An actuator sector method for efficient transient wind turbine simulation

This paper investigates a new method for transient simulation of flow through a wind turbine using an actuator technique. The aim, in the context of wind turbine wake simulation, is to develop an alternative to the widely used actuator disc model with an increased resolution and range of applications, for the same or less computational expense. In this new model, the actuator sector method, forces applied to the fluid are distributed azimuthally to maintain a continuous flow solution for increased time-step intervals compared with the actuator line method. Actuator sector results are presented in comparison with actuator disc and actuator line models initially for a non-dimensionalized turbine in laminar onset flow. Subsequent results are presented for a turbine operating in a turbulent atmospheric boundary layer. Results show significant increases in flow fidelity compared with actuator disc model results; this includes the resolution of diametric variation in rotor loading caused by horizontal or vertical wind shear and the helical vortex system shed from the turbine blade tips. Significant reductions in computational processing time were achieved with wake velocities and turbulence statistics comparable with actuator line model results. The actuator sector method offers an improved alternative to applications employing conventional actuator disc models, with little or no additional computational cost. This technique in conjunction with a Cartesian mesh-based parallel flow solver leads to efficient simulation of turbines in atmospheric boundary layer flows. Copyright © 2014 John Wiley & Sons, Ltd.

[1]  J. Sørensen,et al.  Unsteady actuator disc model for horizontal axis wind turbines , 1992 .

[2]  J. Jonkman,et al.  Definition of a 5-MW Reference Wind Turbine for Offshore System Development , 2009 .

[3]  J. Smagorinsky,et al.  GENERAL CIRCULATION EXPERIMENTS WITH THE PRIMITIVE EQUATIONS , 1963 .

[4]  Stefan Ivanell,et al.  Numerical computations of wind turbine wakes , 2007 .

[5]  Robert L. Street,et al.  An analysis and comparison of the time accuracy of fractional‐step methods for the Navier–Stokes equations on staggered grids , 2002 .

[6]  Robert L. Street,et al.  A Parallel Non-Staggered Navier-Stokes Solver Implemented on a Workstation Cluster , 2003 .

[7]  Karl Stol,et al.  Large eddy simulation of dynamically controlled wind turbines in an offshore environment , 2013 .

[8]  P. J. Mason,et al.  On the magnitude of the subgrid-scale eddy coefficient in large-eddy simulations of turbulent channel flow , 1986, Journal of Fluid Mechanics.

[9]  F. Porté-Agel,et al.  Simulation of Turbulent Flow Inside and Above Wind Farms: Model Validation and Layout Effects , 2012, Boundary-Layer Meteorology.

[10]  Karl Stol,et al.  Large Eddy Simulation of Dynamically Controlled Wind Turbines using Actuator Discs , 2012 .

[11]  Jens Nørkær Sørensen,et al.  Numerical simulations of wake interaction between two wind turbines at various inflow conditions , 2011 .

[12]  Karl Stol,et al.  Wind Turbine Wake Modelling using Large Eddy Simulation , 2010 .

[13]  Christophe Leclerc,et al.  A Viscous Three-Dimensional Differential/Actuator-Disk Method for the Aerodynamic Analysis of Wind Farms , 2002 .

[14]  J. Sørensen,et al.  Wind turbine wake aerodynamics , 2003 .

[15]  J. Sørensen,et al.  Analysis of wake states by a full‐field actuator disc model , 1998 .

[16]  Wen Zhong Shen,et al.  The Actuator Surface Model: A New Navier-Stokes Based Model for Rotor Computations , 2009 .

[17]  Stuart Norris.  A Parallel Navier-Stokes Solver for Natural Convection and Free Surface Flow , 2000 .

[18]  Jens Nørkær Sørensen,et al.  Numerical simulations of wake characteristics of a wind turbine in uniform inflow , 2010 .

[19]  D. Thomson,et al.  Stochastic backscatter in large-eddy simulations of boundary layers , 1992, Journal of Fluid Mechanics.

[20]  Jens Nørkær Sørensen,et al.  Numerical Modeling of Wind Turbine Wakes , 2002 .

[21]  J. Sørensen.  Aerodynamic Aspects of Wind Energy Conversion , 2011 .

[22]  B. P. Leonard,et al.  Beyond first‐order upwinding: The ultra‐sharp alternative for non‐oscillatory steady‐state simulation of convection , 1990 .

[23]  Christian Masson,et al.  Application of the actuator surface concept to wind turbine rotor aerodynamics , 2009 .

[24]  Christian Masson,et al.  Modeling of lifting-device aerodynamics using the actuator surface concept , 2009 .

[25]  J. Mann.  Wind field simulation , 1998 .