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| Dict[str, float] | _reference (EngineSampler sampler, float p_O, float p_F) |
| Any | _constant_cd (float value) |
| Any | _chamber (Any design, Any table, float ambient_pa, **float losses) |
| EngineLink | link_engine (Any config, *, float tank_pa_O, float tank_pa_F, Optional[Path] cea_path, float ambient_pa, Any fluid_at, str mode="card", Optional[float] card_center_pa=None) |
| Dict[str, Tuple[float, float]] | twin_injector_check (EngineLink link, Any fluid_at) |
The engine on the end of the feed system: EngineDesign's, as the twin runs it.
The twin's own engine is simple:
* an orifice leg per side, with the config's Reynolds-law Cd;
* ``p_c = mdot c* eta / A_t`` on the CEA table, with ``eta_c* = 1``. Its importer says
that chamber pressure is an upper bound.
EngineDesign's engine has much more in it:
* a plate-passage Cd and a ring-network manifold;
* the Borda dump of the feed line into that manifold;
* a spray/mixing/heat-loss c* efficiency;
* a stagnation loss and the real nozzle exit.
On the 6.8 kN engine at 578 psia the two differ by ~14 % in flow. Three ways to put
an engine on the end of the twin, as ``mode``:
``card`` (default, phase 2)
EngineDesign sampled across the burn envelope and tabulated as an engine card
(:mod:`engine.layerx.card`, :mod:`feedtwin.engine.card`). The twin evaluates
EngineDesign's injector and chamber at every coupling step, everywhere the
burn goes. The card carries its own measured error.
``calibrated`` (phase 1)
The twin's engine, with four constants set so that it reproduces EngineDesign
at one point, T-0:
* a Cd per side;
* ``eta_c*``;
* ``eta_n``.
Away from T-0 they are held constant. Kept for comparison.
``native``
The twin's engine as imported. For seeing what the other two change.
Both EngineDesign modes put the boundary at the **line exit**. EngineDesign is
solved with its feed-line losses zeroed and its exit dump kept
(:func:`engine.layerx.card.line_exit_config`), because the drawing's lines carry
every loss upstream of the injector face and none downstream of it.
Phase 1 calibrated against EngineDesign's still-manifold injector drop, which
left that ~26 psi LOX dump on neither side.
| EngineLink engine.layerx.link.link_engine |
( |
Any | config, |
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* | , |
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|
float | tank_pa_O, |
|
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float | tank_pa_F, |
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|
Optional[Path] | cea_path, |
|
|
float | ambient_pa, |
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Any | fluid_at, |
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str | mode = "card", |
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Optional[float] | card_center_pa = None ) |
The live config as the twin's engine, in ``mode`` (see the module docstring).
``fluid_at(side, pressure_pa) -> (rho, mu)`` is the twin's own propellant state at the
injector inlet, used where a Cd has to be recovered at the density the twin's leg sees.
``card_center_pa`` centres the engine card somewhere other than this burn's T-0, so that
burns at several tank pressures share one card (the optimiser); the card's own envelope
check and the run's ``card_outside_steps`` say whether the burn stayed inside it.
Definition at line 100 of file link.py.
References _chamber(), _constant_cd(), and _reference().
1.15.0