Connector Protrusions for Flexible Pipe VIV Suppression
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Solution Overview
Problem
Flexible pipes in riser configurations experience vortex-induced vibrations (VIV) due to water flow, leading to excessive motions and potential fatigue failure, especially when buoyancy aids are used underwater, as they can excite the natural resonant frequency of the pipeline, causing larger oscillations and increased risk of failure.
Innovation Solution
A connector assembly with protrusions, such as strakes or fin elements, is integrated with buoyancy compensating elements to reduce or interrupt vortex-induced vibrations by breaking up vortices and altering the fluid flow around the flexible pipe, thereby suppressing oscillations and reducing the risk of fatigue failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If buoyancy aids are provided at discrete locations along the flexible pipe to counteract the weight of the riser, then the installation cost is reduced and installation time is shortened, but vortex-induced vibrations are intensified and the pipe experiences larger oscillations
Solution Approach 1:
The invention converts the harmful vortex-induced vibrations into a beneficial effect by using the protrusions to intentionally generate controlled turbulence that disrupts the harmful vortex shedding pattern. The protrusions create a turbulent boundary layer that prevents the formation of coherent vortices, thereby converting the harmful VIV into a beneficial flow disruption that reduces oscillations.
Solution Approach 2:
The protrusions on the connector assembly serve as an intermediary element between the buoyancy aid and the flexible pipe. This intermediary structure modifies the fluid flow in the vicinity of the pipe, creating turbulence that interrupts the vortex shedding process and reduces VIV without requiring changes to the buoyancy aid itself or the pipe structure.
2Device complexity
If buoyancy aids are provided at discrete locations along the flexible pipe to support the riser, then installation complexity is reduced, but the pipe experiences excessive motions due to excited natural resonant frequency
Solution Approach 1:
The invention converts the harmful resonance excitation into a beneficial effect by using the protrusions to generate controlled turbulence that damps the natural oscillations. The turbulence created by the protrusions increases energy dissipation and reduces the amplitude of resonant vibrations, thereby converting the harmful resonance into a stabilizing effect.
Solution Approach 2:
The invention changes the flow parameters in the vicinity of the pipe by introducing protrusions that modify the boundary layer characteristics. This parameter change creates a turbulent flow regime that disrupts the coherent vortex shedding and reduces the amplitude of pipe oscillations, effectively changing the dynamic response of the system.
3Ease of manufacture
If traditional smooth connector surfaces are used on buoyancy compensating elements, then manufacturing is simpler, but vortex-induced vibrations cause fatigue damage to the pipe
Solution Approach 1:
The invention converts the harmful VIV-induced fatigue into a beneficial effect by using the protrusions to generate turbulence that reduces vortex shedding. The protrusions create a turbulent boundary layer that prevents the formation of coherent vortices, thereby converting the harmful fatigue-inducing vibrations into a beneficial flow disruption that extends pipe life.
Solution Approach 2:
The invention applies local quality changes by adding protrusions only to specific locations on the connector assembly where they will be most effective in disrupting vortex shedding. The protrusions are strategically positioned to create turbulence in the critical flow regions, providing localized protection against VIV without requiring complete redesign of the entire connector or pipe system.
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
The solution effectively reduces forces exerted on flexible pipes from VIV, prolongs the lifetime of the pipe and riser assemblies, and allows for cost-effective production and installation by minimizing vortex-generated oscillations and enhancing structural integrity.
Implementation Method 1
Flexible pipes in riser configurations experience vortex-induced vibrations (VIV) due to water flow, leading to excessive motions and potential fatigue failure
Implementation Method 2
The solution effectively reduces forces exerted on flexible pipes from VIV, prolongs the lifetime of the pipe and riser assemblies, and allows for cost-effective production and installation by minimizing vortex-generated oscillations
Data Source
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AI summary
A connector assembly, riser assembly and method of producing a connector assembly are disclosed. The connector assembly includes a body portion for locating over a flexible pipe and arranged to be connectible to or formed integrally with one or more buoyancy compensating element, and one or more protrusion extending from the body portion and arranged to reduce or interrupt vortex induced vibrations in water surrounding the flexible pipe in use.