Branch data Line data Source code
1 : : /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2 : :
3 : : Module: FGPiston.cpp
4 : : Author: Jon S. Berndt, JSBSim framework
5 : : Dave Luff, Piston engine model
6 : : Ronald Jensen, Piston engine model
7 : : Date started: 09/12/2000
8 : : Purpose: This module models a Piston engine
9 : :
10 : : ------------- Copyright (C) 2000 Jon S. Berndt (jon@jsbsim.org) --------------
11 : :
12 : : This program is free software; you can redistribute it and/or modify it under
13 : : the terms of the GNU Lesser General Public License as published by the Free Software
14 : : Foundation; either version 2 of the License, or (at your option) any later
15 : : version.
16 : :
17 : : This program is distributed in the hope that it will be useful, but WITHOUT
18 : : ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
19 : : FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
20 : : details.
21 : :
22 : : You should have received a copy of the GNU Lesser General Public License along with
23 : : this program; if not, write to the Free Software Foundation, Inc., 59 Temple
24 : : Place - Suite 330, Boston, MA 02111-1307, USA.
25 : :
26 : : Further information about the GNU Lesser General Public License can also be found on
27 : : the world wide web at http://www.gnu.org.
28 : :
29 : : FUNCTIONAL DESCRIPTION
30 : : --------------------------------------------------------------------------------
31 : :
32 : : This class descends from the FGEngine class and models a Piston engine based on
33 : : parameters given in the engine config file for this class
34 : :
35 : : HISTORY
36 : : --------------------------------------------------------------------------------
37 : : 09/12/2000 JSB Created
38 : :
39 : : %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
40 : : INCLUDES
41 : : %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
42 : :
43 : : #include <sstream>
44 : :
45 : : #include "FGPiston.h"
46 : : #include "models/FGAtmosphere.h"
47 : : #include "models/FGAuxiliary.h"
48 : : #include "models/FGPropulsion.h"
49 : : #include "FGPropeller.h"
50 : : #include <iostream>
51 : :
52 : : using namespace std;
53 : :
54 : : namespace JSBSim {
55 : :
56 : : static const char *IdSrc = "$Id: FGPiston.cpp,v 1.53 2010/08/21 17:13:48 jberndt Exp $";
57 : : static const char *IdHdr = ID_PISTON;
58 : :
59 : : /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
60 : : CLASS IMPLEMENTATION
61 : : %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
62 : :
63 : 0 : FGPiston::FGPiston(FGFDMExec* exec, Element* el, int engine_number)
64 : : : FGEngine(exec, el, engine_number),
65 : : R_air(287.3), // Gas constant for air J/Kg/K
66 : : rho_fuel(800), // estimate
67 : : calorific_value_fuel(47.3e6),
68 : : Cp_air(1005), // Specific heat (constant pressure) J/Kg/K
69 : : Cp_fuel(1700),
70 : 0 : standard_pressure(101320.73)
71 : : {
72 : 0 : string token;
73 : :
74 : : // Defaults and initializations
75 : :
76 : 0 : Type = etPiston;
77 : 0 : dt = FDMExec->GetDeltaT();
78 : :
79 : : // These items are read from the configuration file
80 : : // Defaults are from a Lycoming O-360, more or less
81 : :
82 : 0 : Cycles = 4;
83 : 0 : IdleRPM = 600;
84 : 0 : MaxRPM = 2800;
85 : 0 : Displacement = 360;
86 : 0 : SparkFailDrop = 1.0;
87 : 0 : MaxHP = 200;
88 : 0 : MinManifoldPressure_inHg = 6.5;
89 : 0 : MaxManifoldPressure_inHg = 28.5;
90 : 0 : ISFC = -1;
91 : 0 : volumetric_efficiency = 0.85;
92 : 0 : Bore = 5.125;
93 : 0 : Stroke = 4.375;
94 : 0 : Cylinders = 4;
95 : 0 : CompressionRatio = 8.5;
96 : 0 : Z_airbox = -999;
97 : 0 : Ram_Air_Factor = 1;
98 : 0 : PeakMeanPistonSpeed_fps = 100;
99 : 0 : FMEPDynamic= 18400;
100 : 0 : FMEPStatic = 46500;
101 : :
102 : :
103 : : // These are internal program variables
104 : :
105 : 0 : crank_counter = 0;
106 : 0 : Magnetos = 0;
107 : 0 : minMAP = 21950;
108 : 0 : maxMAP = 96250;
109 : :
110 : 0 : ResetToIC();
111 : :
112 : : // Supercharging
113 : 0 : BoostSpeeds = 0; // Default to no supercharging
114 : 0 : BoostSpeed = 0;
115 : 0 : Boosted = false;
116 : 0 : BoostOverride = 0;
117 : 0 : BoostManual = 0;
118 : 0 : bBoostOverride = false;
119 : 0 : bTakeoffBoost = false;
120 : 0 : TakeoffBoost = 0.0; // Default to no extra takeoff-boost
121 : : int i;
122 [ # # ][ # # ]: 0 : for (i=0; i<FG_MAX_BOOST_SPEEDS; i++) {
123 : 0 : RatedBoost[i] = 0.0;
124 : 0 : RatedPower[i] = 0.0;
125 : 0 : RatedAltitude[i] = 0.0;
126 : 0 : BoostMul[i] = 1.0;
127 : 0 : RatedMAP[i] = 100000;
128 : 0 : RatedRPM[i] = 2500;
129 : 0 : TakeoffMAP[i] = 100000;
130 : : }
131 [ # # ][ # # ]: 0 : for (i=0; i<FG_MAX_BOOST_SPEEDS-1; i++) {
132 : 0 : BoostSwitchAltitude[i] = 0.0;
133 : 0 : BoostSwitchPressure[i] = 0.0;
134 : : }
135 : :
136 : : // First column is thi, second is neta (combustion efficiency)
137 : 0 : Lookup_Combustion_Efficiency = new FGTable(12);
138 : 0 : *Lookup_Combustion_Efficiency << 0.00 << 0.980;
139 : 0 : *Lookup_Combustion_Efficiency << 0.90 << 0.980;
140 : 0 : *Lookup_Combustion_Efficiency << 1.00 << 0.970;
141 : 0 : *Lookup_Combustion_Efficiency << 1.05 << 0.950;
142 : 0 : *Lookup_Combustion_Efficiency << 1.10 << 0.900;
143 : 0 : *Lookup_Combustion_Efficiency << 1.15 << 0.850;
144 : 0 : *Lookup_Combustion_Efficiency << 1.20 << 0.790;
145 : 0 : *Lookup_Combustion_Efficiency << 1.30 << 0.700;
146 : 0 : *Lookup_Combustion_Efficiency << 1.40 << 0.630;
147 : 0 : *Lookup_Combustion_Efficiency << 1.50 << 0.570;
148 : 0 : *Lookup_Combustion_Efficiency << 1.60 << 0.525;
149 : 0 : *Lookup_Combustion_Efficiency << 2.00 << 0.345;
150 : :
151 : 0 : Mixture_Efficiency_Correlation = new FGTable(15);
152 : 0 : *Mixture_Efficiency_Correlation << 0.05000 << 0.00000;
153 : 0 : *Mixture_Efficiency_Correlation << 0.05137 << 0.00862;
154 : 0 : *Mixture_Efficiency_Correlation << 0.05179 << 0.21552;
155 : 0 : *Mixture_Efficiency_Correlation << 0.05430 << 0.48276;
156 : 0 : *Mixture_Efficiency_Correlation << 0.05842 << 0.70690;
157 : 0 : *Mixture_Efficiency_Correlation << 0.06312 << 0.83621;
158 : 0 : *Mixture_Efficiency_Correlation << 0.06942 << 0.93103;
159 : 0 : *Mixture_Efficiency_Correlation << 0.07786 << 1.00000;
160 : 0 : *Mixture_Efficiency_Correlation << 0.08845 << 1.00000;
161 : 0 : *Mixture_Efficiency_Correlation << 0.09270 << 0.98276;
162 : 0 : *Mixture_Efficiency_Correlation << 0.10120 << 0.93103;
163 : 0 : *Mixture_Efficiency_Correlation << 0.11455 << 0.72414;
164 : 0 : *Mixture_Efficiency_Correlation << 0.12158 << 0.45690;
165 : 0 : *Mixture_Efficiency_Correlation << 0.12435 << 0.23276;
166 : 0 : *Mixture_Efficiency_Correlation << 0.12500 << 0.00000;
167 : :
168 : :
169 : : // Read inputs from engine data file where present.
170 : :
171 [ # # ][ # # ]: 0 : if (el->FindElement("minmp")) // Should have ELSE statement telling default value used?
172 : 0 : MinManifoldPressure_inHg = el->FindElementValueAsNumberConvertTo("minmp","INHG");
173 [ # # ][ # # ]: 0 : if (el->FindElement("maxmp"))
174 : 0 : MaxManifoldPressure_inHg = el->FindElementValueAsNumberConvertTo("maxmp","INHG");
175 [ # # ][ # # ]: 0 : if (el->FindElement("displacement"))
176 : 0 : Displacement = el->FindElementValueAsNumberConvertTo("displacement","IN3");
177 [ # # ][ # # ]: 0 : if (el->FindElement("maxhp"))
178 : 0 : MaxHP = el->FindElementValueAsNumberConvertTo("maxhp","HP");
179 [ # # ][ # # ]: 0 : if (el->FindElement("sparkfaildrop"))
180 : 0 : SparkFailDrop = Constrain(0, 1 - el->FindElementValueAsNumber("sparkfaildrop"), 1);
181 [ # # ][ # # ]: 0 : if (el->FindElement("cycles"))
182 : 0 : Cycles = el->FindElementValueAsNumber("cycles");
183 [ # # ][ # # ]: 0 : if (el->FindElement("idlerpm"))
184 : 0 : IdleRPM = el->FindElementValueAsNumber("idlerpm");
185 [ # # ][ # # ]: 0 : if (el->FindElement("maxrpm"))
186 : 0 : MaxRPM = el->FindElementValueAsNumber("maxrpm");
187 [ # # ][ # # ]: 0 : if (el->FindElement("maxthrottle"))
188 : 0 : MaxThrottle = el->FindElementValueAsNumber("maxthrottle");
189 [ # # ][ # # ]: 0 : if (el->FindElement("minthrottle"))
190 : 0 : MinThrottle = el->FindElementValueAsNumber("minthrottle");
191 [ # # ][ # # ]: 0 : if (el->FindElement("bsfc"))
192 : 0 : ISFC = el->FindElementValueAsNumberConvertTo("bsfc", "LBS/HP*HR");
193 [ # # ][ # # ]: 0 : if (el->FindElement("volumetric-efficiency"))
194 : 0 : volumetric_efficiency = el->FindElementValueAsNumber("volumetric-efficiency");
195 [ # # ][ # # ]: 0 : if (el->FindElement("compression-ratio"))
196 : 0 : CompressionRatio = el->FindElementValueAsNumber("compression-ratio");
197 [ # # ][ # # ]: 0 : if (el->FindElement("bore"))
198 : 0 : Bore = el->FindElementValueAsNumberConvertTo("bore","IN");
199 [ # # ][ # # ]: 0 : if (el->FindElement("stroke"))
200 : 0 : Stroke = el->FindElementValueAsNumberConvertTo("stroke","IN");
201 [ # # ][ # # ]: 0 : if (el->FindElement("cylinders"))
202 : 0 : Cylinders = el->FindElementValueAsNumber("cylinders");
203 [ # # ][ # # ]: 0 : if (el->FindElement("air-intake-impedance-factor"))
204 : 0 : Z_airbox = el->FindElementValueAsNumber("air-intake-impedance-factor");
205 [ # # ][ # # ]: 0 : if (el->FindElement("ram-air-factor"))
206 : 0 : Ram_Air_Factor = el->FindElementValueAsNumber("ram-air-factor");
207 [ # # ][ # # ]: 0 : if (el->FindElement("dynamic-fmep"))
208 : 0 : FMEPDynamic= el->FindElementValueAsNumberConvertTo("dynamic-fmep","PA");
209 [ # # ][ # # ]: 0 : if (el->FindElement("static-fmep"))
210 : 0 : FMEPStatic = el->FindElementValueAsNumberConvertTo("static-fmep","PA");
211 [ # # ][ # # ]: 0 : if (el->FindElement("peak-piston-speed"))
212 : 0 : PeakMeanPistonSpeed_fps = el->FindElementValueAsNumber("peak-piston-speed");
213 [ # # ][ # # ]: 0 : if (el->FindElement("numboostspeeds")) { // Turbo- and super-charging parameters
214 : 0 : BoostSpeeds = (int)el->FindElementValueAsNumber("numboostspeeds");
215 [ # # ][ # # ]: 0 : if (el->FindElement("boostoverride"))
216 : 0 : BoostOverride = (int)el->FindElementValueAsNumber("boostoverride");
217 [ # # ][ # # ]: 0 : if (el->FindElement("boostmanual"))
218 : 0 : BoostManual = (int)el->FindElementValueAsNumber("boostmanual");
219 [ # # ][ # # ]: 0 : if (el->FindElement("takeoffboost"))
220 : 0 : TakeoffBoost = el->FindElementValueAsNumberConvertTo("takeoffboost", "PSI");
221 [ # # ][ # # ]: 0 : if (el->FindElement("ratedboost1"))
222 : 0 : RatedBoost[0] = el->FindElementValueAsNumberConvertTo("ratedboost1", "PSI");
223 [ # # ][ # # ]: 0 : if (el->FindElement("ratedboost2"))
224 : 0 : RatedBoost[1] = el->FindElementValueAsNumberConvertTo("ratedboost2", "PSI");
225 [ # # ][ # # ]: 0 : if (el->FindElement("ratedboost3"))
226 : 0 : RatedBoost[2] = el->FindElementValueAsNumberConvertTo("ratedboost3", "PSI");
227 [ # # ][ # # ]: 0 : if (el->FindElement("ratedpower1"))
228 : 0 : RatedPower[0] = el->FindElementValueAsNumberConvertTo("ratedpower1", "HP");
229 [ # # ][ # # ]: 0 : if (el->FindElement("ratedpower2"))
230 : 0 : RatedPower[1] = el->FindElementValueAsNumberConvertTo("ratedpower2", "HP");
231 [ # # ][ # # ]: 0 : if (el->FindElement("ratedpower3"))
232 : 0 : RatedPower[2] = el->FindElementValueAsNumberConvertTo("ratedpower3", "HP");
233 [ # # ][ # # ]: 0 : if (el->FindElement("ratedrpm1"))
234 : 0 : RatedRPM[0] = el->FindElementValueAsNumber("ratedrpm1");
235 [ # # ][ # # ]: 0 : if (el->FindElement("ratedrpm2"))
236 : 0 : RatedRPM[1] = el->FindElementValueAsNumber("ratedrpm2");
237 [ # # ][ # # ]: 0 : if (el->FindElement("ratedrpm3"))
238 : 0 : RatedRPM[2] = el->FindElementValueAsNumber("ratedrpm3");
239 [ # # ][ # # ]: 0 : if (el->FindElement("ratedaltitude1"))
240 : 0 : RatedAltitude[0] = el->FindElementValueAsNumberConvertTo("ratedaltitude1", "FT");
241 [ # # ][ # # ]: 0 : if (el->FindElement("ratedaltitude2"))
242 : 0 : RatedAltitude[1] = el->FindElementValueAsNumberConvertTo("ratedaltitude2", "FT");
243 [ # # ][ # # ]: 0 : if (el->FindElement("ratedaltitude3"))
244 : 0 : RatedAltitude[2] = el->FindElementValueAsNumberConvertTo("ratedaltitude3", "FT");
245 : : }
246 : :
247 : 0 : StarterHP = sqrt(MaxHP) * 0.4;
248 : 0 : displacement_SI = Displacement * in3tom3;
249 : 0 : RatedMeanPistonSpeed_fps = ( MaxRPM * Stroke) / (360); // AKA 2 * (RPM/60) * ( Stroke / 12) or 2NS
250 : :
251 : : // Create IFSC to match the engine if not provided
252 [ # # # # ]: 0 : if (ISFC < 0) {
253 : 0 : double pmep = 29.92 - MaxManifoldPressure_inHg;
254 : 0 : pmep *= inhgtopa * volumetric_efficiency;
255 : 0 : double fmep = (FMEPDynamic * RatedMeanPistonSpeed_fps * fttom + FMEPStatic);
256 : 0 : double hp_loss = ((pmep + fmep) * displacement_SI * MaxRPM)/(Cycles*22371);
257 : 0 : ISFC = ( 1.1*Displacement * MaxRPM * volumetric_efficiency *(MaxManifoldPressure_inHg / 29.92) ) / (9411 * (MaxHP+hp_loss));
258 : : // cout <<"FMEP: "<< fmep <<" PMEP: "<< pmep << " hp_loss: " <<hp_loss <<endl;
259 : : }
260 [ # # ][ # # ]: 0 : if ( MaxManifoldPressure_inHg > 29.9 ) { // Don't allow boosting with a bogus number
261 : 0 : MaxManifoldPressure_inHg = 29.9;
262 : : }
263 : 0 : minMAP = MinManifoldPressure_inHg * inhgtopa; // inHg to Pa
264 : 0 : maxMAP = MaxManifoldPressure_inHg * inhgtopa;
265 : :
266 : : // For throttle
267 : : /*
268 : : * Pm = ( Ze / ( Ze + Zi + Zt ) ) * Pa
269 : : * Where:
270 : : * Pm = Manifold Pressure
271 : : * Pa = Ambient Pressre
272 : : * Ze = engine impedance, Ze is effectively 1 / Mean Piston Speed
273 : : * Zi = airbox impedance
274 : : * Zt = throttle impedance
275 : : *
276 : : * For the calculation below throttle is fully open or Zt = 0
277 : : *
278 : : *
279 : : *
280 : : */
281 : :
282 [ # # ][ # # ]: 0 : if(Z_airbox < 0.0){
283 : 0 : double Ze=PeakMeanPistonSpeed_fps/RatedMeanPistonSpeed_fps; // engine impedence
284 : 0 : Z_airbox = (standard_pressure *Ze / maxMAP) - Ze; // impedence of airbox
285 : : }
286 : : // Constant for Throttle impedence
287 : 0 : Z_throttle=(PeakMeanPistonSpeed_fps/((IdleRPM * Stroke) / 360))*(standard_pressure/minMAP - 1) - Z_airbox;
288 : : // Z_throttle=(MaxRPM/IdleRPM )*(standard_pressure/minMAP+2); // Constant for Throttle impedence
289 : :
290 : 0 : string property_name, base_property_name;
291 : 0 : base_property_name = CreateIndexedPropertyName("propulsion/engine", EngineNumber);
292 : 0 : property_name = base_property_name + "/power-hp";
293 : 0 : PropertyManager->Tie(property_name, &HP);
294 : 0 : property_name = base_property_name + "/bsfc-lbs_hphr";
295 : 0 : PropertyManager->Tie(property_name, &ISFC);
296 : 0 : property_name = base_property_name + "/volumetric-efficiency";
297 : 0 : PropertyManager->Tie(property_name, &volumetric_efficiency);
298 : 0 : property_name = base_property_name + "/map-pa";
299 : 0 : PropertyManager->Tie(property_name, &MAP);
300 : 0 : property_name = base_property_name + "/map-inhg";
301 : 0 : PropertyManager->Tie(property_name, &ManifoldPressure_inHg);
302 : 0 : property_name = base_property_name + "/air-intake-impedance-factor";
303 : 0 : PropertyManager->Tie(property_name, &Z_airbox);
304 : 0 : property_name = base_property_name + "/ram-air-factor";
305 : 0 : PropertyManager->Tie(property_name, &Ram_Air_Factor);
306 : 0 : property_name = base_property_name + "/boost-speed";
307 : 0 : PropertyManager->Tie(property_name, &BoostSpeed);
308 : :
309 : : // Set up and sanity-check the turbo/supercharging configuration based on the input values.
310 [ # # ][ # # ]: 0 : if (TakeoffBoost > RatedBoost[0]) bTakeoffBoost = true;
311 [ # # ][ # # ]: 0 : for (i=0; i<BoostSpeeds; ++i) {
312 : 0 : bool bad = false;
313 [ # # ][ # # ]: 0 : if (RatedBoost[i] <= 0.0) bad = true;
314 [ # # ][ # # ]: 0 : if (RatedPower[i] <= 0.0) bad = true;
315 [ # # ][ # # ]: 0 : if (RatedAltitude[i] < 0.0) bad = true; // 0.0 is deliberately allowed - this corresponds to unregulated supercharging.
316 [ # # ][ # # ]: 0 : if (i > 0 && RatedAltitude[i] < RatedAltitude[i - 1]) bad = true;
[ # # ][ # # ]
317 [ # # ][ # # ]: 0 : if (bad) {
318 : : // We can't recover from the above - don't use this supercharger speed.
319 : 0 : BoostSpeeds--;
320 : : // TODO - put out a massive error message!
321 : 0 : break;
322 : : }
323 : : // Now sanity-check stuff that is recoverable.
324 [ # # ][ # # ]: 0 : if (i < BoostSpeeds - 1) {
325 [ # # ][ # # ]: 0 : if (BoostSwitchAltitude[i] < RatedAltitude[i]) {
326 : : // TODO - put out an error message
327 : : // But we can also make a reasonable estimate, as below.
328 : 0 : BoostSwitchAltitude[i] = RatedAltitude[i] + 1000;
329 : : }
330 : 0 : BoostSwitchPressure[i] = Atmosphere->GetPressure(BoostSwitchAltitude[i]) * psftopa;
331 : : //cout << "BoostSwitchAlt = " << BoostSwitchAltitude[i] << ", pressure = " << BoostSwitchPressure[i] << '\n';
332 : : // Assume there is some hysteresis on the supercharger gear switch, and guess the value for now
333 : 0 : BoostSwitchHysteresis = 1000;
334 : : }
335 : : // Now work out the supercharger pressure multiplier of this speed from the rated boost and altitude.
336 : 0 : RatedMAP[i] = Atmosphere->GetPressureSL() * psftopa + RatedBoost[i] * 6895; // psi*6895 = Pa.
337 : : // Sometimes a separate BCV setting for takeoff or extra power is fitted.
338 [ # # ][ # # ]: 0 : if (TakeoffBoost > RatedBoost[0]) {
339 : : // Assume that the effect on the BCV is the same whichever speed is in use.
340 : 0 : TakeoffMAP[i] = RatedMAP[i] + ((TakeoffBoost - RatedBoost[0]) * 6895);
341 : 0 : bTakeoffBoost = true;
342 : : } else {
343 : 0 : TakeoffMAP[i] = RatedMAP[i];
344 : 0 : bTakeoffBoost = false;
345 : : }
346 : 0 : BoostMul[i] = RatedMAP[i] / (Atmosphere->GetPressure(RatedAltitude[i]) * psftopa);
347 : :
348 : : }
349 : :
350 [ # # ][ # # ]: 0 : if (BoostSpeeds > 0) {
351 : 0 : Boosted = true;
352 : 0 : BoostSpeed = 0;
353 : : }
354 : 0 : bBoostOverride = (BoostOverride == 1 ? true : false);
355 : 0 : bBoostManual = (BoostManual == 1 ? true : false);
356 : 0 : Debug(0); // Call Debug() routine from constructor if needed
357 : 0 : }
358 : :
359 : : //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
360 : :
361 : 0 : FGPiston::~FGPiston()
362 : : {
363 [ # # ][ # # ]: 0 : delete Lookup_Combustion_Efficiency;
[ # # ]
364 [ # # ][ # # ]: 0 : delete Mixture_Efficiency_Correlation;
[ # # ]
365 : 0 : Debug(1); // Call Debug() routine from constructor if needed
366 [ # # ][ # # ]: 0 : }
[ # # ]
367 : :
368 : : //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
369 : :
370 : 0 : void FGPiston::ResetToIC(void)
371 : : {
372 : 0 : FGEngine::ResetToIC();
373 : :
374 : 0 : ManifoldPressure_inHg = Atmosphere->GetPressure() * psftoinhg; // psf to in Hg
375 : 0 : MAP = Atmosphere->GetPressure() * psftopa;
376 : 0 : TMAP = MAP;
377 : 0 : double airTemperature_degK = RankineToKelvin(Atmosphere->GetTemperature());
378 : 0 : OilTemp_degK = airTemperature_degK;
379 : 0 : CylinderHeadTemp_degK = airTemperature_degK;
380 : 0 : ExhaustGasTemp_degK = airTemperature_degK;
381 : 0 : EGT_degC = ExhaustGasTemp_degK - 273;
382 : 0 : Thruster->SetRPM(0.0);
383 : 0 : RPM = 0.0;
384 : 0 : OilPressure_psi = 0.0;
385 : 0 : }
386 : :
387 : : //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
388 : 0 : void FGPiston::Calculate(void)
389 : : {
390 : 0 : RunPreFunctions();
391 : :
392 [ # # ]: 0 : if (FuelFlow_gph > 0.0) ConsumeFuel();
393 : :
394 : 0 : Throttle = FCS->GetThrottlePos(EngineNumber);
395 : 0 : Mixture = FCS->GetMixturePos(EngineNumber);
396 : :
397 : : // Input values.
398 : :
399 : 0 : p_amb = Atmosphere->GetPressure() * psftopa;
400 : 0 : double p = Auxiliary->GetTotalPressure() * psftopa;
401 : 0 : p_ram = (p - p_amb) * Ram_Air_Factor + p_amb;
402 : 0 : T_amb = RankineToKelvin(Atmosphere->GetTemperature());
403 : :
404 : 0 : RPM = Thruster->GetRPM() * Thruster->GetGearRatio();
405 : 0 : MeanPistonSpeed_fps = ( RPM * Stroke) / (360); // AKA 2 * (RPM/60) * ( Stroke / 12) or 2NS
406 : :
407 : 0 : IAS = Auxiliary->GetVcalibratedKTS();
408 : :
409 : 0 : doEngineStartup();
410 [ # # ]: 0 : if (Boosted) doBoostControl();
411 : 0 : doMAP();
412 : 0 : doAirFlow();
413 : 0 : doFuelFlow();
414 : :
415 : : //Now that the fuel flow is done check if the mixture is too lean to run the engine
416 : : //Assume lean limit at 22 AFR for now - thats a thi of 0.668
417 : : //This might be a bit generous, but since there's currently no audiable warning of impending
418 : : //cutout in the form of misfiring and/or rough running its probably reasonable for now.
419 : :
420 : : // if (equivalence_ratio < 0.668)
421 : : // Running = false;
422 : :
423 : 0 : doEnginePower();
424 [ # # ]: 0 : if (IndicatedHorsePower < 0.1250) Running = false;
425 : :
426 : 0 : doEGT();
427 : 0 : doCHT();
428 : 0 : doOilTemperature();
429 : 0 : doOilPressure();
430 : :
431 [ # # ]: 0 : if (Thruster->GetType() == FGThruster::ttPropeller) {
432 : 0 : ((FGPropeller*)Thruster)->SetAdvance(FCS->GetPropAdvance(EngineNumber));
433 : 0 : ((FGPropeller*)Thruster)->SetFeather(FCS->GetPropFeather(EngineNumber));
434 : : }
435 : :
436 : 0 : PowerAvailable = (HP * hptoftlbssec) - Thruster->GetPowerRequired();
437 : 0 : Thruster->Calculate(PowerAvailable);
438 : :
439 : 0 : RunPostFunctions();
440 : 0 : }
441 : :
442 : : //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
443 : :
444 : 0 : double FGPiston::CalcFuelNeed(void)
445 : : {
446 : 0 : double dT = FDMExec->GetDeltaT() * Propulsion->GetRate();
447 : 0 : FuelExpended = FuelFlowRate * dT;
448 : 0 : return FuelExpended;
449 : : }
450 : :
451 : : //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
452 : :
453 : 0 : int FGPiston::InitRunning(void) {
454 : 0 : Magnetos=3;
455 : 0 : p_amb = Atmosphere->GetPressure() * psftopa;
456 : 0 : double mix= p_amb / (101325.0*1.3);
457 : 0 : FCS->SetMixturePos(EngineNumber, mix);
458 : 0 : Thruster->SetRPM( 2.*IdleRPM/Thruster->GetGearRatio() );
459 : : //Thruster->SetRPM( 1000 );
460 : 0 : Running=true;
461 : : // cout <<"Set Running in FGPiston. RPM:" << Thruster->GetRPM()*Thruster->GetGearRatio() <<" Pressure:"<<p_amb<<" Mixture:"<< mix <<endl;
462 : 0 : return 1;
463 : : }
464 : :
465 : : //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
466 : : /**
467 : : * Start or stop the engine.
468 : : */
469 : :
470 : 0 : void FGPiston::doEngineStartup(void)
471 : : {
472 : : // Check parameters that may alter the operating state of the engine.
473 : : // (spark, fuel, starter motor etc)
474 : : bool spark;
475 : : bool fuel;
476 : : // Check for spark
477 : 0 : Magneto_Left = false;
478 : 0 : Magneto_Right = false;
479 : : // Magneto positions:
480 : : // 0 -> off
481 : : // 1 -> left only
482 : : // 2 -> right only
483 : : // 3 -> both
484 [ # # ]: 0 : if (Magnetos != 0) {
485 : 0 : spark = true;
486 : : } else {
487 : 0 : spark = false;
488 : : } // neglects battery voltage, master on switch, etc for now.
489 : :
490 [ # # ][ # # ]: 0 : if ((Magnetos == 1) || (Magnetos > 2)) Magneto_Left = true;
491 [ # # ]: 0 : if (Magnetos > 1) Magneto_Right = true;
492 : :
493 : : // Assume we have fuel for now
494 : 0 : fuel = !Starved;
495 : :
496 : : // Check if we are turning the starter motor
497 [ # # ]: 0 : if (Cranking != Starter) {
498 : : // This check saves .../cranking from getting updated every loop - they
499 : : // only update when changed.
500 : 0 : Cranking = Starter;
501 : 0 : crank_counter = 0;
502 : : }
503 : :
504 [ # # ]: 0 : if (Cranking) crank_counter++; //Check mode of engine operation
505 : :
506 [ # # ][ # # ]: 0 : if (!Running && spark && fuel) { // start the engine if revs high enough
[ # # ]
507 [ # # ]: 0 : if (Cranking) {
508 [ # # ][ # # ]: 0 : if ((RPM > IdleRPM*0.8) && (crank_counter > 175)) // Add a little delay to startup
509 : 0 : Running = true; // on the starter
510 : : } else {
511 [ # # ]: 0 : if (RPM > IdleRPM*0.8) // This allows us to in-air start
512 : 0 : Running = true; // when windmilling
513 : : }
514 : : }
515 : :
516 : : // Cut the engine *power* - Note: the engine may continue to
517 : : // spin if the prop is in a moving airstream
518 : :
519 [ # # ][ # # ]: 0 : if ( Running && (!spark || !fuel) ) Running = false;
[ # # ]
520 : :
521 : : // Check for stalling (RPM = 0).
522 [ # # ]: 0 : if (Running) {
523 [ # # ]: 0 : if (RPM == 0) {
524 : 0 : Running = false;
525 [ # # ][ # # ]: 0 : } else if ((RPM <= IdleRPM *0.8 ) && (Cranking)) {
526 : 0 : Running = false;
527 : : }
528 : : }
529 : 0 : }
530 : :
531 : : //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
532 : :
533 : : /**
534 : : * Calculate the Current Boost Speed
535 : : *
536 : : * This function calculates the current turbo/supercharger boost speed
537 : : * based on altitude and the (automatic) boost-speed control valve configuration.
538 : : *
539 : : * Inputs: p_amb, BoostSwitchPressure, BoostSwitchHysteresis
540 : : *
541 : : * Outputs: BoostSpeed
542 : : */
543 : :
544 : 0 : void FGPiston::doBoostControl(void)
545 : : {
546 [ # # ]: 0 : if(BoostManual) {
547 [ # # ]: 0 : if(BoostSpeed > BoostSpeeds-1) BoostSpeed = BoostSpeeds-1;
548 [ # # ]: 0 : if(BoostSpeed < 0) BoostSpeed = 0;
549 : : } else {
550 [ # # ]: 0 : if(BoostSpeed < BoostSpeeds - 1) {
551 : : // Check if we need to change to a higher boost speed
552 [ # # ]: 0 : if(p_amb < BoostSwitchPressure[BoostSpeed] - BoostSwitchHysteresis) {
553 : 0 : BoostSpeed++;
554 : : }
555 [ # # ]: 0 : } if(BoostSpeed > 0) {
556 : : // Check if we need to change to a lower boost speed
557 [ # # ]: 0 : if(p_amb > BoostSwitchPressure[BoostSpeed - 1] + BoostSwitchHysteresis) {
558 : 0 : BoostSpeed--;
559 : : }
560 : : }
561 : : }
562 : 0 : }
563 : :
564 : : //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
565 : :
566 : : /**
567 : : * Calculate the manifold absolute pressure (MAP) in inches hg
568 : : *
569 : : * This function calculates manifold absolute pressure (MAP)
570 : : * from the throttle position, turbo/supercharger boost control
571 : : * system, engine speed and local ambient air density.
572 : : *
573 : : * Inputs: p_amb, Throttle,
574 : : * MeanPistonSpeed_fps, dt
575 : : *
576 : : * Outputs: MAP, ManifoldPressure_inHg, TMAP
577 : : */
578 : :
579 : 0 : void FGPiston::doMAP(void)
580 : : {
581 : 0 : double Zt = (1-Throttle)*(1-Throttle)*Z_throttle; // throttle impedence
582 [ # # ]: 0 : double Ze= MeanPistonSpeed_fps > 0 ? PeakMeanPistonSpeed_fps/MeanPistonSpeed_fps : 999999; // engine impedence
583 : :
584 : 0 : double map_coefficient = Ze/(Ze+Z_airbox+Zt);
585 : :
586 : : // Add a one second lag to manifold pressure changes
587 : 0 : double dMAP = (TMAP - p_ram * map_coefficient) * dt;
588 : 0 : TMAP -=dMAP;
589 : :
590 : : // Find the mean effective pressure required to achieve this manifold pressure
591 : : // Fixme: determine the HP consumed by the supercharger
592 : :
593 : 0 : PMEP = (TMAP - p_amb) * volumetric_efficiency; // Fixme: p_amb should be exhaust manifold pressure
594 : :
595 [ # # ]: 0 : if (Boosted) {
596 : : // If takeoff boost is fitted, we currently assume the following throttle map:
597 : : // (In throttle % - actual input is 0 -> 1)
598 : : // 99 / 100 - Takeoff boost
599 : : // In real life, most planes would be fitted with a mechanical 'gate' between
600 : : // the rated boost and takeoff boost positions.
601 : :
602 : 0 : bool bTakeoffPos = false;
603 [ # # ]: 0 : if (bTakeoffBoost) {
604 [ # # ]: 0 : if (Throttle > 0.98) {
605 : 0 : bTakeoffPos = true;
606 : : }
607 : : }
608 : : // Boost the manifold pressure.
609 : 0 : double boost_factor = (( BoostMul[BoostSpeed] - 1 ) / RatedRPM[BoostSpeed] ) * RPM + 1;
610 : 0 : MAP = TMAP * boost_factor;
611 : : // Now clip the manifold pressure to BCV or Wastegate setting.
612 [ # # ]: 0 : if (bTakeoffPos) {
613 [ # # ]: 0 : if (MAP > TakeoffMAP[BoostSpeed]) MAP = TakeoffMAP[BoostSpeed];
614 : : } else {
615 [ # # ]: 0 : if (MAP > RatedMAP[BoostSpeed]) MAP = RatedMAP[BoostSpeed];
616 : : }
617 : : } else {
618 : 0 : MAP = TMAP;
619 : : }
620 : :
621 : : // And set the value in American units as well
622 : 0 : ManifoldPressure_inHg = MAP / inhgtopa;
623 : 0 : }
624 : :
625 : : //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
626 : : /**
627 : : * Calculate the air flow through the engine.
628 : : * Also calculates ambient air density
629 : : * (used in CHT calculation for air-cooled engines).
630 : : *
631 : : * Inputs: p_amb, R_air, T_amb, MAP, Displacement,
632 : : * RPM, volumetric_efficiency,
633 : : *
634 : : * TODO: Model inlet manifold air temperature.
635 : : *
636 : : * Outputs: rho_air, m_dot_air
637 : : */
638 : :
639 : 0 : void FGPiston::doAirFlow(void)
640 : : {
641 : 0 : double gamma = 1.3; // specific heat constants
642 : : // loss of volumentric efficiency due to difference between MAP and exhaust pressure
643 : : // Eq 6-10 from The Internal Combustion Engine - Charles Taylor Vol 1
644 : 0 : double ve =((gamma-1)/gamma) +( CompressionRatio -(p_amb/MAP))/(gamma*( CompressionRatio - 1));
645 : :
646 : 0 : rho_air = p_amb / (R_air * T_amb);
647 : 0 : double swept_volume = (displacement_SI * (RPM/60)) / 2;
648 : 0 : double v_dot_air = swept_volume * volumetric_efficiency *ve;
649 : :
650 : 0 : double rho_air_manifold = MAP / (R_air * T_amb);
651 : 0 : m_dot_air = v_dot_air * rho_air_manifold;
652 : :
653 : 0 : }
654 : :
655 : : //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
656 : : /**
657 : : * Calculate the fuel flow into the engine.
658 : : *
659 : : * Inputs: Mixture, thi_sea_level, p_amb, m_dot_air
660 : : *
661 : : * Outputs: equivalence_ratio, m_dot_fuel
662 : : */
663 : :
664 : 0 : void FGPiston::doFuelFlow(void)
665 : : {
666 : 0 : double thi_sea_level = 1.3 * Mixture; // Allows an AFR of infinity:1 to 11.3075:1
667 : 0 : equivalence_ratio = thi_sea_level * 101325.0 / p_amb;
668 : : // double AFR = 10+(12*(1-Mixture));// mixture 10:1 to 22:1
669 : : // m_dot_fuel = m_dot_air / AFR;
670 : 0 : m_dot_fuel = (m_dot_air * equivalence_ratio) / 14.7;
671 : 0 : FuelFlowRate = m_dot_fuel * 2.2046; // kg to lb
672 : 0 : FuelFlow_pph = FuelFlowRate * 3600; // seconds to hours
673 : 0 : FuelFlow_gph = FuelFlow_pph / 6.0; // Assumes 6 lbs / gallon
674 : 0 : }
675 : :
676 : : //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
677 : : /**
678 : : * Calculate the power produced by the engine.
679 : : *
680 : : * Inputs: ManifoldPressure_inHg, p_amb, RPM, T_amb, ISFC,
681 : : * Mixture_Efficiency_Correlation, Cycles, MaxHP, PMEP,
682 : : * MeanPistonSpeed_fps
683 : : *
684 : : * Outputs: PctPower, HP, FMEP, IndicatedHorsePower
685 : : */
686 : :
687 : 0 : void FGPiston::doEnginePower(void)
688 : : {
689 : 0 : IndicatedHorsePower = 0;
690 : 0 : FMEP = 0;
691 [ # # ]: 0 : if (Running) {
692 : : // FIXME: this needs to be generalized
693 : : double ME, percent_RPM, power; // Convienience term for use in the calculations
694 : 0 : ME = Mixture_Efficiency_Correlation->GetValue(m_dot_fuel/m_dot_air);
695 : :
696 : 0 : percent_RPM = RPM/MaxRPM;
697 : : // Guestimate engine friction losses from Figure 4.4 of "Engines: An Introduction", John Lumley
698 : 0 : FMEP = (-FMEPDynamic * MeanPistonSpeed_fps * fttom - FMEPStatic);
699 : :
700 : 0 : power = 1;
701 : :
702 [ # # ]: 0 : if ( Magnetos != 3 ) power *= SparkFailDrop;
703 : :
704 : :
705 : 0 : IndicatedHorsePower = (FuelFlow_pph / ISFC )* ME * power;
706 : :
707 : : } else {
708 : : // Power output when the engine is not running
709 [ # # ]: 0 : if (Cranking) {
710 [ # # ]: 0 : if (RPM < 10) {
711 : 0 : IndicatedHorsePower = StarterHP;
712 [ # # ]: 0 : } else if (RPM < IdleRPM*0.8) {
713 : 0 : IndicatedHorsePower = StarterHP + ((IdleRPM*0.8 - RPM) / 8.0);
714 : : // This is a guess - would be nice to find a proper starter moter torque curve
715 : : } else {
716 : 0 : IndicatedHorsePower = StarterHP;
717 : : }
718 : : }
719 : : }
720 : :
721 : : // Constant is (1/2) * 60 * 745.7
722 : : // (1/2) convert cycles, 60 minutes to seconds, 745.7 watts to hp.
723 : 0 : double pumping_hp = ((PMEP + FMEP) * displacement_SI * RPM)/(Cycles*22371);
724 : :
725 : 0 : HP = IndicatedHorsePower + pumping_hp - 1.5; //FIXME 1.5 static friction should depend on oil temp and configuration
726 : : // cout << "pumping_hp " <<pumping_hp << FMEP << PMEP <<endl;
727 : 0 : PctPower = HP / MaxHP ;
728 : : // cout << "Power = " << HP << " RPM = " << RPM << " Running = " << Running << " Cranking = " << Cranking << endl;
729 : 0 : }
730 : :
731 : : //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
732 : : /**
733 : : * Calculate the exhaust gas temperature.
734 : : *
735 : : * Inputs: equivalence_ratio, m_dot_fuel, calorific_value_fuel,
736 : : * Cp_air, m_dot_air, Cp_fuel, m_dot_fuel, T_amb, PctPower
737 : : *
738 : : * Outputs: combustion_efficiency, ExhaustGasTemp_degK
739 : : */
740 : :
741 : 0 : void FGPiston::doEGT(void)
742 : : {
743 : : double delta_T_exhaust;
744 : : double enthalpy_exhaust;
745 : : double heat_capacity_exhaust;
746 : : double dEGTdt;
747 : :
748 [ # # ][ # # ]: 0 : if ((Running) && (m_dot_air > 0.0)) { // do the energy balance
749 : 0 : combustion_efficiency = Lookup_Combustion_Efficiency->GetValue(equivalence_ratio);
750 : : enthalpy_exhaust = m_dot_fuel * calorific_value_fuel *
751 : 0 : combustion_efficiency * 0.33;
752 : 0 : heat_capacity_exhaust = (Cp_air * m_dot_air) + (Cp_fuel * m_dot_fuel);
753 : 0 : delta_T_exhaust = enthalpy_exhaust / heat_capacity_exhaust;
754 : 0 : ExhaustGasTemp_degK = T_amb + delta_T_exhaust;
755 : 0 : ExhaustGasTemp_degK *= 0.444 + ((0.544 - 0.444) * PctPower);
756 : : } else { // Drop towards ambient - guess an appropriate time constant for now
757 : 0 : combustion_efficiency = 0;
758 : 0 : dEGTdt = (RankineToKelvin(Atmosphere->GetTemperature()) - ExhaustGasTemp_degK) / 100.0;
759 : 0 : delta_T_exhaust = dEGTdt * dt;
760 : 0 : ExhaustGasTemp_degK += delta_T_exhaust;
761 : : }
762 : 0 : }
763 : :
764 : : //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
765 : : /**
766 : : * Calculate the cylinder head temperature.
767 : : *
768 : : * Inputs: T_amb, IAS, rho_air, m_dot_fuel, calorific_value_fuel,
769 : : * combustion_efficiency, RPM, MaxRPM, Displacement
770 : : *
771 : : * Outputs: CylinderHeadTemp_degK
772 : : */
773 : :
774 : 0 : void FGPiston::doCHT(void)
775 : : {
776 : 0 : double h1 = -95.0;
777 : 0 : double h2 = -3.95;
778 : 0 : double h3 = -140.0; // -0.05 * 2800 (default maxrpm)
779 : :
780 : 0 : double arbitary_area = Displacement/360.0;
781 : 0 : double CpCylinderHead = 800.0;
782 : 0 : double MassCylinderHead = 8.0;
783 : :
784 : 0 : double temperature_difference = CylinderHeadTemp_degK - T_amb;
785 : 0 : double v_apparent = IAS * 0.5144444;
786 : 0 : double v_dot_cooling_air = arbitary_area * v_apparent;
787 : 0 : double m_dot_cooling_air = v_dot_cooling_air * rho_air;
788 : : double dqdt_from_combustion =
789 : 0 : m_dot_fuel * calorific_value_fuel * combustion_efficiency * 0.33;
790 : : double dqdt_forced = (h2 * m_dot_cooling_air * temperature_difference) +
791 : 0 : (h3 * RPM * temperature_difference / MaxRPM);
792 : 0 : double dqdt_free = h1 * temperature_difference;
793 : 0 : double dqdt_cylinder_head = dqdt_from_combustion + dqdt_forced + dqdt_free;
794 : :
795 : 0 : double HeatCapacityCylinderHead = CpCylinderHead * MassCylinderHead;
796 : :
797 : : CylinderHeadTemp_degK +=
798 : 0 : (dqdt_cylinder_head / HeatCapacityCylinderHead) * dt;
799 : 0 : }
800 : :
801 : : //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
802 : : /**
803 : : * Calculate the oil temperature.
804 : : *
805 : : * Inputs: CylinderHeadTemp_degK, T_amb, OilPressure_psi.
806 : : *
807 : : * Outputs: OilTemp_degK
808 : : */
809 : :
810 : 0 : void FGPiston::doOilTemperature(void)
811 : : {
812 : : double target_oil_temp; // Steady state oil temp at the current engine conditions
813 : : double time_constant; // The time constant for the differential equation
814 : 0 : double efficiency = 0.667; // The aproximate oil cooling system efficiency // FIXME: may vary by engine
815 : :
816 : : // Target oil temp is interpolated between ambient temperature and Cylinder Head Tempurature
817 : : // target_oil_temp = ( T_amb * efficiency ) + (CylinderHeadTemp_degK *(1-efficiency)) ;
818 : 0 : target_oil_temp = CylinderHeadTemp_degK + efficiency * (T_amb - CylinderHeadTemp_degK) ;
819 : :
820 [ # # ]: 0 : if (OilPressure_psi > 5.0 ) {
821 : 0 : time_constant = 5000 / OilPressure_psi; // Guess at a time constant for circulated oil.
822 : : // The higher the pressure the faster it reaches
823 : : // target temperature. Oil pressure should be about
824 : : // 60 PSI yielding a TC of about 80.
825 : : } else {
826 : 0 : time_constant = 1000; // Time constant for engine-off; reflects the fact
827 : : // that oil is no longer getting circulated
828 : : }
829 : :
830 : 0 : double dOilTempdt = (target_oil_temp - OilTemp_degK) / time_constant;
831 : :
832 : 0 : OilTemp_degK += (dOilTempdt * dt);
833 : 0 : }
834 : :
835 : : //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
836 : : /**
837 : : * Calculate the oil pressure.
838 : : *
839 : : * Inputs: RPM, MaxRPM, OilTemp_degK
840 : : *
841 : : * Outputs: OilPressure_psi
842 : : */
843 : :
844 : 0 : void FGPiston::doOilPressure(void)
845 : : {
846 : 0 : double Oil_Press_Relief_Valve = 60; // FIXME: may vary by engine
847 : 0 : double Oil_Press_RPM_Max = MaxRPM * 0.75; // 75% of max rpm FIXME: may vary by engine
848 : 0 : double Design_Oil_Temp = 358; // degK; FIXME: may vary by engine
849 : 0 : double Oil_Viscosity_Index = 0.25;
850 : :
851 : 0 : OilPressure_psi = (Oil_Press_Relief_Valve / Oil_Press_RPM_Max) * RPM;
852 : :
853 [ # # ]: 0 : if (OilPressure_psi >= Oil_Press_Relief_Valve) {
854 : 0 : OilPressure_psi = Oil_Press_Relief_Valve;
855 : : }
856 : :
857 : 0 : OilPressure_psi += (Design_Oil_Temp - OilTemp_degK) * Oil_Viscosity_Index * OilPressure_psi / Oil_Press_Relief_Valve;
858 : 0 : }
859 : :
860 : : //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
861 : :
862 : 0 : string FGPiston::GetEngineLabels(const string& delimiter)
863 : : {
864 : 0 : std::ostringstream buf;
865 : :
866 : : buf << Name << " Power Available (engine " << EngineNumber << " in HP)" << delimiter
867 : : << Name << " HP (engine " << EngineNumber << ")" << delimiter
868 : : << Name << " equivalent ratio (engine " << EngineNumber << ")" << delimiter
869 : : << Name << " MAP (engine " << EngineNumber << " in inHg)" << delimiter
870 : 0 : << Thruster->GetThrusterLabels(EngineNumber, delimiter);
871 : :
872 : 0 : return buf.str();
873 : : }
874 : :
875 : : //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
876 : :
877 : 0 : string FGPiston::GetEngineValues(const string& delimiter)
878 : : {
879 : 0 : std::ostringstream buf;
880 : :
881 : : buf << PowerAvailable << delimiter << HP << delimiter
882 : : << equivalence_ratio << delimiter << ManifoldPressure_inHg << delimiter
883 : 0 : << Thruster->GetThrusterValues(EngineNumber, delimiter);
884 : :
885 : 0 : return buf.str();
886 : : }
887 : :
888 : : //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
889 : : //
890 : : // The bitmasked value choices are as follows:
891 : : // unset: In this case (the default) JSBSim would only print
892 : : // out the normally expected messages, essentially echoing
893 : : // the config files as they are read. If the environment
894 : : // variable is not set, debug_lvl is set to 1 internally
895 : : // 0: This requests JSBSim not to output any messages
896 : : // whatsoever.
897 : : // 1: This value explicity requests the normal JSBSim
898 : : // startup messages
899 : : // 2: This value asks for a message to be printed out when
900 : : // a class is instantiated
901 : : // 4: When this value is set, a message is displayed when a
902 : : // FGModel object executes its Run() method
903 : : // 8: When this value is set, various runtime state variables
904 : : // are printed out periodically
905 : : // 16: When set various parameters are sanity checked and
906 : : // a message is printed out when they go out of bounds
907 : :
908 : 0 : void FGPiston::Debug(int from)
909 : : {
910 [ # # ]: 0 : if (debug_lvl <= 0) return;
911 : :
912 [ # # ]: 0 : if (debug_lvl & 1) { // Standard console startup message output
913 [ # # ]: 0 : if (from == 0) { // Constructor
914 : :
915 : 0 : cout << "\n Engine Name: " << Name << endl;
916 : 0 : cout << " MinManifoldPressure: " << MinManifoldPressure_inHg << endl;
917 : 0 : cout << " MaxManifoldPressure: " << MaxManifoldPressure_inHg << endl;
918 : 0 : cout << " MinMaP (Pa): " << minMAP << endl;
919 : 0 : cout << " MaxMaP (Pa): " << maxMAP << endl;
920 : 0 : cout << " Displacement: " << Displacement << endl;
921 : 0 : cout << " Bore: " << Bore << endl;
922 : 0 : cout << " Stroke: " << Stroke << endl;
923 : 0 : cout << " Cylinders: " << Cylinders << endl;
924 : 0 : cout << " Compression Ratio: " << CompressionRatio << endl;
925 : 0 : cout << " MaxHP: " << MaxHP << endl;
926 : 0 : cout << " Cycles: " << Cycles << endl;
927 : 0 : cout << " IdleRPM: " << IdleRPM << endl;
928 : 0 : cout << " MaxRPM: " << MaxRPM << endl;
929 : 0 : cout << " Throttle Constant: " << Z_throttle << endl;
930 : 0 : cout << " ISFC: " << ISFC << endl;
931 : 0 : cout << " Volumetric Efficiency: " << volumetric_efficiency << endl;
932 : 0 : cout << " PeakMeanPistonSpeed_fps: " << PeakMeanPistonSpeed_fps << endl;
933 : 0 : cout << " Intake Impedance Factor: " << Z_airbox << endl;
934 : 0 : cout << " Dynamic FMEP Factor: " << FMEPDynamic << endl;
935 : 0 : cout << " Static FMEP Factor: " << FMEPStatic << endl;
936 : :
937 : : cout << endl;
938 : 0 : cout << " Combustion Efficiency table:" << endl;
939 : 0 : Lookup_Combustion_Efficiency->Print();
940 : : cout << endl;
941 : :
942 : : cout << endl;
943 : 0 : cout << " Mixture Efficiency Correlation table:" << endl;
944 : 0 : Mixture_Efficiency_Correlation->Print();
945 : : cout << endl;
946 : :
947 : : }
948 : : }
949 [ # # ]: 0 : if (debug_lvl & 2 ) { // Instantiation/Destruction notification
950 [ # # ]: 0 : if (from == 0) cout << "Instantiated: FGPiston" << endl;
951 [ # # ]: 0 : if (from == 1) cout << "Destroyed: FGPiston" << endl;
952 : : }
953 : 0 : if (debug_lvl & 4 ) { // Run() method entry print for FGModel-derived objects
954 : : }
955 : 0 : if (debug_lvl & 8 ) { // Runtime state variables
956 : : }
957 : 0 : if (debug_lvl & 16) { // Sanity checking
958 : : }
959 [ # # ]: 0 : if (debug_lvl & 64) {
960 [ # # ]: 0 : if (from == 0) { // Constructor
961 : 0 : cout << IdSrc << endl;
962 : 0 : cout << IdHdr << endl;
963 : : }
964 : : }
965 : : }
966 [ + + ][ + - ]: 12 : } // namespace JSBSim
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