Abstract:
In wind tunnel experiment, transition location near minor-axis of hypersonic elliptic cone is quite different from that on each side. This is due to the streamwise vortices near minor-axis, which lead to significant difference of basic flow from that on each side. Consequently, instability near minor-axis has essential difference from that on each side, resulting in different transition locations. In this paper, Bi-Global instability analysis is carried out to investigate the instability near minor-axis. Arnoldi method is employed, and the numerical results are validated by comparing with those calculated through other methods. Unstable outer modes are found, and the variation of their growth is studied against frequency, wavenumber, and streamwise location. The physical mechanism of unstable modes is found that they are caused by inviscid inflection instability of shearing basic flow. Unstable inner mode does not exist, because there is no Fjortoft inflection point corresponding to inner mode characteristic.