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

3. Experimental Set-Up 40cm x 40cm “Trisonic” Wind Tunnel 1:150 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 (Δα = -5° to +10 °)

4. Test Geometry Relative separation distance also planned but not possible

5. Flow Visualisation Pressure Measurement 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 coefficient C p calculated from difference between static wall pressure p and ambient pressure p 0.

6. 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

7. Colour Schlieren Observed shock system very weak Shock geometry used with shock theory to calculate flow conditions Disturbances from flat plate very visible

8. 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

9. 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 methods: All test methods consistent in providing location of shock impingement points. Schlieren is best for visualising system.

10. 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

13. Shock induced BL Separation

14. Shock Reflection

15. Colour Schlierem Photo Ma = 2.0  = +5°  h = 40mm

16. Static Wall Pressure Measurement Ma = 2.0  = +5°  h = 40mm