Modular Foil Sections with Adjustable Angle of Attack for Towed Arrays
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Solution Overview
Problem
Conventional marine depressors for maintaining seismic equipment at submerged depths have poor aspect ratios, leading to low lift and difficulty in maintaining stable depth across varying operational speeds, and deadweight methods provide constant downforce regardless of tow speed.
Innovation Solution
A marine array with modular foil sections coupled by converging cables, adjustable by actuators to alter tension, allowing control of the angle of attack and lift generation for precise positioning and depth maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional depressors are used to maintain equipment at submerged depth, then depth maintenance is achieved, but the aspect ratio is poor resulting in low lift and high drag
Solution Approach 1:
The depressor is divided into multiple foil sections (first foil section, second foil section, etc.) arranged in series along the tow line. Each foil section can be independently configured with specific aspect ratios optimized for hydrodynamic efficiency. This segmentation allows the system to achieve high lift-to-drag ratios while maintaining depth stability, resolving the contradiction between reliability and device complexity.
Solution Approach 2:
The foil sections are connected through cables that allow dynamic adjustment of the foil configuration. The cables can be tensioned or relaxed to adjust the angle of attack and spacing between foil sections, enabling the system to adapt to varying tow speeds and water conditions. This dynamic capability maintains optimal hydrodynamic performance across different operating conditions while preserving depth maintenance reliability.
2Force
If deadweight is used to generate downforce, then constant downforce is provided, but the downforce does not scale with tow speed and depth stability is compromised at varying speeds
Solution Approach 1:
The hydrodynamic foil sections generate lift forces that are dynamically dependent on water flow velocity (tow speed). By changing the geometric parameters of the foils (aspect ratio, angle of attack, spacing) and the flow conditions, the system automatically scales the downforce to match tow speed variations. This eliminates the need for deadweight and provides both constant proportional downforce and speed adaptability simultaneously.
3Force
If high aspect ratio wings are used to generate high lift, then lift-to-drag ratio improves, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The high aspect ratio foil system is segmented into multiple standardized foil section modules that can be manufactured separately and assembled along the tow line. Each module uses conventional hydrofoil geometry that is easy to manufacture, but when combined in series, achieves the overall high aspect ratio configuration. This modular approach simplifies manufacturing while preserving the hydrodynamic efficiency of high aspect ratio wings.
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 dynamic adjustment of foil sections to generate varying lifts, facilitating stable depth and lateral positioning of seismic receivers, even in changing marine conditions, enhancing operational flexibility and efficiency.
Implementation Method 1
A modular foil system is coupled with the cable and configured to bias the payload toward a target position. The modular foil system includes a group of foil sections collectively defining an angle of attack.
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A marine array having various embodiments of a modular foil system is disclosed. The modular foil system may be configured to generate lift when towed in a marine environment, and thus used to move, position, and/or depress instrument of the array. The modular foil system may include multiple groups of foil sections, each having an angle of attack that is adjustable relative to other groups of foil sections. For example, each group may be supported by a pair of through cables, and an actuator may adjust a tension in one or both of through cables, thereby alerting the angle of attack. The pair of through cables may converge toward one another at connection points adjacent opposing ends of a given group of foil sections of the modular system. The connection points thus establishing a modular framework to couple the given group to other groups of foils of the system.