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.SortedMap;\r
   6 import java.util.TreeMap;\r
   7 \r
   8 import javax.measure.quantity.Area;\r
   9 import javax.measure.quantity.Dimensionless;\r
  10 import javax.measure.quantity.Duration;\r
  11 import javax.measure.quantity.Force;\r
  12 import javax.measure.quantity.Length;\r
  13 import javax.measure.quantity.Mass;\r
  14 import javax.measure.quantity.MassFlowRate;\r
  15 import javax.measure.quantity.Pressure;\r
  16 import javax.measure.quantity.Temperature;\r
  17 import javax.measure.quantity.Velocity;\r
  18 import javax.measure.quantity.Volume;\r
  19 import javax.measure.quantity.VolumetricDensity;\r
  20 import javax.measure.unit.SI;\r
  21 \r
  22 import org.apache.log4j.Logger;\r
  23 import org.jscience.physics.amount.Amount;\r
  24 import org.jscience.physics.amount.Constants;\r
  25 \r
  26 public class Burn {\r
  27         \r
  28         private static Logger log = Logger.getLogger(Burn.class);\r
  29         protected final Motor motor;\r
  30         \r
  31         private static final Amount<Pressure> atmosphereicPressure = Amount.valueOf(101000, SI.PASCAL);\r
  32         \r
  33         \r
  34         private static double combustionEfficency = 0.97;\r
  35         \r
  36         private static double densityRatio = 0.96;\r
  37         \r
  38         public class Interval{\r
  39                 public Amount<Duration> time;\r
  40                 public Amount<Duration> dt;\r
  41                 public Amount<Length> regression;\r
  42                 public Amount<Pressure> chamberPressure;\r
  43                 Amount<Mass> chamberProduct;\r
  44                 public Amount<Force> thrust;\r
  45 \r
  46                 public String toString(){\r
  47                         return time + " " + dt + " " + regression + " " + chamberPressure + " " + chamberProduct;\r
  48                 }\r
  49         }\r
  50         \r
  51         protected SortedMap<Amount<Duration>,Interval> data = new TreeMap<Amount<Duration>, Interval>();\r
  52         \r
  53         public SortedMap<Amount<Duration>,Interval> getData(){\r
  54                 return data;\r
  55         }\r
  56         \r
  57         public Motor getMotor(){\r
  58                 return motor;\r
  59         }\r
  60 \r
  61         public Amount<Duration> burnTime(){\r
  62                 return data.lastKey();\r
  63         }\r
  64         \r
  65         public Burn(Motor m){\r
  66                 motor = m;\r
  67                 burn();\r
  68         }\r
  69         \r
  70         private void burn(){\r
  71                 log.info("Starting burn...");\r
  72                 \r
  73                 Amount<Length> regStep = Amount.valueOf(0.0119904077, SI.MILLIMETER);\r
  74 \r
  75                 //if ( motor.getGrain() instanceof Grain.DiscreteRegression )\r
  76                         //regStep = ((Grain.DiscreteRegression)motor.getGrain()).optimalRegressionStep();\r
  77                 \r
  78                 Interval initial = new Interval();\r
  79                 initial.time = Amount.valueOf(0, SI.SECOND);\r
  80                 initial.dt = Amount.valueOf(0, SI.SECOND);\r
  81                 initial.regression = Amount.valueOf(0, SI.MILLIMETER);\r
  82                 initial.chamberPressure = atmosphereicPressure;\r
  83                 initial.chamberProduct = Amount.valueOf(0, SI.KILOGRAM);\r
  84                 initial.thrust = Amount.valueOf(0, SI.NEWTON);\r
  85                 \r
  86                 data.put(Amount.valueOf(0, SI.SECOND), initial);\r
  87                 \r
  88                 for ( int i = 0; i < 5000; i++ ){\r
  89 \r
  90                         Interval prev = data.get(data.lastKey());\r
  91                         log.debug(prev);\r
  92                         log.debug("Step " + i + " ==============================");\r
  93                         Interval next = new Interval();\r
  94                         \r
  95                         Amount<Velocity> burnRate = motor.getFuel().burnRate(prev.chamberPressure);\r
  96                         \r
  97                         log.debug("Burn Rate: " + burnRate);\r
  98                         \r
  99                         Amount<Duration> dt = regStep.divide(burnRate).to(Duration.UNIT);\r
 100                         next.dt = dt;\r
 101                         \r
 102                         data.put(data.lastKey().plus(dt), next);\r
 103                         \r
 104                         log.debug("Dt: " + dt);\r
 105                         \r
 106                         next.regression = prev.regression.plus(regStep);\r
 107                         \r
 108                         log.info("Regression: " + next.regression);\r
 109                         \r
 110                         next.time = prev.time.plus(dt);\r
 111                         \r
 112                         log.debug("Vold: " + motor.getGrain().volume(prev.regression).to(SI.MILLIMETER.pow(3)));\r
 113                         \r
 114                         log.debug("Vnew: " + motor.getGrain().volume(next.regression).to(SI.MILLIMETER.pow(3)));\r
 115                         \r
 116                         //TODO Amount<Volume> volumeBurnt = motor.getGrain().volume(prev.regression).minus(motor.getGrain().volume(next.regression));\r
 117                         Amount<Volume> volumeBurnt = motor.getGrain().surfaceArea(prev.regression).times(regStep).to(Volume.UNIT);\r
 118                         \r
 119                         log.info("Volume Burnt: " + volumeBurnt.to(SI.MILLIMETER.pow(3)));\r
 120                         \r
 121                         Amount<MassFlowRate> mGenRate = volumeBurnt.times(motor.getFuel().getIdealDensity().times(motor.getFuel().getDensityRatio())).divide(dt).to(MassFlowRate.UNIT);\r
 122                         \r
 123                         log.debug("Mass Gen Rate: " + mGenRate);\r
 124                         \r
 125                         Amount specificGasConstant = Constants.R.divide(motor.getFuel().getCombustionProduct().getEffectiveMolarWeight());\r
 126                         Amount<Temperature> chamberTemp = motor.getFuel().getCombustionProduct().getIdealCombustionTemperature().times(motor.getFuel().getCombustionEfficiency());\r
 127                         \r
 128                         Amount<MassFlowRate> mNozzle;\r
 129                         {\r
 130                                 Amount<Pressure> pDiff = prev.chamberPressure.minus(atmosphereicPressure);\r
 131                                 \r
 132                                 //pDiff = Amount.valueOf(.7342, MPA).minus(atmosphereicPressure);\r
 133                                 \r
 134                                 log.debug("Pdiff: " + pDiff);\r
 135                                 \r
 136                                 Amount<Area> aStar = motor.getNozzle().throatArea();\r
 137                                 \r
 138                                 double k = motor.getFuel().getCombustionProduct().getRatioOfSpecificHeats();\r
 139                                 \r
 140                                 log.debug("K: " + k);\r
 141                                 \r
 142                                 double kSide = Math.sqrt(k) * Math.pow((2/(k+1)) , (((k+1)/2)/(k-1))); //Math.pow(2/k+1, (k+1)/(2*(k-1)));\r
 143                                 \r
 144                                 log.debug("K-Part: (good)" + kSide);\r
 145                                 \r
 146                                 \r
 147                                 \r
 148                                 //This unit conversion helps JScience to convert nozzle flow rate to\r
 149                                 //kg/s a little later on I verified the conversion by hand and\r
 150                                 //JScience checks it too.\r
 151                                 specificGasConstant = convertSpecificGasConstantUnits(specificGasConstant);\r
 152                                 \r
 153                                 log.debug("Specific Gas Constant: (good)" + specificGasConstant);\r
 154                                 \r
 155                                 Amount sqrtPart = specificGasConstant.times(chamberTemp).sqrt();\r
 156 \r
 157                                 //Unit x = SI.JOULE.divide(SI.KILOGRAM).root(2);\r
 158                                 \r
 159                                 //sqrtPart = sqrtPart.times(Amount.valueOf(1, x));\r
 160                                 \r
 161                                 log.debug("Square Root Part: " + sqrtPart);\r
 162                                 \r
 163                                 mNozzle = pDiff.times(aStar).times(kSide).divide(sqrtPart).to(MassFlowRate.UNIT);\r
 164                                 \r
 165                                 log.debug("Nozzle Flow: " + mNozzle);\r
 166                                 \r
 167                                 log.debug("Nozzle Flow: " + mNozzle.to(MassFlowRate.UNIT));\r
 168                                 \r
 169                                 \r
 170                                 \r
 171                                 \r
 172                         }\r
 173                         \r
 174                         Amount<MassFlowRate> massStorageRate = mGenRate.minus(mNozzle);\r
 175                         \r
 176                         log.debug("Chamber Product rate: " + massStorageRate);\r
 177                         \r
 178                         next.chamberProduct = prev.chamberProduct.plus(massStorageRate.times(dt));\r
 179                         \r
 180                         log.debug("Chamber Product: " + next.chamberProduct);\r
 181                         \r
 182                         Amount<VolumetricDensity> combustionProductDensity = next.chamberProduct.divide(motor.getChamber().chamberVolume().minus(motor.getGrain().volume(next.regression))).to(VolumetricDensity.UNIT);\r
 183                         \r
 184                         log.debug("Product Density: " + combustionProductDensity);\r
 185                         \r
 186                         next.chamberPressure = combustionProductDensity.times(specificGasConstant).times(chamberTemp).plus(atmosphereicPressure).to(Pressure.UNIT);\r
 187                         \r
 188                         next.chamberPressure = Amount.valueOf(\r
 189                                         next.chamberPressure.doubleValue(SI.PASCAL),\r
 190                                         SI.PASCAL);\r
 191                         \r
 192                         next.thrust = motor.getNozzle().thrust(next.chamberPressure, atmosphereicPressure, atmosphereicPressure, motor.getFuel().getCombustionProduct().getRatioOfSpecificHeats2Phase());\r
 193                         \r
 194                         if ( next.chamberPressure.approximates(atmosphereicPressure)){\r
 195                                 log.info("Pressure at Patm on step " + i);\r
 196                                 break;\r
 197                         }\r
 198                 }\r
 199 \r
 200         }\r
 201         \r
 202         @SuppressWarnings("unchecked")\r
 203         /*\r
 204          * This converts the units of this constant to something JScience is able\r
 205          * to work from. This conversion is unchecked at compile time, but\r
 206          * JScience keeps me honest at runtime.\r
 207          */\r
 208         private Amount convertSpecificGasConstantUnits(Amount a){\r
 209                 return a.to(\r
 210                                 SI.METER.pow(2).divide(SI.SECOND.pow(2).times(SI.KELVIN)));\r
 211         }\r
 212         \r
 213         public Amount<Pressure> pressure(Amount<Duration> time){\r
 214                 return data.get(time).chamberPressure;\r
 215         }\r
 216         \r
 217         public Amount<Force> thrust(Amount<Duration> time){\r
 218                 return data.get(time).thrust;\r
 219         }\r
 220         \r
 221         public Amount<Dimensionless> kn(Amount<Length> regression){\r
 222                 return motor.getGrain().surfaceArea(regression).divide(motor.getNozzle().throatArea()).to(Dimensionless.UNIT);\r
 223         }\r
 224         \r
 225 }\r