Controllable Surface for Underwater Boundary Flow
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Solution Overview
Problem
Conventional flow-control systems for underwater vessels face challenges in reducing drag and noise caused by turbulent fluid flow, as they primarily rely on tangential displacement of rubber layers, which limits direct and accurate flexure control and increases complexity, leading to inefficiencies in propulsion and energy usage.
Innovation Solution
A controllable fluid-contacting surface apparatus featuring a flexible membrane with electromagnetic actuators positioned offset from the membrane, allowing for flexure forces perpendicular to the membrane, which reduces frictional drag and delays the transition from laminar to turbulent flow, incorporating a programmable electronic controller and software to adjust actuator energization for optimal membrane shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If tangential displacement of rubber layers is used to reduce drag, then noise from turbulent flow is reduced, but flexure control accuracy is limited and device complexity increases
Solution Approach 1:
The continuous rubber layer is segmented into discrete segments along the flow direction, with independent actuators controlling each segment. This segmentation enables localized flexure control without requiring complex continuous actuation systems, reducing overall system complexity while maintaining drag and noise reduction effectiveness.
Solution Approach 2:
Instead of applying tangential forces parallel to the membrane surface as in conventional systems, this invention applies perpendicular flexure forces to control membrane deformation. This inversion of the force application direction simplifies the actuation mechanism while achieving superior control accuracy for drag and noise reduction.
2Object-affected harmful factors
If tangential displacement of rubber layers is employed, then turbulent flow is reduced, but direct and accurate flexure control is limited
Solution Approach 1:
The invention inverts the conventional approach by applying perpendicular flexure forces instead of tangential forces. This allows direct control of membrane deformation with higher precision, enabling accurate manipulation of the boundary layer to reduce turbulent flow while maintaining laminar flow conditions.
Solution Approach 2:
The membrane is designed as a dynamic, flexible structure that can be actively deformed by independent actuators. This dynamic capability allows real-time adjustment of membrane shape to optimize flow control, improving flexure control accuracy compared to static rubber layers.
3Object-affected harmful factors
If conventional flow-control systems are used, then drag reduction is achieved, but propulsion efficiency is reduced and energy consumption increases
Solution Approach 1:
By segmenting the membrane and using independent actuators, the system achieves more effective drag reduction through localized control. This prevents energy-wasting turbulent flow transitions and maintains laminar flow over a longer portion of the surface, reducing overall energy consumption while achieving drag reduction.
Solution Approach 2:
The system incorporates sensors and controllers that monitor flow conditions and adjust membrane deformation in real-time. This feedback mechanism ensures optimal drag reduction is maintained while minimizing energy consumption by only actuating when and where necessary to prevent turbulent transition.
4Manufacturing precision
If more actuators are placed closer together, then spatial resolution and actuator stroke improve, but device complexity increases
Solution Approach 1:
The actuators are arranged in a two-dimensional array pattern on the membrane surface, allowing dense packing with improved spatial resolution. This dimensional arrangement enables multiple actuators to be positioned closer together without excessive mechanical interference, achieving high precision control while managing packaging complexity through systematic layout.
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
This configuration provides more direct and accurate flexure control, reduces frictional drag, delays turbulent flow transition, and enhances propulsion efficiency and energy savings while minimizing wake signatures.
Implementation Method 1
multiple actuators each having an output shaft or activation member coupled to a water-contacting membrane
Data Source
AI summary
An apparatus including a controllable fluid-contacting surface is provided. In another aspect, the present apparatus includes a flexible membrane and multiple actuators each having an output shaft or activation member coupled to a water-contacting membrane, with the shafts extending in a direction offset from the nominal outer surface of the membrane. A further aspect of the present apparatus includes an underwater vessel including a propulsion source, a flexible membrane having a water-contacting outer surface and an electronic controller including programmable software for actuating the actuators.