Love-Wave Surface Drag Control With Low-Power Shear Actuation
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Solution Overview
Problem
Existing systems for controlling surface drag are inefficient and unreliable, particularly at high flow speeds and frequencies, due to power requirements and unwanted flow fields, and lack scalability and durability.
Innovation Solution
A system comprising a surface, an actuator, and a controller that generates Love waves to modify drag by creating a shear wave in a plane of the surface, using a multilayer stack with materials of differing shear-wave speeds to facilitate continuous and localized deformation, reducing power consumption and mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional actuators are used to control surface drag, then drag modification is achieved, but power consumption increases and reliability decreases at high flow speeds
Solution Approach 1:
The patent replaces conventional mechanical actuators with a piezoelectric actuator that generates shear waves through electro-mechanical coupling. This substitution eliminates the need for high-power mechanical systems while achieving effective drag control through acoustic wave generation in the multilayer stack structure
Solution Approach 2:
The patent utilizes mechanical vibration in the form of shear waves propagating through the multilayer stack. The piezoelectric actuator generates these vibrations at specific frequencies that resonate with the structure, creating surface deformations that modify drag without requiring continuous high-power input
2Adaptability or versatility
If conventional drag control systems are used, then drag modification is achieved, but scalability and durability are limited
Solution Approach 1:
The multilayer stack structure serves multiple functions: it acts as both the structural component and the medium for wave propagation. The same structure enables drag control, turbulence reduction, and potential sensing applications, making the system scalable across different flow conditions and geometries without requiring separate systems for each function
Solution Approach 2:
The patent achieves scalability by changing operational parameters (frequency, amplitude, mode of vibration) rather than redesigning the physical structure. The multilayer stack can operate at different frequencies and modes to control drag across various flow speeds and geometries, providing versatility without increasing device complexity
3Reliability
If surface deformation is used to control drag, then drag modification is achieved, but unwanted flow fields and mechanical stress increase
Solution Approach 1:
The patent applies local quality by generating shear waves that create localized surface deformations only where needed. The piezoelectric actuator targets specific regions of the multilayer stack, producing controlled surface undulations that modify drag without creating large-scale unwanted flow fields or excessive mechanical stress across the entire structure
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
Enables effective and power-efficient control of surface drag, reducing turbulence and improving efficiency in various transportation modes and fluid flow systems by minimizing unwanted motion and wear, while maintaining mechanical robustness.
Implementation Method 1
The actuator can cause the surface to generate a Love wave
Implementation Method 2
cause the surface to generate a shear wave in a plane of the surface that modifies drag in the fluid
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A system includes a surface (308), an actuator (304), and a controller (320). The surface (308) has a fluid flowing over the surface. The actuator (304) is coupled to the surface (308) to move the surface relative to the fluid. The controller (320) causes the actuator (304) to cause the surface to generate a surface wave that modifies drag in the fluid. The actuator (304) can cause the surface to generate a Love wave.