An experimental investigation of the control of the shear-layer flow over a cavity.

摘要

An experimental investigation into the characteristics of the unsteady laminar shear layer developed over a wall-mounted cavity was conducted, and the effects of the addition of a flush-mounted rotating cylinder to the leading edge or trailing edge of the cavity were quantified through extensive velocity and frequency measurements. It is shown that the injection of circulation resulting from the rotation of the leading edge cylinder caused the shear layer deflect into the cavity and re-attach to the cavity floor at greater cavity depths; also, the additional momentum caused a delay of the formation of shear-layer vortices, interrupting the cavity vortex formation-impingement feedback phenomenon. Higher leading-edge cylinder rotation speeds induced rapid laminar-to-turbulent transition, precluding any of the periodicity associated with laminar shear-layer flow. Furthermore, though the trailing-edge is the source of the feedback information for the self-sustained vortex formation, rotation of a cylinder at the trailing edge had little effect on the flow fields. Experiments were carried out with a ratio of separating boundary layer momentum thickness to impingement length of 6.07 x 10-3 .