2010 年 58 巻 679 号 p. 226-232
This paper describes results of an exploratory study to investigate the capability of a passive approach for controlling the characteristic spanwise length of Görtler vortices generated in hypersonic flows: a serrated leading edge. Heat transfer, pressure measurements, encapsulated thermochromic liquid crystal, schlieren and glow spark visualizations were conducted with a flat plate/ramp model whose leading edge had a triangular wave shape in a gun tunnel at Mach number 10. Effect of wavelength Λ of the triangular waves on downstream flows was studied. Aerodynamic heating patterns observed with the liquid crystal confirmed that the vortex wavelength was equal to Λ. This was also supported by the spark results that filamentary bright lines perpendicular to an installed line-anode parallel to the spanwise direction at the ramp surface emerged at intervals of Λ. Phase lag was observed only between heat transfer data measured in the spanwise direction, which suggests that the vortex structure existed in the reattaching boundary layers. Pressure distribution in the streamwise direction was similar among all of the Λ tested. In contrast, the heat transfer data points exhibited a large scatter and the peak heating value for the finite Λ was somewhat larger than that for the infinite Λ. Schlieren results indicated that the appropriate Λ can mitigate flow separation.