INCLUDES
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
+#include <sstream>
+
#include "FGPiston.h"
#include "FGPropulsion.h"
+#include "FGPropeller.h"
+
+namespace JSBSim {
static const char *IdSrc = "$Id$";
static const char *IdHdr = ID_PISTON;
CLASS IMPLEMENTATION
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
-FGPiston::FGPiston(FGFDMExec* exec, FGConfigFile* Eng_cfg) : FGEngine(exec),
- CONVERT_CUBIC_INCHES_TO_METERS_CUBED(1.638706e-5),
+FGPiston::FGPiston(FGFDMExec* exec, FGConfigFile* Eng_cfg, int engine_number)
+ : FGEngine(exec, engine_number),
R_air(287.3),
rho_fuel(800), // estimate
calorific_value_fuel(47.3e6),
{
string token;
+ Type = etPiston;
+ crank_counter = 0;
+ OilTemp_degK = 298;
MinManifoldPressure_inHg = 6.5;
MaxManifoldPressure_inHg = 28.5;
+ ManifoldPressure_inHg = Atmosphere->GetPressure() * psftoinhg; // psf to in Hg
+ minMAP = 21950;
+ maxMAP = 96250;
+ MAP = Atmosphere->GetPressure() * 47.88; // psf to Pa
+ CylinderHeadTemp_degK = 0.0;
Displacement = 360;
MaxHP = 200;
Cycles = 2;
IdleRPM = 600;
-
- Name = Eng_cfg->GetValue("NAME");
- Eng_cfg->GetNextConfigLine();
- while (Eng_cfg->GetValue() != string("/FG_PISTON")) {
- *Eng_cfg >> token;
- if (token == "MINMP") *Eng_cfg >> MinManifoldPressure_inHg;
- else if (token == "MAXMP") *Eng_cfg >> MaxManifoldPressure_inHg;
- else if (token == "DISPLACEMENT") *Eng_cfg >> Displacement;
- else if (token == "MAXHP") *Eng_cfg >> MaxHP;
- else if (token == "CYCLES") *Eng_cfg >> Cycles;
- else if (token == "IDLERPM") *Eng_cfg >> IdleRPM;
- else if (token == "MAXTHROTTLE") *Eng_cfg >> MaxThrottle;
- else if (token == "MINTHROTTLE") *Eng_cfg >> MinThrottle;
- else cerr << "Unhandled token in Engine config file: " << token << endl;
- }
-
- Type = etPiston;
- crank_counter = 0;
- EngineNumber = 0;
- OilTemp_degK = 298;
- ManifoldPressure_inHg = Atmosphere->GetPressure() * 0.014138; // psf to in Hg
+ Magnetos = 0;
+ ExhaustGasTemp_degK = 0.0;
+ EGT_degC = 0.0;
dt = State->Getdt();
+ // Supercharging
+ BoostSpeeds = 0; // Default to no supercharging
+ BoostSpeed = 0;
+ Boosted = false;
+ BoostOverride = 0;
+ bBoostOverride = false;
+ bTakeoffBoost = false;
+ TakeoffBoost = 0.0; // Default to no extra takeoff-boost
+ int i;
+ for (i=0; i<FG_MAX_BOOST_SPEEDS; i++) {
+ RatedBoost[i] = 0.0;
+ RatedPower[i] = 0.0;
+ RatedAltitude[i] = 0.0;
+ BoostMul[i] = 1.0;
+ RatedMAP[i] = 100000;
+ RatedRPM[i] = 2500;
+ TakeoffMAP[i] = 100000;
+ }
+ for (i=0; i<FG_MAX_BOOST_SPEEDS-1; i++) {
+ BoostSwitchAltitude[i] = 0.0;
+ BoostSwitchPressure[i] = 0.0;
+ }
+
// Initialisation
volumetric_efficiency = 0.8; // Actually f(speed, load) but this will get us running
*Power_Mixture_Correlation << 20 << 74.0;
*Power_Mixture_Correlation << (14.7/0.6) << 58;
+ Name = Eng_cfg->GetValue("NAME");
+ Eng_cfg->GetNextConfigLine();
+ while (Eng_cfg->GetValue() != string("/FG_PISTON")) {
+ *Eng_cfg >> token;
+ if (token == "MINMP") *Eng_cfg >> MinManifoldPressure_inHg;
+ else if (token == "MAXMP") *Eng_cfg >> MaxManifoldPressure_inHg;
+ else if (token == "DISPLACEMENT") *Eng_cfg >> Displacement;
+ else if (token == "MAXHP") *Eng_cfg >> MaxHP;
+ else if (token == "CYCLES") *Eng_cfg >> Cycles;
+ else if (token == "IDLERPM") *Eng_cfg >> IdleRPM;
+ else if (token == "MAXTHROTTLE") *Eng_cfg >> MaxThrottle;
+ else if (token == "MINTHROTTLE") *Eng_cfg >> MinThrottle;
+ else if (token == "NUMBOOSTSPEEDS") *Eng_cfg >> BoostSpeeds;
+ else if (token == "BOOSTOVERRIDE") *Eng_cfg >> BoostOverride;
+ else if (token == "TAKEOFFBOOST") *Eng_cfg >> TakeoffBoost;
+ else if (token == "RATEDBOOST1") *Eng_cfg >> RatedBoost[0];
+ else if (token == "RATEDBOOST2") *Eng_cfg >> RatedBoost[1];
+ else if (token == "RATEDBOOST3") *Eng_cfg >> RatedBoost[2];
+ else if (token == "RATEDPOWER1") *Eng_cfg >> RatedPower[0];
+ else if (token == "RATEDPOWER2") *Eng_cfg >> RatedPower[1];
+ else if (token == "RATEDPOWER3") *Eng_cfg >> RatedPower[2];
+ else if (token == "RATEDRPM1") *Eng_cfg >> RatedRPM[0];
+ else if (token == "RATEDRPM2") *Eng_cfg >> RatedRPM[1];
+ else if (token == "RATEDRPM3") *Eng_cfg >> RatedRPM[2];
+ else if (token == "RATEDALTITUDE1") *Eng_cfg >> RatedAltitude[0];
+ else if (token == "RATEDALTITUDE2") *Eng_cfg >> RatedAltitude[1];
+ else if (token == "RATEDALTITUDE3") *Eng_cfg >> RatedAltitude[2];
+ else cerr << "Unhandled token in Engine config file: " << token << endl;
+ }
+
+ minMAP = MinManifoldPressure_inHg * 3376.85; // inHg to Pa
+ maxMAP = MaxManifoldPressure_inHg * 3376.85;
+
+ // Set up and sanity-check the turbo/supercharging configuration based on the input values.
+ if(TakeoffBoost > RatedBoost[0]) bTakeoffBoost = true;
+ for(i=0; i<BoostSpeeds; ++i) {
+ bool bad = false;
+ if(RatedBoost[i] <= 0.0) bad = true;
+ if(RatedPower[i] <= 0.0) bad = true;
+ if(RatedAltitude[i] < 0.0) bad = true; // 0.0 is deliberately allowed - this corresponds to unregulated supercharging.
+ if(i > 0 && RatedAltitude[i] < RatedAltitude[i - 1]) bad = true;
+ if(bad) {
+ // We can't recover from the above - don't use this supercharger speed.
+ BoostSpeeds--;
+ // TODO - put out a massive error message!
+ break;
+ }
+ // Now sanity-check stuff that is recoverable.
+ if(i < BoostSpeeds - 1) {
+ if(BoostSwitchAltitude[i] < RatedAltitude[i]) {
+ // TODO - put out an error message
+ // But we can also make a reasonable estimate, as below.
+ BoostSwitchAltitude[i] = RatedAltitude[i] + 1000;
+ }
+ BoostSwitchPressure[i] = Atmosphere->GetPressure(BoostSwitchAltitude[i]) * 47.88;
+ //cout << "BoostSwitchAlt = " << BoostSwitchAltitude[i] << ", pressure = " << BoostSwitchPressure[i] << '\n';
+ // Assume there is some hysteresis on the supercharger gear switch, and guess the value for now
+ BoostSwitchHysteresis = 1000;
+ }
+ // Now work out the supercharger pressure multiplier of this speed from the rated boost and altitude.
+ RatedMAP[i] = Atmosphere->GetPressureSL() * 47.88 + RatedBoost[i] * 6895; // psf*47.88 = Pa, psi*6895 = Pa.
+ // Sometimes a separate BCV setting for takeoff or extra power is fitted.
+ if(TakeoffBoost > RatedBoost[0]) {
+ // Assume that the effect on the BCV is the same whichever speed is in use.
+ TakeoffMAP[i] = RatedMAP[i] + ((TakeoffBoost - RatedBoost[0]) * 6895);
+ bTakeoffBoost = true;
+ } else {
+ TakeoffMAP[i] = RatedMAP[i];
+ bTakeoffBoost = false;
+ }
+ BoostMul[i] = RatedMAP[i] / (Atmosphere->GetPressure(RatedAltitude[i]) * 47.88);
+
+ // TODO - get rid of the debugging output before sending it to Jon
+ //cout << "Speed " << i+1 << '\n';
+ //cout << "BoostMul = " << BoostMul[i] << ", RatedMAP = " << RatedMAP[i] << ", TakeoffMAP = " << TakeoffMAP[i] << '\n';
+ }
+
+ if(BoostSpeeds > 0) {
+ Boosted = true;
+ BoostSpeed = 0;
+ }
+ bBoostOverride = (BoostOverride == 1 ? true : false);
+
+ //cout << "Engine is " << (Boosted ? "supercharged" : "naturally aspirated") << '\n';
+
Debug(0); // Call Debug() routine from constructor if needed
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-double FGPiston::Calculate(double PowerRequired)
+double FGPiston::Calculate(void)
{
- // FIXME: calculate from actual fuel flow
- ConsumeFuel();
+ if (FuelFlow_gph > 0.0) ConsumeFuel();
Throttle = FCS->GetThrottlePos(EngineNumber);
Mixture = FCS->GetMixturePos(EngineNumber);
// Input values.
//
- p_amb = Atmosphere->GetPressure() * 48; // convert from lbs/ft2 to Pa
- p_amb_sea_level = Atmosphere->GetPressureSL() * 48;
+ p_amb = Atmosphere->GetPressure() * 47.88; // convert from lbs/ft2 to Pa
+ p_amb_sea_level = Atmosphere->GetPressureSL() * 47.88;
T_amb = Atmosphere->GetTemperature() * (5.0 / 9.0); // convert from Rankine to Kelvin
- RPM = Propulsion->GetThruster(EngineNumber)->GetRPM();
- //if (RPM < IdleRPM) RPM = IdleRPM; // kludge
-
+ RPM = Thruster->GetRPM() * Thruster->GetGearRatio();
+
IAS = Auxiliary->GetVcalibratedKTS();
- if (Mixture >= 0.3) {
- doEngineStartup();
- doManifoldPressure();
- doAirFlow();
- doFuelFlow();
- doEnginePower();
- doEGT();
- doCHT();
- doOilTemperature();
- doOilPressure();
- } else {
- HP = 0;
+ 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();
+ doEGT();
+ doCHT();
+ doOilTemperature();
+ doOilPressure();
+
+ if (Thruster->GetType() == FGThruster::ttPropeller) {
+ ((FGPropeller*)Thruster)->SetAdvance(FCS->GetPropAdvance(EngineNumber));
}
- PowerAvailable = (HP * hptoftlbssec) - PowerRequired;
- return PowerAvailable;
+ PowerAvailable = (HP * hptoftlbssec) - Thruster->GetPowerRequired();
+
+ return Thrust = Thruster->Calculate(PowerAvailable);
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
void FGPiston::doEngineStartup(void)
{
- // TODO: check magnetos, spark, starter, etc. and decide whether
- // engine is running
-
- // Check parameters that may alter the operating state of the engine.
+ // Check parameters that may alter the operating state of the engine.
// (spark, fuel, starter motor etc)
bool spark;
bool fuel;
} else {
spark = false;
} // neglects battery voltage, master on switch, etc for now.
-
+
if ((Magnetos == 1) || (Magnetos > 2)) Magneto_Left = true;
if (Magnetos > 1) Magneto_Right = true;
// Assume we have fuel for now
- fuel = true;
+ fuel = !Starved;
// Check if we are turning the starter motor
if (Cranking != Starter) {
crank_counter = 0;
}
- //Check mode of engine operation
- // ACK - unfortunately this hack doesn't work in JSBSim since the RPM is reset
- // each iteration by the propeller :-(
- if (Cranking) {
- crank_counter++;
- if (RPM <= 480) {
- RPM += 100;
- if (RPM > 480)
- RPM = 480;
+ if (Cranking) crank_counter++; //Check mode of engine operation
+
+ if (!Running && spark && fuel) { // start the engine if revs high enough
+ if (Cranking) {
+ if ((RPM > 450) && (crank_counter > 175)) // Add a little delay to startup
+ Running = true; // on the starter
} else {
- // consider making a horrible noise if the starter is engaged with
- // the engine running
- }
- // TODO - find a better guess at cranking speed
- }
-
- // if ((!Running) && (spark) && (fuel) && (crank_counter > 120)) {
-
- if ((!Running) && (spark) && (fuel)) {
- // start the engine if revs high enough
- if (RPM > 450) {
- // For now just instantaneously start but later we should maybe crank for
- // a bit
- Running = true;
- // RPM = 600;
+ if (RPM > 450) // This allows us to in-air start
+ Running = true; // when windmilling
}
}
- if ( (Running) && ((!spark)||(!fuel)) ) {
- // Cut the engine
- // note that we only cut the power - the engine may continue to
- // spin if the prop is in a moving airstream
- Running = false;
- }
+ // Cut the engine *power* - Note: the engine may continue to
+ // spin if the prop is in a moving airstream
+
+ if ( Running && (!spark || !fuel) ) Running = false;
- // And finally a last check for stalling
- if (Running) {
- //Check if we have stalled the engine
+ // Check for stalling (RPM = 0).
+ if (Running) {
if (RPM == 0) {
Running = false;
} else if ((RPM <= 480) && (Cranking)) {
- // Make sure the engine noise dosn't play if the engine won't
- // start due to eg mixture lever pulled out.
Running = false;
}
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
/**
- * Calculate the nominal manifold pressure in inches hg
+ * Calculate the Current Boost Speed
+ *
+ * This function calculates the current turbo/supercharger boost speed
+ * based on altitude and the (automatic) boost-speed control valve configuration.
+ *
+ * Inputs: p_amb, BoostSwitchPressure, BoostSwitchHysteresis
+ *
+ * Outputs: BoostSpeed
+ */
+
+void FGPiston::doBoostControl(void)
+{
+ if(BoostSpeed < BoostSpeeds - 1) {
+ // Check if we need to change to a higher boost speed
+ if(p_amb < BoostSwitchPressure[BoostSpeed] - BoostSwitchHysteresis) {
+ BoostSpeed++;
+ }
+ } else if(BoostSpeed > 0) {
+ // Check if we need to change to a lower boost speed
+ if(p_amb > BoostSwitchPressure[BoostSpeed - 1] + BoostSwitchHysteresis) {
+ BoostSpeed--;
+ }
+ }
+}
+
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+/**
+ * Calculate the manifold absolute pressure (MAP) in inches hg
*
- * This function calculates nominal manifold pressure directly
- * from the throttle position, and does not adjust it for the
- * difference between the pressure at sea level and the pressure
- * at the current altitude (that adjustment takes place in
- * {@link #doEnginePower}).
+ * This function calculates manifold absolute pressure (MAP)
+ * from the throttle position, turbo/supercharger boost control
+ * system, engine speed and local ambient air density.
*
* TODO: changes in MP should not be instantaneous -- introduce
* a lag between throttle changes and MP changes, to allow pressure
* to build up or disperse.
*
- * Inputs: MinManifoldPressure_inHg, MaxManifoldPressure_inHg, Throttle
+ * Inputs: minMAP, maxMAP, p_amb, Throttle
*
- * Outputs: ManifoldPressure_inHg
+ * Outputs: MAP, ManifoldPressure_inHg
*/
-void FGPiston::doManifoldPressure(void)
+void FGPiston::doMAP(void)
{
- if (Running || Cranking) {
- ManifoldPressure_inHg = MinManifoldPressure_inHg +
- (Throttle * (MaxManifoldPressure_inHg - MinManifoldPressure_inHg));
+ if(RPM > 10) {
+ // Naturally aspirated
+ MAP = minMAP + (Throttle * (maxMAP - minMAP));
+ MAP *= p_amb / p_amb_sea_level;
+ if(Boosted) {
+ // If takeoff boost is fitted, we currently assume the following throttle map:
+ // (In throttle % - actual input is 0 -> 1)
+ // 99 / 100 - Takeoff boost
+ // 96 / 97 / 98 - Rated boost
+ // 0 - 95 - Idle to Rated boost (MinManifoldPressure to MaxManifoldPressure)
+ // In real life, most planes would be fitted with a mechanical 'gate' between
+ // the rated boost and takeoff boost positions.
+ double T = Throttle; // processed throttle value.
+ bool bTakeoffPos = false;
+ if(bTakeoffBoost) {
+ if(Throttle > 0.98) {
+ //cout << "Takeoff Boost!!!!\n";
+ bTakeoffPos = true;
+ } else if(Throttle <= 0.95) {
+ bTakeoffPos = false;
+ T *= 1.0 / 0.95;
+ } else {
+ bTakeoffPos = false;
+ //cout << "Rated Boost!!\n";
+ T = 1.0;
+ }
+ }
+ // Boost the manifold pressure.
+ MAP *= BoostMul[BoostSpeed];
+ // Now clip the manifold pressure to BCV or Wastegate setting.
+ if(bTakeoffPos) {
+ if(MAP > TakeoffMAP[BoostSpeed]) {
+ MAP = TakeoffMAP[BoostSpeed];
+ }
+ } else {
+ if(MAP > RatedMAP[BoostSpeed]) {
+ MAP = RatedMAP[BoostSpeed];
+ }
+ }
+ }
} else {
- ManifoldPressure_inHg = Atmosphere->GetPressure() * 0.014138; // psf to in Hg
- }
+ // rpm < 10 - effectively stopped.
+ // TODO - add a better variation of MAP with engine speed
+ MAP = Atmosphere->GetPressure() * 47.88; // psf to Pa
+ }
+
+ // And set the value in American units as well
+ ManifoldPressure_inHg = MAP / 3376.85;
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
/**
* Calculate the air flow through the engine.
+ * Also calculates ambient air density
+ * (used in CHT calculation for air-cooled engines).
*
- * At this point, ManifoldPressure_inHg still represents the sea-level
- * MP, not adjusted for altitude.
- *
- * Inputs: p_amb, R_air, T_amb, ManifoldPressure_inHg, Displacement,
+ * Inputs: p_amb, R_air, T_amb, MAP, Displacement,
* RPM, volumetric_efficiency
*
+ * TODO: Model inlet manifold air temperature.
+ *
* Outputs: rho_air, m_dot_air
*/
void FGPiston::doAirFlow(void)
{
rho_air = p_amb / (R_air * T_amb);
- double rho_air_manifold = rho_air * ManifoldPressure_inHg / 29.6;
- double displacement_SI = Displacement * CONVERT_CUBIC_INCHES_TO_METERS_CUBED;
+ double rho_air_manifold = MAP / (R_air * T_amb);
+ double displacement_SI = Displacement * in3tom3;
double swept_volume = (displacement_SI * (RPM/60)) / 2;
double v_dot_air = swept_volume * volumetric_efficiency;
m_dot_air = v_dot_air * rho_air_manifold;
* When tested with sufficient RPM, it has no trouble reaching
* 200HP.
*
- * Inputs: ManifoldPressure_inHg, p_amb, p_amb_sea_level, RPM, T_amb,
+ * Inputs: ManifoldPressure_inHg, p_amb, p_amb_sea_level, RPM, T_amb,
* equivalence_ratio, Cycles, MaxHP
*
* Outputs: Percentage_Power, HP
void FGPiston::doEnginePower(void)
{
- ManifoldPressure_inHg *= p_amb / p_amb_sea_level;
- double ManXRPM = ManifoldPressure_inHg * RPM;
- // FIXME: this needs to be generalized
- Percentage_Power = (6e-9 * ManXRPM * ManXRPM) + (8e-4 * ManXRPM) - 1.0;
- double T_amb_degF = (T_amb * 1.8) - 459.67;
- double T_amb_sea_lev_degF = (288 * 1.8) - 459.67;
- Percentage_Power =
- Percentage_Power + ((T_amb_sea_lev_degF - T_amb_degF) * 7 /120);
- double Percentage_of_best_power_mixture_power =
- Power_Mixture_Correlation->GetValue(14.7 / equivalence_ratio);
- Percentage_Power =
- Percentage_Power * Percentage_of_best_power_mixture_power / 100.0;
- if (Percentage_Power < 0.0)
- Percentage_Power = 0.0;
- else if (Percentage_Power > 100.0)
- Percentage_Power = 100.0;
- HP = Percentage_Power * MaxHP / 100.0;
-
- //Hack
- if (!Running) {
+ if (Running) {
+ double T_amb_degF = KelvinToFahrenheit(T_amb);
+ double T_amb_sea_lev_degF = KelvinToFahrenheit(288);
+
+ // FIXME: this needs to be generalized
+ double ManXRPM; // Convienience term for use in the calculations
+ if(Boosted) {
+ // Currently a simple linear fit.
+ // The zero crossing is moved up the speed-load range to reduce the idling power.
+ // This will change!
+ double zeroOffset = (minMAP / 2.0) * (IdleRPM / 2.0);
+ ManXRPM = MAP * (RPM > RatedRPM[BoostSpeed] ? RatedRPM[BoostSpeed] : RPM);
+ // The speed clip in the line above is deliberate.
+ Percentage_Power = ((ManXRPM - zeroOffset) / ((RatedMAP[BoostSpeed] * RatedRPM[BoostSpeed]) - zeroOffset)) * 107.0;
+ Percentage_Power -= 7.0; // Another idle power reduction offset - see line above with 107.
+ if (Percentage_Power < 0.0) Percentage_Power = 0.0;
+ // Note that %power is allowed to go over 100 for boosted powerplants
+ // such as for the BCV-override or takeoff power settings.
+ // TODO - currently no altitude effect (temperature & exhaust back-pressure) modelled
+ // for boosted engines.
+ } else {
+ ManXRPM = ManifoldPressure_inHg * RPM; // Note that inHg must be used for the following correlation.
+ Percentage_Power = (6e-9 * ManXRPM * ManXRPM) + (8e-4 * ManXRPM) - 1.0;
+ Percentage_Power += ((T_amb_sea_lev_degF - T_amb_degF) * 7 /120);
+ if (Percentage_Power < 0.0) Percentage_Power = 0.0;
+ else if (Percentage_Power > 100.0) Percentage_Power = 100.0;
+ }
+
+ double Percentage_of_best_power_mixture_power =
+ Power_Mixture_Correlation->GetValue(14.7 / equivalence_ratio);
+
+ Percentage_Power *= Percentage_of_best_power_mixture_power / 100.0;
+
+ if(Boosted) {
+ HP = Percentage_Power * RatedPower[BoostSpeed] / 100.0;
+ } else {
+ HP = Percentage_Power * MaxHP / 100.0;
+ }
+
+ } else {
+
+ // Power output when the engine is not running
if (Cranking) {
- if (RPM < 480) {
+ if (RPM < 10) {
+ HP = 3.0; // This is a hack to prevent overshooting the idle rpm in
+ // the first time step. It may possibly need to be changed
+ // if the prop model is changed.
+ } else if (RPM < 480) {
HP = 3.0 + ((480 - RPM) / 10.0);
+ // This is a guess - would be nice to find a proper starter moter torque curve
} else {
HP = 3.0;
}
HP = 0.0;
}
}
+ //cout << "Power = " << HP << '\n';
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
/**
* Calculate the exhaust gas temperature.
*
- * Inputs: equivalence_ratio, m_dot_fuel, calorific_value_fuel,
+ * Inputs: equivalence_ratio, m_dot_fuel, calorific_value_fuel,
* Cp_air, m_dot_air, Cp_fuel, m_dot_fuel, T_amb, Percentage_Power
*
* Outputs: combustion_efficiency, ExhaustGasTemp_degK
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 *
+ enthalpy_exhaust = m_dot_fuel * calorific_value_fuel *
combustion_efficiency * 0.33;
heat_capacity_exhaust = (Cp_air * m_dot_air) + (Cp_fuel * m_dot_fuel);
delta_T_exhaust = enthalpy_exhaust / heat_capacity_exhaust;
double v_apparent = IAS * 0.5144444;
double v_dot_cooling_air = arbitary_area * v_apparent;
double m_dot_cooling_air = v_dot_cooling_air * rho_air;
- double dqdt_from_combustion =
+ double dqdt_from_combustion =
m_dot_fuel * calorific_value_fuel * combustion_efficiency * 0.33;
- double dqdt_forced = (h2 * m_dot_cooling_air * temperature_difference) +
+ double dqdt_forced = (h2 * m_dot_cooling_air * temperature_difference) +
(h3 * RPM * temperature_difference);
double dqdt_free = h1 * temperature_difference;
double dqdt_cylinder_head = dqdt_from_combustion + dqdt_forced + dqdt_free;
-
+
double HeatCapacityCylinderHead = CpCylinderHead * MassCylinderHead;
-
- CylinderHeadTemp_degK = dqdt_cylinder_head / HeatCapacityCylinderHead;
+
+ CylinderHeadTemp_degK +=
+ (dqdt_cylinder_head / HeatCapacityCylinderHead) * dt;
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
target_oil_temp = 363;
time_constant = 500; // Time constant for engine-on idling.
if (Percentage_Power > idle_percentage_power) {
- time_constant /= ((Percentage_Power / idle_percentage_power) / 10.0); // adjust for power
+ time_constant /= ((Percentage_Power / idle_percentage_power) / 10.0); // adjust for power
}
} else {
target_oil_temp = 298;
{
double Oil_Press_Relief_Valve = 60; // FIXME: may vary by engine
double Oil_Press_RPM_Max = 1800; // FIXME: may vary by engine
- double Design_Oil_Temp = 85; // FIXME: may vary by engine
- // FIXME: WRONG!!! (85 degK???)
+ double Design_Oil_Temp = 358; // degK; FIXME: may vary by engine
double Oil_Viscosity_Index = 0.25;
OilPressure_psi = (Oil_Press_Relief_Valve / Oil_Press_RPM_Max) * RPM;
OilPressure_psi += (Design_Oil_Temp - OilTemp_degK) * Oil_Viscosity_Index;
}
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+string FGPiston::GetEngineLabels(string delimeter)
+{
+ std::ostringstream buf;
+
+ buf << Name << "_PwrAvail[" << EngineNumber << "]" << delimeter
+ << Name << "_HP[" << EngineNumber << "]" << delimeter
+ << Thruster->GetThrusterLabels(EngineNumber, delimeter);
+
+ return buf.str();
+}
+
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+string FGPiston::GetEngineValues(string delimeter)
+{
+ std::ostringstream buf;
+
+ buf << PowerAvailable << delimeter << HP << delimeter
+ << Thruster->GetThrusterValues(EngineNumber, delimeter);
+
+ return buf.str();
+}
+
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
//
// The bitmasked value choices are as follows:
double
FGPiston::CalcFuelNeed(void)
{
- // FIXME: is this right?
- return FuelFlow_gph * State->Getdt() * Propulsion->GetRate();
+ return FuelFlow_gph / 3600 * 6 * State->Getdt() * Propulsion->GetRate();
}
+
+} // namespace JSBSim
projects / flightgear.git / blobdiff