Flapping Foil Drive Mechanism for Adjustable Shaft Motion
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Solution Overview
Problem
Existing flapping foil systems face inefficiencies due to hydrodynamic disturbances, asymmetrical kinematics, complex mechanical structures, and limited adjustability, which hinder their performance and versatility in applications such as propulsion and energy recovery.
Innovation Solution
A combined flapping drive device for a foil comprising three intercooperating systems (S1, S2, S3) that enable a primary shaft to perform heave translation, roll or pitch swing, and pivoting, allowing for adjustable pitch and transverse movements, with a connection system (S4) to transmit these motions to the foil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a propeller system is used for propulsion, then thrust generation is achieved, but hydrodynamic losses increase due to helical wake, radial pressure variation, and marginal vortices
Solution Approach 1:
The patent inverts the conventional propeller concept by using alternating flapping wings instead of rotating blades. The wings oscillate in a figure-eight pattern, generating thrust through alternating lift forces on opposite sides of the vessel, thereby eliminating the helical wake and radial pressure variations inherent in rotating propellers.
Solution Approach 2:
The patent employs periodic flapping motion of the wings, where each wing alternates between upward and downward strokes. This periodic action creates alternating lift forces that generate continuous thrust while reducing energy losses associated with continuous rotation and vortex formation.
2Adaptability or versatility
If variable pitch propellers are used to respond to different advance conditions, then adaptability improves, but technological complexity increases due to dynamic twisting and restricted hub requirements
Solution Approach 1:
The patent implements dynamic adaptability through adjustable flapping amplitude and frequency of the wings, rather than dynamic twisting of blades. The flapping parameters can be modified to optimize performance across different advance conditions, achieving versatility without the mechanical complexity of variable pitch mechanisms.
Solution Approach 2:
The alternating flapping wing system serves multiple functions: it generates thrust for propulsion, provides steering capability through asymmetric flapping, and can be adapted to different operating conditions by adjusting flapping parameters, all within a single simplified mechanical structure.
3Ease of operation
If additional manoeuvring devices like rudders or pivoting pods are added to propeller systems, then manoeuvrability improves, but device complexity and drag increase
Solution Approach 1:
The patent combines propulsion and steering functions into a single integrated system. The alternating flapping wings generate both thrust and steering control through asymmetric modulation of flapping amplitude or frequency on opposite sides, eliminating the need for separate rudders or pivoting pods and their associated complex kinematic chains.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device achieves efficient, robust, and adaptable flapping motions, enhancing hydrodynamic performance and enabling versatile applications in propulsion and energy recovery systems.
Implementation Method 1
The velocity of movement of the support of the wing indeed generates on this wing a hydrodynamic lift capable of lifting for example a boat hull
Implementation Method 2
to recover the kinetic energy of a fluid or to move a machine or a fluid
Data Source
AI summary
A device for driving a primary shaft, the device including: a first system including an element for driving movement of a control member along a looped trajectory having two axial components; a second system including an element for pivoting the shaft about its longitudinal axis, actuated by the movement of the member along at least one component of the looped trajectory; a third system including an element for driving movement of the shaft, actuated by the movement of the control member along at least the other component of the looped trajectory, the control member projecting from the plane of the components and engaged with both the driving element for pivoting and for moving of the shaft, the movement of the control member along the looped trajectory generating a pivoting of the shaft in alternating directions and its movement in alternating directions.