Filter pressure drop (fluids.filters)¶
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 or contact the author at Caleb.Andrew.Bell@gmail.com.
Loss Coefficients for Screens¶
- fluids.filters.round_edge_screen(alpha, Re, angle=0.0)[source]¶
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
- Returns
- K
float
Loss coefficient [-]
- K
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.
References
- 1
Blevins, Robert D. Applied Fluid Dynamics Handbook. New York, N.Y.: Van Nostrand Reinhold Co., 1984.
Examples
>>> round_edge_screen(0.5, 100) 2.0999999999999996 >>> round_edge_screen(0.5, 100, 45) 1.05
- fluids.filters.round_edge_open_mesh(alpha, subtype='diamond pattern wire', angle=0.0)[source]¶
Returns the loss coefficient for a round edged open net/screen made of one of the following patterns, according to [1]:
‘round bar screen’:
‘diamond pattern wire’:
‘knotted net’:
‘knotless net’:
- Parameters
- Returns
- K
float
Loss coefficient [-]
- K
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.
References
- 1
Blevins, Robert D. Applied Fluid Dynamics Handbook. New York, N.Y.: Van Nostrand Reinhold Co., 1984.
Examples
>>> round_edge_open_mesh(0.96, angle=33.) 0.02031327712601458
- fluids.filters.square_edge_screen(alpha)[source]¶
Returns the loss coefficient for a square wire screen or square bar screen or perforated plate with squared edges, as shown in [1].
Notes
Linear interpolation between a table of values. The velocity the loss coefficient relates to is the approach velocity before the screen.
References
- 1
Blevins, Robert D. Applied Fluid Dynamics Handbook. New York, N.Y.: Van Nostrand Reinhold Co., 1984.
Examples
>>> square_edge_screen(0.99) 0.008000000000000007
Loss Coefficients for Grills¶
- fluids.filters.square_edge_grill(alpha, l=None, Dh=None, fd=None)[source]¶
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
else:
- Parameters
- Returns
- K
float
Loss coefficient [-]
- K
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.
References
- 1
Blevins, Robert D. Applied Fluid Dynamics Handbook. New York, N.Y.: Van Nostrand Reinhold Co., 1984.
Examples
>>> square_edge_grill(.45) 5.296296296296296 >>> square_edge_grill(.45, l=.15, Dh=.002, fd=.0185) 12.148148148148147
- fluids.filters.round_edge_grill(alpha, l=None, Dh=None, fd=None)[source]¶
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
else:
- Parameters
- Returns
- K
float
Loss coefficient [-]
- K
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.
References
- 1
Blevins, Robert D. Applied Fluid Dynamics Handbook. New York, N.Y.: Van Nostrand Reinhold Co., 1984.
Examples
>>> round_edge_grill(.4) 1.0 >>> round_edge_grill(.4, l=.15, Dh=.002, fd=.0185) 2.3874999999999997