Coanda Flow Hull Drag Reduction via Fluid Jetting
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Solution Overview
Problem
Existing methods for reducing ship resistance and drag on vessel hulls are limited in effectiveness, as traditional hull design optimizations and material advancements can only go so far in minimizing frictional resistance.
Innovation Solution
The creation of Coanda flows on the hull of a vessel by jetting a fluid, such as water, onto the hull above the waterline, which extends below the waterline and entrains air to form an air cavity, thereby reducing frictional resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional hull design optimization and advanced materials are used, then manufacturing precision and strength are improved, but drag reduction is limited
Solution Approach 1:
A liquid Coanda flow is introduced as an intermediary between the hull surface and the surrounding water. This liquid layer acts as a mediator that reduces direct contact and friction between the hull and water, significantly decreasing drag while the hull maintains its traditional optimized design
Solution Approach 2:
The invention utilizes hydraulic principles by employing a liquid jet (Coanda flow) to create a boundary layer between the hull and water. The liquid flow adheres to the hull surface and extends into the water, reducing friction through fluid-fluid interaction rather than solid-liquid contact
2Object-generated harmful factors
If friction-reducing fluids are sprayed on the hull, then drag is reduced, but the system complexity increases
Solution Approach 1:
The liquid Coanda flow system is designed to be self-sustaining, where the liquid jet automatically adheres to the hull surface and extends into the water without requiring complex control mechanisms. The Coanda effect itself provides the self-direction and attachment functionality, reducing the need for additional control systems
Solution Approach 2:
The liquid Coanda flow serves multiple functions simultaneously: it reduces frictional resistance, creates a protective boundary layer, and can be applied to various hull shapes and sizes without modifying the fundamental mechanism, making the system universally applicable across different vessel types
3Object-generated harmful factors
If air cavity is created between hull and water, then drag is significantly reduced, but energy consumption increases
Solution Approach 1:
The invention changes the physical parameters at the hull-water interface by introducing a liquid Coanda flow that creates an air cavity. This parameter change transforms the contact interface from solid-liquid to air-liquid, dramatically reducing friction while the energy input is only required to maintain the liquid jet, not to continuously generate the air cavity
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 method significantly reduces drag on the vessel by minimizing friction between the hull and surrounding water, with the air cavity accounting for approximately 95% of the reduced friction, leading to lower fuel consumption and emissions.
Implementation Method 1
The Coanda effect is a natural phenomenon whereby a fluid jet, when directed at a convex surface, stays attached to the convex surface, creating what we will refer to as a Coanda flow. The jetted fluid may follow a flat or curved surface
Implementation Method 2
The jetted fluid may follow a flat or curved surface and also may entrain fluid from the surroundings. A region of lower pressure may develop adjacent to or in the area of the Coanda flow.
Implementation Method 3
creation of an air cavity between the forced Coanda flow and the water in which the hull is traveling through... significantly reduces drag on the vessel by minimizing friction between the hull and surrounding water, with the air cavity accounting for approximately 95% of the reduced friction
Data Source
AI summary
Disclosed is a method of reducing drag on the hull of the vessel by creating a Coanda flow on the hull by jetting a fluid onto the hull or surface continuous with hull at a location above the waterline in the vessel. The Coanda flow extends below the waterline, entraining air below the waterline and adjacent to the hull. The Coanda flows generated by the free jets impacting targets embedded in wear plates can be created in any direction relative to the vessel forward direction. An air cavity is also created by the jetted fluid. A system for reducing drag is also disclosed, wherein the system includes a pump in fluid communication with a source of fluid, power source connected to the pump and at least one nozzle positioned above the waterline of the vessel and oriented towards the hull of the vessel so as to jet the fluid thereon.