Changes between Version 9 and Version 10 of doc/tec/wtm
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- May 24, 2019 1:09:49 PM (6 years ago)
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doc/tec/wtm
v9 v10 9 9 10 10 == Technical description of the PALM-WTM == 11 The PALM-WTM is based on the common actuator disk model (ADM) approach in which the rotor of a wind turbine is represented by a permeable disk that extracts energy from the flow by applying a thrust force at the disk. While in the frequently used simple version of the ADM (e.g. as proposed by [#calaf Calaf et al. (2010)] the forces are uniformly distributed and only the thrust force is considered (thus ignoring the torque), the WTM provides an advanced ADM (ADM-R) that considers varying forces over the rotor disk and rotation of the rotor blades although these are not resolved. The basic concept is similar to the ADM-R proposed by [#wu Wu and Porté-Agel (2011)] with several modifications. The rotor plane is divided into rings and segments such that the segments have an equal size which is a function of the grid spacing .11 The PALM-WTM is based on the common actuator disk model (ADM) approach in which the rotor of a wind turbine is represented by a permeable disk that extracts energy from the flow by applying a thrust force at the disk. While in the frequently used simple version of the ADM (e.g. as proposed by [#calaf Calaf et al. (2010)] the forces are uniformly distributed and only the thrust force is considered (thus ignoring the torque), the WTM provides an advanced ADM (ADM-R) that considers varying forces over the rotor disk and rotation of the rotor blades although these are not resolved. The basic concept is similar to the ADM-R proposed by [#wu Wu and Porté-Agel (2011)] with several modifications. The rotor plane is divided into rings and segments such that the segments have an equal size which is a function of the grid spacing (see Figure 1 (left)). 12 12 13 13 [[Image(ADM-R_neu.png,150px)]] [[Image(Fig3-BEM-Illustration.png,300px)]] … … 44 44 \end{equation*} 45 45 }}} 46 with 46 with the angle φ between the tangential wind speed component and the wind speed relative to the rotor blade element (see Figure 1 (right)) 47 47 {{{ 48 48 #!Latex … … 51 51 \end{equation*} 52 52 }}} 53 where ''U'',,N,, is the velocity in axial direction and ''U'',,θ,, the velocity in tangential direction (along the circular movement of the rotor blade element, as shown in Figure 2).''Ω'' denotes the rotational speed of the rotor.53 where ''U'',,N,, is the velocity in axial direction and ''U'',,θ,, the velocity in tangential direction (along the circular movement of the rotor blade element, as shown in Figure 1 (right)).''Ω'' denotes the rotational speed of the rotor. 54 54 55 55 Finally, the forces are smeared and interpolated to the cartesian PALM grid. To optimise the performance of the time-consuming 3d smearing process. the smearing is done with a Polynomial function instead of the standard Gaussian smearing and confined to the region around the rotor: … … 82 82 The smearing width ''ϵ'' is set to twice the grid spacing the horizontal grid spacing which has turned out to be a reasonable value (see e.g. [#troldborg Troldborg et al. (2013)]). 83 83 84 The effect of the tower and nacelle are considered by a simple drag force approach: 85 {{{ 86 #!Latex 87 \begin{equation*} 88 f_{d,t} = \frac{1}{2}\rho U^{2}_{ref}c_{d,t} 89 \end{equation*} 90 \begin{equation*} 91 f_{d,n} = \frac{1}{2}\rho U^{2}_{ref}c_{d,n} 92 \end{equation*} 93 }}} 94 where ''f'',,d,t,, and ''f'',,d,n,, are the drag forces of the tower and the nacelle, respectively, with their drag coefficients ''c'',,d,t,, and ''c'',,d,n,,. Per default, ''c'',,d,t,, = 1.2 and ''c'',,d,n,, = 0.85. These values can be changed in the parameter namelist. 84 95 96 The WTM contains a wind turbine controller including speed control, pitch control and yaw control which can be switched on and off separately. The baseline generator torque speed and pitch controller is implemented as described in [#jonkman Jonkman et al. (2009)] and is only valid for the NREL 5 MW reference turbine. For different turbine types, the speed controller has to be adjusted. The yaw controller is implemented following [#storey Storey et al. (2013)] and allows active and automatic yaw control. 85 97 86 87 88 to be continued...89 98 90 99 == How to use the PALM-WTM with other turbine data == … … 96 105 * [=#calaf]'''Calaf M, Meneveau C, Meyers J''' 2010. Large eddy simulation study of fully developed wind-turbine array boundary layers. Phys. Fluids, 22, 015110, doi:10.1063/1.3291077. 97 106 * [=#jonkman]'''Jonkman JM, Butterfield S, Musial W, Scott G''' 2009. Definition of a 5-MW reference wind turbine for offshore system development. Technical Report NREL/TP-500-38060, National Renewable Energy Laboratory, Golden, Colorado. 107 * [=#storey]'''Storey R, Norris S, Cater J''' 2013. Large Eddy Simulation of Wind Events Propagating through an Array of Wind Turbines. Proceedings of the World Congress on Engineering 2013 Vol III, WCE 2013, 3–5 July 2013, London, UK, 2013. 98 108 * [=#troldborg]'''Troldborg N, Sørensen JN, Mikkelsen R, Sørensen NN''' 2013. A simple atmospheric boundary layer model applied to large eddy simulations of wind turbine wakes. Wind Energy, 17(4), 657-669, doi:10.1002/we.1608. 99 109 * [=#wu]'''Wu Y-T, Porté-Agel F''' 2011. Large-Eddy Simulation of Wind-Turbine Wakes: Evaluation of Turbine Parametrisations. Boundary Layer Meteorol., 138, 345-366, doi:10.1007/s10546-010-9569-x.
