"""
Estimation of nacelle and pylon geometry
"""
# 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/>.
from math import sqrt
import numpy as np
import openmdao.api as om
[docs]class ComputeNacelleAndPylonsGeometry(om.ExplicitComponent):
# TODO: Document equations. Cite sources
""" Nacelle and pylon geometry estimation """
[docs] def setup(self):
self.add_input("data:propulsion:MTO_thrust", val=np.nan, units="N")
self.add_input("data:geometry:propulsion:engine:y_ratio", val=np.nan)
self.add_input("data:geometry:propulsion:layout", val=np.nan)
self.add_input("data:geometry:wing:span", val=np.nan, units="m")
self.add_input("data:geometry:wing:MAC:length", val=np.nan, units="m")
self.add_input("data:geometry:wing:MAC:leading_edge:x:local", val=np.nan, units="m")
self.add_input("data:geometry:wing:root:chord", val=np.nan, units="m")
self.add_input("data:geometry:wing:root:y", val=np.nan, units="m")
self.add_input("data:geometry:wing:kink:chord", val=np.nan, units="m")
self.add_input("data:geometry:wing:kink:y", val=np.nan, units="m")
self.add_input("data:geometry:wing:kink:leading_edge:x:local", val=np.nan, units="m")
self.add_input("data:geometry:wing:MAC:at25percent:x", val=np.nan, units="m")
self.add_input("data:geometry:fuselage:length", val=np.nan, units="m")
self.add_input("data:geometry:fuselage:maximum_width", val=np.nan, units="m")
self.add_output("data:geometry:propulsion:pylon:length", units="m")
self.add_output("data:geometry:propulsion:fan:length", units="m")
self.add_output("data:geometry:propulsion:nacelle:length", units="m")
self.add_output("data:geometry:propulsion:nacelle:diameter", units="m")
self.add_output("data:geometry:landing_gear:height", units="m")
self.add_output("data:geometry:propulsion:nacelle:y", units="m")
self.add_output("data:geometry:propulsion:pylon:wetted_area", units="m**2")
self.add_output("data:geometry:propulsion:nacelle:wetted_area", units="m**2")
self.add_output("data:weight:propulsion:engine:CG:x", units="m")
[docs] def setup_partials(self):
self.declare_partials(
"data:geometry:propulsion:nacelle:diameter", "data:propulsion:MTO_thrust", method="fd"
)
self.declare_partials(
"data:geometry:propulsion:nacelle:length", "data:propulsion:MTO_thrust", method="fd"
)
self.declare_partials(
"data:geometry:landing_gear:height", "data:propulsion:MTO_thrust", method="fd"
)
self.declare_partials(
"data:geometry:propulsion:fan:length", "data:propulsion:MTO_thrust", method="fd"
)
self.declare_partials(
"data:geometry:propulsion:pylon:length", "data:propulsion:MTO_thrust", method="fd"
)
self.declare_partials(
"data:geometry:propulsion:nacelle:y",
[
"data:propulsion:MTO_thrust",
"data:geometry:fuselage:maximum_width",
"data:geometry:propulsion:engine:y_ratio",
"data:geometry:wing:span",
],
method="fd",
)
self.declare_partials(
"data:weight:propulsion:engine:CG:x",
[
"data:geometry:wing:MAC:at25percent:x",
"data:geometry:wing:MAC:length",
"data:geometry:wing:MAC:leading_edge:x:local",
"data:geometry:wing:kink:leading_edge:x:local",
"data:geometry:wing:root:y",
"data:geometry:wing:kink:y",
"data:geometry:wing:root:chord",
"data:geometry:wing:kink:chord",
"data:geometry:fuselage:length",
"data:propulsion:MTO_thrust",
"data:geometry:fuselage:maximum_width",
"data:geometry:propulsion:engine:y_ratio",
"data:geometry:wing:span",
],
method="fd",
)
self.declare_partials(
"data:geometry:propulsion:nacelle:wetted_area",
"data:propulsion:MTO_thrust",
method="fd",
)
self.declare_partials(
"data:geometry:propulsion:pylon:wetted_area", "data:propulsion:MTO_thrust", method="fd"
)
[docs] def compute(self, inputs, outputs):
thrust_sl = inputs["data:propulsion:MTO_thrust"]
y_ratio_engine = inputs["data:geometry:propulsion:engine:y_ratio"]
propulsion_layout = np.round(inputs["data:geometry:propulsion:layout"])
span = inputs["data:geometry:wing:span"]
l0_wing = inputs["data:geometry:wing:MAC:length"]
x0_wing = inputs["data:geometry:wing:MAC:leading_edge:x:local"]
l2_wing = inputs["data:geometry:wing:root:chord"]
y2_wing = inputs["data:geometry:wing:root:y"]
l3_wing = inputs["data:geometry:wing:kink:chord"]
x3_wing = inputs["data:geometry:wing:kink:leading_edge:x:local"]
y3_wing = inputs["data:geometry:wing:kink:y"]
fa_length = inputs["data:geometry:wing:MAC:at25percent:x"]
fus_length = inputs["data:geometry:fuselage:length"]
b_f = inputs["data:geometry:fuselage:maximum_width"]
nac_dia = 0.00904 * sqrt(thrust_sl * 0.225) + 0.7 # FIXME: use output of engine module
lg_height = 1.4 * nac_dia
# The nominal thrust must be used in lbf
nac_length = 0.032 * sqrt(thrust_sl * 0.225) # FIXME: use output of engine module
outputs["data:geometry:propulsion:nacelle:length"] = nac_length
outputs["data:geometry:propulsion:nacelle:diameter"] = nac_dia
outputs["data:geometry:landing_gear:height"] = lg_height
fan_length = 0.60 * nac_length
pylon_length = 1.1 * nac_length
if propulsion_layout == 1:
y_nacell = y_ratio_engine * span / 2
elif propulsion_layout == 2:
y_nacell = b_f / 2.0 + 0.5 * nac_dia
else:
raise ValueError("Value of data:geometry:propulsion:layout can only be 1 or 2")
l_wing_nac = l3_wing + (l2_wing - l3_wing) * (y3_wing - y_nacell) / (y3_wing - y2_wing)
if propulsion_layout == 1:
delta_x_nacell = 0.05 * l_wing_nac
x_nacell_cg = (
x3_wing * (y_nacell - y2_wing) / (y3_wing - y2_wing)
- delta_x_nacell
- 0.2 * nac_length
)
x_nacell_cg_absolute = fa_length - 0.25 * l0_wing - (x0_wing - x_nacell_cg)
elif propulsion_layout == 2:
x_nacell_cg_absolute = 0.8 * fus_length
else:
raise ValueError("Value of data:geometry:propulsion:layout can only be 1 or 2")
outputs["data:geometry:propulsion:pylon:length"] = pylon_length
outputs["data:geometry:propulsion:fan:length"] = fan_length
outputs["data:geometry:propulsion:nacelle:y"] = y_nacell
outputs["data:weight:propulsion:engine:CG:x"] = x_nacell_cg_absolute
# Wet surfaces
wet_area_nac = 0.0004 * thrust_sl * 0.225 + 11 # By engine
wet_area_pylon = 0.35 * wet_area_nac
outputs["data:geometry:propulsion:nacelle:wetted_area"] = wet_area_nac
outputs["data:geometry:propulsion:pylon:wetted_area"] = wet_area_pylon