m_alm_element

Actuator lines for the actuator line model (ALM): blade-element geometry, rigid-body kinematics and aerodynamic loads.

Ported from Incompact3d's acl_elem.f90 and acl_utils.f90. An actuator line is defined by its stations (element ends) on the quarter-chord line; element centres, unit vectors (spanwise s, chordwise t, normal n), areas and chords are derived from them by make_line_geometry. Loads come from the static airfoil polars, $\alpha = \operatorname{atan2}(u_n, u_t),\qquad \mathbf{F} = \tfrac12\rho\,U_r^2 A\,F_{end} \left(C_N\mathbf{n} + C_T\mathbf{t}\right),$ with $C_N = C_L\cos\alpha + C_D\sin\alpha$ , $C_T = -C_L\sin\alpha + C_D\cos\alpha$ and $u_n, u_t$ the normal and chordwise components of the fluid velocity relative to the element.

The dynamic-stall, added-mass, random-walk and constant-circulation options of Incompact3d are not ported.

Uses

- m_alm_airfoil
- m_common
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Used by

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Graph Key

Nodes of different colours represent the following:

Solid arrows point from a submodule to the (sub)module which it is descended from. Dashed arrows point from a module or program unit to modules which it uses.
Where possible, edges connecting nodes are given different colours to make them easier to distinguish in large graphs.

Variables

Type	Visibility	Attributes		Name		Initial
real(kind=dp),	public,	parameter	::	deg2rad	=	pi/180._dp

Derived Types

type, public :: actuator_line_t

Components

Type	Visibility	Attributes		Name		Initial
character(len=256),	public		::	name	=	''
integer,	public		::	n_elem	=	0
logical,	public		::	flip_n	=	.false.	flip the normal (clockwise rotor)
real(kind=dp),	public		::	cor(3)	=	0._dp	centre of rotation
real(kind=dp),	public		::	length	=	0._dp	reference length (blade radius)
real(kind=dp),	public,	allocatable	::	qc(:,:)			(3, n_elem + 1) quarter-chord points
real(kind=dp),	public,	allocatable	::	t(:,:)			(3, n_elem + 1) chordwise unit vec
real(kind=dp),	public,	allocatable	::	chord(:)
real(kind=dp),	public,	allocatable	::	thick(:)			thickness to chord ratio
real(kind=dp),	public,	allocatable	::	pitch(:)			station pitch [rad]
real(kind=dp),	public,	allocatable	::	pe(:,:)			(3, n_elem) element centres
real(kind=dp),	public,	allocatable	::	te(:,:)			chordwise unit vector
real(kind=dp),	public,	allocatable	::	ne(:,:)			normal unit vector
real(kind=dp),	public,	allocatable	::	se(:,:)			spanwise unit vector
real(kind=dp),	public,	allocatable	::	ec(:)			chord
real(kind=dp),	public,	allocatable	::	eds(:)			spanwise length
real(kind=dp),	public,	allocatable	::	earea(:)			planform area
real(kind=dp),	public,	allocatable	::	erdist(:)			distance from cor
real(kind=dp),	public,	allocatable	::	ettoc(:)			thickness to chord ratio
real(kind=dp),	public,	allocatable	::	epitch(:)			pitch [rad]
integer,	public,	allocatable	::	eairfoil(:)			index into the owner's airfoils
real(kind=dp),	public,	allocatable	::	evel(:,:)			(3, n_elem) sampled fluid velocity
real(kind=dp),	public,	allocatable	::	evb(:,:)			(3, n_elem) body velocity
real(kind=dp),	public,	allocatable	::	eaoa(:)			angle of attack [rad]
real(kind=dp),	public,	allocatable	::	ere(:)			chord Reynolds number
real(kind=dp),	public,	allocatable	::	eur(:)			relative speed
real(kind=dp),	public,	allocatable	::	ecl(:)
real(kind=dp),	public,	allocatable	::	ecd(:)
real(kind=dp),	public,	allocatable	::	ecm(:)
real(kind=dp),	public,	allocatable	::	ecn(:)
real(kind=dp),	public,	allocatable	::	ect(:)
real(kind=dp),	public,	allocatable	::	efn(:)
real(kind=dp),	public,	allocatable	::	eft(:)
real(kind=dp),	public,	allocatable	::	ems(:)
real(kind=dp),	public,	allocatable	::	ef(:,:)			(3, n_elem) force [N]
real(kind=dp),	public,	allocatable	::	end_factor(:)			tip/root loss factor

Functions

public pure function quat_rot(v, theta, axis, origin) result(v_rot)

Rotate point v by theta [rad] about axis through origin (right-hand rule). Equivalent to Incompact3d's quaternion QuatRot, written in Rodrigues' form; axis need not be normalised.

Arguments

Type	Intent		Name
real(kind=dp),	intent(in)	::	v(3)
real(kind=dp),	intent(in)	::	theta
real(kind=dp),	intent(in)	::	axis(3)
real(kind=dp),	intent(in)	::	origin(3)

Return Value real(kind=dp), (3)

public pure function cross(a, b) result(c)

Arguments

Type	Intent	Optional	Attributes		Name
real(kind=dp),	intent(in)			::	a(3)
real(kind=dp),	intent(in)			::	b(3)

Return Value real(kind=dp), (3)

Subroutines

public subroutine allocate_line(line, n_stations)

(Re)allocate the station and element arrays of line.

Arguments

Type	Intent	Optional	Attributes		Name
type(actuator_line_t),	intent(inout)			::	line
integer,	intent(in)			::	n_stations

public subroutine read_line_geometry(filename, length, span_vec, r_over_l, c_over_l, pitch, thick)

Read an actuator line geometry (.al) file: <label>: <length>, <label>: <sx> <sy> <sz>, <label>: <n>, then n rows of r/L c/L pitch[deg] t/c.

Arguments

Type	Intent	Attributes		Name
character(len=*),	intent(in)		::	filename
real(kind=dp),	intent(out)		::	length
real(kind=dp),	intent(out)		::	span_vec(3)
real(kind=dp),	intent(out),	allocatable	::	r_over_l(:)
real(kind=dp),	intent(out),	allocatable	::	c_over_l(:)
real(kind=dp),	intent(out),	allocatable	::	pitch(:)
real(kind=dp),	intent(out),	allocatable	::	thick(:)

public subroutine make_line_geometry(line)

Element centres, unit vectors, areas and chords from the stations.

Arguments

Type	Intent	Optional	Attributes		Name
type(actuator_line_t),	intent(inout)			::	line

public subroutine rotate_line(line, origin, axis, theta)

Rotate the stations of line by theta about axis through origin (chordwise vectors about axis through zero). Element geometry is not rebuilt; call make_line_geometry afterwards.

Arguments

Type	Intent		Name
type(actuator_line_t),	intent(inout)	::	line
real(kind=dp),	intent(in)	::	origin(3)
real(kind=dp),	intent(in)	::	axis(3)
real(kind=dp),	intent(in)	::	theta

public subroutine pitch_line(line, pitch_angle)

Pitch every station by pitch_angle [rad] about the line's root-to-tip direction, then rebuild the element geometry.

Arguments

Type	Intent	Optional	Attributes		Name
type(actuator_line_t),	intent(inout)			::	line
real(kind=dp),	intent(in)			::	pitch_angle

public subroutine populate_line_airfoils(line, airfoils)

Give every element the airfoil whose thickness ratio is closest to its own, clamped to the thinnest and thickest available.

Arguments

Type	Intent	Optional	Attributes		Name
type(actuator_line_t),	intent(inout)			::	line
type(airfoil_t),	intent(in)			::	airfoils(:)

public subroutine compute_line_forces(line, airfoils, rho_air, visc)

Blade-element loads of every element from the sampled fluid velocity, the body velocity and the static polars.

Arguments

Type	Intent		Name
type(actuator_line_t),	intent(inout)	::	line
type(airfoil_t),	intent(in)	::	airfoils(:)
real(kind=dp),	intent(in)	::	rho_air
real(kind=dp),	intent(in)	::	visc

public subroutine compute_tower_forces(tower, rho_air, visc, time, cl, cd, strouhal, noise)

Tower loads: constant drag and a lift oscillating at the shedding frequency St*U/D, perturbed by noise (uniform in [0, 1) per element).

Arguments

Type	Intent		Name
type(actuator_line_t),	intent(inout)	::	tower
real(kind=dp),	intent(in)	::	rho_air
real(kind=dp),	intent(in)	::	visc
real(kind=dp),	intent(in)	::	time
real(kind=dp),	intent(in)	::	cl
real(kind=dp),	intent(in)	::	cd
real(kind=dp),	intent(in)	::	strouhal
real(kind=dp),	intent(in)	::	noise(:)

m_alm_element Module

Contents

Variables

Derived Types

Functions

Subroutines

Uses

Used by

Variables

Derived Types

type, public :: actuator_line_t

Components

Functions

public pure function quat_rot(v, theta, axis, origin) result(v_rot)

Arguments

Return Value real(kind=dp), (3)

public pure function cross(a, b) result(c)

Arguments

Return Value real(kind=dp), (3)

Subroutines

public subroutine allocate_line(line, n_stations)

Arguments

public subroutine read_line_geometry(filename, length, span_vec, r_over_l, c_over_l, pitch, thick)

Arguments

public subroutine make_line_geometry(line)

Arguments

public subroutine rotate_line(line, origin, axis, theta)

Arguments

public subroutine pitch_line(line, pitch_angle)

Arguments

public subroutine populate_line_airfoils(line, airfoils)

Arguments

public subroutine compute_line_forces(line, airfoils, rho_air, visc)

Arguments

public subroutine compute_tower_forces(tower, rho_air, visc, time, cl, cd, strouhal, noise)

Arguments