"""Computation of form drag for wing."""
# This file is part of FAST-OAD : A framework for rapid Overall Aircraft Design
# Copyright (C) 2021 ONERA & ISAE-SUPAERO
# FAST is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <https://www.gnu.org/licenses/>.
import numpy as np
import openmdao.api as om
from fastoad.module_management.service_registry import RegisterSubmodel
from .utils.cd0_lifting_surface import LiftingSurfaceGeometry, compute_cd0_lifting_surface
from ..constants import SERVICE_CD0_WING
[docs]@RegisterSubmodel(SERVICE_CD0_WING, "fastoad.submodel.aerodynamics.CD0.wing.legacy")
class Cd0Wing(om.ExplicitComponent):
"""
Computation of form drag for wing.
See :meth:`~fastoad.models.aerodynamics.components.utils.cd0_lifting_surface` for used method.
"""
[docs] def initialize(self):
self.options.declare("low_speed_aero", default=False, types=bool)
[docs] def setup(self):
if self.options["low_speed_aero"]:
self.add_input("data:aerodynamics:wing:low_speed:reynolds", val=np.nan)
self.add_input(
"data:aerodynamics:aircraft:low_speed:CL", shape_by_conn=True, val=np.nan
)
self.add_input("data:aerodynamics:aircraft:takeoff:mach", val=np.nan)
self.add_output(
"data:aerodynamics:wing:low_speed:CD0",
copy_shape="data:aerodynamics:aircraft:low_speed:CL",
)
else:
self.add_input("data:aerodynamics:wing:cruise:reynolds", val=np.nan)
self.add_input("data:aerodynamics:aircraft:cruise:CL", shape_by_conn=True, val=np.nan)
self.add_input("data:TLAR:cruise_mach", val=np.nan)
self.add_output(
"data:aerodynamics:wing:cruise:CD0",
copy_shape="data:aerodynamics:aircraft:cruise:CL",
)
self.add_input("data:geometry:wing:area", val=np.nan, units="m**2")
self.add_input("data:geometry:wing:thickness_ratio", val=np.nan)
self.add_input("data:geometry:wing:wetted_area", val=np.nan, units="m**2")
self.add_input("data:geometry:wing:MAC:length", val=np.nan, units="m")
self.add_input("data:geometry:wing:sweep_25", val=np.nan, units="deg")
[docs] def setup_partials(self):
self.declare_partials("*", "*", method="fd")
[docs] def compute(self, inputs, outputs, discrete_inputs=None, discrete_outputs=None):
wing_geometry = LiftingSurfaceGeometry(
thickness_ratio=inputs["data:geometry:wing:thickness_ratio"],
MAC_length=inputs["data:geometry:wing:MAC:length"],
sweep_angle_25=inputs["data:geometry:wing:sweep_25"],
wet_area=inputs["data:geometry:wing:wetted_area"],
cambered=True,
interaction_coeff=0.04,
)
wing_area = inputs["data:geometry:wing:area"]
if self.options["low_speed_aero"]:
cl = inputs["data:aerodynamics:aircraft:low_speed:CL"]
mach = inputs["data:aerodynamics:aircraft:takeoff:mach"]
reynolds = inputs["data:aerodynamics:wing:low_speed:reynolds"]
else:
cl = inputs["data:aerodynamics:aircraft:cruise:CL"]
mach = inputs["data:TLAR:cruise_mach"]
reynolds = inputs["data:aerodynamics:wing:cruise:reynolds"]
cd0_wing = compute_cd0_lifting_surface(wing_geometry, mach, reynolds, wing_area, cl)
if self.options["low_speed_aero"]:
outputs["data:aerodynamics:wing:low_speed:CD0"] = cd0_wing
else:
outputs["data:aerodynamics:wing:cruise:CD0"] = cd0_wing