Transition to Turbulence in 3-D Boundary Layers on a Rotating Disk (Triad Resonance)

摘要

This work is an experimental study of the resonant interaction between traveling cross-flow modes and low-mode-number stationary modes m transition to turbulence of the three-dimensional boundary layer flow over a rotating disk. A distributed array of ink dots are placed on the disk surface to enhance a narrow band of azimuthal and radial wave numbers of both stationary and traveling modes The size of the dots is small (d = 1.6 mm. h = 0.06 mm, h{w/v}~(1/2) = 0.16) so that the disturbance the produce is linear. Two hot-wires are used to perform spatial contributions measurements giving the wavenumber vector. The time series were sorted in terms of the separate contributions of the traveling and stationary modes. Cross-bicoherence was used to identify triad phase locking. The presence of wave number matching which indicates a triad resonance was then verified.