"""Simple module for cruise computation."""
# 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 logging
import time
import numpy as np
# noinspection PyProtectedMember
from fastoad.module_management._bundle_loader import BundleLoader
import fastoad.api as oad
from fastoad.constants import EngineSetting
from stdatm import Atmosphere
from ..dynamic_equilibrium import DynamicEquilibrium
from ..constants import SUBMODEL_CRUISE
_LOGGER = logging.getLogger(__name__)
POINTS_NB_CRUISE = 100
MAX_CALCULATION_TIME = 15 # time in seconds
oad.RegisterSubmodel.active_models[SUBMODEL_CRUISE] = (
"fastga.submodel.performances.mission.cruise.legacy"
)
[docs]@oad.RegisterSubmodel(SUBMODEL_CRUISE, "fastga.submodel.performances.mission.cruise.legacy")
class ComputeCruise(DynamicEquilibrium):
"""
Compute the fuel consumption on cruise segment with constant VTAS and altitude.
The hypothesis of small alpha/gamma angles is done.
"""
def __init__(self, **kwargs):
super().__init__(**kwargs)
self._engine_wrapper = None
[docs] def initialize(self):
super().initialize()
self.options.declare("propulsion_id", default="", types=str)
[docs] def setup(self):
super().setup()
self._engine_wrapper = BundleLoader().instantiate_component(self.options["propulsion_id"])
self._engine_wrapper.setup(self)
self.add_input("data:TLAR:range", np.nan, units="m")
self.add_input("data:TLAR:v_cruise", val=np.nan, units="m/s")
self.add_input("data:aerodynamics:aircraft:cruise:CD0", np.nan)
self.add_input("data:aerodynamics:wing:cruise:induced_drag_coefficient", np.nan)
self.add_input("data:aerodynamics:horizontal_tail:cruise:induced_drag_coefficient", np.nan)
self.add_input("data:weight:aircraft:MTOW", np.nan, units="kg")
self.add_input("data:mission:sizing:taxi_out:fuel", np.nan, units="kg")
self.add_input("data:mission:sizing:takeoff:fuel", np.nan, units="kg")
self.add_input("data:mission:sizing:initial_climb:fuel", np.nan, units="kg")
self.add_input("data:mission:sizing:main_route:climb:fuel", np.nan, units="kg")
self.add_input("data:mission:sizing:main_route:climb:distance", np.nan, units="m")
self.add_input("data:mission:sizing:main_route:descent:distance", np.nan, units="m")
self.add_input("data:mission:sizing:main_route:climb:duration", np.nan, units="s")
self.add_output("data:mission:sizing:main_route:cruise:fuel", units="kg")
self.add_output("data:mission:sizing:main_route:cruise:distance", units="m")
self.add_output("data:mission:sizing:main_route:cruise:duration", units="s")
self.declare_partials("*", "*", method="fd")
[docs] def compute(self, inputs, outputs, discrete_inputs=None, discrete_outputs=None):
propulsion_model = self._engine_wrapper.get_model(inputs)
v_tas = inputs["data:TLAR:v_cruise"]
cruise_distance = max(
0.0,
(
inputs["data:TLAR:range"]
- inputs["data:mission:sizing:main_route:climb:distance"]
- inputs["data:mission:sizing:main_route:descent:distance"]
),
)
if cruise_distance == 0.0:
_LOGGER.warning(
"Cruise distance is negative, check the input value mainly the range "
"and/or the climb and descent inputs"
)
wing_area = inputs["data:geometry:wing:area"]
cruise_altitude = inputs["data:mission:sizing:main_route:cruise:altitude"]
mtow = inputs["data:weight:aircraft:MTOW"]
m_to = inputs["data:mission:sizing:taxi_out:fuel"]
m_tk = inputs["data:mission:sizing:takeoff:fuel"]
m_ic = inputs["data:mission:sizing:initial_climb:fuel"]
m_cl = inputs["data:mission:sizing:main_route:climb:fuel"]
# Define specific time step ~POINTS_NB_CRUISE points for calculation
time_step = (cruise_distance / v_tas) / float(POINTS_NB_CRUISE)
# Define initial conditions
t_start = time.time()
distance_t = 0.0
time_t = 0.0
mass_fuel_t = 0.0
mass_t = mtow - (m_to + m_tk + m_ic + m_cl)
atm = Atmosphere(cruise_altitude, altitude_in_feet=False)
atm.true_airspeed = v_tas
previous_step = ()
self.flight_points = []
while distance_t < cruise_distance:
flight_point = oad.FlightPoint(
altitude=cruise_altitude,
time=time_t,
ground_distance=distance_t,
engine_setting=EngineSetting.CRUISE,
thrust_is_regulated=True,
mass=mass_t,
name="sizing:main_route:cruise",
)
self.complete_flight_point(flight_point, v_tas=v_tas)
# Calculate dynamic pressure
dynamic_pressure = 0.5 * atm.density * v_tas**2
# Find equilibrium
previous_step = self.dynamic_equilibrium(
inputs, 0.0, dynamic_pressure, 0.0, 0.0, mass_t, "none", previous_step[0:2]
)
flight_point.thrust = float(previous_step[1])
# Compute consumption
propulsion_model.compute_flight_points(flight_point)
if flight_point.thrust_rate > 1.0:
_LOGGER.warning("Thrust rate is above 1.0, value clipped at 1.0")
# Save results
self.compute_flight_point_drag(
flight_point=flight_point, equilibrium_result=previous_step, wing_area=wing_area
)
self.add_flight_point(flight_point=flight_point, equilibrium_result=previous_step)
consumed_mass_1s = propulsion_model.get_consumed_mass(flight_point, 1.0)
# Calculate distance increase
distance_t += v_tas * min(time_step, (cruise_distance - distance_t) / v_tas)
# Estimate mass evolution and update time
mass_fuel_t += consumed_mass_1s * min(time_step, (cruise_distance - distance_t) / v_tas)
mass_t = mass_t - consumed_mass_1s * min(
time_step, (cruise_distance - distance_t) / v_tas
)
time_t += min(time_step, (cruise_distance - distance_t) / v_tas)
# Check calculation duration
if (time.time() - t_start) > MAX_CALCULATION_TIME:
raise Exception(
"Time calculation duration for cruise phase [%f s] exceeded!"
% MAX_CALCULATION_TIME
)
# Save results
if self.options["out_file"] != "":
self.save_csv()
outputs["data:mission:sizing:main_route:cruise:fuel"] = mass_fuel_t
outputs["data:mission:sizing:main_route:cruise:distance"] = distance_t
outputs["data:mission:sizing:main_route:cruise:duration"] = time_t