03.3 - Basic Fluid Dynamics and Flow Control
CROSSFLOW AND GÖRTLER INSTABILITIES IN HYPERSONIC BOUNDARY LAYERS
Y. Xi¹, S. Fu¹; ¹School of Aerospace Engineering, Tsinghua University, China
In three-dimensional hypersonic boundary layers, the crossflow and Görtler instabilities are of great importancernand may trigger transition. Using the numerical simulations, stability theory, and together with somernideas from classical differential geometry, we found the origin of both crossflow and Görtler instabilities overrna three-dimensional hypersonic boundary layer are because of the bending of local inviscid streamline. Thernappearance of which instabilities depends on the ratio between the normal curvature and geodesic curvature.rnThe study suggests that as the crossflow increase, the geodesic curvature of the inviscid streamline wouldrnbecome much larger than the normal curvature, which shows that the crossflow instability is the dominative atrnlarger swept angles. The influences of crossflow and surface curvature on the nonlinear developments and therntheir secondary instabilities are also discussed.