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1 : : /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2 : :
3 : : Header: FGGasCell.h
4 : : Author: Anders Gidenstam
5 : : Date started: 01/21/2006
6 : :
7 : : ----- Copyright (C) 2006 - 2008 Anders Gidenstam (anders(at)gidenstam.org) --
8 : :
9 : : This program is free software; you can redistribute it and/or modify it under
10 : : the terms of the GNU Lesser General Public License as published by the Free Software
11 : : Foundation; either version 2 of the License, or (at your option) any later
12 : : version.
13 : :
14 : : This program is distributed in the hope that it will be useful, but WITHOUT
15 : : ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
16 : : FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
17 : : details.
18 : :
19 : : You should have received a copy of the GNU Lesser General Public License along with
20 : : this program; if not, write to the Free Software Foundation, Inc., 59 Temple
21 : : Place - Suite 330, Boston, MA 02111-1307, USA.
22 : :
23 : : Further information about the GNU Lesser General Public License can also be found on
24 : : the world wide web at http://www.gnu.org.
25 : :
26 : : FUNCTIONAL DESCRIPTION
27 : : --------------------------------------------------------------------------------
28 : :
29 : : This class simulates a generic gas cell for static buoyancy.
30 : :
31 : : %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
32 : : SENTRY
33 : : %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
34 : :
35 : : #ifndef FGGasCell_H
36 : : #define FGGasCell_H
37 : :
38 : : /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
39 : : INCLUDES
40 : : %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
41 : :
42 : : #include "FGJSBBase.h"
43 : : #include "math/FGColumnVector3.h"
44 : : #include "models/propulsion/FGForce.h"
45 : : #include "math/FGFunction.h"
46 : :
47 : : #include <string>
48 : :
49 : : /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
50 : : DEFINITIONS
51 : : %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
52 : :
53 : : #define ID_GASCELL "$Id: FGGasCell.h,v 1.10 2009/10/24 22:59:30 jberndt Exp $"
54 : :
55 : : /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
56 : : FORWARD DECLARATIONS
57 : : %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
58 : :
59 : : namespace JSBSim {
60 : :
61 : : class FGBallonet;
62 : : class Element;
63 : :
64 : : /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
65 : : CLASS DOCUMENTATION
66 : : %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
67 : :
68 : : /** Models a gas cell.
69 : : @author Anders Gidenstam
70 : :
71 : : <h3>Configuration File Format:</h3>
72 : : @code
73 : : <buoyant_forces>
74 : : <gas_cell type="{HYDROGEN | HELIUM | AIR}">
75 : : <location unit="{M | IN}">
76 : : <x> {number} </x>
77 : : <y> {number} </y>
78 : : <z> {number} </z>
79 : : </location>
80 : : <x_width unit="{M | IN}"> {number} </x_width>
81 : : <y_radius unit="{M | IN}"> {number} </y_radius>
82 : : <z_radius unit="{M | IN}"> {number} </z_radius>
83 : : <max_overpressure unit="{PA | PSI}"> {number} </max_overpressure>
84 : : <valve_coefficient unit="{M4*SEC/KG | FT4*SEC/SLUG}"> {number} </valve_coefficient>
85 : : <fullness> {number} </fullness>
86 : : <heat>
87 : : {heat transfer coefficients} [lbs ft / sec]
88 : : </heat>
89 : : <ballonet>
90 : : <location unit="{M | IN}">
91 : : <x> {number} </x>
92 : : <y> {number} </y>
93 : : <z> {number} </z>
94 : : </location>
95 : : <x_width unit="{M | IN}"> {number} </x_width>
96 : : <y_radius unit="{M | IN}"> {number} </y_radius>
97 : : <z_radius unit="{M | IN}"> {number} </z_radius>
98 : : <max_overpressure unit="{PA | PSI}"> {number} </max_overpressure>
99 : : <valve_coefficient unit="{M4*SEC/KG | FT4*SEC/SLUG}"> {number} </valve_coefficient>
100 : : <fullness> {number} </fullness>
101 : : <heat>
102 : : {heat transfer coefficients} [lb ft / (sec Rankine)]
103 : : </heat>
104 : : <blower_input>
105 : : {input air flow function} [ft^3 / sec]
106 : : </blower_input>
107 : : </ballonet>
108 : : </gas_cell>
109 : : </buoyant_forces>
110 : : @endcode
111 : :
112 : : Definition of the gas cell configuration file parameters:
113 : : - <b>type</b> -
114 : : One of HYDROGEN, HELIUM or AIR.
115 : : - <b>location</b> -
116 : : Location of cell center in the aircraft's structural frame.
117 : : Currently this is were the forces of the cell is applied.
118 : : - <b>{x|y|z}_radius</b> -
119 : : Radius along in the respective direction (both ends).
120 : : - <b>{x|y|z}_width</b> -
121 : : Width in the respective direction.
122 : : <b>NOTE:</b> A 'x', 'y', 'z'-radius/width combination must be specified.
123 : : - <b>fullness</b> -
124 : : Initial fullness of the cell, normally [0,1],
125 : : values >1 initialize the cell at pressure.
126 : : - <b>max_overpressure</b> -
127 : : Maximum cell overpressure (excess is automatically valved off).
128 : : - <b>valve_coefficient</b> -
129 : : Capacity of the manual valve. The valve is
130 : : considered to be located at the top of the cell.
131 : : The valve coefficient determine the flow out
132 : : of the cell according to:
133 : : <i>dVolume/dt = ValveCoefficient * DeltaPressure</i>.
134 : : - <b>heat</b> -
135 : : Zero or more FGFunction:s describing the heat flow from
136 : : the atmosphere into the gas cell.
137 : : Unit: [lb ft / (sec Rankine)].
138 : : If there are no heat transfer functions at all the gas cell
139 : : temperature will equal that of the surrounding atmosphere.
140 : : A constant function returning 0 results in adiabatic behaviour.
141 : : - <b>ballonet</b> -
142 : : Zero or more ballonets, i.e. air bags inside the gas cell.
143 : : Ballonets are used to maintain the volume of the gas cell
144 : : and keep its internal pressure higher than that of the
145 : : surrounding environment.
146 : : - <b>location</b> -
147 : : Location of ballonet center in the aircraft's structural frame.
148 : : - <b>{x|y|z}_radius</b> -
149 : : Radius along in the respective direction (both ends).
150 : : - <b>{x|y|z}_width</b> -
151 : : Width in the respective direction.
152 : : - <b>max_overpressure</b> -
153 : : Maximum ballonet overpressure (excess is automatically valved off).
154 : : - <b>valve_coefficient</b> -
155 : : Capacity of the exit valve between the ballonet
156 : : and the atmosphere. The valve coefficient
157 : : determine the flow out of the cell according to:
158 : : <i>dVolume/dt = ValveCoefficient * DeltaPressure</i>.
159 : : - <b>heat</b> -
160 : : Zero or more FGFunction:s describing the heat flow from
161 : : the enclosing gas cell into the ballonet.
162 : : Unit: [lb ft / (sec Rankine)]
163 : : - <b>blower_input</b> -
164 : : One FGFunction describing the air flow into the
165 : : ballonet. Unit: [ft<sup>3</sup> / sec] (at the temperature and
166 : : pressure of the ballonet.)
167 : : */
168 : :
169 : : /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
170 : : CLASS DECLARATION
171 : : %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
172 : : class FGGasCell : public FGForce
173 : : {
174 : : public:
175 : : /** Constructor
176 : : @param exec Executive a pointer to the parent executive object
177 : : @param el Pointer to configuration file XML node
178 : : @param num Gas cell index number. */
179 : : FGGasCell(FGFDMExec* exec, Element* el, int num);
180 : : ~FGGasCell();
181 : :
182 : : /** Runs the gas cell model; called by BuoyantForces
183 : : */
184 : : void Calculate(double dt);
185 : :
186 : : /** Get the index of this gas cell
187 : : @return gas cell index. */
188 : 0 : int GetIndex(void) const {return CellNum;}
189 : :
190 : : /** Get the center of gravity location of the gas cell
191 : : (including any ballonets)
192 : : @return CoG location in the structural frame. */
193 : 0 : const FGColumnVector3& GetXYZ(void) const {return vXYZ;}
194 : :
195 : : /** Get the center of gravity location of the gas cell
196 : : (including any ballonets)
197 : : @return CoG location in the structural frame. */
198 : 0 : double GetXYZ(int idx) const {return vXYZ(idx);}
199 : :
200 : : /** Get the current mass of the gas cell (including any ballonets)
201 : : @return gas mass in slug. */
202 : 0 : double GetMass(void) const {return Mass;}
203 : :
204 : : /** Get the moments of inertia of the gas cell (including any ballonets)
205 : : @return moments of inertia matrix relative the gas cell location
206 : : in slug ft<sup>2</sup>. */
207 : 0 : const FGMatrix33& GetInertia(void) const {return gasCellJ;}
208 : :
209 : : /** Get the moment due to mass of the gas cell (including any ballonets)
210 : :
211 : : Note that the buoyancy of the gas cell is handled separately by the
212 : : FGForce part and not included here.
213 : : @return moment vector in lbs ft. */
214 : 0 : const FGColumnVector3& GetMassMoment(void) const {return gasCellM;}
215 : :
216 : : /** Get the current gas temperature inside the gas cell
217 : : @return gas temperature in Rankine. */
218 : 0 : double GetTemperature(void) const {return Temperature;}
219 : :
220 : : /** Get the current gas pressure inside the gas cell
221 : : @return gas pressure in lbs / ft<sup>2</sup>. */
222 : 0 : double GetPressure(void) const {return Pressure;}
223 : :
224 : : private:
225 : :
226 : : enum GasType {ttUNKNOWN, ttHYDROGEN, ttHELIUM, ttAIR};
227 : :
228 : : GasType Type;
229 : : std::string type;
230 : : int CellNum;
231 : : // Structural constants
232 : : double MaxVolume; // [ft�]
233 : : double MaxOverpressure; // [lbs/ft�]
234 : : FGColumnVector3 vXYZ; // [in]
235 : : double Xradius, Yradius, Zradius; // [ft]
236 : : double Xwidth, Ywidth, Zwidth; // [ft]
237 : : double ValveCoefficient; // [ft^4 sec / slug]
238 : : typedef vector <FGFunction*> CoeffArray;
239 : : CoeffArray HeatTransferCoeff;
240 : : typedef vector <FGBallonet*> BallonetArray;
241 : : BallonetArray Ballonet;
242 : : // Variables
243 : : double Pressure; // [lbs/ft�]
244 : : double Contents; // [mol]
245 : : double Volume; // [ft�]
246 : : double dVolumeIdeal; // [ft�]
247 : : double Temperature; // [Rankine]
248 : : double Buoyancy; // [lbs] Note: Gross lift.
249 : : // Does not include the weight of the gas itself.
250 : : double ValveOpen; // 0 <= ValveOpen <= 1 (or higher).
251 : : double Mass; // [slug]
252 : : FGMatrix33 gasCellJ; // [slug foot�]
253 : : FGColumnVector3 gasCellM; // [lbs ft]
254 : :
255 : : FGAuxiliary* Auxiliary;
256 : : FGAtmosphere* Atmosphere;
257 : : FGPropertyManager* PropertyManager;
258 : : FGInertial* Inertial;
259 : : FGMassBalance* MassBalance;
260 : : void Debug(int from);
261 : :
262 : : /* Constants. */
263 : : const static double R; // [lbs ft/(mol Rankine)]
264 : : const static double M_air; // [slug/mol]
265 : : const static double M_hydrogen; // [slug/mol]
266 : : const static double M_helium; // [slug/mol]
267 : :
268 : : double M_gas() { // [slug/mol]
269 [ # # # # : 0 : switch (Type) {
# # # # ]
[ # # # # ]
[ # # # # ]
270 : : case ttHYDROGEN:
271 : 0 : return M_hydrogen;
272 : : case ttHELIUM:
273 : 0 : return M_helium;
274 : : case ttAIR:
275 : 0 : return M_air;
276 : : default:
277 : 0 : return M_air;
278 : : }
279 : : }
280 : :
281 : : double Cv_gas() { // [??]
282 [ # # # # ]: 0 : switch (Type) {
283 : : case ttHYDROGEN:
284 : 0 : return 5.0/2.0;
285 : : case ttHELIUM:
286 : 0 : return 3.0/2.0;
287 : : case ttAIR:
288 : 0 : return 5.0/2.0;
289 : : default:
290 : 0 : return 5.0/2.0;
291 : : }
292 : : }
293 : :
294 : : };
295 : :
296 : : //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
297 : : /** Models a ballonet inside a gas cell.
298 : : Models a ballonet inside a gas cell.
299 : : Not intended to be used outside FGGasCell.
300 : : See FGGasCell for the configuration file format.
301 : : @author Anders Gidenstam
302 : : */
303 : : class FGBallonet : public FGJSBBase
304 : : {
305 : : public:
306 : : FGBallonet(FGFDMExec* exec, Element* el, int num, FGGasCell* parent);
307 : : ~FGBallonet();
308 : :
309 : : /** Runs the ballonet model; called by FGGasCell
310 : : */
311 : : void Calculate(double dt);
312 : :
313 : :
314 : : /** Get the center of gravity location of the ballonet
315 : : @return CoG location in the structural frame. */
316 : 0 : const FGColumnVector3& GetXYZ(void) const {return vXYZ;}
317 : : /** Get the center of gravity location of the ballonet
318 : : @return CoG location in the structural frame. */
319 : 0 : double GetXYZ(int idx) const {return vXYZ(idx);}
320 : :
321 : : /** Get the current mass of the ballonets
322 : : @return mass in slug. */
323 : 0 : double GetMass(void) const {return Contents * M_air;}
324 : :
325 : : /** Get the moments of inertia of the ballonet
326 : : @return moments of inertia matrix in slug ft<sup>2</sup>. */
327 : 0 : const FGMatrix33& GetInertia(void) const {return ballonetJ;}
328 : :
329 : : /** Get the current volume of the ballonet
330 : : @return volume in ft<sup>3</sup>. */
331 : 0 : double GetVolume(void) const {return Volume;}
332 : : /** Get the current heat flow into the ballonet
333 : : @return heat flow in lbs ft / sec. */
334 : 0 : double GetHeatFlow(void) const {return dU;} // [lbs ft / sec]
335 : :
336 : : private:
337 : : int CellNum;
338 : : // Structural constants
339 : : double MaxVolume; // [ft�]
340 : : double MaxOverpressure; // [lbs/ft�]
341 : : FGColumnVector3 vXYZ; // [in]
342 : : double Xradius, Yradius, Zradius; // [ft]
343 : : double Xwidth, Ywidth, Zwidth; // [ft]
344 : : double ValveCoefficient; // [ft^4 sec / slug]
345 : : typedef vector <FGFunction*> CoeffArray;
346 : : CoeffArray HeatTransferCoeff; // [lbs ft / sec]
347 : : FGFunction* BlowerInput; // [ft^3 / sec]
348 : : FGGasCell* Parent;
349 : : // Variables
350 : : double Pressure; // [lbs/ft�]
351 : : double Contents; // [mol]
352 : : double Volume; // [ft�]
353 : : double dVolumeIdeal; // [ft�]
354 : : double dU; // [lbs ft / sec]
355 : : double Temperature; // [Rankine]
356 : : double ValveOpen; // 0 <= ValveOpen <= 1 (or higher).
357 : : FGMatrix33 ballonetJ; // [slug foot�]
358 : :
359 : : FGAuxiliary* Auxiliary;
360 : : FGAtmosphere* Atmosphere;
361 : : FGPropertyManager* PropertyManager;
362 : : FGInertial* Inertial;
363 : : void Debug(int from);
364 : :
365 : : /* Constants. */
366 : : const static double R; // [lbs ft/(mol Rankine)]
367 : : const static double M_air; // [slug/mol]
368 : : const static double Cv_air; // [??]
369 : : };
370 : : }
371 : : //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
372 : : #endif
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