Rocket Nozzle Design

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Rocket Nozzle Design

• Group MembersMike
• Nick

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Introduction...Presentation Outline

• Introduction (Nick)
• Brief Theory / FLUENT Modeling (Mike)
• Literature / Experimental Data (Nick)
• Conclusion (Mike)

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Introduction...Project Objectives

• To analyze four simplified nozzle geometries in a
  model rocket and calculate their maximum thrust.
  
• Compare the theoretical and experimental thrust
  of these nozzles. Choose the best nozzle based
  on our data.

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Introduction...Which simplifications?

• The Nozzle Configurations we modeled
• Orifice
• Converging Nozzle
• Diverging Nozzle
• Converging-Diverging
• (Click on links above to see the various
  configurations)

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Introduction...Rocket Particulars

• The type of rocket we modeled
• Solid Propellant / Core Burning
• Core burning rockets burn propellant from the
  inside out.

This is in comparison to end-burning rockets
which burn propellant from the bottom up.
Graphic from http//www.sewanee.edu/physics/SEMIN
ARS/HTML20Rowland/sld011.htm
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Introduction...Rocket Particulars

• The size of rocket we modeled
• 0.25 Inch diameter casing
• 2) 2.25 Inches Long

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Brief TheoryHow to calculate thrust
The general thrust equation is given as follows
Graphic from http//members.aol.com/ricnakk/th_th
rst.html
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GAMBITBoundaryConditions
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GAMBITThe Mesh
Triangular Elements40 to 400 Intervals/Inch
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FLUENTAssumptions

• Axisymmetric 2D Flow
• Steady State / Constant Pressure Inlet
• Compressible Flow
• Ideal Gas (air)

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FLUENTParticular Settings

• 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

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FLUENTVelocity Contour Plots
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FLUENTPressure Contour Plots
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FLUENTDensity Contour Plots
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FLUENTResults
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FLUENTGraphical Results
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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
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Literature
Similar Pressure Trends
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Experimental DataIntroduction

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

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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.
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Experimental DataTesting 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.
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Experimental DataMethod 1 (Thrust Downward)
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Experimental DataExperimental 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.
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Experimental DataTesting Using Method 2
Note the camcorder was zoomed up close to the
scale. (Right) Movie of Converging-Diverging
Run Click on Image to Play
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Experimental DataData Using Method 2
We were able to go back and watch our results on
TV in slow motion.
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Experimental DataMethod 2 (Thrust Upwards)
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Conclusion
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Next time
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Questions?
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Converging/Diverging
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Diverging
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Converging
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Orifice