Research topics
research topics available
Current and recently completed PhD projects
- Point wave energy absorber/converter strings for coastal protection and electricity generation.
- Wave energy extraction from device arrays: Experimental investigation in a large wave facility.
- Simulation of interactions amongst wave device arrays.
- Optimisation of the Output of a Heaving Wave Energy Converter.
- Turbulence modelling in the near-field of an axial flow tidal turbine in Code Saturne.
Point wave energy absorber/converter strings for coastal protection and electricity generation.
EPSRC Supergen Marine II, Commenced April 2008.
Although wave energy densities at sites in the Western Atlantic regularly exceed 40kW/m, energy densities around much of the UK are considerably lower, typically of the order of 10-15kW/m along the East coast. At present, the deployment of wave energy devices at such low-energy sites is not economic due to the relatively low electrical output and hence revenue that would be generated. However, one route to economic viability is to consider the use of wave devices for both electricity generation and for coastal defence. Coastal erosion, particularly along relatively shallow shorelines of 20-30 m depth, is mainly driven by storm waves hence this project involves investigation of wave transmission through a line of wave devices. Work includes both numerical and experimental analysis to obtain appropriate coefficients and near-bed shear stresses. Derived transmission and absorption coefficients can subsequently be employed to simulate inshore wave propagation and, this will be extended to assess long-term erosion based on hindcast wave conditions.
Wave energy extraction from device arrays: Experimental investigation in a large wave facility.
ESPRC DTA. Commenced October 2007.
An emerging class of wave energy device consists of a number of generating units installed in close proximity and supported from a common structure. At the close separations considered (separation of the order of a diameter) the response of each device is influenced by interactions between the devices caused by both the diffracted and radiated wave field. Much work has been published concerning the interaction of arrays of point absorbers under the assumptions of linear wave forcing and radiation from body motion only. These studies have shown significant amplification of response amplitude and power extraction at certain spacing. Numerical simulations based on linear wave theory have also shown that diffraction of regular waves amongst periodic arrays of closely spaced fixed circular cylinders can generate free-surface amplitudes and cylinder forces which greatly exceed those experienced by an isolated cylinder. With a few important exceptions, there has been little experimental work concerning array interactions and it is unclear how the phenomenon of near-trapping influences the response of near-resonant bodies. To optimise the aggregate output of an array, it is important to understand how response varies with the characteristics of individual devices, their spacing and array configuration. This project involves experimental study of an array of heaving point absorbers using the university of Manchester wide flume. Arrays of up to 25 scale-model wave energy devices are being studied under a range of wave conditions and configurations. The primary objective is to improve understanding of how the complex interactions between multiple oscillating structures can be exploited to optimised power conversion.
Simulation of interactions amongst wave device arrays.
NWDA Joule Centre, Commenced October 2007.
Numerical simulations based on linear wave theory have shown that diffraction of regular waves amongst periodic arrays of circular cylinders can generate free-surface amplitudes and cylinder forces which greatly exceed those experienced by an isolated cylinder. This phenomenon has been termed 'near-trapping'. It is known that irregularity of the incident wave-field and of the array periodicity reduces this amplification. Nevertheless, it is important to understand how such wave interactions influence the response and hence power capture of wave energy devices installed in close proximity. Most of the numerical studies in this area have concerned fixed structures (normally bed-mounted or truncated surface-piercing cylinders) which experience negligible displacement. This is in contrast to the case of wave energy converters for which high amplitude displacements are a primary design objective. This project involves numerical simulation of interactions amongst shallow draft bodies undergoing intermittently damped oscillation. Comparisons are drawn with experimental data collected from wide-flume studies.
Optimisation of the Output of a Heaving Wave Energy Converter.
NWDA Joule Centre, Commenced October 2006.
This project investigates the power generation system and control of the "Manchester Bobber" wave power device. The "Manchester Bobber" is a float based, point absorber extracting the swell energy of sea waves. Its hydrodynamics have been tested at 1/100 scale in university test facilities and at 1/10 scale in a large outdoor test tank. However no research has been undertaken on the power generation system or on control in order to maximise energy extraction. The project commenced with the design and software simulation of the power generation system and is presently evaluating the validity of an optimised generator control algorithm through tank-testing of a laboratory size hardware model. Research will then progress to investigate how to maximise the energy extraction from the waves by dynamically adjusting the torque applied to the drive train and maintaining optimal energy extraction for any wave conditions.
Turbulence modelling in the near-field of an axial flow tidal turbine in Code Saturne.
EdF, commenced October 2009.
This research project aims to create a simulation of a horizontal axis tidal turbine (HATT) using Computational Fluid Dynamics (CFD), and, in particular, using EdF's open source software Code Saturne. The project proposes four key steps leading up to the final simulation. Initially a model based on idealised turbine geometry will be used allowing the verification of results against those in established literature. Later, the turbine geometry, provided to EdF by Tidal Generation Limited, will be taken into account and will be used in simulations that will mirror the conditions experienced by the physical model. The problems that will need to be addressed during this include the meshing of complex geometry, rotating grids, free surface waves and validation against near field velocity and load measurements.