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Merge pull request #1312 from JoePfeiffer/fix-1207a

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Rewrite tube fin and launch lug drag calculations
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SiboVG 2022-04-28 01:33:52 +02:00 committed by GitHub
commit d0348726d3
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10 changed files with 158 additions and 128 deletions
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3
core/resources/l10n/messages.properties
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@ -1756,6 +1756,9 @@ Warning.TUMBLE_UNDER_THRUST = Stage began to tumble under thrust.
Warning.EVENT_AFTER_LANDING = Flight Event occurred after landing:
Warning.ZERO_LENGTH_BODY = Zero length bodies may not result in accurate simulations.
Warning.ZERO_RADIUS_BODY = Zero length bodies may not result in accurate simulations.
Warning.TUBE_STABILITY = Tube fin stability calculations may not be accurate.
Warning.TUBE_SEPARATION = Space between tube fins may not result in accurate simulations.
Warning.TUBE_OVERLAP = Overlapping tube fins may not result in accurate simulations.
! Scale dialog
ScaleDialog.lbl.scaleRocket = Entire rocket

11
core/src/net/sf/openrocket/aerodynamics/BarrowmanCalculator.java
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@ -341,7 +341,7 @@ public class BarrowmanCalculator extends AbstractAerodynamicCalculator {
* for thickness as we go on.
*/
double finFrictionCD = 0;
double otherFrictionCD = 0;
double bodyFrictionCD = 0;
double maxR = 0, minX = Double.MAX_VALUE, maxX = 0;
@ -407,8 +407,8 @@ public class BarrowmanCalculator extends AbstractAerodynamicCalculator {
final double componentMaxR = Math.max(s.getForeRadius(), s.getAftRadius());
maxR = Math.max(maxR, componentMaxR);
} else if (c instanceof FinSet) {
finFrictionCD += componentFrictionCD;
} else {
otherFrictionCD += componentFrictionCD;
}
if (map != null) {
@ -430,7 +430,7 @@ public class BarrowmanCalculator extends AbstractAerodynamicCalculator {
}
}
return finFrictionCD + correction * bodyFrictionCD;
return otherFrictionCD + correction * bodyFrictionCD;
}
@ -585,6 +585,7 @@ public class BarrowmanCalculator extends AbstractAerodynamicCalculator {
final InstanceMap imap = configuration.getActiveInstances();
for(Map.Entry<RocketComponent, ArrayList<InstanceContext>> entry: imap.entrySet() ) {
final RocketComponent c = entry.getKey();
log.debug("component " + c);
if (!c.isAerodynamic())
continue;
@ -593,7 +594,7 @@ public class BarrowmanCalculator extends AbstractAerodynamicCalculator {
final ArrayList<InstanceContext> contextList = entry.getValue();
for(InstanceContext context: contextList ) {
// Pressure fore drag
// Pressure drag
double cd = calcMap.get(c).calculatePressureCD(conditions, stagnation, base,
warningSet);
total += cd;

3
core/src/net/sf/openrocket/aerodynamics/Warning.java
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@ -392,4 +392,7 @@ public abstract class Warning {
public static final Warning ZERO_LENGTH_BODY = new Other(trans.get("Warning.ZERO_LENGTH_BODY"));
public static final Warning ZERO_RADIUS_BODY = new Other(trans.get("Warning.ZERO_RADIUS_BODY"));
public static final Warning TUBE_STABILITY = new Other(trans.get("Warning.TUBE_STABILITY"));
public static final Warning TUBE_SEPARATION = new Other(trans.get("Warning.TUBE_SEPARATION"));
public static final Warning TUBE_OVERLAP = new Other(trans.get("Warning.TUBE_OVERLAP"));
}

20
core/src/net/sf/openrocket/aerodynamics/barrowman/LaunchLugCalc.java
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@ -8,20 +8,10 @@ import net.sf.openrocket.rocketcomponent.RocketComponent;
import net.sf.openrocket.util.MathUtil;
import net.sf.openrocket.util.Transformation;
public class LaunchLugCalc extends RocketComponentCalc {
public class LaunchLugCalc extends TubeCalc {
private final double CDmul;
private final double refArea;
public LaunchLugCalc(RocketComponent component) {
super(component);
LaunchLug lug = (LaunchLug)component;
double ld = lug.getLength() / (2*lug.getOuterRadius());
CDmul = Math.max(1.3 - ld, 1);
refArea = Math.PI * MathUtil.pow2(lug.getOuterRadius()) -
Math.PI * MathUtil.pow2(lug.getInnerRadius()) * Math.max(1 - ld, 0);
}
@Override
@ -35,12 +25,4 @@ public class LaunchLugCalc extends RocketComponentCalc {
// launch lug doesn't add enough area to worry about
return 0;
}
@Override
public double calculatePressureCD(FlightConditions conditions,
double stagnationCD, double baseCD, WarningSet warnings) {
return CDmul*stagnationCD * refArea / conditions.getRefArea();
}
}

45
core/src/net/sf/openrocket/aerodynamics/barrowman/TubeCalc.java Normal file
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@ -0,0 +1,45 @@
package net.sf.openrocket.aerodynamics.barrowman;
import net.sf.openrocket.aerodynamics.FlightConditions;
import net.sf.openrocket.aerodynamics.WarningSet;
import net.sf.openrocket.rocketcomponent.RocketComponent;
import net.sf.openrocket.rocketcomponent.Tube;
import net.sf.openrocket.util.MathUtil;
public abstract class TubeCalc extends RocketComponentCalc {
private final double diameter;
private final double length;
protected double refArea;
public TubeCalc(RocketComponent component) {
super(component);
Tube tube = (Tube)component;
length = tube.getLength();
diameter = 2 * tube.getInnerRadius();
refArea = Math.PI * MathUtil.pow2(tube.getInnerRadius());
}
@Override
public double calculatePressureCD(FlightConditions conditions,
double stagnationCD, double baseCD, WarningSet warnings) {
// calculation of pressure drop through pipe from "Atlas Copco Air Compendium", 1975,
// quoted as equation 14 in Carello, Ivanov, and Mazza, "Pressure drop in pipe
// lines for compressed air: comparison between experimental and theoretical analysis",
// Transactions on Engineering Sciences vol 18, ISSN 1743-35331998, 1998.
// Volume flow rate
final double Q = conditions.getVelocity() * refArea;
// pressure drop
final double deltap = 1.6 * 1000 * Math.pow(Q, 1.85) * Math.pow(Q, 1.85) * length /
(Math.pow(diameter, 5) * conditions.getAtmosphericConditions().getPressure());
// convert to CD and return
return deltap * refArea / conditions.getRefArea();
}
}

183
core/src/net/sf/openrocket/aerodynamics/barrowman/TubeFinSetCalc.java
View File

@ -10,6 +10,7 @@ import net.sf.openrocket.aerodynamics.FlightConditions;
import net.sf.openrocket.aerodynamics.Warning;
import net.sf.openrocket.aerodynamics.Warning.Other;
import net.sf.openrocket.aerodynamics.WarningSet;
import net.sf.openrocket.rocketcomponent.BodyTube;
import net.sf.openrocket.rocketcomponent.FinSet;
import net.sf.openrocket.rocketcomponent.RocketComponent;
import net.sf.openrocket.rocketcomponent.TubeFinSet;
@ -28,14 +29,14 @@ import org.slf4j.LoggerFactory;
* Uses a complete clone of FinSetCalc modelling each tube fin as 3 individual fins. It does not correctly account for
* fin & tube fin interference.
*
* Changes to BarrowmanCalculator's calculateFrictionDrag are also probably required.
*
* @author kruland
*
*/
public class TubeFinSetCalc extends RocketComponentCalc {
public class TubeFinSetCalc extends TubeCalc {
private final static Logger logger = LoggerFactory.getLogger(FinSetCalc.class);
private final static Logger log = LoggerFactory.getLogger(TubeFinSetCalc.class);
final double intersticeArea;
private static final double STALL_ANGLE = (20 * Math.PI / 180);
@ -56,8 +57,12 @@ public class TubeFinSetCalc extends RocketComponentCalc {
protected double[] chordLead = new double[DIVISIONS];
protected double[] chordTrail = new double[DIVISIONS];
protected double[] chordLength = new double[DIVISIONS];
protected final WarningSet geometryWarnings = new WarningSet();
private final double[] poly = new double[6];
private final double wettedArea;
private final double thickness;
private final double bodyRadius;
@ -73,9 +78,53 @@ public class TubeFinSetCalc extends RocketComponentCalc {
throw new IllegalArgumentException("Illegal component type " + component);
}
TubeFinSet fin = (TubeFinSet) component;
final TubeFinSet tubes = (TubeFinSet) component;
final TubeFinSet fin = tubes; // keep this around while we're still leveraging FinSet
geometryWarnings.add(Warning.TUBE_STABILITY);
if (tubes.getTubeSeparation() > MathUtil.EPSILON) {
geometryWarnings.add(Warning.TUBE_SEPARATION);
} else if (tubes.getTubeSeparation() < -MathUtil.EPSILON) {
geometryWarnings.add(Warning.TUBE_OVERLAP);
}
// precompute geometry. This will be the geometry of a single tube, since BarrowmanCalculator
// iterates across them. Doesn't consider interference between them; that should only be relevant for
// fins that are either separated or overlapping.
bodyRadius = tubes.getBodyRadius();
// 1. wetted area for friction drag calculation. We don't consider the inner surface of the tube;
// that affects the pressure drop through the tube and so (indirecctly) affects the pressure drag.
// Area of the outer surface of tubes. Since roughly half
// of the area is "masked" by the interstices between the tubes and the
// body tube, only consider the other half of the area
final double outerArea = tubes.getLength() * Math.PI * tubes.getOuterRadius();
// Surface area of the portion of the body tube masked by the tube fins
final BodyTube parent = (BodyTube) tubes.getParent();
final double maskedArea = tubes.getLength() * 2.0 * Math.PI * parent.getOuterRadius();
wettedArea = outerArea - maskedArea;
log.debug("wetted area of tube fins " + wettedArea);
// 2. frontal area of interstices between tubes for pressure drag calculation.
// We'll treat them as a closed blunt object.
// area of disk passing through tube fin centers
final double tubeDiskArea = Math.PI * MathUtil.pow2(bodyRadius + tubes.getOuterRadius());
// half of combined area of tube fin interiors.
final double tubeInnerArea = tubes.getFinCount() * Math.PI * MathUtil.pow2(tubes.getInnerRadius()) / 2.0;
// body tube area
final double bodyTubeArea = Math.PI * MathUtil.pow2(bodyRadius);
// area of an interstice
intersticeArea = (tubeDiskArea - tubeInnerArea - bodyTubeArea) / tubes.getFinCount();
log.debug("interstice area " + intersticeArea);
thickness = fin.getThickness();
bodyRadius = fin.getBodyRadius();
finCount = 3 * fin.getFinCount();
baseRotation = fin.getBaseRotation();
cantAngle = 0;
@ -94,7 +143,7 @@ public class TubeFinSetCalc extends RocketComponentCalc {
*/
@Override
public void calculateNonaxialForces(FlightConditions conditions, Transformation transform,
AerodynamicForces forces, WarningSet warnings) {
AerodynamicForces forces, WarningSet warnings) {
if (span < 0.001) {
forces.setCm(0);
@ -113,14 +162,13 @@ public class TubeFinSetCalc extends RocketComponentCalc {
if( (0 < bodyRadius) && (thickness > bodyRadius / 2)){
warnings.add(Warning.THICK_FIN);
}
warnings.add(new Other("Tube fin support is experimental"));
//////// Calculate CNa. /////////
// One fin without interference (both sub- and supersonic):
double cna1 = calculateFinCNa1(conditions);
// logger.debug("Component cna1 = {}", cna1);
// log.debug("Component cna1 = {}", cna1);
// Multiple fins with fin-fin interference
double cna;
@ -141,7 +189,7 @@ public class TubeFinSetCalc extends RocketComponentCalc {
cna = cna1 * finCount / 2.0;
}
// logger.debug("Component cna = {}", cna);
// log.debug("Component cna = {}", cna);
// Take into account fin-fin interference effects
switch (interferenceFinCount) {
@ -182,7 +230,7 @@ public class TubeFinSetCalc extends RocketComponentCalc {
tau = 0;
cna *= 1 + tau; // Classical Barrowman
// cna *= pow2(1 + tau); // Barrowman thesis (too optimistic??)
// logger.debug("Component cna = {}", cna);
// log.debug("Component cna = {}", cna);
// TODO: LOW: check for fin tip mach cone interference
// (Barrowman thesis pdf-page 40)
@ -191,9 +239,9 @@ public class TubeFinSetCalc extends RocketComponentCalc {
// Calculate CP position
double x = macLead + calculateCPPos(conditions) * macLength;
// logger.debug("Component macLead = {}", macLead);
// logger.debug("Component macLength = {}", macLength);
// logger.debug("Component x = {}", x);
// log.debug("Component macLead = {}", macLead);
// log.debug("Component macLength = {}", macLength);
// log.debug("Component x = {}", x);
// Calculate roll forces, reduce forcing above stall angle
@ -352,7 +400,7 @@ public class TubeFinSetCalc extends RocketComponentCalc {
double y = i * dy;
macLength += length * length;
logger.debug("macLength = {}, length = {}, i = {}", macLength, length, i);
log.debug("macLength = {}, length = {}, i = {}", macLength, length, i);
macSpan += y * length;
macLead += chordLead[i] * length;
area += length;
@ -368,7 +416,7 @@ public class TubeFinSetCalc extends RocketComponentCalc {
}
macLength *= dy;
logger.debug("macLength = {}", macLength);
log.debug("macLength = {}", macLength);
macSpan *= dy;
macLead *= dy;
area *= dy;
@ -537,7 +585,7 @@ public class TubeFinSetCalc extends RocketComponentCalc {
*/
private double calculateCPPos(FlightConditions cond) {
double m = cond.getMach();
// logger.debug("m = {} ", m);
// log.debug("m = {} ", m);
if (m <= 0.5) {
// At subsonic speeds CP at quarter chord
return 0.25;
@ -556,7 +604,7 @@ public class TubeFinSetCalc extends RocketComponentCalc {
val += poly[i] * x;
x *= m;
}
// logger.debug("val = {}", val);
// log.debug("val = {}", val);
return val;
}
@ -586,83 +634,27 @@ public class TubeFinSetCalc extends RocketComponentCalc {
poly[1] = (-31.6049 * (-0.705375 + ar) * (-0.198476 + ar)) / denom;
poly[0] = (9.16049 * (-0.588838 + ar) * (-0.20624 + ar)) / denom;
}
// @SuppressWarnings("null")
// public static void main(String arg[]) {
// Rocket rocket = TestRocket.makeRocket();
// FinSet finset = null;
//
// Iterator<RocketComponent> iter = rocket.deepIterator();
// while (iter.hasNext()) {
// RocketComponent c = iter.next();
// if (c instanceof FinSet) {
// finset = (FinSet)c;
// break;
// }
// }
//
// ((TrapezoidFinSet)finset).setHeight(0.10);
// ((TrapezoidFinSet)finset).setRootChord(0.10);
// ((TrapezoidFinSet)finset).setTipChord(0.10);
// ((TrapezoidFinSet)finset).setSweep(0.0);
//
//
// FinSetCalc calc = new FinSetCalc(finset);
//
// calc.calculateFinGeometry();
// FlightConditions cond = new FlightConditions(new Configuration(rocket));
// for (double m=0; m < 3; m+=0.05) {
// cond.setMach(m);
// cond.setAOA(0.0*Math.PI/180);
// double cna = calc.calculateFinCNa1(cond);
// System.out.printf("%5.2f "+cna+"\n", m);
// }
//
// }
@Override
public double calculateFrictionCD(FlightConditions conditions, double componentCf, WarningSet warnings) {
warnings.addAll(geometryWarnings);
final double frictionCD = componentCf * wettedArea / conditions.getRefArea();
log.debug("frictionCD " + frictionCD);
return frictionCD;
}
@Override
public double calculatePressureCD(FlightConditions conditions,
double stagnationCD, double baseCD, WarningSet warnings) {
double stagnationCD, double baseCD, WarningSet warnings) {
double mach = conditions.getMach();
double cd = 0;
// Pressure fore-drag
if (crossSection == FinSet.CrossSection.AIRFOIL ||
crossSection == FinSet.CrossSection.ROUNDED) {
// Round leading edge
if (mach < 0.9) {
cd = Math.pow(1 - pow2(mach), -0.417) - 1;
} else if (mach < 1) {
cd = 1 - 1.785 * (mach - 0.9);
} else {
cd = 1.214 - 0.502 / pow2(mach) + 0.1095 / pow2(pow2(mach));
}
} else if (crossSection == FinSet.CrossSection.SQUARE) {
cd = stagnationCD;
} else {
throw new UnsupportedOperationException("Unsupported fin profile: " + crossSection);
warnings.addAll(geometryWarnings);
final double cd = super.calculatePressureCD(conditions, stagnationCD, baseCD, warnings) +
(stagnationCD + baseCD) * intersticeArea / conditions.getRefArea();
log.debug("pressure CD " + cd);
return cd;
}
// Slanted leading edge
cd *= pow2(cosGammaLead);
// Trailing edge drag
if (crossSection == FinSet.CrossSection.SQUARE) {
cd += baseCD;
} else if (crossSection == FinSet.CrossSection.ROUNDED) {
cd += baseCD / 2;
}
// Airfoil assumed to have zero base drag
// Scale to correct reference area
cd *= finCount * span * thickness / conditions.getRefArea();
return cd;
}
private static int calculateInterferenceFinCount(TubeFinSet component) {
RocketComponent parent = component.getParent();
@ -672,11 +664,4 @@ public class TubeFinSetCalc extends RocketComponentCalc {
return 3 * component.getFinCount();
}
@Override
public double calculateFrictionCD(FlightConditions conditions, double componentCf, WarningSet warnings) {
// launch lug doesn't add enough area to worry about
return 0;
}
}

2
core/src/net/sf/openrocket/rocketcomponent/LaunchLug.java
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@ -17,7 +17,7 @@ import net.sf.openrocket.util.MathUtil;
import net.sf.openrocket.util.StateChangeListener;
public class LaunchLug extends ExternalComponent implements AnglePositionable, BoxBounded, Coaxial, LineInstanceable, InsideColorComponent {
public class LaunchLug extends Tube implements AnglePositionable, BoxBounded, LineInstanceable, InsideColorComponent {
private static final Translator trans = Application.getTranslator();

11
core/src/net/sf/openrocket/rocketcomponent/Tube.java Normal file
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@ -0,0 +1,11 @@
package net.sf.openrocket.rocketcomponent;
import net.sf.openrocket.rocketcomponent.position.AxialMethod;
public abstract class Tube extends ExternalComponent implements Coaxial {
public Tube(AxialMethod relativePosition) {
super(relativePosition);
}
}

2
core/src/net/sf/openrocket/rocketcomponent/TubeFinSet.java
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@ -17,7 +17,7 @@ import net.sf.openrocket.rocketcomponent.position.RadiusMethod;
import net.sf.openrocket.startup.Application;
import net.sf.openrocket.util.*;
public class TubeFinSet extends ExternalComponent implements AxialPositionable, BoxBounded, RingInstanceable, InsideColorComponent {
public class TubeFinSet extends Tube implements AxialPositionable, BoxBounded, RingInstanceable, InsideColorComponent {
private static final Translator trans = Application.getTranslator();
private final static double DEFAULT_RADIUS = 0.025;

6
swing/test/net/sf/openrocket/IntegrationTest.java
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@ -124,7 +124,7 @@ public class IntegrationTest {
// Compute cg+cp + altitude
// double cgx, double mass, double cpx, double cna)
checkCgCp(0.248, 0.0645, 0.320, 12.0);
checkAlt(48.2);
checkAlt(49.0);
// Mass modification
document.addUndoPosition("Modify mass");
@ -157,7 +157,7 @@ public class IntegrationTest {
// Check cg+cp + altitude
checkCgCp(0.163, 0.0613, 0.275, 9.95);
checkAlt(45.0);
checkAlt(45.6);
// Undo "Remove component" change
undoAction.actionPerformed(new ActionEvent(this, 0, "foo"));
@ -183,7 +183,7 @@ public class IntegrationTest {
// Check cg+cp + altitude
checkCgCp(0.248, 0.0645, 0.320, 12.0);
checkAlt(48.2);
checkAlt(48.87);
// Redo "Modify mass" change
redoAction.actionPerformed(new ActionEvent(this, 0, "foo"));