FGGasCell.h

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/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 Header:       FGGasCell.h
 Author:       Anders Gidenstam
 Date started: 01/21/2006
 
 ----- Copyright (C) 2006 - 2013  Anders Gidenstam (anders(at)gidenstam.org) --
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU Lesser General Public License as published by the Free Software
 Foundation; either version 2 of the License, or (at your option) any later
 version.
 
 This program is distributed in the hope that it will be useful, but WITHOUT
 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
 details.
 
 You should have received a copy of the GNU Lesser General Public License along with
 this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 Place - Suite 330, Boston, MA  02111-1307, USA.
 
 Further information about the GNU Lesser General Public License can also be found on
 the world wide web at http://www.gnu.org.
 
FUNCTIONAL DESCRIPTION
--------------------------------------------------------------------------------
 
This class simulates a generic gas cell for static buoyancy.
 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
SENTRY
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
#ifndef FGGASCELL_H
#define FGGASCELL_H
 
/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
INCLUDES
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
#include "FGJSBBase.h"
#include "math/FGColumnVector3.h"
#include "models/propulsion/FGForce.h"
#include "math/FGFunction.h"
 
#include <string>
 
/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
FORWARD DECLARATIONS
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
namespace JSBSim {
 
class FGBallonet;
class FGMassBalance;
 
/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
CLASS DOCUMENTATION
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/

 
/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
CLASS DECLARATION
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
class FGGasCell : public FGForce
{
public:
  struct Inputs {
    double Pressure;
    double Temperature;
    double Density;
    double gravity;
  };

  FGGasCell(FGFDMExec* exec, Element* el, unsigned int num,
            const struct Inputs& input);
  ~FGGasCell();

  void Calculate(double dt);

  int GetIndex(void) const {return CellNum;}

  const FGColumnVector3& GetXYZ(void) const {return vXYZ;}

  double GetXYZ(int idx) const {return vXYZ(idx);}

  double GetMass(void) const {return Mass;}

  const FGMatrix33& GetInertia(void) const {return gasCellJ;}

  const FGColumnVector3& GetMassMoment(void) const {return gasCellM;}

  double GetTemperature(void) const {return Temperature;}

  double GetPressure(void) const {return Pressure;}
 
  const struct Inputs& in;
 
private:
 
  enum GasType {ttUNKNOWN, ttHYDROGEN, ttHELIUM, ttAIR};
 
  GasType Type;
  std::string type;
  unsigned int CellNum;
  // Structural constants
  double MaxVolume;                 // [ft^3]
  double MaxOverpressure;           // [lbs/ft^2]
  FGColumnVector3 vXYZ;             // [in]
  double Xradius, Yradius, Zradius; // [ft]
  double Xwidth, Ywidth, Zwidth;    // [ft]
  double ValveCoefficient;          // [ft^4 sec / slug]
  typedef std::vector <FGFunction*> CoeffArray;
  CoeffArray HeatTransferCoeff;
  typedef std::vector <FGBallonet*> BallonetArray;
  BallonetArray Ballonet;
  // Variables
  double Pressure;          // [lbs/ft^2]
  double Contents;          // [mol]
  double Volume;            // [ft^3]
  double dVolumeIdeal;      // [ft^3]
  double Temperature;       // [Rankine]
  double Buoyancy;          // [lbs] Note: Gross lift.
                            // Does not include the weight of the gas itself.
  double ValveOpen;         // 0 <= ValveOpen <= 1 (or higher).
  double Mass;              // [slug]
  FGMatrix33 gasCellJ;      // [slug foot^2]
  FGColumnVector3 gasCellM; // [lbs in]
 
  FGMassBalance* MassBalance;
  void Debug(int from);
 
  /* Constants. */
  const static double R;          // [lbs ft/(mol Rankine)]
  const static double M_air;      // [slug/mol]
  const static double M_hydrogen; // [slug/mol]
  const static double M_helium;   // [slug/mol]
 
  double M_gas() {                // [slug/mol]
    switch (Type) {
    case ttHYDROGEN:
      return M_hydrogen;
    case ttHELIUM:
      return M_helium;
    case ttAIR:
      return M_air;
    default:
      return M_air;
    }
  }
 
  double Cv_gas() {               // [??]
    switch (Type) {
    case ttHYDROGEN:
      return 5.0/2.0;
    case ttHELIUM:
      return 3.0/2.0;
    case ttAIR:
      return 5.0/2.0;
    default:
      return 5.0/2.0;
    }
  }
 
};
 
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
class FGBallonet : public FGJSBBase
{
public:
  FGBallonet(FGFDMExec* exec, Element* el, unsigned int num, FGGasCell* parent,
             const struct FGGasCell::Inputs& input);
  ~FGBallonet();

  void Calculate(double dt);
 

  const FGColumnVector3& GetXYZ(void) const {return vXYZ;}
  double GetXYZ(int idx) const {return vXYZ(idx);}

  double GetMass(void) const {return Contents * M_air;}

  const FGMatrix33& GetInertia(void) const {return ballonetJ;}

  double GetVolume(void) const {return Volume;}
  double GetHeatFlow(void) const {return dU;}       // [lbs ft / sec]
 
  const struct FGGasCell::Inputs& in;
 
private:
  unsigned int CellNum;
  // Structural constants
  double MaxVolume;                 // [ft^3]
  double MaxOverpressure;           // [lbs/ft^2]
  FGColumnVector3 vXYZ;             // [in]
  double Xradius, Yradius, Zradius; // [ft]
  double Xwidth, Ywidth, Zwidth;    // [ft]
  double ValveCoefficient;          // [ft^4 sec / slug]
  typedef std::vector <FGFunction*> CoeffArray;
  CoeffArray HeatTransferCoeff;     // [lbs ft / sec]
  FGFunction* BlowerInput;          // [ft^3 / sec]
  FGGasCell* Parent;
  // Variables
  double Pressure;         // [lbs/ft^2]
  double Contents;         // [mol]
  double Volume;           // [ft^3]
  double dVolumeIdeal;     // [ft^3]
  double dU;               // [lbs ft / sec]
  double Temperature;      // [Rankine]
  double ValveOpen;        // 0 <= ValveOpen <= 1 (or higher).
  FGMatrix33 ballonetJ;     // [slug foot^2]
 
  FGMassBalance* MassBalance;
  void Debug(int from);
 
  /* Constants. */
  const static double R;          // [lbs ft/(mol Rankine)]
  const static double M_air;      // [slug/mol]
  const static double Cv_air;     // [??]
};
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
#endif