"""Chemical Engineering Design Library (ChEDL). Utilities for process modeling.
Copyright (C) 2016, 2017, 2018, 2019, 2020 Caleb Bell <Caleb.Andrew.Bell@gmail.com>
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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The above copyright notice and this permission notice shall be included in all
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
This module contains correlations for the loss coefficient of various types
of filters in a pipe or channel.
For reporting bugs, adding feature requests, or submitting pull requests,
please use the `GitHub issue tracker <https://github.com/CalebBell/fluids/>`_
or contact the author at Caleb.Andrew.Bell@gmail.com.
.. contents:: :local:
Loss Coefficients for Screens
-----------------------------
.. autofunction:: round_edge_screen
.. autofunction:: round_edge_open_mesh
.. autofunction:: square_edge_screen
Loss Coefficients for Grills
----------------------------
.. autofunction:: square_edge_grill
.. autofunction:: round_edge_grill
"""
from math import cos, radians
from fluids.numerics import implementation_optimize_tck, interp, splev
__all__ = ['round_edge_screen', 'round_edge_open_mesh', 'square_edge_screen',
'square_edge_grill', 'round_edge_grill']
round_Res = [20.0, 30.0, 40.0, 60.0, 80.0, 100.0, 200.0, 400.0]
round_betas = [1.3, 1.1, 0.95, 0.83, 0.75, 0.7, 0.6, 0.52]
"""Quadratic interpolation with no smoothing, constant value extremities
returned when outside table limits"""
round_thetas = [0.0, 10.0, 20.0, 30.0, 40.0, 50.0, 60.0, 70.0, 80.0, 85.0]
round_gammas = [1.0, 0.97, 0.88, 0.75, 0.59, 0.45, 0.3, 0.23, 0.15, 0.09]
"""Quadratic interpolation with no smoothing, constant value extremities
returned when outside table limits"""
"""Quadratic interpolation with no smoothing, constant value extremities
returned when outside table limits. Last actual value in the original table is
K=1000 at alpha=0.05; the rest are extrapolated."""
square_alphas = [0.0015625, 0.003125, 0.00625, 0.0125, 0.025, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 1.]
square_Ks = [1024000., 256000, 64000, 16000, 4000, 1000., 250., 85., 52., 30., 17., 11., 7.7, 5.5, 3.8, 2.8, 2, 1.5, 1.1, 0.78, 0.53, 0.35, 0.08, 0.]
grills_rounded_alphas = [0.3, 0.4, 0.5, 0.6, 0.7]
grills_rounded_Ks = [2.0, 1.0, 0.6, 0.4, 0.2]
"""Cubic interpolation with no smoothing, constant value extremities
returned when outside table limits"""
grills_rounded_tck = implementation_optimize_tck([[0.3, 0.3, 0.3, 0.45, 0.55, 0.7, 0.7, 0.7],
[2.0, 1.0014285714285716, 0.5799999999999998,
0.3585714285714287, 0.2, 0.0, 0.0, 0.0],
2])
[docs]def round_edge_screen(alpha, Re, angle=0.0):
r'''Returns the loss coefficient for a round edged wire screen or bar
screen, as shown in [1]_. Angle of inclination may be specified as well.
Parameters
----------
alpha : float
Fraction of screen open to flow [-]
Re : float
Reynolds number of flow through screen with D = space between rods, []
angle : float, optional
Angle of inclination, with 0 being straight and 90 being parallel to
flow [degrees]
Returns
-------
K : float
Loss coefficient [-]
Notes
-----
Linear interpolation between a table of values. Re table extends
from 20 to 400, with constant values outside of the table. This behavior
should be adequate.
alpha should be between 0.05 and 0.8.
If angle is over 85 degrees, the value at 85 degrees is used.
The velocity the loss coefficient relates to is the approach velocity
before the screen.
Examples
--------
>>> round_edge_screen(0.5, 100)
2.0999999999999996
>>> round_edge_screen(0.5, 100, 45)
1.05
References
----------
.. [1] Blevins, Robert D. Applied Fluid Dynamics Handbook. New York, N.Y.:
Van Nostrand Reinhold Co., 1984.
'''
beta = interp(Re, round_Res, round_betas)
alpha2 = alpha*alpha
K = beta*(1.0 - alpha2)/alpha2
if angle is not None:
if angle <= 45.0:
v = cos(radians(angle))
K *= v*v
else:
K *= interp(angle, round_thetas, round_gammas)
return K
[docs]def round_edge_open_mesh(alpha, subtype='diamond pattern wire', angle=0.0):
r'''Returns the loss coefficient for a round edged open net/screen
made of one of the following patterns, according to [1]_:
'round bar screen':
.. math::
K = 0.95(1-\alpha) + 0.2(1-\alpha)^2
'diamond pattern wire':
.. math::
K = 0.67(1-\alpha) + 1.3(1-\alpha)^2
'knotted net':
.. math::
K = 0.70(1-\alpha) + 4.9(1-\alpha)^2
'knotless net':
.. math::
K = 0.72(1-\alpha) + 2.1(1-\alpha)^2
Parameters
----------
alpha : float
Fraction of net/screen open to flow [-]
subtype : str
One of 'round bar screen', 'diamond pattern wire', 'knotted net' or
'knotless net'.
angle : float, optional
Angle of inclination, with 0 being straight and 90 being parallel to
flow [degrees]
Returns
-------
K : float
Loss coefficient [-]
Notes
-----
`alpha` should be between 0.85 and 1 for these correlations.
Flow should be turbulent, with Re > 500.
The velocity the loss coefficient relates to is the approach velocity
before the mesh.
Examples
--------
>>> round_edge_open_mesh(0.96, angle=33.)
0.02031327712601458
References
----------
.. [1] Blevins, Robert D. Applied Fluid Dynamics Handbook. New York, N.Y.:
Van Nostrand Reinhold Co., 1984.
'''
one_m_alpha = (1.0-alpha)
if subtype == 'round bar screen':
K = 0.95 + 0.2*one_m_alpha
elif subtype == 'diamond pattern wire':
K = 0.67 + 1.3*one_m_alpha
elif subtype == 'knotted net':
K = 0.70 + 4.9*one_m_alpha
elif subtype == 'knotless net':
K = 0.72 + 2.1*one_m_alpha
else:
raise ValueError('Subtype not recognized')
K *= one_m_alpha
if angle is not None:
if angle < 45.0:
K *= cos(radians(angle))**2.0
else:
K *= interp(angle, round_thetas, round_gammas)
return K
[docs]def square_edge_screen(alpha):
r'''Returns the loss coefficient for a square wire screen or square bar
screen or perforated plate with squared edges, as shown in [1]_.
Parameters
----------
alpha : float
Fraction of screen open to flow [-]
Returns
-------
K : float
Loss coefficient [-]
Notes
-----
Linear interpolation between a table of values.
The velocity the loss coefficient relates to is the approach velocity
before the screen.
Examples
--------
>>> square_edge_screen(0.99)
0.008000000000000007
References
----------
.. [1] Blevins, Robert D. Applied Fluid Dynamics Handbook. New York, N.Y.:
Van Nostrand Reinhold Co., 1984.
'''
return interp(alpha, square_alphas, square_Ks)
[docs]def square_edge_grill(alpha, l=None, Dh=None, fd=None):
r'''Returns the loss coefficient for a square grill or square bar
screen or perforated plate with squared edges of thickness l, as shown in
[1]_.
for Dh < l < 50D
.. math::
K = \frac{0.5(1-\alpha) + (1-\alpha^2)}{\alpha^2}
else:
.. math::
K = \frac{0.5(1-\alpha) + (1-\alpha^2) + f{l}/D}{\alpha^2}
Parameters
----------
alpha : float
Fraction of grill open to flow [-]
l : float, optional
Thickness of the grill or plate [m]
Dh : float, optional
Hydraulic diameter of gap in grill, [m]
fd : float, optional
Darcy friction factor [-]
Returns
-------
K : float
Loss coefficient [-]
Notes
-----
If l, Dh, or fd is not provided, the first expression is used instead.
The alteration of the expression to include friction factor is there
if the grill is long enough to have considerable friction along the
surface of the grill.
The velocity the loss coefficient relates to is the approach velocity
before the grill.
Examples
--------
>>> square_edge_grill(.45)
5.296296296296296
>>> square_edge_grill(.45, l=.15, Dh=.002, fd=.0185)
12.148148148148147
References
----------
.. [1] Blevins, Robert D. Applied Fluid Dynamics Handbook. New York, N.Y.:
Van Nostrand Reinhold Co., 1984.
'''
x0 = 0.5*(1.0 - alpha)
alpha2 = alpha*alpha
x0 += (1.0 - alpha2)
if Dh is not None and l is not None and fd is not None and l > 50.0*Dh:
x0 += fd*l/Dh
return x0/alpha2
[docs]def round_edge_grill(alpha, l=None, Dh=None, fd=None):
r'''Returns the loss coefficient for a rounded square grill or square bar
screen or perforated plate with rounded edges of thickness l, as shown in
[1]_.
for Dh < l < 50D
.. math::
K = lookup(alpha)
else:
.. math::
K = lookup(alpha) + \frac{fl}{\alpha^2D}
Parameters
----------
alpha : float
Fraction of grill open to flow [-]
l : float, optional
Thickness of the grill or plate [m]
Dh : float, optional
Hydraulic diameter of gap in grill, [m]
fd : float, optional
Darcy friction factor [-]
Returns
-------
K : float
Loss coefficient [-]
Notes
-----
If l, Dh, or fd is not provided, the first expression is used instead.
The alteration of the expression to include friction factor is there
if the grill is long enough to have considerable friction along the
surface of the grill.
alpha must be between 0.3 and 0.7.
The velocity the loss coefficient relates to is the approach velocity
before the grill.
Examples
--------
>>> round_edge_grill(.4)
1.0
>>> round_edge_grill(.4, l=.15, Dh=.002, fd=.0185)
2.3874999999999997
References
----------
.. [1] Blevins, Robert D. Applied Fluid Dynamics Handbook. New York, N.Y.:
Van Nostrand Reinhold Co., 1984.
'''
t1 = float(splev(alpha, grills_rounded_tck))
if Dh and l and fd and l > 50.0*Dh:
return t1 + fd*l/Dh
else:
return t1