Experimental Observations on an Unsteady, Normal Shock/Boundary Layer Interaction,
CAMBRIDGE UNIV (ENGLAND) DEPT OF ENGINEERING
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An experiment is described in which a normal shock interacts with the natural turbulent wall boundary layer in a parallel sided duct at Mach 1.3 and 1.5. The shock wave is vibrated in symmetric fashion by a rotating cam mounted in the tunnel diffuser. The design of this experiment, particularly the efforts to obtain a pure forcing signal, is discussed. Shock motion analysis at reduced frequencies of order 0.2 to 2 and amplitude parameters of 2 to 20 based on equivalent chord is presented. Unsteady surface pressure measurements under the interaction have been made and demonstrate that there is negligible phase change between the shock motion and the surface pressures. It appears reasonable to utilise quasi-steady assumptions in the calculation of the surface pressures at the low frequency conditions tested.
- Fluid Mechanics