/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Module: FGPiston.cpp
- Author: Jon S. Berndt
+ Author: Jon S. Berndt, JSBSim framework
+ Dave Luff, Piston engine model
Date started: 09/12/2000
Purpose: This module models a Piston engine
CLASS IMPLEMENTATION
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
-FGPiston::FGPiston(FGFDMExec* exec, FGConfigFile* Eng_cfg)
- : FGEngine(exec),
- //these must be initialized this way as they are declared const
+FGPiston::FGPiston(FGFDMExec* exec, FGConfigFile* Eng_cfg) : FGEngine(exec),
CONVERT_CUBIC_INCHES_TO_METERS_CUBED(1.638706e-5),
R_air(287.3),
rho_fuel(800), // estimate
Cp_air(1005),
Cp_fuel(1700)
{
-
string token;
- MinManifoldPressure_inHg=6.5;
- MaxManifoldPressure_inHg=28.5;
- Displacement=360;
- MaxHP=200;
- Cycles=2;
- IdleRPM=600;
- // Set constants
-
-
-
+ MinManifoldPressure_inHg = 6.5;
+ MaxManifoldPressure_inHg = 28.5;
+ Displacement = 360;
+ MaxHP = 200;
+ Cycles = 2;
+ IdleRPM = 600;
+
Name = Eng_cfg->GetValue("NAME");
Eng_cfg->GetNextConfigLine();
while (Eng_cfg->GetValue() != string("/FG_PISTON")) {
else if (token == "IDLERPM") *Eng_cfg >> IdleRPM;
else if (token == "MAXTHROTTLE") *Eng_cfg >> MaxThrottle;
else if (token == "MINTHROTTLE") *Eng_cfg >> MinThrottle;
- else if (token == "SLFUELFLOWMAX") *Eng_cfg >> SLFuelFlowMax;
else cerr << "Unhandled token in Engine config file: " << token << endl;
}
- if (debug_lvl > 0) {
- cout << "\n Engine Name: " << Name << endl;
- cout << " MinManifoldPressure: " << MinManifoldPressure_inHg << endl;
- cout << " MaxManifoldPressure: " << MaxManifoldPressure_inHg << endl;
- cout << " Displacement: " << Displacement << endl;
- cout << " MaxHP: " << MaxHP << endl;
- cout << " Cycles: " << Cycles << endl;
- cout << " IdleRPM: " << IdleRPM << endl;
- cout << " MaxThrottle: " << MaxThrottle << endl;
- cout << " MinThrottle: " << MinThrottle << endl;
- cout << " SLFuelFlowMax: " << SLFuelFlowMax << endl;
- }
-
Type = etPiston;
crank_counter = 0;
- EngineNumber = 0; // FIXME: this should be the actual number
- OilTemp_degK = 298; // FIXME: should be initialized in FGEngine
+ EngineNumber = 0;
+ OilTemp_degK = 298;
+ ManifoldPressure_inHg = Atmosphere->GetPressure() * 0.014138; // psf to in Hg
dt = State->Getdt();
*Lookup_Combustion_Efficiency << 1.60 << 0.525;
*Lookup_Combustion_Efficiency << 2.00 << 0.345;
- cout << endl;
- cout << " Combustion Efficiency table:" << endl;
- Lookup_Combustion_Efficiency->Print();
- cout << endl;
-
Power_Mixture_Correlation = new FGTable(13);
*Power_Mixture_Correlation << (14.7/1.6) << 78.0;
*Power_Mixture_Correlation << 10 << 86.0;
*Power_Mixture_Correlation << 20 << 74.0;
*Power_Mixture_Correlation << (14.7/0.6) << 58;
- cout << endl;
- cout << " Power Mixture Correlation table:" << endl;
- Power_Mixture_Correlation->Print();
- cout << endl;
-
- if (debug_lvl & 2) cout << "Instantiated: FGPiston" << endl;
+ Debug(0); // Call Debug() routine from constructor if needed
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
FGPiston::~FGPiston()
{
- if (debug_lvl & 2) cout << "Destroyed: FGPiston" << endl;
+ Debug(1); // Call Debug() routine from constructor if needed
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
double FGPiston::Calculate(double PowerRequired)
{
-
- // FIXME: calculate from actual fuel flow
ConsumeFuel();
Throttle = FCS->GetThrottlePos(EngineNumber);
IAS = Auxiliary->GetVcalibratedKTS();
- if (Mixture >= 0.5) {
+ if (Mixture >= 0.3) {
doEngineStartup();
doManifoldPressure();
doAirFlow();
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.
// (spark, fuel, starter motor etc)
bool spark;
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) {
void FGPiston::doManifoldPressure(void)
{
- ManifoldPressure_inHg = MinManifoldPressure_inHg +
- (Throttle * (MaxManifoldPressure_inHg - MinManifoldPressure_inHg));
+ if (Running || Cranking) {
+ ManifoldPressure_inHg = MinManifoldPressure_inHg +
+ (Throttle * (MaxManifoldPressure_inHg - MinManifoldPressure_inHg));
+ } else {
+ ManifoldPressure_inHg = Atmosphere->GetPressure() * 0.014138; // psf to in Hg
+ }
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
/**
* Calculate the air flow through the engine.
*
+ * 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,
* RPM, volumetric_efficiency
*
double thi_sea_level = 1.3 * Mixture;
equivalence_ratio = thi_sea_level * p_amb_sea_level / p_amb;
m_dot_fuel = m_dot_air / 14.7 * equivalence_ratio;
+ FuelFlow_gph = m_dot_fuel
+ * 3600 // seconds to hours
+ * 2.2046 // kg to lb
+ / 6.6; // lb to gal_us of kerosene
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
/**
* Calculate the power produced by the engine.
*
- * <p>Currently, the JSBSim propellor model does not allow the
+ * Currently, the JSBSim propellor model does not allow the
* engine to produce enough RPMs to get up to a high horsepower.
* When tested with sufficient RPM, it has no trouble reaching
- * 200HP.</p>
+ * 200HP.
*
* Inputs: ManifoldPressure_inHg, p_amb, p_amb_sea_level, RPM, T_amb,
* equivalence_ratio, Cycles, MaxHP
void FGPiston::doEnginePower(void)
{
- double True_ManifoldPressure_inHg = ManifoldPressure_inHg * p_amb / p_amb_sea_level;
- double ManXRPM = True_ManifoldPressure_inHg * RPM;
+ 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;
void FGPiston::doEGT(void)
{
- combustion_efficiency = Lookup_Combustion_Efficiency->GetValue(equivalence_ratio);
- double enthalpy_exhaust = m_dot_fuel * calorific_value_fuel *
- combustion_efficiency * 0.33;
- double heat_capacity_exhaust = (Cp_air * m_dot_air) + (Cp_fuel * m_dot_fuel);
- double delta_T_exhaust = enthalpy_exhaust / heat_capacity_exhaust;
- ExhaustGasTemp_degK = T_amb + delta_T_exhaust;
- ExhaustGasTemp_degK *= 0.444 + ((0.544 - 0.444) * Percentage_Power / 100.0);
+ 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 * 0.33;
+ 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;
+ ExhaustGasTemp_degK *= 0.444 + ((0.544 - 0.444) * Percentage_Power / 100.0);
+ } else { // Drop towards ambient - guess an appropriate time constant for now
+ dEGTdt = (298.0 - ExhaustGasTemp_degK) / 100.0;
+ delta_T_exhaust = dEGTdt * dt;
+ ExhaustGasTemp_degK += delta_T_exhaust;
+ }
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-void FGPiston::Debug(void)
+//
+// The bitmasked value choices are as follows:
+// unset: In this case (the default) JSBSim would only print
+// out the normally expected messages, essentially echoing
+// the config files as they are read. If the environment
+// variable is not set, debug_lvl is set to 1 internally
+// 0: This requests JSBSim not to output any messages
+// whatsoever.
+// 1: This value explicity requests the normal JSBSim
+// startup messages
+// 2: This value asks for a message to be printed out when
+// a class is instantiated
+// 4: When this value is set, a message is displayed when a
+// FGModel object executes its Run() method
+// 8: When this value is set, various runtime state variables
+// are printed out periodically
+// 16: When set various parameters are sanity checked and
+// a message is printed out when they go out of bounds
+
+void FGPiston::Debug(int from)
{
- //TODO: Add your source code here
+ if (debug_lvl <= 0) return;
+
+ if (debug_lvl & 1) { // Standard console startup message output
+ if (from == 0) { // Constructor
+
+ cout << "\n Engine Name: " << Name << endl;
+ cout << " MinManifoldPressure: " << MinManifoldPressure_inHg << endl;
+ cout << " MaxManifoldPressure: " << MaxManifoldPressure_inHg << endl;
+ cout << " Displacement: " << Displacement << endl;
+ cout << " MaxHP: " << MaxHP << endl;
+ cout << " Cycles: " << Cycles << endl;
+ cout << " IdleRPM: " << IdleRPM << endl;
+ cout << " MaxThrottle: " << MaxThrottle << endl;
+ cout << " MinThrottle: " << MinThrottle << endl;
+
+ cout << endl;
+ cout << " Combustion Efficiency table:" << endl;
+ Lookup_Combustion_Efficiency->Print();
+ cout << endl;
+
+ cout << endl;
+ cout << " Power Mixture Correlation table:" << endl;
+ Power_Mixture_Correlation->Print();
+ cout << endl;
+
+ }
+ }
+ if (debug_lvl & 2 ) { // Instantiation/Destruction notification
+ if (from == 0) cout << "Instantiated: FGPiston" << endl;
+ if (from == 1) cout << "Destroyed: FGPiston" << endl;
+ }
+ if (debug_lvl & 4 ) { // Run() method entry print for FGModel-derived objects
+ }
+ if (debug_lvl & 8 ) { // Runtime state variables
+ }
+ if (debug_lvl & 16) { // Sanity checking
+ }
+ if (debug_lvl & 64) {
+ if (from == 0) { // Constructor
+ cout << IdSrc << endl;
+ cout << IdHdr << endl;
+ }
+ }
}
+double
+FGPiston::CalcFuelNeed(void)
+{
+ return FuelFlow_gph / 3600 * State->Getdt() * Propulsion->GetRate();
+}
projects / flightgear.git / blobdiff