Separation Bubble Variation Due to Small Angles of Attack for an Axisymmetric Model at Mach 6
Elizabeth K. Benitez, Joseph S. Jewell, Steven P. Schneider
Abstract
View Video Presentation: https://doi.org/10.2514/6.2021-0245.vid The Boeing/AFOSR Mach 6 Quiet Tunnel (BAM6QT) at Purdue University was used to test a sharp cone-cylinder-flare model at small angles of attack. A 10-degree flare was chosen to generate an axisymmetric separation bubble from shock/boundary-layer interactions (SBLIs). With controlled variation of the model's pitch angle by less than 1 degree, the effect of small angles of attack on surface pressure fluctuations and heat transfer was studied. The separation bubble appeared to decrease in length near the windward side of the model as the angle of attack increased in quiet, laminar flow, while the bubble grew near the windward side in transitional flow under conventional noise. Both the second mode and shear-generated instabilities can be seen in the pressure data for the quiet, laminar flow. The pressure data for the conventional noise, transitional cases suggest the end of transition is at the reattachment point. Weak streamwise vortices can be detected in both flow conditions only when the angle of attack is very close to 0.0 degrees.