Flow Booster Trawl Door Lift Capacity
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Solution Overview
Problem
Current trawl doors face limitations in achieving high lift coefficients, dynamic stability, and efficient space utilization due to their design, which results in increased size, weight, and operational constraints, as well as interference from sensors that reduce lift capacity and increase drag.
Innovation Solution
The introduction of a flow booster, which pre-speeds up the fluid flow over the trawl door, increasing lift force per area, and utilizes internal cavities for buoyancy and gravity elements to enhance stability and accommodate technical equipment, while also allowing for angled spanwise sections and reduced material usage for structural support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the planar area of the trawl door is increased to achieve higher lift force, then the lift coefficient increases, but the size, weight, and handling restrictions increase
Solution Approach 1:
The invention changes the hydrodynamic parameters by introducing a flow booster that pre-accelerates the water flow before it reaches the main hydrofoil sections. This parameter change in flow velocity allows the trawl door to generate higher lift forces without increasing its planar area or weight, as the lift coefficient is enhanced through improved flow conditions rather than increased surface area
2Force
If the planar area of the trawl door is increased to achieve higher lift force, then the lift coefficient increases, but the drag increases
Solution Approach 1:
The flow booster modifies the flow parameters by pre-accelerating the water, which increases the lift-to-drag ratio. The main hydrofoil sections then operate in this pre-conditioned flow, generating higher lift forces with reduced drag compared to conventional designs of the same size, as the flow is already optimized for efficient lift generation
Solution Approach 2:
The flow booster performs a preliminary action by pre-accelerating and conditioning the water flow before it reaches the main hydrofoil sections. This preliminary flow preparation reduces the drag on the main sections while maintaining high lift generation, as the flow is already at optimal velocity and pressure conditions
3Measurement precision
If sensors are positioned adjacent to the hydrodynamic surfaces for measurement, then measurement capability is provided, but the fluid flow is blocked reducing lift capacity and increasing drag
Solution Approach 1:
The invention nests the sensors inside the internal cavity of the flow booster structure. This nesting allows the sensors to be positioned within the trawl door assembly without protruding into the external fluid flow path, thereby maintaining measurement capability while eliminating the flow blockage that would reduce lift capacity and increase drag
4Force
If more spanwise sections are used to increase lift force, then the lift coefficient increases, but the device complexity increases
Solution Approach 1:
The flow booster changes the flow parameters to achieve higher lift coefficients with fewer spanwise sections. By pre-accelerating the flow and optimizing the hydrodynamic conditions, the main hydrofoil sections generate more lift per section, reducing the need for multiple complex spanwise sections and their associated endplates and structural components
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 design achieves a lift coefficient increase of over 25% and improved dynamic stability, reducing drag and enabling a more compact, efficient trawl door with enhanced operational capabilities and space for sensors and equipment.
Implementation Method 1
The flow booster 8 is a thick hydrofoil or bluff body that pre-speeds up the flow over the suction side of a sequence of spanwise sections 20 with one-sided hydrofoils 14
Implementation Method 2
The flow booster 8 may also be used to provide space for buoyancy and gravity elements that contribute to the dynamic stability of the trawl door 37
Data Source
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AI summary
A flow booster (8) is disclosed, shaped as a thick hydrofoil with an internal cavity (32), being aerodynamically inefficient on its own with a bulky relative thickness larger than 24 %, and being arranged to be positioned substantially below the rear part of a trawl door (37) comprising an overlapping sequence of several very slender hydrofoils (2), in such a way that the flow booster (8) forms a structurally connected integrated part to the hydrofoil (2) and impacts the upstream flow forcing it into a velocity boosted region (28) upstream of the flow booster (8) and to the pressure side (31) of the conventional part of the trawl door (1), such that the flow is pre-accelerated prior to running through the conventional trawl door channels (29) between the hydrofoils (2). Furthermore, a trawl door (39) comprising such a flow booster (8) and some uses of such a trawl door is disclosed.