4.2.15.1. Nomenclature

Table 4.12 List of Available FAST.Farm Output Channels

ABLSolver

atmospheric boundary layer solver

AWAE

ambient wind and array effects (module)

\(a(r)\)

axial induction factor, distributed radially

\(a_K\)

coherence decrement parameter

BEM

blade-element momentum

\(b_K\)

coherence offset parameter

\(C^\text{O}_\text{HWkDfl}\), \(C^\text{OY}_\text{HWkDfl}\), \(C^\text{x}_\text{HWkDfl}\), and \(C^\text{xY}_\text{HWkDfl}\)

calibrated parameters in the horizontal wake-deflection correction

\(c_\text{max}\)

maximum blade chord length

\(C_\text{Meander}\)

calibrated parameter for wake meandering

\(C_\text{NearWake}\)

calibrated parameter in the near-wake correction

\(C_\text{WakeDiam}\)

calibrated parameter in the wake-diameter calculation

\(C^\text{DMax}_{\nu \text{Amb}}\), \(C^\text{DMin}_{\nu \text{Amb}}\), \(C^\text{Exp}_{\nu Amb}\), and \(C^\text{FMin}_{\nu Amb}\)

calibrated parameters in the eddy-viscosity filter function for ambient turbulence

\(C^\text{DMax}_{\nu \text{Shr}}\), \(C^\text{DMin}_{\nu \text{Shr}}\), \(C^\text{Exp}_{\nu \text{Shr}}\), and \(C^\text{FMin}_{\nu \text{Shr}}\)

calibrated parameters in the eddy-viscosity filter function for the wake shear layer

\(^\text{AzimAvg}C_t(r)\) and \(^\text{FiltAzimAvg}C_t(r)\)

azimuthally averaged thrust-force coefficient (normal to a rotor disk), distributed radially, and its low-pass time-filtered value

\(Coh_{i,j}\)

magnitude of partial coherence between points \(i\) and \(j\)

DLL

dynamic-link library

DWM

dynamic wake meandering

\(D_\text{Grid}\)

Assumed rotor diameter when generating TurbSim inflow

\(D^\text{Rotor}\) and \(^\text{Filt}D_{n_p}^\text{Rotor}\)

rotor diameter and its low-pass time-filtered value at wake plane \(n_p\)

\(D_{n_p}^\text{Wake}\)

wake diameter at wake plane \(n_p\)

FLORIS

FLOw Redirection and Induction in Steady state

\(f\)

frequency

\(f_c\)

cutoff (corner) frequency of the low-pass time filter

\(\vec{f}_{n_b}(r)\)

aerodynamic applied loads distributed radially per unit length for blade \(n_b\)

\(f_\text{max}\)

maximum excitation frequency

\(F_{\nu \text{Amb}}(x)\)

eddy-viscosity filter function associated with ambient turbulence

\(F_{\nu \text{Shr}}(x)\)

eddy-viscosity filter function associated with the wake shear layer

HFM

high-fidelity modeling

HPC

high-performance computer

\(I\)

three-by-three identify matrix

\(K\)

velocity components \(u\), \(v\), and \(w\)

\(k_{\nu \text{Amb}}\)

calibrated parameter for the influence of ambient turbulence in the eddy viscosity

\(k_{\nu \text{Shr}}\)

calibrated parameter for the influence of the wake shear layer in the eddy viscosity

LES

large-eddy simulation

MFoR

moving frame of reference

MPI

message-passing interface

NaN

not a number

NREL

National Renewable Energy Laboratory

\(N\) and \(n\)

number of discrete-time steps and discrete-time-step counter

\(N_b\) and \(n_b\)

number of rotor blades and blade counter

\(N_{n_p}^\text{Polar}\) and \(n^\text{Polar}\)

number of points in the polar grid of wake plane \(n_p\) and point counter

\(N^\text{Wake}\) and \(n^\text{Wake}\)

number of wakes overlapping a given wind data point in the wind domain and wake counter

\(N_P\) and \(n_P\)

number of wake planes and wake-plane counter

\(N_r\) and \(n_r\)

number of radial nodes and radii counter

\(N_t\) and \(n_t\)

number of wind turbines and turbine counter

OF

OpenFAST (module)

OpenMP

open multiprocessing

\(\vec{p}^\text{Hub}\)

global position of a rotor center

\(\vec{p}^\text{Plane}_{n_p}\)

global position of the center of wake plane \(n_p\)

RAM

random-access memory

RSS

root-sum-squared

\(r\) and \(r^\text{Plane}\)

radius in the axisymmetric coordinate system

\(\hat{r}^\text{Plane}\)

radial unit vector in the axisymmetric coordinate system

\(S\)

global \(X\)-, \(Y\)-, and \(Z\)-coordinate

SC

super controller (module)

SOWFA

Simulator fOr Wind Farm Applications

\(t\)

simulation time

\(TI_\text{Amb}\) and \(^\text{Filt}TI_{\text{Amb}_{n_p}}\)

ambient turbulence intensity of the wind at a rotor and its low-pass time-filtered value for wake plane \(n_p\)

\(u^d\)

discrete-time inputs

\(V_\text{Advect}\)

advection speed of the synthetic wind data

\(\vec{V}_\text{Amb}^\text{High}\)

ambient wind across a high-resolution wind domain around a turbine

\(\vec{V}_\text{Amb}^\text{Low}\)

ambient wind across a low-resolution wind domain throughout the wind farm

\(\vec{V}_\text{Dist}^\text{High}\)

disturbed wind across a high-resolution wind domain around a turbine

\(\vec{V}_\text{Dist}^\text{Low}\)

disturbed wind across a low-resolution wind domain throughout the wind farm

\(V_\text{Hub}\)

mean hub-height wind speed

\(\vec{V}_{n_p}^\text{Plane}\) and \(^\text{Filt}\vec{V}_{n_p}^\text{Plane}\)

advection, deflection, and meandering velocity and its low-pass time-filtered value of wake plane \(n_p\)

\(V_r\)

radial velocity in the axisymmetric coordinate system

\(V_{r_{n_p}}^\text{Wake}(r)\)

radial wake-velocity deficit at wake plane \(n_p\), distributed radially

VTK

Visualization Toolkit

\(^\text{DiskAvg}V_x^\text{Rel}\) and \(^\text{FiltDiskAvg}V_x^\text{Rel}\)

rotor-disk-averaged relative wind speed (ambient plus wakes of neighboring turbines plus turbine motion), normal to the disk, and its low-pass time-filtered value

\(V_x\)

axial velocity in the axisymmetric coordinate system

\(V_{x_{n_p}}^\text{Wake}(r)\)

axial wake-velocity deficit at wake plane \(n_p\), distributed radially

\(^\text{DiskAvg}V_x^\text{Wind}\) and \(^\text{FiltDiskAvg}V_{x_{n_p}}^\text{Wind}\)

rotor-disk-averaged ambient wind speed, normal to the disk, and its low-pass time-filtered value at wake plane \(n_p\)

\(w_{n^\text{Wind}}\)

weighting in the spatial averaging for wind data point \(n^\text{Wind}\)

WD

wake dynamics (module)

WISDEM

Wind-Plant Integrated System Design & Engineering Model

\(x\) and \(x_{n_p}^\text{Plane}\)

downwind distance from a rotor to wake plane \(n_p\) in the axisymmetric coordinate system

\(X\), \(Y\), and \(Z\)

inertial-frame coordinates, with Z directed vertically upward, opposite gravity, X directed horizontally nominally downwind (along the zero-degree wind direction), and Y directed horizontally transversely

\(\hat{X}\), \(\hat{Y}\), and \(\hat{Z}\)

unit vectors of the inertial-frame coordinate system, parallel to the X, Y, and X coordinates

\(x^d\)

discrete-time states

\(X^d(\quad)\)

discrete-time state functions

\(\hat{x}^\text{Disk}\)

orientation of a rotor centerline

\(\hat{x}_{n_p}^\text{Plane}\)

orientation of wake plane \(n_p\)

\(y^d\)

discrete-time outputs

\(Y^d(\quad)\)

discrete-time output functions

\(z_\text{bot}\)

bottom vertical location of synthetic turbulence inflow grid

\(\alpha\)

low-pass time-filter parameter

\(\Delta t\)

discrete time step (increment)

\(\gamma^\text{YawErr}\) and \(^\text{Filt}\gamma_{n_p}^\text{YawErr}\)

nacelle-yaw error of a rotor and its low-pass time-filtered value at wake plane \(n_p\)

\(\nu_T\)

eddy viscosity

\(\rho\)

air density

2D

two dimensional

3D

three dimensional