Development and In-Sea Performance Testing of a Single Point Mooring Supported Contra-Rotating Tidal Turbine

Abstract

A 2 nd generation, contra-rotating marine current turbine has been developed by the Energy Systems Research Unit at the University of Strathclyde. This system can be tuned to extract energy over a wide range of water depths by "flying" a neutrally-buoyant device from a flexible, tensioned mooring. After successful proof of concept turbine trials, the development programme has moved on to investigate the performance of a scaled prototype system comprising of a dual rotor, contra-rotating turbine directly coupled to a submersible contra-rotating generator; and held on station via a gravity based tensioned mooring system. The turbine/generator assembly was initially tested in a towing tank, before the entire system underwent sea trials initially at the Kyles of Bute in the River Clyde Estuary before being deployed in eth Sound of Islay of eth West Coast of Scotland. An investigation into turbine wake development (an area in which it is hoped that the contra-rotating turbine will have uniquely beneficial properties) has recently begun. Small single-rotor model turbines have been deployed in a flume. Trends observed so far are in accordance with those observed by other researchers.

Optimal Hydrokinetic Turbine Array Placement in Asymmetric Quasigeostrophic Flows

“…The physical phenomenon of Taylor columns and their associated flow patterns could develop locally at the site of the engineered structure itself, and it could also develop on/around a bathymetric feature like a ridge or seamount where an array or turbine is deployed. The University of Strathclyde encountered what was described as a spatial-temporal eddy with a 'calm' center when it was testing a tidal current turbine [15]. This could have been caused by a Taylor column which has a stagnant interior.…”

A Design Procedure for Anchors of Floating Ocean Current Turbines on Weak Rock

“…Considering only the case where the turbine is in operational mode, the drag force can be conservatively estimated following Betz Law [62]. Assuming the rotor is operating at the maximum theoretical power coefficient, C P = 0.59, the rotor drag coefficient can be estimated as C drag = 8 9 [63]. Thus, the drag force is:…”

2002–2012: 10 Years of Research Progress in Horizontal-Axis Marine Current Turbines

“…Clarke and co-workers from the UK have designed and tested a contra-rotating HAMCT, which they named the Contra-Rotating Marine Turbine (CoRMaT) [120][121][122][123][124][125]. CoRMaT comprises two turbines with a three-bladed turbine at the front and a four-bladed turbine at the back, both rotating in opposite directions to each other; a detailed design can be found in [120].…”

“…A 250 kW rated CoRMaT was tested in the Sound of Islay in Scotland in order to investigate the feasibility of a single-point tethered floating system for CoRMaT and the performance of a direct drive generator [123,124]. It was claimed that electrical power output underwent rapid fluctuation, which could be improved through a better system design.…”