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Bug fixes for JSBSim atmosphere model at very high altitudes

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* Disables dew point transmission as the humidity model is not handling the case where the vapor saturation pressure gets higher than the ambient pressure.
* Removed computations for temperatures at very high altitudes as they don't match with the rest of JSBSim atmosphere model.
This commit is contained in:
Bertrand Coconnier 2018-10-06 19:24:06 +02:00
parent b0e157dd88
commit 8e05816b43
2 changed files with 6 additions and 30 deletions
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4
src/FDM/JSBSim/JSBSim.cxx
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@ -697,8 +697,8 @@ bool FGJSBsim::copy_to_JSBsim()
Atmosphere->SetTemperature(temperature->getDoubleValue(), get_Altitude(), FGAtmosphere::eCelsius); Atmosphere->SetTemperature(temperature->getDoubleValue(), get_Altitude(), FGAtmosphere::eCelsius);
Atmosphere->SetPressureSL(FGAtmosphere::eInchesHg, pressureSL->getDoubleValue()); Atmosphere->SetPressureSL(FGAtmosphere::eInchesHg, pressureSL->getDoubleValue());
static_cast<FGStandardAtmosphere*>(Atmosphere)->SetDewPoint(FGAtmosphere::eCelsius, // static_cast<FGStandardAtmosphere*>(Atmosphere)->SetDewPoint(FGAtmosphere::eCelsius,
dew_point->getDoubleValue()); // dew_point->getDoubleValue());
Winds->SetTurbType((FGWinds::tType)TURBULENCE_TYPE_NAMES[turbulence_model->getStringValue()]); Winds->SetTurbType((FGWinds::tType)TURBULENCE_TYPE_NAMES[turbulence_model->getStringValue()]);
switch( Winds->GetTurbType() ) { switch( Winds->GetTurbType() ) {

32
src/FDM/JSBSim/models/atmosphere/FGStandardAtmosphere.cpp
View file

@ -254,36 +254,12 @@ double FGStandardAtmosphere::GetTemperature(double altitude) const
double FGStandardAtmosphere::GetStdTemperature(double altitude) const double FGStandardAtmosphere::GetStdTemperature(double altitude) const
{ {
double Lk9 = 0.00658368; // deg R per foot double GeoPotAlt = GeopotentialAltitude(altitude);
double Tinf = 1800.0; // Same as 1000 Kelvin
double temp = Tinf;
if (altitude < 298556.4) { // 91 km - station 8 if (GeoPotAlt >= 0.0)
return StdAtmosTemperatureTable.GetValue(GeoPotAlt);
double GeoPotAlt = GeopotentialAltitude(altitude); return StdAtmosTemperatureTable.GetValue(0.0) + GeoPotAlt*LapseRates[0];
if (GeoPotAlt >= 0.0)
temp = StdAtmosTemperatureTable.GetValue(GeoPotAlt);
else
temp = StdAtmosTemperatureTable.GetValue(0.0) + GeoPotAlt*LapseRates[0];
} else if (altitude < 360892.4) { // 110 km - station 9
temp = 473.7429 - 137.38176 * sqrt(1.0 - pow((altitude - 298556.4)/65429.462, 2.0));
} else if (altitude < 393700.8) { // 120 km - station 10
temp = 432 + Lk9 * (altitude - 360892.4);
} else if (altitude < 3280839.9) { // 1000 km station 12
double lambda = 0.00001870364;
double eps = (altitude - 393700.8) * (20855531.5 + 393700.8) / (20855531.5 + altitude);
temp = Tinf - (Tinf - 648.0) * exp(-lambda*eps);
}
return temp;
} }
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