Design and Structural Testing of Blades for a 2MW Floating Tidal Energy Conversion Device

The floating tidal energy is increasingly recognised to have the potential of delivering a step-change cost reduction to the tidal energy sector, by extracting energy from deeper water sites through energy conversion devices. To ensure the normal operation of a tidal energy convertor within its service life, the device should be designed properly and evaluated through a series of strength and durability testing. The Large Structures Research Group at NUI Galway is working closely with, renewable energy company, Orbital Marine Power and, blade manufacture, ÉireComposites Teo, to design and test the next generation of SR2000 tidal turbine blade, with aims to increase the turbine power production rate and to refine the design for low cost. This paper presents a brief description of the structural design and testing of a blade for the O2-2000 tidal turbine, one of the largest tidal turbines in the world. NUI Galway will utilise their in-house software, BladeComp, to find a blade laminates design that balances both blade strength and material cost. The structural performance of the designed blade will be assessed by conducting static and fatigue testing. To achieve this objective, a support frame to fix the blade is designed, a load application device is introduced and the methodology for design tidal loading conversion is proposed in order to complete the testing at NUI Galway.

The Parametric Estimation of Tidal Potential Power Density using Modeling Strategies at Hajambro Creek of Indus Delta, Pakistan

There are many accessible resources for electricity generation using renewable energy, like, solar, wind, tidal and wave etc. The output of all these resources depend on weather conditions, force of gravity or rotation of the Earth, but tidal energy has a major advantage over many other forms of renewable generation as it is predictable over a long period of time. Pakistan has about 1000 km long coastline with complex network of creeks in the Indus delta region which include 17 major creeks and further divide into a number of estuaries with considerable tidal ranges and tidal current. This research study is carried out at one of these major creeks namely Hajambro (Hajambro river) and extends from Hajambro 24ᵒ 08’N 67ᵒ 22’E (sea mouth) to Keti Bander 24ᵒ 09’N 67ᵒ 27’E (mouth of river Indus). Study area is targeted within creek region where there is a large shortfall of electricity observed and this situation has threaten the community socioeconomically. In this research study, available tidal energy resources of Hajambro creek are assessed, tidal power density models and bathymetry model are developed in Arc-GIS (geographical informationsystem) environment, for the first time. A comprehensive tidal turbine technology review is conducted and based on up-to-date tidal turbine technology review and results achieved from assessment of tidal energy resources, deployment of a turbine at Hajambro creek is proposed. With effective area of 9.46 km2 mean spring estimated power (seasonally) is observed as 14 MW in winter, 12.9 MW in Pre-Monsoon, 13.6 MW in Monsoon and 13.1 MW in Post-Monsoon.

A Numerical Study of Flow Around Different Hydrofoil Systems In Presence of the Free Surface

The hydrofoils are essential element in tidal current turbine and in high speed marine crafts. Hence, the study of hydrodynamic characteristics of hydrofoils are important as they play a vital role in improving the performance of these propulsion devices (hydro-kinetic turbine, marine craft). In the present study, the dynamics of unsteady and viscous flow around a two hydrofoil system is investigated for two different configuration: (a) tandem, and in (b) stagger arrangement. The incompressible Navier-Stokes equations were solved using Finite Volume Solver in STAR-CCM+ commercial software package. k-ε turbulence model is incorporated in the present simulation in order to explain the turbulence flow physics while the free surface is captured using Volume of Fluid (VOF) technique. Further, the obtained numerical simulation results were compared with experimental data available in the literature as a validation purpose. The objective of the present study is to investigate the effects of spacing distance on the lift and drag coefficient generated by two foil system in tandem and stagger arrangements which is one of the important design parameter for a tidal turbine blades in presence of free sea surface. It could be observed that the hydrofoils are arranged in tandem configuration, the lift coefficients of the upstream and downstream hydrofoils are higher in comparison to single hydrofoil. Interference effect didn’t die out even at large spacing for 2-D hydrofoil.

Numerical Performance Model for Tensioned Mooring Tidal Turbine Operating in Combined Wave-Current Sea States

This study proposes the design of a tidal turbine station keeping system based on the adoption of a tensioned mooring system. Damping is introduced to investigate its effect on the reduction in the peak load experienced by tidal turbines during their operational lives in high-energy wave–current environments. A neutrally buoyant turbine is supported using a tensioned cable-based mooring system, where tension is introduced using a buoy fully submersed in water. The loads on the turbine rotor blades and buoy are calculated using a wave and current-coupled model. A modelling algorithm is proposed based on inverted pendulums, which respond to various sea state conditions, to study the behaviour of the system as well as the loads on blades. The results indicate that the tensioned mooring system reduces the peak thrust on the turbine and validates the applicability of the model.

3D Numerical Study of the Impact of Macro-Roughnesses on a Tidal Turbine, on Its Performance and Hydrodynamic Wake

Biofouling is an important factor to consider when calculating the energetic efficiency of tidal farms. Despite the fact that biofouling effects have been widely investigated in the past for naval applications, very few studies concern tidal turbines. This paper proposes a numerical approach to assess the impact of biofouling on tidal turbines, which is efficient for testing many configurations. Two turbulence models are tested (RANS k-ω SST and LES Smagorinsky) for the motionless blade case to validate them. Then we chose to use the Smagorinsky model for the case of a complete tidal turbine rotor with realistically fouled blades. The pressure coefficient is strongly affected by the barnacle in the motionless blade case and the power coefficient is slightly degraded in the complete rotor case. Motionless blade cases do not represent the real biofouling behaviour for two reasons. First, sessile species settle in the down flow part of the chord where their impact is less important. Then, the surrounding turbulence provoked by the blades rotation in the rotor case reduces the impact of biofouling. In the wake, biofouling generates small vortexes that propagate into the larger ones, causing them to spread their energy.