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Commit so I can grab latest changes from unstable

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This commit is contained in:
JoePfeiffer 2023-06-28 15:20:09 -06:00
parent 6908bd8e7b
commit a3aebadcff
2 changed files with 54 additions and 59 deletions
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72
core/src/net/sf/openrocket/aerodynamics/barrowman/TubeCalc.java
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@ -14,15 +14,13 @@ public abstract class TubeCalc extends RocketComponentCalc {
private final static Logger log = LoggerFactory.getLogger(TubeFinSetCalc.class); private final static Logger log = LoggerFactory.getLogger(TubeFinSetCalc.class);
// air density (standard conditions) private final Tube tube;
private final double rho = 1.225; // kg/m^3
private final double diameter; private final double diameter;
private final double length; private final double length;
protected final double innerArea; protected final double innerArea;
private final double totalArea; private final double totalArea;
private final double frontalArea; private final double frontalArea;
private final Tube tube; private final double epsilon;
public TubeCalc(RocketComponent component) { public TubeCalc(RocketComponent component) {
super(component); super(component);
@ -34,63 +32,49 @@ public abstract class TubeCalc extends RocketComponentCalc {
innerArea = Math.PI * MathUtil.pow2(tube.getInnerRadius()); innerArea = Math.PI * MathUtil.pow2(tube.getInnerRadius());
totalArea = Math.PI * MathUtil.pow2(tube.getOuterRadius()); totalArea = Math.PI * MathUtil.pow2(tube.getOuterRadius());
frontalArea = totalArea - innerArea; frontalArea = totalArea - innerArea;
epsilon = tube.getFinish().getRoughnessSize(); // roughness; note we don't maintain surface roughness of
// interior separately from exterior.
} }
@Override @Override
public double calculatePressureCD(FlightConditions conditions, public double calculatePressureCD(FlightConditions conditions,
double stagnationCD, double baseCD, WarningSet warnings) { double stagnationCD, double baseCD, WarningSet warnings) {
// These calculations come from a mix of theoretical and empirical
// results, and are marked with (t) for theoretical and (e) for empirical.
// The theoretical results should not be modified; the empirical can be adjusted
// to better simulate real rockets as we get data.
// For the sources of the empirical formulas, see 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.
// For the rockets for which we have data, the effect of the stagnation CD appears to be
// overstated. This code multiplies it be a factor of 0.7 to better match experimental
// data
// Need to check for tube inner area 0 in case of rockets using launch lugs with // Need to check for tube inner area 0 in case of rockets using launch lugs with
// an inner radius of 0 to emulate rail buttons (or just weird rockets, of course) // an inner radius of 0 to emulate rail guides (or just weird rockets, of course)
double tubeCD = 0.0;
double deltap; double deltap;
if (innerArea > MathUtil.EPSILON) { if (innerArea > MathUtil.EPSILON) {
// Temperature and Pressure // Current atmospheric conditions
final double T = conditions.getAtmosphericConditions().getTemperature(); final double p = conditions.getAtmosphericConditions().getPressure();
final double P = conditions.getAtmosphericConditions().getPressure(); final double t = conditions.getAtmosphericConditions().getTemperature();
final double rho = conditions.getAtmosphericConditions().getDensity();
// Volume flow rate (t) final double v = conditions.getVelocity();
final double Q = conditions.getVelocity() * innerArea;
// Air viscosity
final double mu = conditions.getAtmosphericConditions().getKinematicViscosity();
// Air density
final double rho = 1.225; // at standard temperature and pressure
// Reynolds number (note Reynolds number for the interior of a pipe is based on diameter, // Reynolds number (note Reynolds number for the interior of a pipe is based on diameter,
// not length (t)) // not length (t))
final double Re = (4.0 * rho * Q) / (Math.PI * diameter * mu); final double Re = v * diameter / conditions.getAtmosphericConditions().getKinematicViscosity();
// friction coefficient (for smooth tube interior) (e) // friction coefficient using Swamee-Jain equation
final double lambda = 1/MathUtil.pow2(2 * Math.log(0.5625 * Math.pow(Re, 0.875)) - 0.8); double f = 0.25/MathUtil.pow2(Math.log10((epsilon / (3.7 * diameter) + 5.74/Math.pow(Re, 0.9))));
// pressure drop (e) // If we're supersonic, apply a correction
final double P0 = 101325; // standard pressure // if (conditions.getMach() > 1) {
final double T0 = 273.15; // standard temperature // f = f / conditions.getBeta();
deltap = ((lambda * 8 * length * rho * MathUtil.pow2(Q)) / (MathUtil.pow2(Math.PI) * Math.pow(diameter, 5)) * (T/T0) * (P0/P)); // }
} else {
deltap = 0.0; // pressure drop using Darcy-Weissbach equation
deltap = f * (length * rho * MathUtil.pow2(v)) / (2 * diameter);
System.out.println(tube + ", v " + v + ", Re " + Re + ", p " + p + ": " + "deltap " + deltap);
// drag coefficient of tube interior from pressure drop
tubeCD = 2 * (deltap * innerArea) / (rho * MathUtil.pow2(v) * innerArea);
} }
// convert to CD and return // convert to CD and return
final double cdpress = 2.0 * deltap / (conditions.getAtmosphericConditions().getDensity() * MathUtil.pow2(conditions.getVelocity())); System.out.println(tube + " tube CD " + tubeCD + ", stagnationCD " + stagnationCD + ", baseCD " + baseCD + ", inner area " + innerArea + ", frontal area " + frontalArea);
final double cd = (cdpress * innerArea + 0.43*(stagnationCD + baseCD) * frontalArea)/conditions.getRefArea(); final double cd = (tubeCD * innerArea + (stagnationCD + baseCD) * frontalArea) / conditions.getRefArea();
System.out.println(tube + " cd " + cd);
return cd; return cd;
} }
} }

29
core/src/net/sf/openrocket/aerodynamics/barrowman/TubeFinSetCalc.java
View File

@ -26,6 +26,8 @@ public class TubeFinSetCalc extends TubeCalc {
private static final double STALL_ANGLE = (20 * Math.PI / 180); private static final double STALL_ANGLE = (20 * Math.PI / 180);
private final double[] poly = new double[6]; private final double[] poly = new double[6];
private final TubeFinSet tubes;
// parameters straight from configuration; we'll be grabbing them once // parameters straight from configuration; we'll be grabbing them once
// so code is a bit shorter elsewhere // so code is a bit shorter elsewhere
private final double bodyRadius; private final double bodyRadius;
@ -51,7 +53,7 @@ public class TubeFinSetCalc extends TubeCalc {
throw new IllegalArgumentException("Illegal component type " + component); throw new IllegalArgumentException("Illegal component type " + component);
} }
final TubeFinSet tubes = (TubeFinSet) component; tubes = (TubeFinSet) component;
if (tubes.getTubeSeparation() > MathUtil.EPSILON) { if (tubes.getTubeSeparation() > MathUtil.EPSILON) {
geometryWarnings.add(Warning.TUBE_SEPARATION); geometryWarnings.add(Warning.TUBE_SEPARATION);
@ -88,17 +90,19 @@ public class TubeFinSetCalc extends TubeCalc {
// Find length of d // Find length of d
final double d = Math.sqrt(MathUtil.pow2(bodyRadius + outerRadius) - MathUtil.pow2(outerRadius)); final double d = Math.sqrt(MathUtil.pow2(bodyRadius + outerRadius) - MathUtil.pow2(outerRadius));
// Area of diamond consisting of triangle reflected on its hypotenuse // Area of diamond formed by mirroring triangle on its hypotenuse (same area as rectangle
// formed by d and outerarea, but it *isn't* that rectangle)
double a = d * outerRadius; double a = d * outerRadius;
// angle between outerRadius and bodyRadius+outerRadius // angle between outerRadius and bodyRadius+outerRadius
final double theta1 = Math.acos(outerRadius/(outerRadius + bodyRadius)); final double theta1 = Math.acos(outerRadius/(outerRadius + bodyRadius));
// area of arc from tube fin, doubled so we have area to remove from diamond // area of arc from tube fin, doubled to get both halves of diamond
final double a1 = MathUtil.pow2(outerRadius) * theta1; final double a1 = MathUtil.pow2(outerRadius) * theta1;
// angle between bodyRadius+outerRadius and d // angle between bodyRadius+outerRadius and d
final double theta2 = Math.PI/2.0 - theta1; final double theta2 = Math.PI/2.0 - theta1;
System.out.println("theta2 " + theta2);
// area of arc from body tube. Doubled so we have area to remove from diamond // area of arc from body tube. Doubled so we have area to remove from diamond
final double a2 = MathUtil.pow2(bodyRadius) * theta2; final double a2 = MathUtil.pow2(bodyRadius) * theta2;
@ -113,13 +117,18 @@ public class TubeFinSetCalc extends TubeCalc {
// that affects the pressure drop through the tube and so (indirecctly) affects the pressure drag. // that affects the pressure drop through the tube and so (indirecctly) affects the pressure drag.
// Area of the outer surface of a tube, not including portion masked by interstice // Area of the outer surface of a tube, not including portion masked by interstice
final double outerArea = chord * 2 * (Math.PI - theta1) * outerRadius; final double outerArea = chord * 2.0 * (Math.PI - theta1) * outerRadius;
// Surface area of the portion of the body tube masked by the tube fins, per tube // Area of inner surface of a tube
final BodyTube parent = (BodyTube) tubes.getParent(); final double innerArea = chord * 2.0 * Math.PI * innerRadius;
final double maskedArea = chord * 2.0 * Math.PI * bodyRadius / tubeCount;
wettedArea = outerArea - maskedArea; // Surface area of the portion of the body tube masked by the tube fin. We'll subtract it from
// the tube fin area rather than go in and change the body tube surface area calculation. If tube
// fin and body tube roughness aren't the same this will result in an inaccuracy.
final double maskedArea = chord * 2.0 * theta2 * bodyRadius;
wettedArea = innerArea + outerArea - maskedArea;
System.out.println(tubes + " outer " + outerArea + ", masked " + maskedArea);
log.debug("wetted area of tube fin " + wettedArea); log.debug("wetted area of tube fin " + wettedArea);
// Precompute most of CNa. Equation comes from Ribner, "The ring airfoil in nonaxial // Precompute most of CNa. Equation comes from Ribner, "The ring airfoil in nonaxial
@ -261,6 +270,7 @@ public class TubeFinSetCalc extends TubeCalc {
@Override @Override
public double calculateFrictionCD(FlightConditions conditions, double componentCf, WarningSet warnings) { public double calculateFrictionCD(FlightConditions conditions, double componentCf, WarningSet warnings) {
System.out.println(tubes + "wetted area " + wettedArea);
final double frictionCD = componentCf * wettedArea / conditions.getRefArea(); final double frictionCD = componentCf * wettedArea / conditions.getRefArea();
return frictionCD; return frictionCD;
@ -271,9 +281,10 @@ public class TubeFinSetCalc extends TubeCalc {
double stagnationCD, double baseCD, WarningSet warnings) { double stagnationCD, double baseCD, WarningSet warnings) {
warnings.addAll(geometryWarnings); warnings.addAll(geometryWarnings);
System.out.println(tubes + " stag CD " + stagnationCD + ", base CD " + baseCD);
final double cd = super.calculatePressureCD(conditions, stagnationCD, baseCD, warnings) + final double cd = super.calculatePressureCD(conditions, stagnationCD, baseCD, warnings) +
(stagnationCD + baseCD) * intersticeArea / conditions.getRefArea(); (stagnationCD + baseCD) * intersticeArea / conditions.getRefArea();
return cd; return cd;
} }