BOUNDARY-LAYER STABILITY MEASUREMENTS IN A HYPERSONIC QUIET TUNNEL

Hypersonic boundary-layer measurements were conducted over a flared co ne in a quiet wind tunnel. The flared cone was tested at a freestream unit Reynolds number of 2.82 x 10(6)/ft in a Mach 6 flow. This Reynold s number provided laminar-to-transitional bow over the model in a low- disturbance environment. Point measurements with a single hat wire usi ng a novel constant voltage anemometry system were used to measure the boundary-layer disturbances. Surface temperature and schlieren measur ements were also conducted to characterize the laminar-to-transitional state of the boundary layer and to identify instability modes. Result s suggest that the second mode is the dominant mode of instability. Th e integrated growth rates of the second made compared well with linear stability theory in the linear stability regime. Furthermore, the exi stence of higher harmonics of the fundamental suggests that nonlinear disturbances are not associated with ''high'' freestream disturbance l evels.