TABI£ OF CONTENTS 



Page 



SUMMAEY 1 



INTRODUCTION 1 



USES AND LIMITATIONS OF THE HYDROGEN-BUBBLE , TECHNIQUE 3 



TEST FACILITY 12 



ELECTRONIC EQUIPMENT ............. ...... 13 



LIGHTING 15 



PHOTOGRAPHY . 16 



SOME OPERATIONAL PROCEDURES ..... ......... 17 



SOME PRELIMINARY EXPERLMENTAL RESULTS .... ....... 18 



ACKNOWLEDGMENTS • . ....... ....... 25 



REFERENCES .............. ... 26 



LIST OF FIGURES 



FigTore 1 - Typical Wake Pattern as Seen behind Foil Shape ...... 28 



(Freestream velocity is 1 fps) 



Figure 2 - Platinum Wire Holders 29 



Figure 3a- Bubble Patterns for Longitudinal and Transverse Velocity 



Field .................... 30 



Figi;.re Jh- Wire Conf ig-aration for Longitudinal and Transverse 



Velocity Profile Determination . . 3I 



Figure h - Spider Web Bubble Patterns in the Wake of a Circular 



Cylinder 32 



Figure 5 - Typical Bubble Patterns behind a Two-Inch Plate 



(Freestream velocity is I6 fps) 33 



Figure 6 - Twelve-Inch ID Plexiglas Closed-Jet Test Section with 



Two -Dimensional Sides Installed ..... ... 2^ 



Figure 7 - Enlargement of Bubble Patterns in the Wake of a Flat Plate 



with Sharp Trailing Edge (Freestream velocity is 1 fps) . . 35 



Figure 8 - Leica Camera and Pulse Generation Equipment . . 36 



