git.gag.com Git - sw/motorsim/blob - src/com/billkuker/rocketry/motorsim/Burn.java

   1 package com.billkuker.rocketry.motorsim;\r
   2 \r
   3 \r
   4 \r
   5 import java.util.Date;\r
   6 import java.util.HashSet;\r
   7 import java.util.Set;\r
   8 import java.util.SortedMap;\r
   9 import java.util.TreeMap;\r
  10 \r
  11 import javax.measure.quantity.Area;\r
  12 import javax.measure.quantity.Dimensionless;\r
  13 import javax.measure.quantity.Duration;\r
  14 import javax.measure.quantity.Force;\r
  15 import javax.measure.quantity.Length;\r
  16 import javax.measure.quantity.Mass;\r
  17 import javax.measure.quantity.MassFlowRate;\r
  18 import javax.measure.quantity.Pressure;\r
  19 import javax.measure.quantity.Quantity;\r
  20 import javax.measure.quantity.Temperature;\r
  21 import javax.measure.quantity.Velocity;\r
  22 import javax.measure.quantity.Volume;\r
  23 import javax.measure.quantity.VolumetricDensity;\r
  24 import javax.measure.unit.SI;\r
  25 \r
  26 import org.apache.log4j.Logger;\r
  27 import org.jscience.physics.amount.Amount;\r
  28 import org.jscience.physics.amount.Constants;\r
  29 \r
  30 import com.billkuker.rocketry.motorsim.Validating.ValidationException;\r
  31 \r
  32 public class Burn {\r
  33         private static Logger log = Logger.getLogger(Burn.class);\r
  34         \r
  35         private static final BurnSettings settings = new BurnSettings();\r
  36         public static final BurnSettings getBurnSettings(){\r
  37                 return settings;\r
  38         }\r
  39         \r
  40         /**\r
  41          * A class representing all the settigns one can change on a burn\r
  42          * @author bkuker\r
  43          */\r
  44         public static class BurnSettings {\r
  45                 private BurnSettings(){};\r
  46 \r
  47                 public enum BurnVolumeMethod {\r
  48                         DeltaVolume,\r
  49                         SurfaceTimesRegression;\r
  50                 }\r
  51                 \r
  52                 private BurnVolumeMethod volumeMethod = BurnVolumeMethod.SurfaceTimesRegression;\r
  53                 private double regStepIncreaseFactor = 1.01;\r
  54                 private double regStepDecreaseFactor = .5;\r
  55                 private Amount<Pressure> chamberPressureMaxDelta = Amount.valueOf(.5, SI.MEGA(SI.PASCAL));\r
  56                 private Amount<Pressure> endPressure = Amount.valueOf(.1, RocketScience.PSI);\r
  57                 \r
  58                 public void setVolumeMethod(BurnVolumeMethod volumeMethod) {\r
  59                         this.volumeMethod = volumeMethod;\r
  60                 }\r
  61                 public BurnVolumeMethod getVolumeMethod() {\r
  62                         return volumeMethod;\r
  63                 }\r
  64                 public double getRegStepIncreaseFactor() {\r
  65                         return regStepIncreaseFactor;\r
  66                 }\r
  67                 public void setRegStepIncreaseFactor(double regStepIncreaseFactor) {\r
  68                         this.regStepIncreaseFactor = regStepIncreaseFactor;\r
  69                 }\r
  70                 public double getRegStepDecreaseFactor() {\r
  71                         return regStepDecreaseFactor;\r
  72                 }\r
  73                 public void setRegStepDecreaseFactor(double regStepDecreaseFactor) {\r
  74                         this.regStepDecreaseFactor = regStepDecreaseFactor;\r
  75                 }\r
  76                 public Amount<Pressure> getChamberPressureMaxDelta() {\r
  77                         return chamberPressureMaxDelta;\r
  78                 }\r
  79                 public void setChamberPressureMaxDelta(Amount<Pressure> chamberPressureMaxDelta) {\r
  80                         this.chamberPressureMaxDelta = chamberPressureMaxDelta;\r
  81                 }\r
  82                 public Amount<Pressure> getEndPressure() {\r
  83                         return endPressure;\r
  84                 }\r
  85                 public void setEndPressure(Amount<Pressure> endPressure) {\r
  86                         this.endPressure = endPressure;\r
  87                 }\r
  88         }\r
  89         \r
  90         protected final Motor motor;\r
  91         \r
  92         private boolean burning = false;\r
  93         private boolean done = false;\r
  94         \r
  95         public interface BurnProgressListener{\r
  96                 public void setProgress(float p);\r
  97                 public void burnComplete();\r
  98         }\r
  99         \r
 100 \r
 101 \r
 102         \r
 103         private Set<BurnProgressListener> bpls = new HashSet<Burn.BurnProgressListener>();\r
 104         \r
 105         private static final Amount<Pressure> atmosphereicPressure = Amount.valueOf(101000, SI.PASCAL);\r
 106         \r
 107         public class Interval{\r
 108                 public Amount<Duration> time;\r
 109                 public Amount<Duration> dt;\r
 110                 public Amount<Length> regression;\r
 111                 public Amount<Pressure> chamberPressure;\r
 112                 Amount<Mass> chamberProduct;\r
 113                 public Amount<Force> thrust;\r
 114 \r
 115                 public String toString(){\r
 116                         return time + " " + dt + " " + regression + " " + chamberPressure + " " + chamberProduct;\r
 117                 }\r
 118         }\r
 119         \r
 120         protected SortedMap<Amount<Duration>,Interval> data = new TreeMap<Amount<Duration>, Interval>();\r
 121         \r
 122         public SortedMap<Amount<Duration>,Interval> getData(){\r
 123                 if ( !done )\r
 124                         throw new IllegalStateException("Burn not complete!");\r
 125                 return data;\r
 126         }\r
 127         \r
 128         public Motor getMotor(){\r
 129                 return motor;\r
 130         }\r
 131 \r
 132         public Amount<Duration> burnTime(){\r
 133                 return getData().lastKey();\r
 134         }\r
 135         \r
 136         public Burn(Motor m){\r
 137                 try {\r
 138                         m.validate();\r
 139                 } catch (ValidationException e) {\r
 140                         throw new IllegalArgumentException("Invalid Motor: " + e.getMessage());\r
 141                 }\r
 142                 motor = m;\r
 143         }\r
 144         \r
 145         public void addBurnProgressListener( BurnProgressListener bpl ){\r
 146                 bpls.add(bpl);\r
 147                 if ( done )\r
 148                         bpl.burnComplete();\r
 149         }\r
 150         \r
 151         public void burn(){\r
 152                 synchronized(this){\r
 153                         if ( burning )\r
 154                                 throw new IllegalStateException("Already burning!");\r
 155                         burning = true;\r
 156                 }\r
 157                 log.info("Starting burn...");\r
 158                 for (BurnProgressListener bpl : bpls ){\r
 159                         bpl.setProgress(0);\r
 160                 }\r
 161                 \r
 162                 int endPressureSteps = 0;\r
 163                 long start = new Date().getTime();\r
 164                 \r
 165                 Amount<Length> regStep = Amount.valueOf(0.01, SI.MILLIMETER);\r
 166 \r
 167                 Interval initial = new Interval();\r
 168                 initial.time = Amount.valueOf(0, SI.SECOND);\r
 169                 initial.dt = Amount.valueOf(0, SI.SECOND);\r
 170                 initial.regression = Amount.valueOf(0, SI.MILLIMETER);\r
 171                 initial.chamberPressure = atmosphereicPressure;\r
 172                 initial.chamberProduct = Amount.valueOf(0, SI.KILOGRAM);\r
 173                 initial.thrust = Amount.valueOf(0, SI.NEWTON);\r
 174                 \r
 175                 data.put(Amount.valueOf(0, SI.SECOND), initial);\r
 176                 \r
 177                 step:\r
 178                 for ( int i = 0; i < 5000; i++ ) {\r
 179                         assert(positive(regStep));\r
 180                         regStep = regStep.times(settings.getRegStepIncreaseFactor());\r
 181                         \r
 182                         Interval prev = data.get(data.lastKey());\r
 183                         log.debug(prev);\r
 184                         log.debug("Step " + i + " ==============================");\r
 185                         Interval next = new Interval();\r
 186                         \r
 187                         Amount<Velocity> burnRate = motor.getFuel().burnRate(prev.chamberPressure);\r
 188                         assert(positive(burnRate));\r
 189                         \r
 190                         log.debug("Burn Rate: " + burnRate);\r
 191                         \r
 192                         Amount<Duration> dt = regStep.divide(burnRate).to(Duration.UNIT);\r
 193                         assert(positive(dt));\r
 194                         next.dt = dt;\r
 195                         \r
 196 \r
 197                         \r
 198                         log.debug("Dt: " + dt);\r
 199                         \r
 200                         next.regression = prev.regression.plus(regStep);\r
 201                         assert(positive(next.regression));\r
 202                         \r
 203                         log.debug("Regression: " + next.regression);\r
 204                         \r
 205                         //Update BurnProgressListeners\r
 206                         Amount<Dimensionless> a = next.regression.divide(motor.getGrain().webThickness()).to(Dimensionless.UNIT);\r
 207                         for (BurnProgressListener bpl : bpls ){\r
 208                                 bpl.setProgress((float)a.doubleValue(Dimensionless.UNIT));\r
 209                         }\r
 210 \r
 211                         \r
 212                         next.time = prev.time.plus(dt);\r
 213                         \r
 214                         //log.debug("Vold: " + motor.getGrain().volume(prev.regression).to(SI.MILLIMETER.pow(3)));\r
 215                         \r
 216                         //log.debug("Vnew: " + motor.getGrain().volume(next.regression).to(SI.MILLIMETER.pow(3)));\r
 217                         \r
 218                         Amount<Volume> volumeBurnt;\r
 219                         if ( settings.getVolumeMethod() == BurnSettings.BurnVolumeMethod.DeltaVolume ){\r
 220                                 volumeBurnt = motor.getGrain().volume(prev.regression).minus(motor.getGrain().volume(next.regression));\r
 221                         } else {\r
 222                                 volumeBurnt = motor.getGrain().surfaceArea(prev.regression).times(regStep).to(Volume.UNIT);\r
 223                         }\r
 224                         assert(positive(volumeBurnt));\r
 225                         //log.info("Volume Burnt: " + volumeBurnt.to(SI.MILLIMETER.pow(3)));\r
 226                         \r
 227                         Amount<MassFlowRate> mGenRate = volumeBurnt.times(motor.getFuel().getIdealDensity().times(motor.getFuel().getDensityRatio())).divide(dt).to(MassFlowRate.UNIT);\r
 228                         assert(positive(mGenRate));\r
 229                         \r
 230                         //log.debug("Mass Gen Rate: " + mGenRate);\r
 231                         \r
 232                         //Calculate specific gas constant\r
 233                         Amount<?> specificGasConstant = Constants.R.divide(motor.getFuel().getCombustionProduct().getEffectiveMolarWeight());\r
 234                         //This unit conversion helps JScience to convert nozzle flow rate to\r
 235                         //kg/s a little later on I verified the conversion by hand and\r
 236                         //JScience checks it too.\r
 237                         specificGasConstant = convertSpecificGasConstantUnits(specificGasConstant);\r
 238                         \r
 239                         //Calculate chamber temperature\r
 240                         Amount<Temperature> chamberTemp = motor.getFuel().getCombustionProduct().getIdealCombustionTemperature().times(motor.getFuel().getCombustionEfficiency());\r
 241                         \r
 242                         Amount<MassFlowRate> mNozzle;\r
 243                         {\r
 244                                 Amount<Pressure> pDiff = prev.chamberPressure.minus(atmosphereicPressure);\r
 245                                 //log.debug("Pdiff: " + pDiff);\r
 246                                 Amount<Area> aStar = motor.getNozzle().throatArea();\r
 247                                 double k = motor.getFuel().getCombustionProduct().getRatioOfSpecificHeats();\r
 248                                 double kSide = Math.sqrt(k) * Math.pow((2/(k+1)) , (((k+1)/2)/(k-1)));\r
 249                                 Amount<?> sqrtPart = specificGasConstant.times(chamberTemp).sqrt();\r
 250                                 mNozzle = pDiff.times(aStar).times(kSide).divide(sqrtPart).to(MassFlowRate.UNIT);\r
 251                                 //log.debug("Mass Exit Rate: " + mNozzle.to(MassFlowRate.UNIT));                \r
 252                         }\r
 253                         assert(positive(mNozzle));\r
 254                         \r
 255                         Amount<MassFlowRate> massStorageRate = mGenRate.minus(mNozzle);\r
 256                         \r
 257                         //log.debug("Mass Storage Rate: " + massStorageRate);\r
 258 \r
 259                         next.chamberProduct = prev.chamberProduct.plus(massStorageRate.times(dt));\r
 260                         \r
 261                         //Product can not go negative!\r
 262                         if ( !positive(next.chamberProduct) ){\r
 263                                 log.warn("ChamberProduct Negative on step " + i + "!, Adjusting regstep down and repeating step!");\r
 264                                 regStep = regStep.times(settings.getRegStepDecreaseFactor());\r
 265                                 continue step;\r
 266                         }\r
 267                         assert(positive(next.chamberProduct));\r
 268                         if ( next.chamberProduct.isLessThan(Amount.valueOf(0, SI.KILOGRAM)) )\r
 269                                 next.chamberProduct = Amount.valueOf(0, SI.KILOGRAM);\r
 270                         \r
 271                         //log.debug("Chamber Product: " + next.chamberProduct);\r
 272                         \r
 273                         Amount<VolumetricDensity> combustionProductDensity = next.chamberProduct.divide(motor.getChamber().chamberVolume().minus(motor.getGrain().volume(next.regression))).to(VolumetricDensity.UNIT);\r
 274                         \r
 275                         log.debug("Product Density: " + combustionProductDensity);\r
 276                         \r
 277                         next.chamberPressure = combustionProductDensity.times(specificGasConstant).times(chamberTemp).plus(atmosphereicPressure).to(Pressure.UNIT);\r
 278                         assert(positive(next.chamberPressure));\r
 279                         \r
 280                         next.chamberPressure = Amount.valueOf(\r
 281                                         next.chamberPressure.doubleValue(SI.PASCAL),\r
 282                                         SI.PASCAL);\r
 283                         \r
 284                         Amount<Pressure> dp = next.chamberPressure.minus(prev.chamberPressure);\r
 285                         if ( dp.abs().isGreaterThan(settings.getChamberPressureMaxDelta())){\r
 286                                 log.warn("DP " + dp + " too big!, Adjusting regstep down and repeating step!");\r
 287                                 regStep = regStep.times(settings.getRegStepDecreaseFactor());\r
 288                                 continue step;\r
 289                         }\r
 290                         \r
 291                         next.thrust = motor.getNozzle().thrust(next.chamberPressure, atmosphereicPressure, atmosphereicPressure, motor.getFuel().getCombustionProduct().getRatioOfSpecificHeats2Phase());\r
 292                         assert(positive(next.thrust));\r
 293                         \r
 294                         if ( i > 100 && next.chamberPressure.minus(atmosphereicPressure).abs().isLessThan(settings.getEndPressure())){\r
 295                                 log.info("Pressure at ~Patm on step " + i);\r
 296                                 endPressureSteps++;\r
 297                                 if ( endPressureSteps > 5 )\r
 298                                         break;\r
 299                         }\r
 300                         \r
 301                         data.put(data.lastKey().plus(dt), next);\r
 302                 }\r
 303 \r
 304                 long time = new Date().getTime() - start;\r
 305                 log.info("Burn took " + time + " millis.");\r
 306                 done = true;\r
 307                 for (BurnProgressListener bpl : bpls ){\r
 308                         bpl.burnComplete();\r
 309                 }\r
 310         }\r
 311         \r
 312         @SuppressWarnings("unchecked")\r
 313         /*\r
 314          * This converts the units of this constant to something JScience is able\r
 315          * to work from. This conversion is unchecked at compile time, but\r
 316          * JScience keeps me honest at runtime.\r
 317          */\r
 318         private Amount convertSpecificGasConstantUnits(Amount a){\r
 319                 return a.to(\r
 320                                 SI.METER.pow(2).divide(SI.SECOND.pow(2).times(SI.KELVIN)));\r
 321         }\r
 322         \r
 323         public Amount<Pressure> pressure(Amount<Duration> time){\r
 324                 return getData().get(time).chamberPressure;\r
 325         }\r
 326         \r
 327         public Amount<Force> thrust(Amount<Duration> time){\r
 328                 return getData().get(time).thrust;\r
 329         }\r
 330         \r
 331         public Amount<Dimensionless> kn(Amount<Length> regression){\r
 332                 return motor.getGrain().surfaceArea(regression).divide(motor.getNozzle().throatArea()).to(Dimensionless.UNIT);\r
 333         }\r
 334         \r
 335         \r
 336         private <Q extends Quantity> boolean positive(Amount<Q> a){\r
 337                 return ( a.isGreaterThan(a.minus(a)) || a.equals(a.minus(a)));\r
 338         }\r
 339 \r
 340 }\r