Functions
float	cd_inf_from_orifice_diameter (Optional[float] d_hyd_m, DischargeConfig config)
float	discharge_cd_inf_ratio (float d_hyd_O, float d_hyd_F, DischargeConfig discharge_O, DischargeConfig discharge_F)
float	cd_from_re (float Re, DischargeConfig config, float P_inlet=None, float T_inlet=None, Optional[float] d_hyd_m=None)
float	calculate_reynolds_number (float rho, float u, float d_hyd, float mu)
float	cd_from_inlet_radius_ratio (float r_over_d)
float	cd_length_factor (float l_over_d, str model="lichtarowicz")
float	cd_with_approach (float cd, Optional[float] beta, float k_entrance=COUNTERBORE_ENTRANCE_K)
Optional[float]	cd_inf_from_inlet_geometry (config)
Optional[float]	cd_u_from_inlet_geometry (config)
float	cd_lichtarowicz_re (float cd_u, float Re, float l_over_d)
Optional[tuple]	lichtarowicz_re_inputs (config)
float	contraction_coefficient (float r_over_d)
Dict[str, float]	cavitation_margin (*, float P_in, float Pc, float Pv, float Cd, float r_over_d=0.0)
float	inlet_radius_ratio_of (config)

Variables
dict	INLET_GEOMETRY_CD
dict	INLET_GEOMETRY_RD
float	LICHTAROWICZ_A = 0.827
float	LICHTAROWICZ_B = 0.0085
tuple	LICHTAROWICZ_REF_LD = (LICHTAROWICZ_A - 0.80) / LICHTAROWICZ_B
float	LICHTAROWICZ_LD_MAX = 10.0
float	COUNTERBORE_ENTRANCE_K = 0.5
float	LICHTAROWICZ_RE_A = 20.0
float	LICHTAROWICZ_RE_B = 2.25
float	LICHTAROWICZ_RE_C = 0.0015
float	LICHTAROWICZ_RE_D = 7.5
float	LICHTAROWICZ_RE_E = 0.00015
float	NURICK_CC0 = 0.62
float	NURICK_RD_GAIN = 11.4

Detailed Description

Injector discharge coefficient model Cd(Re, orifice geometry).

A declared orifice inlet (``inlet_geometry`` / ``inlet_radius_ratio``) and L/d set Cd_inf: the
short-tube table with the Lichtarowicz (1965) length fit, which is what a drilled doublet hole
is (the shipped configs declare sharp, L/d 4). Without one, Cd_inf is the thin-plate
sharp-orifice value (ASME / ISO 5167: Cd ≈ 0.60–0.61 at high Re), keyed to d_jet.

Function Documentation

◆ calculate_reynolds_number()

float engine.core.discharge.calculate_reynolds_number	(	float	rho,
		float	u,
		float	d_hyd,
		float	mu )

Calculate Reynolds number.

Re = (ρ × u × d_hyd) / μ

Definition at line 145 of file discharge.py.

◆ cavitation_margin()

Dict[str, float] engine.core.discharge.cavitation_margin	(	*	,
		float	P_in,
		float	Pc,
		float	Pv,
		float	Cd,
		float	r_over_d = 0.0 )

K, K_crit = (Cd/Cc)^2 and their ratio for one orifice. Ratio < 1 means it cavitates.

Definition at line 412 of file discharge.py.

References contraction_coefficient().

◆ cd_from_inlet_radius_ratio()

float engine.core.discharge.cd_from_inlet_radius_ratio ( float r_over_d )

Cd at Re > 1e4 and L/d ~ 2-5 as a continuous function of inlet rounding r/d.

Saturating fit through the practitioner anchors for a SHORT TUBE: 0.80 sharp entry
(r/d = 0), ~0.88 at r/d = 0.1-0.125, 0.95 at r/d >= 0.2. Rounding past r/d ~ 0.2 buys
almost nothing, which is why bellmouth entries are specified at that ratio, not deeper.
For the thin-plate limit multiply by cd_length_factor(L/d), which recovers 0.61 at L/d 0.

Definition at line 220 of file discharge.py.

References max.

Referenced by cd_u_from_inlet_geometry().

◆ cd_from_re()

float engine.core.discharge.cd_from_re	(	float	Re,
		DischargeConfig	config,
		float	P_inlet = None,
		float	T_inlet = None,
		Optional[float]	d_hyd_m = None )

Calculate discharge coefficient as function of Reynolds number, optional orifice
diameter, pressure, and temperature.

``Re`` is on the bulk hole velocity mdot/(rho A) and the hole diameter.

Re law, when the block declares an inlet, an ``orifice_l_over_d`` and
``length_model: lichtarowicz`` (the default) -- Lichtarowicz, Duggins & Markland (1965):
    1/Cd = 1/Cd_u + 20 (1 + 2.25 L/d)/Re - 0.0015 (L/d) / (1 + 7.5 [log10(0.00015 Re)]^2)
with Cd_u the orifice's own high-Re Cd as this module anchors it (inlet table x
cd_length_factor, cd_u_from_inlet_geometry), then the counterbore approach
(approach_beta) and the 0.98 cap exactly as cd_inf_from_inlet_geometry applies them.

Otherwise (``length_model: piecewise``, or no declared inlet / L/d): the LEGACY, unsourced
form Cd(Re) = Cd_inf,eff - a_Re / √Re. ``a_Re`` is a tuned coefficient with no reference
and is ignored whenever the Lichtarowicz law applies.

``Cd_inf,eff`` is ``cd_inf_from_orifice_diameter(d_hyd_m, config)`` when geometry
mode is enabled; otherwise ``config.Cd_inf``.

Corrections (unsourced; off by default):
- Pressure correction: Cd(P) = Cd(Re) × [1 + a_P × (P/P_ref - 1)]
- Temperature correction: Cd(T) = Cd(Re) × [1 + a_T × (T/T_ref - 1)]

Clamped to [Cd_min, Cd_inf,eff]

Definition at line 85 of file discharge.py.

References cd_inf_from_orifice_diameter(), cd_lichtarowicz_re(), cd_with_approach(), lichtarowicz_re_inputs(), max, and min.

◆ cd_inf_from_inlet_geometry()

Optional[float] engine.core.discharge.cd_inf_from_inlet_geometry ( config )

Asymptotic Cd from the orifice's INLET treatment and L/d, or None if not configured.

Returns None when neither ``inlet_geometry`` nor ``inlet_radius_ratio`` is set, so the
caller keeps its existing diameter-based behaviour and nothing changes for old configs.
This is the orifice's own ultimate Cd (cd_u_from_inlet_geometry) seen through the
counterbore approach, capped at 0.98.

Definition at line 305 of file discharge.py.

References cd_u_from_inlet_geometry(), cd_with_approach(), and min.

Referenced by cd_inf_from_orifice_diameter().

◆ cd_inf_from_orifice_diameter()

float engine.core.discharge.cd_inf_from_orifice_diameter	(	Optional[float]	d_hyd_m,
		DischargeConfig	config )

Asymptotic Cd at high Re for a circular injector hole.

A declared inlet (``inlet_geometry`` / ``inlet_radius_ratio``) wins: the short-tube value at
the hole's L/d (cd_inf_from_inlet_geometry). Otherwise this is a THIN-PLATE model:
- **d = d_ref** (default 2 mm): ``Cd_inf`` equals config baseline (default **0.60**),
  matching thin-plate sharp-edged orifice data (Cd ≈ 0.595–0.602, Re > 10⁴).
- **d < d_ref**: ``(d/d_ref)^cd_small_hole_exponent``, default 0 (no change). ISO 5167 and
  Sutton & Biblarz Table 8-2 have small sharp holes flowing slightly MORE; the old 0.2
  penalty had the wrong sign.
- **d > d_ref**: small logarithmic rise toward ``cd_inf_max`` (≤ ~0.62).
- Result clamped to ``[cd_inf_min_geom, cd_inf_max]``.
A drilled hole of L/d 2-10 is not a thin plate (0.79 at L/d 4, Lichtarowicz 1965); this
path under-predicts its flow by ~24%.

When ``use_geometry_cd`` is False or diameter is missing, returns ``config.Cd_inf``.

Definition at line 18 of file discharge.py.

References cd_inf_from_inlet_geometry(), and max.

Referenced by cd_from_re(), and discharge_cd_inf_ratio().

◆ cd_length_factor()

float engine.core.discharge.cd_length_factor	(	float	l_over_d,
		str	model = "lichtarowicz" )

Multiplier on Cd for orifice length.

``lichtarowicz`` (default): the published sharp-inlet fit Cd_u = 0.827 - 0.0085 L/d over
2 <= L/d <= 10, divided by its value at LICHTAROWICZ_REF_LD so the inlet table stays the
anchor. Past 10 (outside the data) the same slope continues, floored at 0.85, and the
extrapolation is recorded. Below 2 it blends linearly to the thin-plate anchor at L/d 0.

``piecewise`` (legacy, unsourced): 1.0 over L/d = 2-5, a steep rise from the thin-plate end
below 2 and a 1.2 %/L/d decline above 5.

Lichtarowicz et al. (1965): steep rise from L/d = 0, maximum near L/d ~ 2 where the
expansion downstream of the vena contracta recovers dynamic pressure, then a slow decline
from wall friction. Below L/d ~ 1 the orifice behaves as a thin plate and loses that
recovery; above ~10 friction dominates.

Definition at line 249 of file discharge.py.

References max.

Referenced by cd_u_from_inlet_geometry().

◆ cd_lichtarowicz_re()

float engine.core.discharge.cd_lichtarowicz_re	(	float	cd_u,
		float	Re,
		float	l_over_d )

Lichtarowicz et al. (1965) Cd at Reynolds number ``Re`` (bulk velocity mdot/(rho A), hole
diameter) for an orifice whose ultimate (high-Re) Cd is ``cd_u`` and length is ``l_over_d``.

Mirrored by ``engine.accel.kernels._cd_lichtarowicz_re``; keep the operation order identical.

Definition at line 356 of file discharge.py.

Referenced by cd_from_re().

◆ cd_u_from_inlet_geometry()

Optional[float] engine.core.discharge.cd_u_from_inlet_geometry ( config )

The ORIFICE's high-Re Cd, inlet table x length factor, before any counterbore approach.

This is Cd_u of Lichtarowicz et al. (1965) as anchored here (sharp 0.80 at
LICHTAROWICZ_REF_LD). None when the config declares no inlet.

Definition at line 320 of file discharge.py.

References cd_from_inlet_radius_ratio(), and cd_length_factor().

Referenced by cd_inf_from_inlet_geometry(), and lichtarowicz_re_inputs().

◆ cd_with_approach()

float engine.core.discharge.cd_with_approach	(	float	cd,
		Optional[float]	beta,
		float	k_entrance = COUNTERBORE_ENTRANCE_K )

Cd of an orifice fed through a counterbore of diameter d / beta, referred to the
plenum-to-chamber drop.

Energy from the plenum: the counterbore entrance costs (1 + K) of the counterbore's
velocity head, and the orifice, with its static tap in the counterbore, discharges
Cd A sqrt(2 rho dp / (1 - beta^4)). Adding the two drops:

    dp_total = rho v^2 / 2 * [ (1 - beta^4) / Cd^2 + beta^4 (1 + K) ]

Wall friction in the counterbore (f L/D ~ 0.05) is neglected: it adds under 0.2 % of the
already-small beta^4 term.

Definition at line 286 of file discharge.py.

Referenced by cd_from_re(), and cd_inf_from_inlet_geometry().

◆ contraction_coefficient()

float engine.core.discharge.contraction_coefficient ( float r_over_d )

Vena-contracta contraction coefficient for inlet rounding r/d (Nurick 1976).

Definition at line 405 of file discharge.py.

References max, and min.

Referenced by cavitation_margin().

◆ discharge_cd_inf_ratio()

float engine.core.discharge.discharge_cd_inf_ratio	(	float	d_hyd_O,
		float	d_hyd_F,
		DischargeConfig	discharge_O,
		DischargeConfig	discharge_F )

High-Re Cd_inf,O / Cd_inf,F from orifice diameters (≈1 when jets share the same hole style).

Definition at line 71 of file discharge.py.

References cd_inf_from_orifice_diameter().

◆ inlet_radius_ratio_of()

float engine.core.discharge.inlet_radius_ratio_of ( config )

r/d a discharge block describes: inlet_radius_ratio, else the named inlet's, else 0 (sharp).

Definition at line 423 of file discharge.py.

◆ lichtarowicz_re_inputs()

Optional[tuple] engine.core.discharge.lichtarowicz_re_inputs ( config )

``(Cd_u, L/d, approach_beta)`` when cd_from_re uses the Lichtarowicz Re law, else None.

It applies when the block declares an inlet (so Cd_u exists), an L/d, and
``length_model: lichtarowicz`` (the default). Otherwise cd_from_re keeps the legacy a_Re form.

Definition at line 370 of file discharge.py.

References cd_u_from_inlet_geometry().

Referenced by cd_from_re().

Variable Documentation

◆ COUNTERBORE_ENTRANCE_K

float engine.core.discharge.COUNTERBORE_ENTRANCE_K = 0.5

Definition at line 246 of file discharge.py.

◆ INLET_GEOMETRY_CD

dict engine.core.discharge.INLET_GEOMETRY_CD

Initial value:

=  {
    "sharp": 0.80,            # plain drilled hole, sharp entry, reattached
    "chamfered": 0.84,        # ~45 deg x 0.1d break on the entry edge
    "conical": 0.86,          # conical/countersunk entrance, included ~60-90 deg
    "rounded_light": 0.85,    # r/d ~ 0.05
    "rounded": 0.88,          # r/d ~ 0.1-0.15 -- "short tube with rounded entrance"
    "bellmouth": 0.95,        # r/d >= 0.2, fully faired entry
}

Definition at line 204 of file discharge.py.

◆ INLET_GEOMETRY_RD

dict engine.core.discharge.INLET_GEOMETRY_RD

Initial value:

=  {
    "sharp": 0.0, "chamfered": 0.03, "conical": 0.04,
    "rounded_light": 0.05, "rounded": 0.125, "bellmouth": 0.20,
}

Definition at line 214 of file discharge.py.

◆ LICHTAROWICZ_A

float engine.core.discharge.LICHTAROWICZ_A = 0.827

Definition at line 237 of file discharge.py.

◆ LICHTAROWICZ_B

float engine.core.discharge.LICHTAROWICZ_B = 0.0085

Definition at line 238 of file discharge.py.

◆ LICHTAROWICZ_LD_MAX

float engine.core.discharge.LICHTAROWICZ_LD_MAX = 10.0

Definition at line 243 of file discharge.py.

◆ LICHTAROWICZ_RE_A

float engine.core.discharge.LICHTAROWICZ_RE_A = 20.0

Definition at line 349 of file discharge.py.

◆ LICHTAROWICZ_RE_B

float engine.core.discharge.LICHTAROWICZ_RE_B = 2.25

Definition at line 350 of file discharge.py.

◆ LICHTAROWICZ_RE_C

float engine.core.discharge.LICHTAROWICZ_RE_C = 0.0015

Definition at line 351 of file discharge.py.

◆ LICHTAROWICZ_RE_D

float engine.core.discharge.LICHTAROWICZ_RE_D = 7.5

Definition at line 352 of file discharge.py.

◆ LICHTAROWICZ_RE_E

float engine.core.discharge.LICHTAROWICZ_RE_E = 0.00015

Definition at line 353 of file discharge.py.

◆ LICHTAROWICZ_REF_LD

tuple engine.core.discharge.LICHTAROWICZ_REF_LD = (LICHTAROWICZ_A - 0.80) / LICHTAROWICZ_B

Definition at line 241 of file discharge.py.

◆ NURICK_CC0

float engine.core.discharge.NURICK_CC0 = 0.62

Definition at line 401 of file discharge.py.

◆ NURICK_RD_GAIN

float engine.core.discharge.NURICK_RD_GAIN = 11.4

Definition at line 402 of file discharge.py.

Functions

Variables