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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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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
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Th
rus
t (o
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Converging
Diverging
Regular Orifice
ConvergingDiverging
Next time…
Questions?
Converging/Diverging
Diverging
Converging
Orifice
