"""Estimation of effective propeller efficiency due to additional cowling drag."""
# 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 warnings
import numpy as np
import openmdao.api as om
import fastoad.api as oad
from stdatm import Atmosphere
from ..constants import SUBMODEL_EFFECTIVE_EFFICIENCY_PROPELLER
[docs]@oad.RegisterSubmodel(
SUBMODEL_EFFECTIVE_EFFICIENCY_PROPELLER,
"fastga.submodel.aerodynamics.propeller.effective_efficiency.legacy",
)
class ComputeEffectiveEfficiencyPropeller(om.ExplicitComponent):
"""
Estimation of the increase in cowling profile drag due to the effect of the propeller
slipstream. It will be modelled as a decrease in efficiency.
"""
[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:propulsion:engine:layout", val=np.nan)
self.add_input("data:geometry:propeller:diameter", val=np.nan, units="m")
self.add_input("data:geometry:wing:area", val=np.nan, units="m**2")
self.add_input("data:geometry:fuselage:wet_area", val=np.nan, units="m**2")
self.add_input("data:geometry:propulsion:nacelle:wet_area", val=np.nan, units="m**2")
if self.options["low_speed_aero"]:
self.add_input("data:aerodynamics:nacelles:low_speed:CD0", val=np.nan)
self.add_input("data:aerodynamics:fuselage:low_speed:CD0", val=np.nan)
self.add_output(
"data:aerodynamics:propeller:installation_effect:effective_efficiency:low_speed",
val=1.0,
desc="Value to multiply the uninstalled efficiency with to obtain the effective "
"efficiency due to the presence of cowling (fuselage or nacelle) behind the "
"propeller",
)
self.declare_partials("*", "*", method="fd")
else:
self.add_input("data:aerodynamics:nacelles:cruise:CD0", val=np.nan)
self.add_input("data:aerodynamics:fuselage:cruise:CD0", val=np.nan)
self.add_input("data:mission:sizing:main_route:cruise:altitude", val=np.nan, units="m")
self.add_output(
"data:aerodynamics:propeller:installation_effect:effective_efficiency:cruise",
val=1.0,
desc="Value to multiply the uninstalled efficiency with to obtain the effective "
"efficiency due to the presence of cowling (fuselage or nacelle) behind the "
"propeller",
)
self.declare_partials("*", "*", method="fd")
[docs] def compute(self, inputs, outputs, discrete_inputs=None, discrete_outputs=None):
propeller_diameter = inputs["data:geometry:propeller:diameter"]
wing_area = inputs["data:geometry:wing:area"]
engine_layout = inputs["data:geometry:propulsion:engine:layout"]
if self.options["low_speed_aero"]:
altitude = 0.0
if engine_layout == 3.0:
wet_area_cowling = inputs["data:geometry:fuselage:wet_area"]
friction_drag_coeff = inputs["data:aerodynamics:fuselage:low_speed:CD0"]
elif engine_layout == 1.0 or engine_layout == 2.0:
wet_area_cowling = inputs["data:geometry:propulsion:nacelle:wet_area"]
friction_drag_coeff = inputs["data:aerodynamics:nacelles:low_speed:CD0"]
else:
wet_area_cowling = inputs["data:geometry:fuselage:wet_area"]
friction_drag_coeff = inputs["data:aerodynamics:fuselage:low_speed:CD0"]
warnings.warn(
"Propulsion layout {} not implemented in model, replaced by layout 3!".format(
engine_layout
)
)
else:
altitude = inputs["data:mission:sizing:main_route:cruise:altitude"]
if engine_layout == 3.0:
wet_area_cowling = inputs["data:geometry:fuselage:wet_area"]
friction_drag_coeff = inputs["data:aerodynamics:fuselage:cruise:CD0"]
elif engine_layout == 1.0 or engine_layout == 2.0:
wet_area_cowling = inputs["data:geometry:propulsion:nacelle:wet_area"]
friction_drag_coeff = inputs["data:aerodynamics:nacelles:cruise:CD0"]
else:
wet_area_cowling = inputs["data:geometry:fuselage:wet_area"]
friction_drag_coeff = inputs["data:aerodynamics:fuselage:cruise:CD0"]
warnings.warn(
"Propulsion layout {} not implemented in model, replaced by layout 3!".format(
engine_layout
)
)
# All drag coefficient are given wrt the wing area but for this formula we need to have
# this coefficient with respect to the cowling wet area
friction_drag_coeff *= wing_area / wet_area_cowling
density = Atmosphere(altitude, altitude_in_feet=False).density
density_sl = Atmosphere(0.0, altitude_in_feet=False).density
effective_efficiency_factor = (
1.0
- 1.558
/ propeller_diameter**2.0
* density
/ density_sl
* friction_drag_coeff
* wet_area_cowling
)
if self.options["low_speed_aero"]:
outputs[
"data:aerodynamics:propeller:installation_effect:effective_efficiency:low_speed"
] = effective_efficiency_factor
else:
outputs[
"data:aerodynamics:propeller:installation_effect:effective_efficiency:cruise"
] = effective_efficiency_factor