Influence of glow discharge on evolution of disturbance in a hypersonic boundary layer: The effect of first mode

Abstract

The evolution of the first- and second-mode instabilities in a hypersonic flat plate boundary layer is investigated. Experiments are conducted in a Mach 6.5 quiet wind tunnel using particle image velocimetry, Rayleigh-scattering flow visualization, and schlieren methods. Glow discharge is introduced as an artificial disturbance. The results show that an artificially introduced disturbance in the first-mode frequency range can excite a specific second-mode wave that is one of the high-order harmonics of the added disturbance. For the first time, we find a clear harmonic relationship between the first- and second-mode waves, as well as the phase lock phenomenon between them.

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