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An unsteady boundary element model is developed to simulate the unsteady flow induced by the motion of a multi-blade vertical axis turbine. The distribution of the sources, bound vortices and wake vortices of the blades are given in detail. In addition, to make the numerical solution more robust, the Kutta condition is also introduced. The developed model is used to predict the hydrodynamic performance of a vertical axis tidal turbine and is validated by comparison with experimental data and other numerical solutions available in the literature. Good agreement is achieved and the calculation of the proposed model is simpler and more efficient than prior numerical solutions. The proposed model shows its capability for future profile design and optimization of vertical axis tidal turbines.
Guangnian Li; Qingren Chen; Hanbin Gu. An Unsteady Boundary Element Model for Hydrodynamic Performance of a Multi-Blade Vertical-Axis Tidal Turbine. Water 2018, 10, 1413 .
AMA StyleGuangnian Li, Qingren Chen, Hanbin Gu. An Unsteady Boundary Element Model for Hydrodynamic Performance of a Multi-Blade Vertical-Axis Tidal Turbine. Water. 2018; 10 (10):1413.
Chicago/Turabian StyleGuangnian Li; Qingren Chen; Hanbin Gu. 2018. "An Unsteady Boundary Element Model for Hydrodynamic Performance of a Multi-Blade Vertical-Axis Tidal Turbine." Water 10, no. 10: 1413.
The hydrodynamic interference between tidal turbines must be considered when predicting their overall hydrodynamic performance and optimizing the layout of the turbine array. These factors are of great significance to the development and application of tidal energy. In this paper, the phenomenon of hydrodynamic interference of the tidal turbine array is studied by the hydrodynamic performance forecast program based on an unsteady boundary element model for the vertical-axis turbine array. By changing the relative positions of two turbines in the double turbine array to simulate the arrangement of different turbines, the hydrodynamic interference law between the turbines in the array and the influence of relative positions on the hydrodynamic characteristics in the turbine array are explored. The manner in which the turbines impact each other, the degree of influence, and rules for turbine array arrangement for maximum efficiency of the array will be discussed. The results of this study will provide technical insights to relevant researchers.
Guangnian Li; Qingren Chen; Hanbin Gu. Study of Hydrodynamic Interference of Vertical-Axis Tidal Turbine Array. Water 2018, 10, 1228 .
AMA StyleGuangnian Li, Qingren Chen, Hanbin Gu. Study of Hydrodynamic Interference of Vertical-Axis Tidal Turbine Array. Water. 2018; 10 (9):1228.
Chicago/Turabian StyleGuangnian Li; Qingren Chen; Hanbin Gu. 2018. "Study of Hydrodynamic Interference of Vertical-Axis Tidal Turbine Array." Water 10, no. 9: 1228.
Forced heave and surge motion of axisymmetric vertical cylindrical bodies with flat and rounded bases are simulated using the advanced CFD software STAR-CCM+ where the overset method is used so that the mesh local to the body moves within a stationary outer mesh. Viscous effects generating drag, and also influencing added mass and radiation damping, are determined. The Reynolds-Averaged Navier–Stokes (RANS) equations are adopted with different turbulence closure models and the water surface is captured by the volume of fluid (VOF) method. These results are of basic interest but the main motive is to assess appropriate drag coefficients for use with linear diffraction models of wave energy converters (WEC) and we have particular interest in the multi-body WEC M4. A basic dynamical model is set up so that drag, added mass and radiation damping coefficients may be obtained from the CFD results. Added mass and radiation damping coefficients were also obtained from the potential flow solver WAMIT for comparison. Mesh convergence studies were undertaken and while mesh independence was achieved for total force it was not possible for the very small shear force. In the laboratory a free heave decay test was undertaken without mechanical contact for bodies with rounded bases and the inferred drag and added mass coefficients were very close to those from CFD. Some general observations are possible for motion in heave. For the hemispherical base the drag coefficient Cd is very low for small amplitudes but this increases as amplitude is increased. For the rounded base with a flat central area the Cd is larger and for the wholly flat base it is larger again but with values less than 0.35. For a larger geometric scale (times 32) for the hemisphere and round base cases the Cd are generally somewhat reduced. For surge motion the Cd show less variation and are always greater than heave values by at least a factor of 2 which is indicative of effects due to separation and wake generation.
Hanbin Gu; Peter Stansby; Tim Stallard; Efrain Carpintero Moreno. Drag, added mass and radiation damping of oscillating vertical cylindrical bodies in heave and surge in still water. Journal of Fluids and Structures 2018, 82, 343 -356.
AMA StyleHanbin Gu, Peter Stansby, Tim Stallard, Efrain Carpintero Moreno. Drag, added mass and radiation damping of oscillating vertical cylindrical bodies in heave and surge in still water. Journal of Fluids and Structures. 2018; 82 ():343-356.
Chicago/Turabian StyleHanbin Gu; Peter Stansby; Tim Stallard; Efrain Carpintero Moreno. 2018. "Drag, added mass and radiation damping of oscillating vertical cylindrical bodies in heave and surge in still water." Journal of Fluids and Structures 82, no. : 343-356.