The vorticity dynamics and its relationship to dissipation in the wake of a utility-scale wind turbine are investigated through large-eddy simulation.The vorticity dynamics is assessed through the enstrophy,which is r...The vorticity dynamics and its relationship to dissipation in the wake of a utility-scale wind turbine are investigated through large-eddy simulation.The vorticity dynamics is assessed through the enstrophy,which is related to the turbulent dissipation.The averaged enstrophy and turbulent dissipation are shown to be quantitatively similar in the wake.Using temporal phase averaging,the vorticity fluctuations are decomposed into coherent and random fluctuations with respect to the frequency of the tip vortices.The enstrophy in the tip vortices is dominated by coherent fluctuations,while the coherent fluctuations of root vortices are immediately saturated by the random vorticity fluctuations of the unstable hub vortex.The coherent strain rate has significant differences com pared to the coherent enstrophy within one diameter downwind of blade tip,but the random enstrophy and strain rate are relatively similar.Differences in coherent enstrophy and strain rate decrease further from the rotor.展开更多
With the increased penetration of wind energy in our nation’s energy portfolio, wind farms are placed in a way close to each other. Thus, their wakes have to be fully considered in the design and operation of a wind ...With the increased penetration of wind energy in our nation’s energy portfolio, wind farms are placed in a way close to each other. Thus, their wakes have to be fully considered in the design and operation of a wind farm. In this study, we investigate the wake of a wind farm using large-eddy simulation with wind turbine rotor modelled by the actuator disk model. The simulated results show that the wake of a wind farm can persist for a long distance in its downstream. For the considered wind farm layout, the velocity in the wake recovers 95% of that of the undisturbed inflow at 55 rotor diameters downstream from its last row, suggesting that the wake of a wind farm should be fully considered in the optimal design and operation for its downstream wind farms.展开更多
文摘The vorticity dynamics and its relationship to dissipation in the wake of a utility-scale wind turbine are investigated through large-eddy simulation.The vorticity dynamics is assessed through the enstrophy,which is related to the turbulent dissipation.The averaged enstrophy and turbulent dissipation are shown to be quantitatively similar in the wake.Using temporal phase averaging,the vorticity fluctuations are decomposed into coherent and random fluctuations with respect to the frequency of the tip vortices.The enstrophy in the tip vortices is dominated by coherent fluctuations,while the coherent fluctuations of root vortices are immediately saturated by the random vorticity fluctuations of the unstable hub vortex.The coherent strain rate has significant differences com pared to the coherent enstrophy within one diameter downwind of blade tip,but the random enstrophy and strain rate are relatively similar.Differences in coherent enstrophy and strain rate decrease further from the rotor.
基金supported by the National Natural Science Foundation of China(Nos.11988102,12172360)Institute of Mechanics and Chinese Academy of Sciences。
文摘With the increased penetration of wind energy in our nation’s energy portfolio, wind farms are placed in a way close to each other. Thus, their wakes have to be fully considered in the design and operation of a wind farm. In this study, we investigate the wake of a wind farm using large-eddy simulation with wind turbine rotor modelled by the actuator disk model. The simulated results show that the wake of a wind farm can persist for a long distance in its downstream. For the considered wind farm layout, the velocity in the wake recovers 95% of that of the undisturbed inflow at 55 rotor diameters downstream from its last row, suggesting that the wake of a wind farm should be fully considered in the optimal design and operation for its downstream wind farms.
