# This file is part of FAST-OAD_CS23 : A framework for rapid Overall Aircraft Design
# Copyright (C) 2022 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
import fastoad.api as oad
from ...constants import SUBMODEL_DOWNWASH
[docs]@oad.RegisterSubmodel(
SUBMODEL_DOWNWASH, "fastga.submodel.aerodynamics.horizontal_tail.downwash.legacy"
)
class DownWashGradientComputation(om.ExplicitComponent):
[docs] def initialize(self):
"""Declaring the low_speed_aero options so we can use low speed and cruise conditions."""
self.options.declare("low_speed_aero", default=False, types=bool)
[docs] def setup(self):
self.add_input("data:geometry:wing:aspect_ratio", val=np.nan)
if self.options["low_speed_aero"]:
self.add_input("data:aerodynamics:wing:low_speed:CL_alpha", val=np.nan, units="rad**-1")
self.add_output(
"data:aerodynamics:horizontal_tail:low_speed:downwash_gradient",
val=0.35,
)
self.declare_partials(
of="data:aerodynamics:horizontal_tail:low_speed:downwash_gradient",
wrt=[
"data:geometry:wing:aspect_ratio",
"data:aerodynamics:wing:low_speed:CL_alpha",
],
method="exact",
)
else:
self.add_input("data:aerodynamics:wing:cruise:CL_alpha", val=np.nan, units="rad**-1")
self.add_output(
"data:aerodynamics:horizontal_tail:cruise:downwash_gradient",
val=0.35,
)
self.declare_partials(
of="data:aerodynamics:horizontal_tail:cruise:downwash_gradient",
wrt=["data:geometry:wing:aspect_ratio", "data:aerodynamics:wing:cruise:CL_alpha"],
method="exact",
)
[docs] def compute(self, inputs, outputs, discrete_inputs=None, discrete_outputs=None):
wing_ar = inputs["data:geometry:wing:aspect_ratio"]
if self.options["low_speed_aero"]:
cl_alpha = inputs["data:aerodynamics:wing:low_speed:CL_alpha"]
else:
cl_alpha = inputs["data:aerodynamics:wing:cruise:CL_alpha"]
downwash_gradient = 2 * cl_alpha / (np.pi * wing_ar)
if self.options["low_speed_aero"]:
outputs["data:aerodynamics:horizontal_tail:low_speed:downwash_gradient"] = (
downwash_gradient
)
else:
outputs["data:aerodynamics:horizontal_tail:cruise:downwash_gradient"] = (
downwash_gradient
)
[docs] def compute_partials(self, inputs, partials, discrete_inputs=None):
wing_ar = inputs["data:geometry:wing:aspect_ratio"]
if self.options["low_speed_aero"]:
cl_alpha = inputs["data:aerodynamics:wing:low_speed:CL_alpha"]
partials[
"data:aerodynamics:horizontal_tail:low_speed:downwash_gradient",
"data:geometry:wing:aspect_ratio",
] = -2 * cl_alpha / (np.pi * wing_ar**2.0)
partials[
"data:aerodynamics:horizontal_tail:low_speed:downwash_gradient",
"data:aerodynamics:wing:low_speed:CL_alpha",
] = 2 / (np.pi * wing_ar)
else:
cl_alpha = inputs["data:aerodynamics:wing:cruise:CL_alpha"]
partials[
"data:aerodynamics:horizontal_tail:cruise:downwash_gradient",
"data:geometry:wing:aspect_ratio",
] = -2 * cl_alpha / (np.pi * wing_ar**2.0)
partials[
"data:aerodynamics:horizontal_tail:cruise:downwash_gradient",
"data:aerodynamics:wing:cruise:CL_alpha",
] = 2 / (np.pi * wing_ar)