Witt Limited and Solis Marine Consultants release a paper
In July 2019, Simon Hindley from Solis Marine Engineering and members from Witt Limited jointly published a paper in the USA through the Marine Technology Society. The research relates to harvesting energy from vortex-induced vibration in the sub-sea sector.
An energy device called the WITT (Whatever Input to Torsion Transfer) converted chaotic motion in six degrees of freedom to a single unidirectional output, which can be coupled to a generator to provide electrical power. The WITT energy device of this size order has an operational sweet spot of approximately 2 Hz, with up to 100 mm amplitude displacements, although it is tunable within the WITT device by varying the pendulum length and mass. To operate in this nature, subsea vortex-induced vibration (VIV) was chosen to drive the system.
This is achieved by connecting the WITT energy transmission to cylindrical cross-section pipe sections, creating a modular system that can be varied for sites with different conditions or power requirements. Numerical predictions were performed for a wide range of design variations over a broad range of operating conditions using different VIV calculation techniques. This informed the likely dimensions for different sites and power requirements, so that an off-the-shelf solution could be quickly provided to a client, providing a sealed modular subsea energy solution. Tank testing was performed to compare to the numerical predictions and determine the effect of the WITT energy device on the system dynamics, demonstrating the concept is feasible. Within the paper, a range of possible applications are provided, from powering subsea monitoring equipment through to reduction of riser fatigue by reducing VIV.
The paper can be accessed with this link : https://www.ingentaconnect.com/contentone/mts/mtsj/2019/00000053/00000004/art00005