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Starzmann R.,Voith Hydro Wavegen Ltd | Starzmann R.,SCHOTTEL Josef Becker Forschungszentrum GmbH | Moisel C.,Voith Hydro Wavegen Ltd | Carolus T.H.,Voith Hydro Wavegen Ltd | And 2 more authors.
International Journal of Marine Energy | Year: 2013

The oscillating water column (OWC) is a system for sea wave energy conversion. This paper deals with the axial Wells turbine. Main objectives of this study are the experimental determination of aerodynamic and aero-acoustic characteristics of a laboratory scale turbine and their subsequent usage for full scale turbine performance prediction. For that a model Wells turbine was built and tested on a laboratory test rig at the University of Siegen. Assuming that the steady-state characteristics hold in unsteady operation, mean quantities such as a mean efficiency and an equivalent sound power level are defined that allow the quantification of the overall performance during cyclic operation. The steady-state quantities are used to assess various control strategies and to predict the aero-acoustic performance of the full scale LIMPET turbine on Islay, Scotland. In general, scaled-up acoustic laboratory test rig data correlates well with measurements from the full scale LIMPET turbine. A theoretical assessment of different control strategies under regular wave conditions demonstrates the potential of a variable speed control for reduction of equivalent sound power. Turbine operation which admits stall yields a typical signature in the equivalent sound power spectrum: a stalled Wells turbine emits low frequency noise at a level far above all levels encountered in the unstalled flow regime and hence significantly contributes to the equivalent sound power. © 2013 Elsevier Ltd. All rights reserved.

Jeffcoate P.,Queen's University of Belfast | Starzmann R.,SCHOTTEL Josef Becker Forschungszentrum GmbH | Elsaesser B.,Queen's University of Belfast | Scholl S.,SCHOTTEL Josef Becker Forschungszentrum GmbH | Bischoff S.,SCHOTTEL Josef Becker Forschungszentrum GmbH
International Journal of Marine Energy | Year: 2015

Field testing studies are required for tidal turbine device developers to determine the performance of their turbines in tidal flows. Full-scale testing of the SCHOTTEL tidal turbine has been conducted at Queen's University Belfast's tidal site at Strangford Lough, NI. The device was mounted on a floating barge. Testing was conducted over 48. days, for 288. h, during flood tides in daylight hours. Several instruments were deployed, resulting in an expansive data set. The performance results from this data set are presented here. The device, rated to 50. kW at 2.75. m/s was tested in flows up to 2.5. m/s, producing up to 19. kW, when time-averaged. The thrust on the turbine reached 17. kN in the maximum flow. The maximum system efficiency of the turbine in these flows reached 35%. The test campaign was very successful and further tests may be conducted at higher flow speeds in a similar tidal environment. © 2015 Elsevier Ltd.

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