protected void CalculateTTR()
{
//calculate TTR at design point first
// Don't overwrite th0 and th1
EngineThermodynamics ambientTherm = EngineThermodynamics.StandardConditions(false);
ambientTherm.T = T_d;
EngineThermodynamics inletTherm = ambientTherm.ChangeReferenceFrameMach(M_d);
// Note that this work is negative
// Different mass flows between compressor, turbine, and bypass automatically taken care of by MassRatio
double compressorWork;
th3 = inletTherm.AdiabaticProcessWithPressureRatio(CPR, out compressorWork, efficiency: eta_c);
double fanWork = 0d;
if (BPR > 0d)
{
th2 = inletTherm.AdiabaticProcessWithPressureRatio(FPR, out fanWork, efficiency: eta_c);
fanWork *= BPR;
fanWorkConstant = fanWork / compressorWork;
}
double turbineWork = compressorWork + fanWork;
th4 = th3.AddFuelToTemperature(Tt4, h_f);
th5 = th4.AdiabaticProcessWithWork(turbineWork, efficiency: eta_t);
TTR = th5.T / th4.T;
}
protected void InitializeEngine()
{
//calculate TTR at design point first
// Don't overwrite th0 and th1
EngineThermodynamics ambientTherm = EngineThermodynamics.StandardConditions(false);
ambientTherm.T = T_d;
EngineThermodynamics inletTherm = ambientTherm.ChangeReferenceFrameMach(M_d);
th7 = inletTherm.AddFuelToTemperature(9999d, h_f, throttle: throttle, maxFar: maxFar);
th7.P *= 0.95;
double massFlow = inletTherm.CalculateMassFlow(Aref, 0.5d);
Athroat = th7.CalculateFlowArea(massFlow * th7.MassRatio, 1d);
if (!adjustableNozzle)
{
p8 = ambientTherm.P;
CalculateANozzle();
}
}
public override void CalculatePerformance(double airRatio, double commandedThrottle, double flowMult, double ispMult)
{
// set base bits
base.CalculatePerformance(airRatio, commandedThrottle, flowMult, ispMult);
// if we're not combusting, don't combust and start cooling off
combusting = running;
statusString = "Nominal";
if (running && (!oxygen || eair0 <= 0d))
{
combusting = false;
statusString = "No oxygen";
}
else if (ffFraction <= 0d)
{
combusting = false;
statusString = "No fuel";
}
else if (airRatio < 0.01d)
{
combusting = false;
statusString = "Insufficient intake area";
}
else if (underwater)
{
combusting = false;
statusString = "Nozzle in water";
}
if (combusting)
{
if (Tt7 > 0)
{
if (unifiedThrottle)
{
mainThrottle = commandedThrottle;
abThrottle = commandedThrottle;
}
else
{
mainThrottle = Math.Min(commandedThrottle * 1.5d, 1d);
abThrottle = Math.Max(commandedThrottle * 3d - 2d, 0d);
}
}
else
{
mainThrottle = commandedThrottle;
abThrottle = 0d;
}
double coreThrottle = SolverMathUtil.Lerp(minThrottle, 1d, mainThrottle);
prat3 = CPR;
double invfac = eta_c * th1.Gamma / (th1.Gamma - 1.0);
double turbineWork = 0d;
for (int i = 0; i < 20; i++) //use iteration to calculate CPR
{
th3 = th1.AdiabaticProcessWithPressureRatio(prat3, efficiency: eta_c);
// FIXME use ffFraction here? Instead of just multiplying thrust by fuel fraction in the module?
// is so, set multiplyThrustByFuelFrac = false in the ModuleEnginesAJEJet.
th4 = th3.AddFuelToTemperature(Tt4, h_f, throttle: coreThrottle);
th5 = th4.AdiabaticProcessWithTempRatio(TTR, out turbineWork, eta_t);
th3 = th1.AdiabaticProcessWithWork(turbineWork / (1d + fanWorkConstant), efficiency: eta_c);
double x = prat3;
prat3 = th3.P / th1.P;
if (Math.Abs(x - prat3) < 0.01)
{
break;
}
}
if (BPR > 0d)
{
th2 = th1.AdiabaticProcessWithWork(turbineWork * fanWorkConstant / (1d + fanWorkConstant) / BPR, efficiency: eta_c);
th2.MassRatio = BPR;
prat2 = th2.P / th1.P;
}
if (exhaustMixer && BPR > 0)//exhaust mixer
{
th2.P *= 0.98;
th6 = EngineThermodynamics.MixStreams(th5, th2);
}
else
{
th6 = th5;
}
if (Tt7 > 0)
{
th7 = th6.AddFuelToTemperature(Tt7, h_f, throttle: abThrottle);
}
else
{
th7 = th6;
}
//Nozzle code is from NASA
double p8, V8;
//double A8;
double epr = th7.P / th1.P;
double etr = th7.T / th1.T;
// The factor of 0.75 implies that the mach number of air entering the compressor is about 0.5
// The factor can be calculated as
// 1 / (1 - ff_ab) * sqrt(gamma_c/gamma_ab * R_ab / R_c) * M * (1 + (gamma_c + 1)/2 * M^2)^(-(gamma_c + 1)/(2 * (gamma_c - 1)) / ((gamma_ab + 1) / 2)^(-(gamma_ab + 1)/(2 * (gamma_ab - 1))
//
//A8 = .75 * Aref * th7.MassRatio * Math.Sqrt(th1.Gamma / th7.Gamma * th7.R / th1.R) * Math.Sqrt(etr) / epr;//ratio of nozzle area to ref area
//double area8max = .75 * Math.Sqrt(etr) / epr;//ratio of nozzle area to ref area
//A8 = area8max * Aref;
//if (exhaustMixer && BPR > 0)
// A8 *= (1 + BPR);
//double eair = th7.P * Math.Sqrt(th7.Gamma / th7.R / th7.T) *
// Math.Pow((0.5d + 0.5d * th7.Gamma), 0.5d * (1d + th7.Gamma) / (1d - th7.Gamma));//corrected mass flow per area
//mdot = eair * A8;
// Assume turbine is choked all the time
coreAirflow = th4.CalculateMassFlow(Aref * turbineAreaRatio, 1d) / th4.MassRatio;
mdot = th7.MassRatio * coreAirflow;
if (!adjustableNozzle)
{
p8 = th7.ChokedPressure();
if (p8 < th0.P)
{
p8 = th0.P;
}
}
else
{
p8 = th0.P;
}
double exitEnergy = th7.Cp * th7.T * eta_n * (1.0 - Math.Pow(p8 / th7.P, th7.R / th7.Cp));
V8 = Math.Sqrt(Math.Abs(2d * exitEnergy)); //exit velocity - may be negative under certain conditions
V8 *= Math.Sign(exitEnergy);
double exitMach = th7.CalculateMach(Math.Abs(V8));
Anozzle = th7.CalculateFlowArea(mdot, exitMach);
thrust = V8 * mdot + (p8 - th0.P) * Anozzle;
thrust -= mdot * (1d - th7.FF) * (vel);//ram drag
if (BPR > 0d && FPR > 1d && exhaustMixer == false)
{
//fan thrust from NASA
double pfexit = th2.ChokedPressure();
if (pfexit < th0.P)
{
pfexit = th0.P;
}
double fExitEnergy = th2.Cp * th2.T * eta_n * (1d - Math.Pow(pfexit / th2.P, th2.R / th2.Cp));
double ues = Math.Sqrt(Math.Abs(2d * fExitEnergy));
ues *= Math.Sign(fExitEnergy);
double bypassAirFlow = coreAirflow * th2.MassRatio; // th2.MassRatio will be equal to BPR at this point
double ANozzleBypass = th2.CalculateFlowArea(bypassAirFlow, th2.CalculateMach(ues));
thrust += bypassAirFlow * ues + (pfexit - p0) * ANozzleBypass;
thrust -= bypassAirFlow * vel;
}
thrust *= flowMult * ispMult;
fuelFlow = mdot * th7.FF * flowMult;
Isp = thrust / (fuelFlow * 9.80665);
SFC = 3600d / Isp;
/*
* debugstring = "";
* debugstring += "TTR:\t" + TTR.ToString("F3") + "\r\n";
* debugstring += "CPR:\t" + prat3.ToString("F3") + "\r\n"; ;
* debugstring += "p0: " + th0.P.ToString("F2") + "\tt0: " + th0.T.ToString("F2") + "\r\n";
* debugstring += "P1: " + th1.P.ToString("F2") + "\tT1: " + th1.T.ToString("F2") + "\r\n";
* debugstring += "P2: " + th2.P.ToString("F2") + "\tT2: " + th2.T.ToString("F2") + "\r\n";
* debugstring += "P3: " + th3.P.ToString("F2") + "\tT3: " + th3.T.ToString("F2") + "\r\n";
* debugstring += "P4: " + th4.P.ToString("F2") + "\tT4: " + th4.T.ToString("F2") + "\r\n";
* debugstring += "P5: " + th5.P.ToString("F2") + "\tT5: " + th5.T.ToString("F2") + "\r\n";
* debugstring += "P6: " + th6.P.ToString("F2") + "\tT6: " + th6.T.ToString("F2") + "\r\n";
* debugstring += "P7: " + th7.P.ToString("F2") + "\tT7: " + th7.ToString("F2") + "\r\n";
* debugstring += "EPR: " + epr.ToString("F2") + "\tETR: " + etr.ToString("F2") + "\r\n";
*
* debugstring += "FF: " + th5.FF.ToString("P") + "\t";
* debugstring += "FF_AB: " + th7.FF.ToString("P") + "\r\n";
* debugstring += "V8: " + V8.ToString("F2") + "\tA8: " + A8.ToString("F2") + "\r\n";
* debugstring += "Thrust: " + (thrust / 1000).ToString("F1") + "\tmdot: " + mdot.ToString("F2") + "\r\n";
* debugstring += "Isp: " + Isp.ToString("F0") + "\tSFC: " + (3600 / Isp).ToString("F3") + "\r\n";
* Debug.Log(debugstring);*/
}
else
{
double shutdownScalar = Math.Pow(spoolFactor, TimeWarp.fixedDeltaTime);
th3.T = Math.Max(t0, th3.T * shutdownScalar - 4d);
mainThrottle = Math.Max(0d, mainThrottle * shutdownScalar - 0.05d);
if (Tt7 > 0)
{
abThrottle = Math.Max(0d, abThrottle * shutdownScalar - 0.05d);
}
}
// Set FX power
if (Tt7 == 0)
{
fxPower = (float)mainThrottle;
}
else
{
fxPower = (float)(mainThrottle * 0.25d + abThrottle * 0.75d);
}
}
