Functions
float	calculate_Lstar (float V_chamber, float A_throat, Optional[float] Lstar_override=None)
Tuple[float, Dict[str, float]]	wall_heat_lost_W (Optional[Dict[str, Any]] cooling_results)
float	heat_loss_cstar_efficiency (float Q_lost, float m_dot_total, float Tc, float gamma, float R)
float	eta_cstar (float Lstar, CombustionEfficiencyConfig config, float cooling_efficiency, Dict[str, Any] advanced_params, bool debug=False)
float	calculate_actual_chamber_temp (float Tc_ideal, float eta, float gamma)
float	calculate_frozen_flow_correction (float Lstar, float gamma_ideal, float alpha=0.1)

Variables
tuple	_HEAT_RETURNED_TO_PROPELLANT = ("regen", "film")

Detailed Description

c* efficiency: vaporization and mixing (combustion_physics) and heat lost to the wall.

Function Documentation

◆ calculate_actual_chamber_temp()

float engine.pipeline.combustion_eff.calculate_actual_chamber_temp	(	float	Tc_ideal,
		float	eta,
		float	gamma )

Calculate actual chamber temperature accounting for combustion efficiency.

T_c,actual = T_c,ideal × [η / (1 - (1-η) × (γ-1)/γ)]

Parameters:
-----------
Tc_ideal : float
    Ideal chamber temperature from CEA [K]
eta : float
    Combustion efficiency
gamma : float
    Specific heat ratio

Returns:
--------
Tc_actual : float [K]

Definition at line 187 of file combustion_eff.py.

◆ calculate_frozen_flow_correction()

float engine.pipeline.combustion_eff.calculate_frozen_flow_correction	(	float	Lstar,
		float	gamma_ideal,
		float	alpha = 0.1 )

Calculate frozen flow correction factor for gamma.

γ_actual = γ_ideal × [1 - α × (1 - η_c*)]

This accounts for incomplete chemical reactions in the nozzle.

Parameters:
-----------
Lstar : float
    Characteristic length [m]
gamma_ideal : float
    Ideal gamma from CEA
alpha : float
    Frozen flow parameter (default 0.1)

Returns:
--------
correction_factor : float
    Factor to multiply gamma_ideal by

Definition at line 221 of file combustion_eff.py.

◆ calculate_Lstar()

float engine.pipeline.combustion_eff.calculate_Lstar	(	float	V_chamber,
		float	A_throat,
		Optional[float]	Lstar_override = None )

Calculate characteristic length L*.

L* = V_chamber / A_throat

Parameters:
-----------
V_chamber : float
    Chamber volume [m³]
A_throat : float
    Throat area [m²]
Lstar_override : float, optional
    Override value if provided in config

Returns:
--------
Lstar : float [m]

Definition at line 17 of file combustion_eff.py.

◆ eta_cstar()

float engine.pipeline.combustion_eff.eta_cstar	(	float	Lstar,
		CombustionEfficiencyConfig	config,
		float	cooling_efficiency,
		Dict[str, Any]	advanced_params,
		bool	debug = False )

c* efficiency, eta_vap * eta_mix * eta_HL.

eta_vap and eta_mix come from combustion_physics. eta_HL is the heat lost through the wall,
taken from the cooling results the chamber solver leaves in the spray diagnostics
(``spray_diagnostics["cooling"]``); ``cooling_efficiency`` is used only when the call carries
none. The breakdown, with its inputs and assumptions, is written back to
``spray_diagnostics["cstar_efficiency"]`` so it reaches the reported diagnostics.

advanced_params: Pc, Tc (CEA, adiabatic), cstar_ideal, gamma, R, MR, Ac, At, m_dot_total,
u_fuel, u_lox, spray_diagnostics, fuel_props, and optionally ox_props; cea_cache (the design's
CEACache, whose propellant pair selects the wide c*(O/F) table) or cstar_fn for the mixing and
vaporized-gas c* ratios.

Definition at line 98 of file combustion_eff.py.

References heat_loss_cstar_efficiency(), info, and wall_heat_lost_W().

◆ heat_loss_cstar_efficiency()

float engine.pipeline.combustion_eff.heat_loss_cstar_efficiency	(	float	Q_lost,
		float	m_dot_total,
		float	Tc,
		float	gamma,
		float	R )

c* retained when Q_lost [W] leaves the gas upstream of the throat.

c* = sqrt(gamma R T0) / Gamma(gamma) (Sutton & Biblarz eq. 3-32), so at fixed composition
c* ~ sqrt(T0). Removing Q lowers the stagnation enthalpy by Q/mdot and T0 by Q/(mdot cp):

    eta_HL = sqrt(1 - Q/(mdot cp Tc)),   cp = gamma R/(gamma - 1),  Tc the adiabatic CEA value.

Against rocketcea with the propellant enthalpy lowered by Q/mdot (LOX/ethanol, 200-800 psia,
O/F 1.0-2.2, 188 kJ/kg) the loss is 0.94-1.34x CEA's; the excess near stoichiometric is heat
that recombination returns. The linear 1 - Q/(mdot cp T_eff) it replaces was 1.9-2.7x.

Definition at line 68 of file combustion_eff.py.

References max.

Referenced by eta_cstar().

◆ wall_heat_lost_W()

Tuple[float, Dict[str, float]] engine.pipeline.combustion_eff.wall_heat_lost_W ( Optional[Dict[str, Any]] cooling_results )

Heat [W] that leaves the propellant through the chamber wall, and its split by source.

Definition at line 56 of file combustion_eff.py.

Referenced by eta_cstar().

Variable Documentation

◆ _HEAT_RETURNED_TO_PROPELLANT

tuple engine.pipeline.combustion_eff._HEAT_RETURNED_TO_PROPELLANT = ("regen", "film")

protected

Definition at line 53 of file combustion_eff.py.

Functions

Variables