1. Rocket Nozzle Design
Group Members:
Mike
Nick

2. Introduction...
Presentation Outline

Introduction (Nick)

Brief Theory / FLUENT Modeling (Mike)

Literature / Experimental Data (Nick)

Conclusion (Mike)

3. 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.

4. Introduction...
Which simplifications?
The Nozzle Configurations we modeled:
1)
2)
3)
4)
Orifice
Converging Nozzle
Diverging Nozzle
Converging-Diverging
(Click on links above to see the various
configurations)

5. Introduction...
Rocket Particulars
The type of rocket we modeled:
1) Solid Propellant / Core Burning
Core burning rockets burn propellant from the
“inside out.”
This is in comparison to endburning rockets which burn
propellant from the “bottom up.”
Graphic from: http://www.sewanee.edu/physics/SEMINARS/HTML%20Rowland/sld011.htm

6. Introduction...
Rocket Particulars
The size of rocket
we modeled:
0.25 Inch diameter
casing
2) 2.25 Inches Long

7. Brief Theory
How to calculate thrust
The general thrust
equation is given as
follows:
Graphic from: http://members.aol.com/ricnakk/th_thrst.html

8. GAMBIT
Boundary
Conditions

9. GAMBIT
The Mesh
Triangular Elements
40 to 400
Intervals/Inch

10. FLUENT
Assumptions
1)
2)
3)
4)
Axisymmetric 2D Flow
Steady State / Constant Pressure Inlet
Compressible Flow
Ideal Gas (air)

11. FLUENT
Particular Settings
1)
2)
3)
4)
On all configurations the iterations
were run to a residual of 1e-3
Turbulent Flow (K-E model)
Variable Density
Used 2nd Order Equations to Calculate
Density / Pressure / Momentum

12. FLUENT
Velocity Contour Plots

13. FLUENT
Pressure Contour Plots

14. FLUENT
Density Contour Plots

15. FLUENT
Results
Nozzle Type
Force (oz)
Converging
4.56841
Diverging
3.81035
Regular Orifice
4.18331
Converging - Diverging
7.53282

16. FLUENT
Graphical Results
FLUENT Results
Thrust (oz)
8.00
Converging
7.00
6.00
Diverging
5.00
4.00
3.00
Regular Orifice
2.00
1.00
0.00
1
Converging
Diverging

17. Literature
The preponderance of literature clearly shows
the Converging – Diverging Nozzle as the most
efficient nozzle design.
Diagrams like this
(right) are not
uncommon:
Graphic from: http://www.nakka-rocketry.net/lambda_p.html

18. Literature
Similar Pressure Trends

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

20. Experimental Data
Experimental 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.

21. Experimental Data
Testing Using Method #1
For record keeping, a
camcorder was
zoomed up close to the
scale and recording.
Note the metal plate protecting the
plastic of the scale.

22. Experimental Data
Method #1 (Thrust Downward)
Set 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
Nozzle Type

23. Experimental Data
Experimental Setup Method #2
Method #2
In this case the
nozzle was
placed into a
hollow tube and
thrust was
directed
upward. Thus
the rocket
pushed onto
the scale.

24. Experimental Data
Testing Using Method #2
Note the
camcorder was
zoomed up
close to the
scale.
(Right) Movie of
ConvergingDiverging Run:
Click on Image
to Play

25. Experimental Data
Data Using Method #2
We were able to
go back and
watch our results
on TV in slow
motion.

26. Experimental Data
Method #2 (Thrust Upwards)
Nozzle Type
Set 3 (oz)
Converging
0.6
Diverging
0.45
Regular Orifice
0.25
Converging - Diverging
0.90

27. Conclusion
FLUENT Results
Thrust (oz)
8.00
Converging
7.00
6.00
Diverging
5.00
4.00
3.00
Regular Orifice
2.00
1.00
0.00
1
Converging
Diverging
Experimental Data Results
Thrust (oz)
1
Converging
0.8
Diverging
0.6
0.4
Regular Orifice
0.2
0
1
Converging
Diverging

28. Next time…

29. Questions?

30. Converging/
Diverging

31. Diverging

32. Converging

33. Orifice