Source code for RCAIDE.Library.Methods.Aerodynamics.Common.Drag.parasite_total
# RCAIDE/Methods/Aerodynamics/Common/Drag/parasite_drag_total.py
# (c) Copyright 2023 Aerospace Research Community LLC
#
# Created: Jun 2024, M. Clarke
# ----------------------------------------------------------------------------------------------------------------------
# IMPORT
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import numpy as np
# package imports
import numpy as np
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# Total Parasite Drag
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[docs]
def parasite_total(state,settings,geometry):
"""
Computes the total parasite drag coefficient by summing contributions from all aircraft components.
Parameters
----------
state : Data
Flight conditions and aerodynamic state containing:
- conditions.aerodynamics.coefficients.drag.parasite : dict
Dictionary of parasite drag coefficients indexed by component tag containing:
- total : float
Parasite drag coefficient for each component [unitless]
settings : dict
Aerodynamic analysis settings containing:
- drag_reduction_factors.parasite_drag : float
Parasite drag reduction factor [unitless]
geometry : Data
Aircraft geometry containing:
- reference_area : float
Vehicle reference area for drag coefficient normalization [m²]
- wings : list
List of wing objects containing:
- tag : str
Unique identifier for the wing
- areas.reference : float
Reference area of the wing [m²]
- fuselages : list
List of fuselage objects containing:
- tag : str
Unique identifier for the fuselage
- areas.front_projected : float
Front projected area of the fuselage [m²]
- booms : list
List of boom objects containing:
- tag : str
Unique identifier for the boom
- areas.front_projected : float
Front projected area of the boom [m²]
- networks : list
List of propulsion networks containing propulsors
- propulsors : list
List of propulsor objects with nacelle attributes
- nacelle : Nacelle, optional
Nacelle object containing:
- tag : str
Unique identifier for the nacelle
- diameter : float
Diameter of the nacelle [m]
Returns
-------
None
Results are stored in state.conditions.aerodynamics.coefficients.drag.parasite.total
Notes
-----
This function aggregates parasite drag contributions from all aircraft components
(wings, fuselages, booms, nacelles, and pylons) and normalizes them to the vehicle
reference area. The total is then adjusted by a drag reduction factor to account
for interference effects and other corrections.
**Major Assumptions**
* Component drag coefficients are normalized to their respective reference areas
* Vehicle reference area is used for final normalization
* Drag reduction factor accounts for interference effects
* Nacelle front area is calculated as circular cross-section
* Component contributions are additive
**Theory**
The total parasite drag coefficient is calculated as the sum of all component contributions:
:math:`C_{D,parasite,total} = \\sum_{i=1}^{n} C_{D,parasite,i} \\cdot \\frac{S_{ref,i}}{S_{ref,vehicle}}`
where:
- :math:`C_{D,parasite,i}` is the parasite drag coefficient of component :math:`i`
- :math:`S_{ref,i}` is the reference area of component :math:`i`
- :math:`S_{ref,vehicle}` is the vehicle reference area
For wings:
:math:`S_{ref,wing} = S_{wing}` (wing reference area)
For fuselages and booms:
:math:`S_{ref,fuselage} = S_{front,projected}` (front projected area)
For nacelles:
:math:`S_{ref,nacelle} = \\frac{\\pi d_{nacelle}^2}{4}` (circular cross-section area)
The final total parasite drag coefficient includes a reduction factor (user defined):
:math:`C_{D,parasite,final} = C_{D,parasite,total} \\cdot (1 - f_{reduction})`
where :math:`f_{reduction}` is the parasite drag reduction factor.
See Also
--------
RCAIDE.Library.Methods.Aerodynamics.Common.Drag.parasite_drag_wing
RCAIDE.Library.Methods.Aerodynamics.Common.Drag.parasite_drag_fuselage
RCAIDE.Library.Methods.Aerodynamics.Common.Drag.parasite_drag_nacelle
RCAIDE.Library.Methods.Aerodynamics.Common.Drag.parasite_drag_pylon
"""
# unpack
conditions = state.conditions
vehicle_reference_area = geometry.reference_area
#compute parasite drag total
total_parasite_drag = 0.0
total_wing_parasite_drag = 0.0
total_boom_parasite_drag = 0.0
total_fuselage_parasite_drag = 0.0
total_nacelle_parasite_drag = 0.0
total_parasite_drag = 0.0
# renormalize parasite drag from wings using reference area of aircraft
for wing in geometry.wings:
wing_parasite_drag = conditions.aerodynamics.coefficients.drag.parasite[wing.tag].total
conditions.aerodynamics.coefficients.drag.parasite[wing.tag].total = wing_parasite_drag * wing.areas.reference/vehicle_reference_area
total_wing_parasite_drag += wing_parasite_drag * wing.areas.reference/vehicle_reference_area
# renormalize parasite drag from fuselages using reference area of aircraft
for fuselage in geometry.fuselages:
fuselage_parasite_drag = conditions.aerodynamics.coefficients.drag.parasite[fuselage.tag].total
conditions.aerodynamics.coefficients.drag.parasite[fuselage.tag].total = fuselage_parasite_drag * fuselage.areas.front_projected/vehicle_reference_area
total_fuselage_parasite_drag += fuselage_parasite_drag * fuselage.areas.front_projected/vehicle_reference_area
# renormalize parasite drag from booms using reference area of aircraft
for boom in geometry.booms:
boom_parasite_drag = conditions.aerodynamics.coefficients.drag.parasite[boom.tag].total
conditions.aerodynamics.coefficients.drag.parasite[boom.tag].total = boom_parasite_drag * boom.areas.front_projected/vehicle_reference_area
total_boom_parasite_drag += boom_parasite_drag * boom.areas.front_projected/vehicle_reference_area
# renormalize parasite drag from nacelles and pylons using reference area of aircraft
for network in geometry.networks:
for propulsor in network.propulsors:
if propulsor.nacelle != None:
nacelle = propulsor.nacelle
front_area = np.pi * (nacelle.diameter ** 2) /4
nacelle_parasite_drag = conditions.aerodynamics.coefficients.drag.parasite[nacelle.tag].total
conditions.aerodynamics.coefficients.drag.parasite[nacelle.tag].total = nacelle_parasite_drag * front_area/vehicle_reference_area
total_nacelle_parasite_drag += nacelle_parasite_drag * front_area/vehicle_reference_area
total_parasite_drag = total_nacelle_parasite_drag + total_fuselage_parasite_drag + total_wing_parasite_drag + total_boom_parasite_drag
state.conditions.aerodynamics.coefficients.drag.parasite.total = total_parasite_drag * (1 - settings.drag_reduction_factors.parasite_drag)
state.conditions.aerodynamics.coefficients.drag.parasite.nacelles = total_nacelle_parasite_drag * (1 - settings.drag_reduction_factors.parasite_drag)
state.conditions.aerodynamics.coefficients.drag.parasite.fuselages = total_fuselage_parasite_drag * (1 - settings.drag_reduction_factors.parasite_drag)
state.conditions.aerodynamics.coefficients.drag.parasite.wings = total_wing_parasite_drag * (1 - settings.drag_reduction_factors.parasite_drag)
state.conditions.aerodynamics.coefficients.drag.parasite.booms = total_boom_parasite_drag * (1 - settings.drag_reduction_factors.parasite_drag)
return
