SONIC BOOM MODELING INVESTIGATION OF TOPOGRAPHICAL AND ATMOSPHERIC EFFECTS
Final rept. Jun 1969-Jul 1970
DOUGLAS AIRCRAFT CO LONG BEACH CA
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An experimental program was undertaken to study the effects of topographical and structural shapes on sonic boom focusing and to study the effects of atmospheric turbulence on sonic boom signatures. These effects were modeled by firing projectiles and by allowing the projectile N waves to interact with model shapes and with turbulent jets. The wave interactions were studied by means of shadowgraph pictures and microphone pressure records. The boom focusing parameters were related to the work of Ting and Pan. A canyon model showed wave amplification factors as large as 14 for a special shape and a particular wave direction of propagation. A large amount of statistical information was obtained from the turbulence interactions. This information was studied and found to be in essential agreement with the theory of Crew, but the mechanisms of the shock front breakup and of certain nonlinear features are not understood. Turbulence scaling parameters are developed and used to relate the model results to full scale.