blade actuators or additionalmoving parts; (2) it is easily retrofitted into existing propulsor systems; (3) it works equally well with ducted and unducted, single and counter-rotating propulsors; and (4) It is low cost and will be simple to implement. C.D.I. is uniquelypositioned to develop this concept, having extensive experience in the development of the fast aerodynamic computational tools needed to reduce this concept to practice. The proposed Phase I effort will carry out the conceptual design and hydrodynamicanalysis studies demonstrating "proof of concept," which can then be carried to Phase II/III product development. Development of this thrust enhancement concept for marine propellers offers im