Rocketproject

Rocket Nozzle DesignRocket Nozzle Design

Group Members:Group Members:MikeMikeNickNick

Introduction...

Presentation Outline Introduction (Nick)

Brief Theory / FLUENT Modeling (Mike)

Literature / Experimental Data (Nick)

Conclusion (Mike)

Introduction...

Project Objectives

1)To analyze four simplified nozzle geometries in a model rocket and calculate their maximum thrust.

2) Compare the theoretical and experimental thrust of these nozzles. Choose the best nozzle based on our data.

Introduction...

Which simplifications?The Nozzle Configurations we modeled:1) Orifice 2) Converging Nozzle3) Diverging Nozzle4) Converging-Diverging

(Click on links above to see the various configurations)

Introduction...

Rocket Particulars

The type of rocket we modeled:

1) Solid Propellant / Core Burning

Core burning rockets burn propellant from the “inside out.”

Graphic from: http://www.sewanee.edu/physics/SEMINARS/HTML%20Rowland/sld011.htm

This is in comparison to end-burning rockets which burn propellant from the “bottom up.”

Introduction...

Rocket ParticularsThe size of rocket

we modeled:

0.25 Inch diameter casing

2) 2.25 Inches Long

Brief Theory

How to calculate thrust

The general thrust equation is given as follows:

Graphic from: http://members.aol.com/ricnakk/th_thrst.html

GAMBIT

BoundaryConditions

GAMBIT

The Mesh

Triangular Elements

40 to 400 Intervals/Inch

FLUENT

Assumptions

1) Axisymmetric 2D Flow2) Steady State / Constant Pressure Inlet3) Compressible Flow 4) Ideal Gas (air)

FLUENT

Particular Settings1) On all configurations the iterations

were run to a residual of 1e-32) Turbulent Flow (K-E model) 3) Variable Density4) Used 2nd Order Equations to Calculate

Density / Pressure / Momentum

FLUENT

Velocity Contour Plots

FLUENT

Pressure Contour Plots

FLUENT

Density Contour Plots

FLUENT

Results

Nozzle Type Force (oz)

Converging 4.56841

Diverging 3.81035

Regular Orifice 4.18331

Converging - Diverging 7.53282

FLUENT

Graphical Results

FLUENT Results

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1.00

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4.00

5.00

6.00

7.00

8.00

1

Th

rus

t (o

z)

Converging

Diverging

Regular Orifice

ConvergingDiverging

Literature

Graphic from: http://www.nakka-rocketry.net/lambda_p.html

The preponderance of literature clearly shows the Converging – Diverging Nozzle as the most efficient nozzle design.

Diagrams like this (right) are not uncommon:

LiteratureSimilar Pressure Trends

Experimental DataIntroduction

Homemade rockets with these four various nozzle geometries were built and tested. All thrust values were measured and recorded.

Experimental DataExperimental Setup Method #1

Method #1

In this case the nozzle thrust was downward onto the scale.

Before ignition, a thin metal plate was placed on top of the scale to protect it from the flame.

Experimental DataTesting Using Method #1

Note the metal plate protecting the plastic of the scale.

For record keeping, a camcorder was zoomed up close to the scale and recording.

Experimental DataMethod #1 (Thrust Downward)

Nozzle TypeSet 1

(oz)Set 2

(oz)

Converging 0.5 0.4

Diverging 0.25 dud

Regular Orifice 0.6 0.7

Converging - Diverging n/a n/a

Experimental DataExperimental Setup Method #2Method #2

In this case the nozzle was placed into a hollow tube and thrust was directed upward. Thus the rocket pushed onto the scale.

Experimental DataTesting Using Method #2

Note the camcorder was zoomed up close to the scale.(Right) Movie ofConverging-Diverging Run:Click on Image to Play

Experimental DataData Using Method #2

We were able to go back and watch our results on TV in slow motion.

Experimental DataMethod #2 (Thrust Upwards)

Nozzle Type Set 3 (oz)

Converging 0.6

Diverging 0.45

Regular Orifice 0.25

Converging - Diverging 0.90

Conclusion FLUENT Results

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1T

hru

st

(oz)

Converging

Diverging

Regular Orifice

ConvergingDiverging

Experimental Data Results

0

0.2

0.4

0.6

0.8

1

1

Th

rus

t (o

z)

Converging

Diverging

Regular Orifice

ConvergingDiverging

Next time…

Questions?

Converging/Diverging

Diverging

Converging

Orifice