Drag comparison mini presentation
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Transcript of Drag comparison mini presentation
Drag comparison Cable Protection Systems
Do Product Diameters Really matter?
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The Short answer is YES they do.A section exposed to dynamic influences will experience drag induced forces.Based on Hydrodynamics the formula for Drag is defined as:
Where:
As area is directly related to diameter we would expect the diameter to influence resulting drag forces
Simple Explanation
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Plastic System OD : 400mm
CPNL System OD : 260mm (Max)Area of Drag for 4m Length : 1.6m2
Area of Drag for 4m Length : 1.04m2
Reduction in Drag Area of 35%
400mm
260mm
The Result
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From the equation, the resulting drag force is directly proportional to the area exposed to moving fluid.
Water Velocity (kts)
Dra
g Fo
rce
(kgF
)
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
Plastic System
CPNL System
Figures based on force applicable on a 4.3m length cylinder
Conclusion
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A larger OD diameter will increase forces associated with Drag, vs a smaller OD System.
These systems require thicker walls, which increase thermal insulation of the power cable
The increase in forces invariably results in a need for additional material to prevent failure.
More material, results in higher likelihood of issues during plastic production process, not to mention cost.
These increased forces will be present throughout the lifetime of the system, but cannot be designed out in a plastic system due to material limitations.
Video
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