Extensive Research and Development (R&D) within the tidal energy industry is pushing this sector ... more Extensive Research and Development (R&D) within the tidal energy industry is pushing this sector towards commercial viability, with full scale prototypes starting to meet the challenges of the marine environment. This paper combines velocity data collected from Ramsey Sound (Pembrokeshire, Wales), with Computational Fluid Dynamics (CFD) to assess the impact of non-rectilinear flows on turbine rotor performance. This requires both the geometry of the turbine and the surrounding free stream velocity to be studied. From the site data, the majority of the velocities tend to fall within a ±20° misalignment to the principle flow direction for velocities greater than the economic viable threshold of 2 ms-1. From the CFD it was found that the non-dimensional performance parameters reduced with increasing angles of misalignment between the axis of rotation and free stream velocity. The resultant magnitude of the bending moments about the head of the driveshaft for the misaligned turbines wer...
Tidal energy is on the verge of commercial viability and full scale prototypes are meeting the ch... more Tidal energy is on the verge of commercial viability and full scale prototypes are meeting the challenges of the marine environment. The primary focus of the sector has concerned Horizontal Axis Tidal Turbines (HATTs); comprising a turbine supported by a tubular stanchion operating on a bi-directional, or yaw system. The direction of tidal flow, however, varies over the ebb or flood phases of a tidal cycle. This pa-per utilises tidal velocity data measured in Ramsey Sound (Pembrokeshire, Wales, UK), a macrotidal strait and proposed HATT installation site and combines with Computational Fluid Dynamics (CFD) to assess the impact of misalignment between a HATT and its surrounding free stream velocity. The majority of the veloci-ties within the northern area of Ramsey Sound tend to fall within a misalignment of ±20° for velocities greater than the economic viable threshold of 2 ms-1. However, bathymetry and coastline configuration influence both flow magnitude and direction. At the outer margins for the Sound, the velocities are acted upon by various promontories, reefs and shelving areas, which deflect and retard the flow, resulting in a flow direction greater than 20°, particularly towards the outer edges of the Sound. Utilising field data for numerical simulations will help inform the industry and increase investor confidence in this technology, whilst avoiding costly scaled ex-perimentation. It was found that an axial flow misalignment of ±10° results in approximately a 7% reduction in peak power, 3% in peak torque and 5% in peak thrust. The axial wake recovery length was shorter for the ±10° cases, recovering to 90% by 7D downstream, as opposed to 10D downstream for the aligned turbine.
Tidal energy is on the verge of commercial viability and full scale prototypes are meeting the ch... more Tidal energy is on the verge of commercial viability and full scale prototypes are meeting the challenges of the marine environment. The primary focus of the sector has concerned Horizontal Axis Tidal Turbines (HATTs); comprising a turbine supported by a tubular stanchion operating on a bi-directional, or yaw system. The direction of tidal flow, however, varies over the ebb or flood phases of a tidal cycle. This paper utilises tidal velocity data measured in Ramsey Sound (Pembrokeshire, Wales, UK), a macrotidal strait and proposed HATT installation site and combines with Computational Fluid Dynamics (CFD) to assess the impact of misalignment between a HATT and its surrounding free stream velocity. The majority of the velocities with-in the northern area of Ramsey Sound tend to fall within a misalignment of ±20° for velocities greater than the economic viable threshold of 2 ms-1. However, bathymetry and coastline configuration influence both flow magnitude and direction. At the outer margins for the Sound, the velocities are acted upon by various promontories, reefs and shelving areas, which deflect and retard the flow, resulting in a flow direction greater than 20°, particularly towards the outer edges of the Sound. Utilising field data for numerical simulations will help in-form the industry and increase investor confidence in this technology, whilst avoiding costly scaled experimen-tation. It was found that an axial flow misalignment of ±10° results in approximately a 7% reduction in peak power, 3% in peak torque and 5% in peak thrust. The axial wake recovery length was shorter for the ±10° cases, recovering to 90% by 7D downstream, as opposed to 10D downstream for the aligned turbine.
With many Tidal Energy Conversion (TEC) devices at full scale prototype stage there are two disti... more With many Tidal Energy Conversion (TEC) devices at full scale prototype stage there are two distinct
design groups for Horizontal Axis Tidal Turbines (HATTs). Devices with a yaw mechanism allowing the
turbine to always face into the flow, and devices with blades that can rotate through 180° to harness
a strongly bi-directional flow. As marine turbine technology verges on the realm of economic
viability this paper reveals the performance of Cardiff University’s concept tidal turbine with its
support structure either upstream or downstream and with various proximities between the rotating
plane of the turbine and its support stanchion. Through the use of validated Computational Fluid
Dynamics (CFD) modelling this work shows the optimal proximity between rotor plane and stanchion
as well as establishing, in the given context, the use of a yaw mechanism to be superior to a bidirectional
system from a performance perspective.
Extensive Research and Development (R&D) within the tidal energy industry is pushing this sector ... more Extensive Research and Development (R&D) within the tidal energy industry is pushing this sector towards commercial viability, with full scale prototypes starting to meet the challenges of the marine environment. This paper combines velocity data collected from Ramsey Sound (Pembrokeshire, Wales), with Computational Fluid Dynamics (CFD) to assess the impact of non-rectilinear flows on turbine rotor performance. This requires both the geometry of the turbine and the surrounding free stream velocity to be studied. From the site data, the majority of the velocities tend to fall within a ±20° misalignment to the principle flow direction for velocities greater than the economic viable threshold of 2 ms-1. From the CFD it was found that the non-dimensional performance parameters reduced with increasing angles of misalignment between the axis of rotation and free stream velocity. The resultant magnitude of the bending moments about the head of the driveshaft for the misaligned turbines wer...
Tidal energy is on the verge of commercial viability and full scale prototypes are meeting the ch... more Tidal energy is on the verge of commercial viability and full scale prototypes are meeting the challenges of the marine environment. The primary focus of the sector has concerned Horizontal Axis Tidal Turbines (HATTs); comprising a turbine supported by a tubular stanchion operating on a bi-directional, or yaw system. The direction of tidal flow, however, varies over the ebb or flood phases of a tidal cycle. This pa-per utilises tidal velocity data measured in Ramsey Sound (Pembrokeshire, Wales, UK), a macrotidal strait and proposed HATT installation site and combines with Computational Fluid Dynamics (CFD) to assess the impact of misalignment between a HATT and its surrounding free stream velocity. The majority of the veloci-ties within the northern area of Ramsey Sound tend to fall within a misalignment of ±20° for velocities greater than the economic viable threshold of 2 ms-1. However, bathymetry and coastline configuration influence both flow magnitude and direction. At the outer margins for the Sound, the velocities are acted upon by various promontories, reefs and shelving areas, which deflect and retard the flow, resulting in a flow direction greater than 20°, particularly towards the outer edges of the Sound. Utilising field data for numerical simulations will help inform the industry and increase investor confidence in this technology, whilst avoiding costly scaled ex-perimentation. It was found that an axial flow misalignment of ±10° results in approximately a 7% reduction in peak power, 3% in peak torque and 5% in peak thrust. The axial wake recovery length was shorter for the ±10° cases, recovering to 90% by 7D downstream, as opposed to 10D downstream for the aligned turbine.
Tidal energy is on the verge of commercial viability and full scale prototypes are meeting the ch... more Tidal energy is on the verge of commercial viability and full scale prototypes are meeting the challenges of the marine environment. The primary focus of the sector has concerned Horizontal Axis Tidal Turbines (HATTs); comprising a turbine supported by a tubular stanchion operating on a bi-directional, or yaw system. The direction of tidal flow, however, varies over the ebb or flood phases of a tidal cycle. This paper utilises tidal velocity data measured in Ramsey Sound (Pembrokeshire, Wales, UK), a macrotidal strait and proposed HATT installation site and combines with Computational Fluid Dynamics (CFD) to assess the impact of misalignment between a HATT and its surrounding free stream velocity. The majority of the velocities with-in the northern area of Ramsey Sound tend to fall within a misalignment of ±20° for velocities greater than the economic viable threshold of 2 ms-1. However, bathymetry and coastline configuration influence both flow magnitude and direction. At the outer margins for the Sound, the velocities are acted upon by various promontories, reefs and shelving areas, which deflect and retard the flow, resulting in a flow direction greater than 20°, particularly towards the outer edges of the Sound. Utilising field data for numerical simulations will help in-form the industry and increase investor confidence in this technology, whilst avoiding costly scaled experimen-tation. It was found that an axial flow misalignment of ±10° results in approximately a 7% reduction in peak power, 3% in peak torque and 5% in peak thrust. The axial wake recovery length was shorter for the ±10° cases, recovering to 90% by 7D downstream, as opposed to 10D downstream for the aligned turbine.
With many Tidal Energy Conversion (TEC) devices at full scale prototype stage there are two disti... more With many Tidal Energy Conversion (TEC) devices at full scale prototype stage there are two distinct
design groups for Horizontal Axis Tidal Turbines (HATTs). Devices with a yaw mechanism allowing the
turbine to always face into the flow, and devices with blades that can rotate through 180° to harness
a strongly bi-directional flow. As marine turbine technology verges on the realm of economic
viability this paper reveals the performance of Cardiff University’s concept tidal turbine with its
support structure either upstream or downstream and with various proximities between the rotating
plane of the turbine and its support stanchion. Through the use of validated Computational Fluid
Dynamics (CFD) modelling this work shows the optimal proximity between rotor plane and stanchion
as well as establishing, in the given context, the use of a yaw mechanism to be superior to a bidirectional
system from a performance perspective.
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Papers by Carwyn H Frost
design groups for Horizontal Axis Tidal Turbines (HATTs). Devices with a yaw mechanism allowing the
turbine to always face into the flow, and devices with blades that can rotate through 180° to harness
a strongly bi-directional flow. As marine turbine technology verges on the realm of economic
viability this paper reveals the performance of Cardiff University’s concept tidal turbine with its
support structure either upstream or downstream and with various proximities between the rotating
plane of the turbine and its support stanchion. Through the use of validated Computational Fluid
Dynamics (CFD) modelling this work shows the optimal proximity between rotor plane and stanchion
as well as establishing, in the given context, the use of a yaw mechanism to be superior to a bidirectional
system from a performance perspective.
design groups for Horizontal Axis Tidal Turbines (HATTs). Devices with a yaw mechanism allowing the
turbine to always face into the flow, and devices with blades that can rotate through 180° to harness
a strongly bi-directional flow. As marine turbine technology verges on the realm of economic
viability this paper reveals the performance of Cardiff University’s concept tidal turbine with its
support structure either upstream or downstream and with various proximities between the rotating
plane of the turbine and its support stanchion. Through the use of validated Computational Fluid
Dynamics (CFD) modelling this work shows the optimal proximity between rotor plane and stanchion
as well as establishing, in the given context, the use of a yaw mechanism to be superior to a bidirectional
system from a performance perspective.