"""Estimation of the nacelle profile drag."""
# Thi file is part of FAST : A framework for rapid Overall Aircraft Design
# Copyright (C) 2020 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 warnings
import numpy as np
# noinspection PyProtectedMember
from fastoad.module_management._bundle_loader import BundleLoader
import fastoad.api as oad
from openmdao.core.explicitcomponent import ExplicitComponent
from fastga.models.propulsion.fuel_propulsion.base import FuelEngineSet
from ..constants import SUBMODEL_CD0_NACELLE
[docs]@oad.RegisterSubmodel(SUBMODEL_CD0_NACELLE, "fastga.submodel.aerodynamics.nacelle.cd0.legacy")
class Cd0Nacelle(ExplicitComponent):
"""
Profile drag estimation for the engine nacelle
Based on : Gudmundsson, Snorri. General aviation aircraft design: Applied Methods and
Procedures. Butterworth-Heinemann, 2013.
"""
def __init__(self, **kwargs):
super().__init__(**kwargs)
self._engine_wrapper = None
[docs] def initialize(self):
self.options.declare("low_speed_aero", default=False, types=bool)
self.options.declare("propulsion_id", default="", types=str)
[docs] def setup(self):
self._engine_wrapper = BundleLoader().instantiate_component(self.options["propulsion_id"])
self._engine_wrapper.setup(self)
self.add_input("data:geometry:wing:MAC:length", val=np.nan, units="m")
self.add_input("data:geometry:wing:area", val=np.nan, units="m**2")
if self.options["low_speed_aero"]:
self.add_input("data:aerodynamics:low_speed:mach", val=np.nan)
self.add_input("data:aerodynamics:low_speed:unit_reynolds", val=np.nan, units="m**-1")
self.add_output("data:aerodynamics:nacelles:low_speed:CD0")
else:
self.add_input("data:aerodynamics:cruise:mach", val=np.nan)
self.add_input("data:aerodynamics:cruise:unit_reynolds", val=np.nan, units="m**-1")
self.add_output("data:aerodynamics:nacelles:cruise:CD0")
self.declare_partials("*", "*", method="fd")
[docs] def compute(self, inputs, outputs, discrete_inputs=None, discrete_outputs=None):
propulsion_model = FuelEngineSet(self._engine_wrapper.get_model(inputs), 1.0)
engine_number = inputs["data:geometry:propulsion:engine:count"]
prop_layout = inputs["data:geometry:propulsion:engine:layout"]
l0_wing = inputs["data:geometry:wing:MAC:length"]
wing_area = inputs["data:geometry:wing:area"]
if self.options["low_speed_aero"]:
mach = inputs["data:aerodynamics:low_speed:mach"]
unit_reynolds = inputs["data:aerodynamics:low_speed:unit_reynolds"]
else:
mach = inputs["data:aerodynamics:cruise:mach"]
unit_reynolds = inputs["data:aerodynamics:cruise:unit_reynolds"]
drag_force = propulsion_model.compute_drag(mach, unit_reynolds, l0_wing)
if (prop_layout == 1.0) or (prop_layout == 2.0):
cd0 = drag_force / wing_area * engine_number
elif prop_layout == 3.0:
cd0 = 0.0
else:
cd0 = 0.0
warnings.warn(
"Propulsion layout {} not implemented in model, replaced by layout 1!".format(
prop_layout
)
)
if self.options["low_speed_aero"]:
outputs["data:aerodynamics:nacelles:low_speed:CD0"] = cd0
else:
outputs["data:aerodynamics:nacelles:cruise:CD0"] = cd0