Propellant feed system physics.
Real-gas properties, the parameter model and the liquid-side component library
are in. The network solver is next::
from feedtwin.props import Fluid
from feedtwin.model import Param, Provenance, ComponentInstance
Fluid("LOX").get("rho", p=3.0e6, T=90.0) # 1148 kg/m3
from feedtwin.comps import build_component, conditions_from_fluid
line = build_component(ComponentInstance.build("FL-01", "pipe", {
"length": Param(18.0, "in", Provenance.MEASURED, "tape, 2026-09-08"),
"bore": Param(0.305, "in", Provenance.MANUFACTURER, "3/8 x 0.035 tube"),
}))
line.pressure_drop(0.5, conditions_from_fluid(Fluid("LOX"), 3.0e6, 90.0))
:mod:`feedtwin.props` is imported explicitly rather than re-exported here, so
``import feedtwin`` stays cheap for callers that only want version metadata --
the API container asks for that on every health check.
What goes where, as the phases land::
feedtwin.props Phase 01 real-gas properties, tabulated [DONE]
feedtwin.model Phase 02 Param, ComponentSpec, the catalog [DONE]
feedtwin.comps Phase 03 pipes, fittings, valves, orifices [DONE]
feedtwin.solve Phase 04 steady network [DONE]
feedtwin.vessels Phase 05 gas side and tank thermodynamics [DONE]
feedtwin.session the stand in time: vessels marched against the
network, the chamber closed, a burn [DONE]
(Phase 07's stiff integrator, feedtwin.transient,
was replaced by it and removed 2026-10-08)
feedtwin.engine Phase 08 a Layer-1 engine on the end [DONE]
feedtwin.pid Phase 11 the drawing is the document [DONE]
feedtwin.vessels.vapour Phase 14 ullage vapour, chilldown [DONE, opt-in]
feedtwin.fit Phase 12 parameter identification from test data
-- NOT BUILT. The reader belongs in the DAQ;
what crosses is a fitted K, and the shapes for
it already exist. See
docs/integration/daq-k-fitting.md.
Phase 15 constraint API (MEOP, NPSH, injector margins)
-- not started.
Before changing any of it, and after: **run
``python3 scripts/physics_benchmark.py``**, and read ``docs/PHYSICS-BENCHMARK.md``.
Every expected value there was checked against hand calculation, ``fluids``, CoolProp
or a handbook rather than against this package, which is the only kind of check worth
having on a simulator.
Nothing here imports a web framework, and nothing here should. The package has
two callers with incompatible needs -- the feed-twin API, and EngineDesign's
optimizer calling it in-process thousands of times per run -- and only a plain
library serves both. See docs/adr/0001-feed-system-physics-is-a-library.md.
1.15.0