35th Aerospace Sciences Meeting and Exhibit
Jan. 6-9, 1997, Reno, Nevada
Paper number: AIAA-1997-611
An experimental study was conducted to investigate the phenomenon of supersonic inlet buzz on a generic, axisymmetric, external-compression inlet. An inlet model with a cowl lip diameter of 7.37cm (2.9in) was tested in the Virginia Tech Supersonic Blowdown Tunnel at a freestream Mach number of 2.4. The Reynolds number based on the model cowl lip diameter is 2.8x106. The inlet model has fixed geometry and no internal bleed, and has a mass captured raio of about 60%. Experimental measurements include multicolored internal surface oil flow visualization, static pressure measurements along the inlet's internal cowl surface, Pitot-static measurements at the exit plane, and shadowgraph movies and photography of the shock structure at the inlet entrance. Results show that the model exhibits Dailey's type inlet buzz, which is characterized by the separation on the cone surface. The initiation of the inlet buzz is consistent with the vortex sheet theory. The buzz frequency was measured at 150Hz. The plausible internal flow patterns developed, based on the measurements during the stable operations, indicate a substantial influence of the separated flow inside the inlet on the onset of instability.