Effect of Wavy Wall on the Stability of Conical Hypersonic Boundary Layer at Small Angle of Attack

Abstract

In order to obtain a high lift-drag ratio, hypersonic vehicles usually fly with a certain angle of attack. As a potential means to delay hypersonic boundary layer transition at 0° angle of attack, it is not clear how wavy wall affect the deve-lopment of instability waves with angles of attack. In order to study the influence of wavy wall on the development of instability waves in hypersonic boundary layer at small angle of attack, the stability of boundary layer was studied by adopting high-speed infrared camera and high-frequency pressure sensor (PCB) in Mach 6 Ludwieg tube wind tunnel. The development of instability waves along different azimuths and flow directions was analyzed. The experimental results show that the instability waves leading transition at 1° angle of attack are the second-mode waves. Under the condition of 1° angle of attack, the wavy wall has no delay effect on transition at 45° azimuth angle, but has a promotion effect at 90°, 135° and 180° azimuth angles.

Keywords

• hypersonic speed
• boundary layer stability
• small angle of attack
• wavy wall
• transition