Experimental investigations of the flow during the stage separation of a space transportation system

1
Experimental investigations of the flow during
the stage separation of a space transportation
system
Andrew Hay Aerospace Engineering with German
2
Project Brief

• The ELAC 1 and EOS configuration is a
  two-stage-to-orbit space transportation system
• Stage separation occurs at Mach number Ma 6.8
  and at an altitude of 31 km
• Flow visualisation - Oil flow pattern and colour
  Schlieren photography
• Static wall pressure measurement
• Identify aerodynamic interaction effects

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Experimental Set-Up

• 40cm x 40cm Trisonic Wind Tunnel
• 1150 scale EOS upper stage model and flat plate
  to simulate ELAC 1 lower stage

• Test Parameters
• Freestream Mach number (Ma 2.0 to 2.2)
• Relative angle of attack (?a -5 to 10 )

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Test Geometry

• Relative separation distance also planned but not
  possible

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Flow Visualisation

• Oil flow pattern - to visualise the near surface
  flow.Emulsion of oil and pigments move along
  wall shear stress flow lines.
• Colour Schlieren photography - to visualise the
  shock system. Density gradients are made
  visible, because refraction index changes with
  density.

Pressure Measurement

• Pressure coefficient Cp calculated from
  difference between static wall pressure p and
  ambient pressure p0.

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Oil Flow Pattern

• EOS bow shock impingement line on flat plate is
  visible
• No shock induced boundary layer separation is
  visible
• Reflected shock impingement line is not visible
  on EOS model

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Colour Schlieren

• Observed shock system very weak
• Shock geometry used with shock theory to
  calculate flow conditions
• Disturbances from flat plate very visible

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Pressure Measurement

• Shock impingement points visible (pressure
  increase)
• Overall trend is a decrease in pressure
  downstream
• Reason - 3D effects of the closed wind tunnel
  test section

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Results Discussion

• No boundary layer separation observed - confirmed
  by Schlieren and comparison with experimental
  data.
• Shock systems very weak - shock intensities very
  close to 1
• 3D effects of test section have a stronger
  influence on the pressure results than the shock
  system
• Comparison of testing methodsAll test methods
  consistent in providing location of shock
  impingement points. Schlieren is best for
  visualising system.

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Conclusions

• Shock systems visible, but very weak at tested
  Mach numbers
• No shock induced boundary layer separation
  observed
• 3D effects of the closed test section had a
  significant influence on the results
• Improved test set-up is required to enable
  testing at more parameter variables

11
Experimental investigations of the flow during
the stage separation of a space transportation
system
Andrew Hay Aerospace Engineering with German
12
Shock Theory
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Shock induced BL Separation
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Shock Reflection
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Colour Schlierem Photo
Ma 2.0 ?? 5 ?h 40mm
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Static Wall Pressure Measurement
Ma 2.0 ?? 5 ?h 40mm