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

   1 package com.billkuker.rocketry.motorsim;\r
   2 \r
   3 import java.awt.Shape;\r
   4 import java.awt.geom.AffineTransform;\r
   5 import java.awt.geom.GeneralPath;\r
   6 import java.awt.geom.Line2D;\r
   7 \r
   8 import javax.measure.quantity.Area;\r
   9 import javax.measure.quantity.Dimensionless;\r
  10 import javax.measure.quantity.Force;\r
  11 import javax.measure.quantity.Length;\r
  12 import javax.measure.quantity.Pressure;\r
  13 import javax.measure.unit.SI;\r
  14 \r
  15 import org.jscience.physics.amount.Amount;\r
  16 \r
  17 public class ConvergentDivergentNozzle implements Nozzle, Validating {\r
  18 \r
  19         private Amount<Length> throatDiameter;\r
  20         \r
  21         private Amount<Length> exitDiameter;\r
  22         \r
  23         private double efficiency = 1.0;\r
  24         \r
  25         \r
  26         public Amount<Area> throatArea() {\r
  27                 return throatDiameter.divide(2).pow(2).times(Math.PI).to(Area.UNIT);\r
  28         }\r
  29         \r
  30         public Amount<Area> exitArea() {\r
  31                 return exitDiameter.divide(2).pow(2).times(Math.PI).to(Area.UNIT);\r
  32         }\r
  33 \r
  34 \r
  35         public Amount<Length> getThroatDiameter() {\r
  36                 return throatDiameter;\r
  37         }\r
  38 \r
  39 \r
  40         public void setThroatDiameter(Amount<Length> throatDiameter) {\r
  41                 this.throatDiameter = throatDiameter;\r
  42         }\r
  43         \r
  44 \r
  45         public Amount<Length> getExitDiameter() {\r
  46                 return exitDiameter;\r
  47         }\r
  48 \r
  49 \r
  50         public void setExitDiameter(Amount<Length> exitDiameter) {\r
  51                 this.exitDiameter = exitDiameter;\r
  52         }\r
  53         \r
  54         public Amount<Force> thrust(Amount<Pressure> Po, Amount<Pressure> Pe, Amount<Pressure> Patm, final double k ){\r
  55                 double cF = thrustCoefficient(Po, Pe, Patm, k);\r
  56                 return Po.times(throatArea()).times(cF).to(Force.UNIT);\r
  57         }\r
  58 \r
  59         public double thrustCoefficient(Amount<Pressure> Po, Amount<Pressure> Pe, Amount<Pressure> Patm, final double k ){\r
  60                 double pRatio = Pe.divide(Po).to(Dimensionless.UNIT).doubleValue(Dimensionless.UNIT);\r
  61 \r
  62                 double a = (2*k*k)/(k-1);\r
  63                 \r
  64                 double b = Math.pow(2/(k+1), (k+1)/(k-1) );\r
  65                 \r
  66                 double c = 1.0 - Math.pow(pRatio, (k-1)/k);\r
  67                 \r
  68                 Amount<Pressure> pDiff = Pe.minus(Patm);\r
  69                 \r
  70                 double d = pDiff.times(exitArea()).divide(Po.times(throatArea())).to(Dimensionless.UNIT).doubleValue(Dimensionless.UNIT);\r
  71                 \r
  72                 double Cf = efficiency * Math.sqrt(a*b*c)+d;\r
  73                 \r
  74                 return Cf;\r
  75         }\r
  76 \r
  77         public double getEfficiency() {\r
  78                 return efficiency;\r
  79         }\r
  80 \r
  81         public void setEfficiency(double efficiency) {\r
  82                 this.efficiency = efficiency;\r
  83         }\r
  84 \r
  85         public Shape nozzleShape(Amount<Length> chamberDiameter){\r
  86                 GeneralPath s = new GeneralPath();\r
  87                 double throatR = throatDiameter.divide(2).doubleValue(SI.MILLIMETER);\r
  88                 double exitR = exitDiameter.divide(2).doubleValue(SI.MILLIMETER);\r
  89                 double cR;\r
  90                 if (chamberDiameter == null)\r
  91                         cR = exitR;\r
  92                 else\r
  93                         cR = chamberDiameter.divide(2).doubleValue(SI.MILLIMETER);\r
  94                 \r
  95                 double diff = exitR-throatR;\r
  96                 double cDiff = cR-throatR;\r
  97                 \r
  98                 s.append(new Line2D.Double(0,0,diff,diff*3), false);\r
  99                 s.append(new Line2D.Double(0,0,cDiff,-cDiff), true);\r
 100                 \r
 101                 s.transform(AffineTransform.getScaleInstance(-1, 1));\r
 102                 s.transform(AffineTransform.getTranslateInstance(-throatR * 2, 0));\r
 103                 \r
 104                 s.append(new Line2D.Double(0,0,diff,diff*3), false);\r
 105                 s.append(new Line2D.Double(0,0,cDiff,-cDiff), true);\r
 106                 \r
 107                 s.transform(AffineTransform.getTranslateInstance(throatR, cDiff));\r
 108                 //a.add(new java.awt.geom.Area( new Ellipse2D.Double(0,0,5,5)));\r
 109                 \r
 110                 return s;\r
 111         }\r
 112 \r
 113         @Override\r
 114         public void validate() throws ValidationException {\r
 115                 if ( exitDiameter != null && throatDiameter.isGreaterThan(exitDiameter))\r
 116                         throw new IllegalArgumentException("Throat > Exit");\r
 117         }\r
 118 }\r