Actuator volumes and hr‐adaptive methods for three‐dimensional simulation of wind turbine wakes and performance

Abstract

This paper presents a three‐dimensional numerical model for horizontal axis wind turbines, capable of simulating both the dynamic response of the turbine to changing flow conditions, and the full wake generated by the turbine. The turbine model is coupled to computational fluid dynamics software using Large Eddy Simulation to solve for unsteady flow conditions, with the Smagorinsky method handling sub‐grid turbulence. Wind tunnel simulations are compared with experimental data, and then a simulation of a real turbine in complex terrain is compared with LIDAR data from the same site, in both cases agreeing favourably. Copyright © 2011 John Wiley & Sons, Ltd.

Effects of Support Structures in an LES Actuator Line Model of a Tidal Turbine with Contra-Rotating Rotors

“…where T is the Prandtl tip-loss factor [15,58]. As with previous work [4,15,23], blade-generated turbulence was then added via randomly fluctuating components.…”

“…As with previous work [4,15,23], blade-generated turbulence was then added via randomly fluctuating components. These body forces acting on the blades are translated into axial and azimuthal components; from Newton's third law, the consequent body forces on the flow are equal and opposite.…”

“…The turbine model developed here builds upon previous work, where dynamic torque-controlled actuator discs with active-pitch correction were used to model wind turbines [15] and wind farms [4,16]. In the present model, actuator line techniques [5] have been used to represent the rotor, whereby the blades themselves are not resolved, but the forces exerted by them on the fluid are still present.…”

“…One striking feature of these models is that, barring a few exceptions [13,14], the turbine support structure is not modelled explicitly, and so, only the rotors affect the downwind flow. It is quite likely that, in the mid-to-far wake region, wake effects due to the structure are not important in wind farms; indeed, previous, validated studies of single wind turbines [15] and wind farms [4,16] have indicated that the tower and nacelle have negligible impact on the wake and consequently the performance of downwind turbines. The pertinent question here is, then, can the same be said for tidal turbines sited in swiftly flowing water, whose density is over 800 times that of air?…”

High-resolution CFD modelling of Lillgrund Wind farm

“…These can be embedded in RANS fluids solvers [6] or fixed-mesh LES codes [4] [7] or an LES finite element solver with an unstructured, hr-adaptive mesh [8].…”