Nomenclature

Acronym	Definition
BEM	Blade Element Theory
CFD	Computational Fluid Dynamics
DMST	Double Multiple Stream Tube
HWAT	Horizontal Axis Wind Turbine
MST	Multiple Stream Tube
NACA	National Advisory Committee for Aeronautics
SST	Single Stream Tube
VAWT	Vertical Axis Wind Turbine
Symbol	Definition
a	Axial Induction Factor (−)
au	Upstream Induction Factor (−)
ad	Downstream Induction Factor (−)
A	Rotor Swept Area (m2)
c	Blade Chord Length (m)
Cd	Coefficient of Drag (−)
Cl	Coefficient of Lift (−)
Cm	Coefficient of Moment (−)
Cn	Normal Force Coefficient (−)
Cp	Coefficient of Performance (−)
Ct	Tangential Force Coefficient (−)
Ft	Tangential Force Component (N)
Fn	Normal Force Component (N)
FTavg	Average Tangential Force Component (N)
Fup	Upwind Function (−)
N	Number of Blades (−)
Nst	Number of Stream Tubes (−)
L	Turbine Span Length (m)
P	Power (W)
R	Rotor radius (m)
S	Maximum local angle of attack (degree)
T	Torque (N/m)
${\mathrm{V}}_{{\mathrm{a}}_{\mathrm{d}}}$	Downstream Axial Induction Velocity (m/s)
${\mathrm{V}}_{{\mathrm{a}}_{\mathrm{u}}}$	Upstream Axial Induction Velocity (m/s)
${\mathrm{V}}_e$	Equilibrium Induced Velocity (m/s)
Vc	Blade Cordial Velocity (m/s)
Vn	Blade Normal Velocity (m/s)
Va	Induced Axial Velocity (m/s)
${\mathrm{V}}_{\mathrm{R}}$	Local Blade Relative Velocity (m/s)
${\mathrm{V}}_{\mathrm{R}}^{\mathrm{u}}$	Local Blade Relative Velocity Upstream (m/s)
${\mathrm{V}}_{\infty }$	Wind Freestream Velocity (m/s)
Greek letter	Definition
$\alpha$	Angle of Attack (degree)
${\alpha }^u$	Upstream Angle of Attack (degree)
${\alpha }^d$	Downstream Angle of Attack (degree)
$\beta$	Initial Blade Pitch Angle (degree)
$\mathrm{\lambda }$	Tip Speed Ratio (−)
$\rho$	Air Density (kg/m3)
$\theta$	Blade Azimuth Position (degree)
$\omega$	Rotor Rotational Speed (rad/sec or rpm)
$\sigma$	Solidity of Turbine (−)
ν	kinematic viscosity (m2/s)