Merge pull request #181 from fast-aircraft-design/engine-rework

Engine rework

.github/workflows/tests.yml

@@ -38,7 +38,7 @@ jobs:
       - uses: actions/cache@v2
         if: startsWith(runner.os, 'macOS')
         with:
-          path: ~/Library/Caches/pypoetry
+          path: /Users/runner/Library/Caches/pypoetry
           key: ${{ runner.os }}-Py${{ matrix.python-version }}-pypoetry-${{ hashFiles('**/poetry.lock') }}
           restore-keys: |
             ${{ runner.os }}-Py${{ matrix.python-version }}-pypoetry-

docs/conf.py

@@ -153,6 +153,8 @@
 # If true, keep warnings as "system message" paragraphs in the built documents.
 # keep_warnings = False
 
+# Use docstring from class and __init__
+autoclass_content = "both"
 
 # -- Options for HTML output ---------------------------------------------------
 

src/fastoad/cmd/resources/fastoad.toml

@@ -30,8 +30,7 @@ driver = "om.ScipyOptimizeDriver(tol=1e-6, optimizer='COBYLA')"
         use_xfoil = false
     [model.performance]
         id = "fastoad.performances.breguet"
-    [model.propulsion]
-        id = "fastoad.propulsion.rubber_engine"
+        propulsion_id = "fastoad.wrapper.propulsion.rubber_engine"
     [model.hq.tail_sizing]
         id = "fastoad.handling_qualities.tail_sizing"
     [model.hq.static_margin]

src/fastoad/exceptions.py

@@ -38,3 +38,9 @@ class XMLReadError(FastError):
 
     This exception indicates that an error occurred when reading an xml file.
     """
+
+
+class FastUnknownFlightPhaseError(FastError):
+    """
+    Raised when an unknown flight phase code has been encountered
+    """

src/fastoad/models/performances/breguet.py

@@ -1,6 +1,4 @@
-"""
-Simple module for performances
-"""
+"""Simple module for performances."""
 #  This 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
@@ -16,6 +14,7 @@
 
 import numpy as np
 import openmdao.api as om
+from fastoad import BundleLoader
 from fastoad.constants import FlightPhase
 from fastoad.utils.physics import Atmosphere
 from scipy.constants import g
@@ -28,48 +27,63 @@
 
 class BreguetFromMTOW(om.Group):
     """
-    Estimation of fuel consumption through Breguet formula with a rough estimate
-    of climb and descent phases.
+    Estimation of fuel consumption through Breguet formula.
+
+    It uses a rough estimate of climb and descent phases.
 
     MTOW (Max TakeOff Weight) being an input, the model computes the ZFW (Zero Fuel
     Weight) considering that all fuel but the reserve has been consumed during the
     mission.
-    This model does not ensure consistency with OWE (Operating Empty Weight)
+    This model does not ensure consistency with OWE (Operating Empty Weight).
     """
 
+    def initialize(self):
+        self.options.declare("propulsion_id", default=None, types=str, allow_none=True)
+
     # TODO: in a more general case, this module will link the starting mass to
     #   the ending mass. Could we make the module more generic ?
     def setup(self):
-        self.add_subsystem("propulsion", _BreguetPropulsion(), promotes=["*"])
+        if self.options["propulsion_id"] is None:
+            self.add_subsystem("propulsion_link", _BreguetPropulsion(), promotes=["*"])
+        else:
+            self.add_subsystem(
+                "propulsion",
+                _BreguetEngine(propulsion_id=self.options["propulsion_id"]),
+                promotes=["*"],
+            )
         self.add_subsystem("distances", _Distances(), promotes=["*"])
         self.add_subsystem("cruise_mass_ratio", _CruiseMassRatio(), promotes=["*"])
         self.add_subsystem("fuel_weights", _FuelWeightFromMTOW(), promotes=["*"])
         self.add_subsystem("consumption", _Consumption(), promotes=["*"])
 
 
-class BreguetFromOWE(om.Group):
+class BreguetFromOWE(BreguetFromMTOW):
     """
-    Estimation of fuel consumption through Breguet formula with a rough estimate
-    of climb and descent phases.
+    Estimation of fuel consumption through Breguet formula.
+
+    It uses a rough estimate of climb and descent phases.
 
     For the sizing mission, the Breguet formula links MTOW (Max TakeOff Weight) to
     ZFW (Zero Fuel Weight).
     OWE (Operating Weight Empty) being linked to ZFW and MTOW, a cycle is implemented
     to have consistency between these 3 values.
+
+    Options:
+      - propulsion_id:
+        - if not provided, the propulsion model is expected to be an outside OpenMDAO
+          component
+        - if provided, the propulsion model matching the provided identifier will be
+          called directly in the performance process
+
     """
 
     def setup(self):
-        self.add_subsystem("propulsion", _BreguetPropulsion(), promotes=["*"])
-        self.add_subsystem("distances", _Distances(), promotes=["*"])
-        self.add_subsystem("cruise_mass_ratio", _CruiseMassRatio(), promotes=["*"])
+        super().setup()
         self.add_subsystem("mtow", _MTOWFromOWE(), promotes=["*"])
-        self.add_subsystem("fuel_weights", _FuelWeightFromMTOW(), promotes=["*"])
-        self.add_subsystem("consumption", _Consumption(), promotes=["*"])
 
         self.nonlinear_solver = om.NewtonSolver()
         self.nonlinear_solver.options["iprint"] = 0
         self.nonlinear_solver.options["solve_subsystems"] = False
-        self.nonlinear_solver.linesearch = om.BoundsEnforceLS()
         self.linear_solver = om.DirectSolver()
 
 
@@ -94,9 +108,53 @@ def compute(self, inputs, outputs, discrete_inputs=None, discrete_outputs=None):
         outputs["data:mission:sizing:fuel:unitary"] = fuel / npax / distance
 
 
+class _BreguetEngine(om.ExplicitComponent):
+    def __init__(self, **kwargs):
+        """
+        Computes thrust, SFC and thrust rate by direct call to engine model.
+        """
+        super().__init__(**kwargs)
+        self._engine_wrapper = BundleLoader().instantiate_component(self.options["propulsion_id"])
+
+    def initialize(self):
+        self.options.declare("propulsion_id", default="", types=str)
+
+    def setup(self):
+        self._engine_wrapper.setup(self)
+        self.add_input("data:mission:sizing:cruise:altitude", np.nan, units="m")
+        self.add_input("data:TLAR:cruise_mach", np.nan)
+        self.add_input("data:weight:aircraft:MTOW", np.nan, units="kg")
+        self.add_input("data:aerodynamics:aircraft:cruise:L_D_max", np.nan)
+        self.add_input("data:geometry:propulsion:engine:count", 2)
+
+        self.add_output("data:propulsion:SFC", units="kg/s/N", ref=1e-4)
+        self.add_output("data:propulsion:thrust_rate", lower=0.0, upper=1.0)
+        self.add_output("data:propulsion:thrust", units="N", ref=1e5)
+
+        self.declare_partials("*", "*", method="fd")
+
+    def compute(self, inputs, outputs, discrete_inputs=None, discrete_outputs=None):
+
+        engine_count = inputs["data:geometry:propulsion:engine:count"]
+        ld_ratio = inputs["data:aerodynamics:aircraft:cruise:L_D_max"]
+        mtow = inputs["data:weight:aircraft:MTOW"]
+        initial_cruise_mass = mtow * CLIMB_MASS_RATIO
+
+        thrust = initial_cruise_mass / ld_ratio * g / engine_count
+        sfc, thrust_rate, _ = self._engine_wrapper.get_engine(inputs).compute_flight_points(
+            inputs["data:TLAR:cruise_mach"],
+            inputs["data:mission:sizing:cruise:altitude"],
+            FlightPhase.CRUISE,
+            thrust=thrust,
+        )
+        outputs["data:propulsion:thrust"] = thrust
+        outputs["data:propulsion:SFC"] = sfc
+        outputs["data:propulsion:thrust_rate"] = thrust_rate
+
+
 class _BreguetPropulsion(om.ExplicitComponent):
     """
-    Link with engine computation
+    Link with engine computation.
     """
 
     def setup(self):
@@ -113,8 +171,6 @@ def setup(self):
         self.add_output("data:propulsion:altitude", units="m", ref=1e4)
         self.add_output("data:propulsion:mach")
 
-        self.declare_partials("data:propulsion:phase", "*", method="fd")
-        self.declare_partials("data:propulsion:use_thrust_rate", "*", method="fd")
         self.declare_partials("data:propulsion:required_thrust_rate", "*", method="fd")
         self.declare_partials("data:propulsion:required_thrust", "*", method="fd")
         self.declare_partials(
@@ -140,7 +196,7 @@ def compute(self, inputs, outputs, discrete_inputs=None, discrete_outputs=None):
 class _FuelWeightFromMTOW(om.ExplicitComponent):
     """
     Estimation of fuel consumption through Breguet formula with a rough estimate
-    of climb and descent phases
+    of climb and descent phases.
     """
 
     def setup(self):
@@ -193,7 +249,7 @@ def compute(self, inputs, outputs, discrete_inputs=None, discrete_outputs=None):
 class _MTOWFromOWE(om.ImplicitComponent):
     """
     Estimation of fuel consumption through Breguet formula with a rough estimate
-    of climb and descent phases
+    of climb and descent phases.
     """
 
     def setup(self):
@@ -202,7 +258,8 @@ def setup(self):
         self.add_input("data:weight:aircraft:OWE", np.nan, units="kg")
         self.add_input("data:weight:aircraft:payload", np.nan, units="kg")
 
-        self.add_output("data:weight:aircraft:MTOW", units="kg", ref=1e5)
+        # The upper bound helps for convergence
+        self.add_output("data:weight:aircraft:MTOW", units="kg", ref=1e5, lower=0.0, upper=1e6)
 
         self.declare_partials("data:weight:aircraft:MTOW", "*", method="fd")
 
@@ -227,7 +284,9 @@ def guess_nonlinear(
 
 
 class _Distances(om.ExplicitComponent):
-    """ Rough estimation of distances for each flight phase"""
+    """
+    Rough estimation of distances for each flight phase.
+    """
 
     def setup(self):
         self.add_input("data:TLAR:range", np.nan, units="m")
@@ -248,7 +307,7 @@ def compute(self, inputs, outputs, discrete_inputs=None, discrete_outputs=None):
 
 class _CruiseMassRatio(om.ExplicitComponent):
     """
-    Estimation of fuel consumption through Breguet formula for a given cruise distance
+    Estimation of fuel consumption through Breguet formula for a given cruise distance.
     """
 
     def setup(self):
@@ -258,7 +317,8 @@ def setup(self):
         self.add_input("data:mission:sizing:cruise:altitude", np.nan, units="m")
         self.add_input("data:mission:sizing:cruise:distance", np.nan, units="m")
 
-        self.add_output("data:mission:sizing:cruise:mass_ratio")
+        # The lower bound helps a lot for convergence
+        self.add_output("data:mission:sizing:cruise:mass_ratio", lower=0.5, upper=1.0)
 
         self.declare_partials("data:mission:sizing:cruise:mass_ratio", "*", method="fd")
 

src/fastoad/models/performances/tests/test_breguet.py

@@ -12,11 +12,14 @@
 #  along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 import openmdao.api as om
+from fastoad.constants import FlightPhase
+from fastoad.models.propulsion.fuel_engine.rubber_engine import RubberEngine
 from numpy.testing import assert_allclose
+from scipy.constants import foot
 
 from tests.testing_utilities import run_system
 from ..breguet import BreguetFromMTOW, BreguetFromOWE
-from ...propulsion.fuel_engine.rubber_engine import OMRubberEngine
+from ...propulsion.fuel_engine.rubber_engine import OMRubberEngineComponent
 
 
 def test_breguet_from_mtow():
@@ -83,16 +86,26 @@ def test_breguet_from_mtow_with_rubber_engine():
     ivc.add_output("data:propulsion:rubber_engine:overall_pressure_ratio", 30)
     ivc.add_output("data:propulsion:rubber_engine:turbine_inlet_temperature", 1500, units="K")
 
+    # With rubber engine OM component
     group = om.Group()
     group.add_subsystem("breguet", BreguetFromMTOW(), promotes=["*"])
-    group.add_subsystem("engine", OMRubberEngine(), promotes=["*"])
+    group.add_subsystem("engine", OMRubberEngineComponent(), promotes=["*"])
     group.nonlinear_solver = om.NonlinearBlockGS()
     problem = run_system(group, ivc)
 
     assert_allclose(problem["data:mission:sizing:ZFW"], 65076.0, atol=1)
     assert_allclose(problem["data:mission:sizing:fuel"], 8924.0, atol=1)
     assert_allclose(problem["data:mission:sizing:fuel:unitary"], 0.0642, rtol=1e-3)
 
+    # With direct call to rubber engine
+    problem2 = run_system(
+        BreguetFromMTOW(propulsion_id="fastoad.wrapper.propulsion.rubber_engine"), ivc
+    )
+
+    assert_allclose(problem2["data:mission:sizing:ZFW"], 65076.0, atol=1)
+    assert_allclose(problem2["data:mission:sizing:fuel"], 8924.0, atol=1)
+    assert_allclose(problem2["data:mission:sizing:fuel:unitary"], 0.0642, rtol=1e-3)
+
 
 def test_breguet_from_owe():
     ivc = om.IndepVarComp()
@@ -130,14 +143,43 @@ def test_breguet_from_owe_with_rubber_engine():
     ivc.add_output("data:propulsion:rubber_engine:overall_pressure_ratio", 30)
     ivc.add_output("data:propulsion:rubber_engine:turbine_inlet_temperature", 1500, units="K")
 
+    # With rubber engine OM component
     group = om.Group()
 
-    group.add_subsystem("engine", OMRubberEngine(), promotes=["*"])
+    group.add_subsystem("engine", OMRubberEngineComponent(), promotes=["*"])
     group.add_subsystem("breguet", BreguetFromOWE(), promotes=["*"])
     group.nonlinear_solver = om.NonlinearBlockGS()
     problem = run_system(group, ivc)
 
+    engine = RubberEngine(5, 30, 1500, 100000, 0.95, 35000 * foot, -50)
+    assert_allclose(
+        engine.compute_flight_points(
+            0.78,
+            35000 * foot,
+            FlightPhase.CRUISE,
+            thrust=problem["data:propulsion:required_thrust"],
+        )[0],
+        problem["data:propulsion:SFC"],
+    )
+
     assert_allclose(problem["data:weight:aircraft:MTOW"], 74000.0, atol=10)
     assert_allclose(problem["data:mission:sizing:ZFW"], 65076.0, atol=1)
     assert_allclose(problem["data:mission:sizing:fuel"], 8924.0, atol=1)
     assert_allclose(problem["data:mission:sizing:fuel:unitary"], 0.0642, rtol=1e-3)
+
+    # With direct call to rubber engine
+    problem2 = run_system(
+        BreguetFromOWE(propulsion_id="fastoad.wrapper.propulsion.rubber_engine"), ivc
+    )
+
+    assert_allclose(
+        engine.compute_flight_points(
+            0.78, 35000 * foot, FlightPhase.CRUISE, thrust=problem2["data:propulsion:thrust"],
+        )[0],
+        problem2["data:propulsion:SFC"],
+    )
+
+    assert_allclose(problem2["data:weight:aircraft:MTOW"], 74000.0, atol=10)
+    assert_allclose(problem2["data:mission:sizing:ZFW"], 65076.0, atol=1)
+    assert_allclose(problem2["data:mission:sizing:fuel"], 8924.0, atol=1)
+    assert_allclose(problem2["data:mission:sizing:fuel:unitary"], 0.0642, rtol=1e-3)

src/fastoad/models/propulsion/__init__.py

@@ -14,4 +14,4 @@
 #  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 .engine import IEngine, IEngineSubclass, OMIEngine
+from .engine import IEngine, IOMEngineWrapper, BaseOMEngineComponent