CCBlade Airfoil Types

AlphaAF(alpha, cl, cd, info, Re, Mach)
AlphaAF(alpha, cl, cd, info, Re=0.0, Mach=0.0)
AlphaAF(alpha, cl, cd, info="CCBlade generated airfoil", Re=0.0, Mach=0.0)
AlphaAF(filename::String; radians=true)

Airfoil data that varies with angle of attack. Data is fit with an Akima spline.

Arguments:

• alpha::Vector{Float64}: angles of attack
• cl::Vector{Float64}: corresponding lift coefficients
• cd::Vector{Float64}: corresponding drag coefficients
• info::String: a description of this airfoil data (just informational)
• Re::Float64: Reynolds number data was taken at (just informational)
• Mach::Float64: Mach number data was taken at (just informational)

or

a file

Arguments:

• filename::String: name/path of file to read in
• radians::Bool: true if angle of attack in file is given in radians

AlphaMachAF(alpha, Mach, cl, cd, info, Re)
AlphaMachAF(alpha, Mach, cl, cd, info)
AlphaMachAF(alpha, Mach, cl, cd)
AlphaMachAF(filenames::Vector{String}; radians=true)

Airfoil data that varies with angle of attack and Mach number. Data is fit with a recursive Akima spline.

Arguments:

• alpha::Vector{Float64}: angles of attack
• Mach::Vector{Float64}: Mach numbers
• cl::Matrix{Float64}: lift coefficients where cl[i, j] corresponds to alpha[i], Mach[j]
• cd::Matrix{Float64}: drag coefficients where cd[i, j] corresponds to alpha[i], Mach[j]
• info::String: a description of this airfoil data (just informational)
• Re::Float64: Reynolds number data was taken at (just informational)

or

filenames with one file per Mach number.

Arguments:

• filenames::Vector{String}: name/path of files to read in, each at a different Mach number in ascending order
• radians::Bool: true if angle of attack in file is given in radians

AlphaReAF(alpha, Re, cl, cd, info, Mach)
AlphaReAF(alpha, Re, cl, cd, info)
AlphaReAF(alpha, Re, cl, cd)
read_AlphaReAF(filenames::Vector{String}; radians=true)

Airfoil data that varies with angle of attack and Reynolds number. Data is fit with a recursive Akima spline.

Arguments:

• alpha::Vector{Float64}: angles of attack
• Re::Vector{Float64}: Reynolds numbers
• cl::Matrix{Float64}: lift coefficients where cl[i, j] corresponds to alpha[i], Re[j]
• cd::Matrix{Float64}: drag coefficients where cd[i, j] corresponds to alpha[i], Re[j]
• info::String: a description of this airfoil data (just informational)
• Mach::Float64: Mach number data was taken at (just informational)

or

filenames with one file per Reynolds number.

Arguments:

• filenames::Vector{String}: name/path of files to read in, each at a different Reynolds number in ascending order
• radians::Bool: true if angle of attack in file is given in radians

AlphaReMachAF(alpha, Re, Mach, cl, cd, info)
AlphaReMachAF(alpha, Re, Mach, cl, cd)
AlphaReMachAF(filenames::Matrix{String}; radians=true)

Airfoil data that varies with angle of attack, Reynolds number, and Mach number. Data is fit with a recursive Akima spline.

Arguments:

• alpha::Vector{Float64}: angles of attack
• Re::Vector{Float64}: Reynolds numbers
• Mach::Vector{Float64}: Mach numbers
• cl::Array{Float64}: lift coefficients where cl[i, j, k] corresponds to alpha[i], Re[j], Mach[k]
• cd::Array{Float64}: drag coefficients where cd[i, j, k] corresponds to alpha[i], Re[j], Mach[k]
• info::String: a description of this airfoil data (just informational)

or files with one per Re/Mach combination

Arguments:

• filenames::Matrix{String}: name/path of files to read in. filenames[i, j] corresponds to Re[i] Mach[j] with Reynolds number and Mach number in ascending order.
• radians::Bool: true if angle of attack in file is given in radians

DuSeligEggers(a, b, d, m, alpha0)
DuSeligEggers(a=1.0, b=1.0, d=1.0, m=2*pi, alpha0=0.0)  # uses defaults

DuSelig correction for lift an Eggers correction for drag.

Arguments:

• a, b, d::Float64: parameters in Du-Selig paper. Normally just 1.0 for each.
• m::Float64: lift curve slope. Defaults to 2 pi for zero argument version.
• alpha0::Float64: zero-lift angle of attack. Defaults to 0 for zero argument version.

PrandtlTip()

Standard Prandtl tip loss correction.

PrandtlTipHub()

Standard Prandtl tip loss correction plus hub loss correction of same form.

SimpleAF(m, alpha0, clmax, clmin, cd0, cd2)

A simple parameterized lift and drag curve.

• cl = m (alpha - alpha0) (capped by clmax/clmin)
• cd = cd0 + cd2 * cl^2

Arguments:

• m::Float64: lift curve slope
• alpha0::Float64: zero-lift angle of attack
• clmax::Float64: maximum lift coefficient
• clmin::Float64: minimum lift coefficient
• cd0::Float64: zero lift drag
• cd2::Float64: quadratic drag term

SkinFriction(Re0, p)

Skin friction model for a flat plate. cd *= (Re0 / Re)^p

Arguments:

• Re0::Float64: reference Reynolds number (i.e., no corrections at this number)
• p::Float64: exponent in flat plate model. 0.5 for laminar (Blasius solution), ~0.2 for fully turbulent (Schlichting empirical fit)

afeval(af::AFType, alpha, Re, Mach)

Evaluate airfoil aerodynamic performance

Arguments:

• af::AFType or Function: dispatch on AFType or if function call: cl, cd = af(alpha, Re, Mach)
• alpha::Float64: angle of attack in radians
• Re::Float64: Reynolds number
• Mach::Float64: Mach number

Returns:

• cl::Float64: lift coefficient
• cd::Float64: drag coefficient

mach_correction(::MachCorrection, cl, cd, Mach)

Mach number correction for lift/drag coefficient

Arguments:

• mc::MachCorrection: used for dispatch
• cl::Float64: lift coefficient before correction
• cd::Float64: drag coefficient before correction
• Mach::Float64: Mach number

Returns:

• cl::Float64: lift coefficient after correction
• cd::Float64: drag coefficient after correction

mach_correction(::PrandtlGlauert, cl, cd, Mach)

Prandtl/Glauert Mach number correction for lift coefficient

A basic airfoil file format. nheader is the number of header lines, which will be skipped. For one Reynolds/Mach number. Additional data like cm is optional but will be ignored.

format:

informational header

Re

Mach

alpha1 cl1 cd1 ...

alpha2 cl2 cd2

alpha3 cl3 cd3

...

re_correction(re::ReCorrection, cl, cd, Re)

Reynolds number correction for lift/drag coefficient

Arguments:

• re::ReCorrection: used for dispatch
• cl::Float64: lift coefficient before correction
• cd::Float64: drag coefficient before correction
• Re::Float64: Reynolds number

Returns:

• cl::Float64: lift coefficient after correction
• cd::Float64: drag coefficient after correction

re_correction(sf::SkinFriction, cl, cd, Re)

Skin friction coefficient correction based on flat plat drag increases with Reynolds number.

rotation_correction(rc::RotationCorrection, cl, cd, cr, rR, tsr, alpha, phi=alpha, alpha_max_corr=30*pi/180)

Rotation correction (3D stall delay).

Arguments:

• rc::RotationCorrection: used for dispatch
• cl::Float64: lift coefficient before correction
• cd::Float64: drag coefficient before correction
• cr::Float64: local chord / local radius
• rR::Float64: local radius / tip radius
• tsr::Float64: local tip speed ratio (Omega r / Vinf)
• alpha::Float64: local angle of attack
• phi::Float64: local inflow angles (defaults to angle of attack is precomputing since it is only known for on-the-fly computations)
• alpha_max_corr::Float64: angle of attack for maximum correction (tapers off to zero by 90 degrees)

Returns:

• cl::Float64: lift coefficient after correction
• cd::Float64: drag coefficient after correction

tip_correction(::TipCorrection, r, Rhub, Rtip, phi, B)

Tip corrections for 3D flow.

Arguments:

• tc::TipCorrection: used for dispatch
• r::Float64: local radius
• Rhub::Float64: hub radius
• Rtip::Float64: tip radius
• phi::Float64: inflow angle
• B::Integer: number of blades

Returns:

• F::Float64: tip loss factor to multiple against loads.

viterna(alpha, cl, cd, cr75, nalpha=50)

Viterna extrapolation. Follows Viterna paper and somewhat follows NREL version of AirfoilPrep, but with some modifications for better robustness and smoothness.

Arguments:

• alpha::Vector{Float64}: angles of attack
• cl::Vector{Float64}: correspnding lift coefficients
• cd::Vector{Float64}: correspnding drag coefficients
• cr75::Float64: chord/Rtip at 75% Rtip
• nalpha::Int64: number of discrete points (angles of attack) to include in extrapolation

Returns:

• alpha::Vector{Float64}: angle of attack from -pi to pi
• cl::Vector{Float64}: correspnding extrapolated lift coefficients
• cd::Vector{Float64}: correspnding extrapolated drag coefficients

write_af(filename(s), af::AFType; radians=true)

Write airfoil data to file

Arguments:

• filename(s)::String or Vector{String} or Matrix{String}: name/path of file to write to
• af::AFType: writing is dispatched based on type (AlphaAF, AlphaReAF, etc.)
• radians::Bool: true if you want angle of attack to be written in radians