//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
void FGPiston::Calculate(void)
{
RunPreFunctions();
if (FuelFlow_gph > 0.0) ConsumeFuel();
Throttle = FCS->GetThrottlePos(EngineNumber);
Mixture = FCS->GetMixturePos(EngineNumber);
// Input values.
p_amb = Atmosphere->GetPressure() * psftopa;
double p = Auxiliary->GetTotalPressure() * psftopa;
p_ram = (p - p_amb) * Ram_Air_Factor + p_amb;
T_amb = RankineToKelvin(Atmosphere->GetTemperature());
RPM = Thruster->GetRPM() * Thruster->GetGearRatio();
MeanPistonSpeed_fps = ( RPM * Stroke) / (360); // AKA 2 * (RPM/60) * ( Stroke / 12) or 2NS
IAS = Auxiliary->GetVcalibratedKTS();
doEngineStartup();
if (Boosted) doBoostControl();
doMAP();
doAirFlow();
doFuelFlow();
//Now that the fuel flow is done check if the mixture is too lean to run the engine
//Assume lean limit at 22 AFR for now - thats a thi of 0.668
//This might be a bit generous, but since there's currently no audiable warning of impending
//cutout in the form of misfiring and/or rough running its probably reasonable for now.
// if (equivalence_ratio < 0.668)
// Running = false;
doEnginePower();
if (IndicatedHorsePower < 0.1250) Running = false;
doEGT();
doCHT();
doOilTemperature();
doOilPressure();
if (Thruster->GetType() == FGThruster::ttPropeller) {
((FGPropeller*)Thruster)->SetAdvance(FCS->GetPropAdvance(EngineNumber));
((FGPropeller*)Thruster)->SetFeather(FCS->GetPropFeather(EngineNumber));
}
PowerAvailable = (HP * hptoftlbssec) - Thruster->GetPowerRequired();
Thruster->Calculate(PowerAvailable);
RunPostFunctions();
}
void FGPiston::Calculate(void)
{
// Input values.
p_amb = in.Pressure * psftopa;
double p = in.TotalPressure * psftopa;
p_ram = (p - p_amb) * Ram_Air_Factor + p_amb;
T_amb = RankineToKelvin(in.Temperature);
RunPreFunctions();
TotalDeltaT = ( in.TotalDeltaT < 1e-9 ) ? 1.0 : in.TotalDeltaT;
/* The thruster controls the engine RPM because it encapsulates the gear ratio and other transmission variables */
RPM = Thruster->GetEngineRPM();
MeanPistonSpeed_fps = ( RPM * Stroke) / (360); // AKA 2 * (RPM/60) * ( Stroke / 12) or 2NS
IAS = in.Vc;
doEngineStartup();
if (Boosted) doBoostControl();
doMAP();
doAirFlow();
doFuelFlow();
//Now that the fuel flow is done check if the mixture is too lean to run the engine
//Assume lean limit at 22 AFR for now - thats a thi of 0.668
//This might be a bit generous, but since there's currently no audiable warning of impending
//cutout in the form of misfiring and/or rough running its probably reasonable for now.
// if (equivalence_ratio < 0.668)
// Running = false;
doEnginePower();
if (IndicatedHorsePower < 0.1250) Running = false;
doEGT();
doCHT();
doOilTemperature();
doOilPressure();
if (Thruster->GetType() == FGThruster::ttPropeller) {
((FGPropeller*)Thruster)->SetAdvance(in.PropAdvance[EngineNumber]);
((FGPropeller*)Thruster)->SetFeather(in.PropFeather[EngineNumber]);
}
LoadThrusterInputs();
Thruster->Calculate(HP * hptoftlbssec);
RunPostFunctions();
}
void FGPiston::ResetToIC(void)
{
FGEngine::ResetToIC();
ManifoldPressure_inHg = in.Pressure * psftoinhg; // psf to in Hg
MAP = in.Pressure * psftopa;
TMAP = MAP;
double airTemperature_degK = RankineToKelvin(in.Temperature);
OilTemp_degK = airTemperature_degK;
CylinderHeadTemp_degK = airTemperature_degK;
ExhaustGasTemp_degK = airTemperature_degK;
EGT_degC = ExhaustGasTemp_degK - 273;
Thruster->SetRPM(0.0);
RPM = 0.0;
OilPressure_psi = 0.0;
}
void FGPiston::doEGT(void)
{
double delta_T_exhaust;
double enthalpy_exhaust;
double heat_capacity_exhaust;
double dEGTdt;
if ((Running) && (m_dot_air > 0.0)) { // do the energy balance
combustion_efficiency = Lookup_Combustion_Efficiency->GetValue(equivalence_ratio);
enthalpy_exhaust = m_dot_fuel * calorific_value_fuel *
combustion_efficiency * 0.30;
heat_capacity_exhaust = (Cp_air * m_dot_air) + (Cp_fuel * m_dot_fuel);
delta_T_exhaust = enthalpy_exhaust / heat_capacity_exhaust;
ExhaustGasTemp_degK = T_amb + delta_T_exhaust;
} else { // Drop towards ambient - guess an appropriate time constant for now
combustion_efficiency = 0;
dEGTdt = (RankineToKelvin(in.Temperature) - ExhaustGasTemp_degK) / 100.0;
delta_T_exhaust = dEGTdt * TotalDeltaT;
ExhaustGasTemp_degK += delta_T_exhaust;
}
}
