β Scribed by H.R. Graf; W.W. Durgin
No coin nor oath required. For personal study only.
Flow past the opening of a cavity can excite acoustic resonance. The periodic velocity field in the region of the cavity opening has been measured for various flow conditions and the vorticity distribution has been computed from the measured data using numerical differentiation. The results indicate that the shear layer rolls up into discrete vortices, which travel across the cavity opening. Two resonances were found. The first is characterized by a single vortex being present and results in the greatest amplitude. The second is characterized by the presence of two vortices which excite a distinct but lesser amplitude resonance. As the flow velocity changes, the position of these vortices shifts relative to the phase of the acoustic cycle. The timing of the interaction between the moving vortices and the acoustic particle velocity determines, to a large extent, the intensity of the excitation, and therefore also the oscillation amplitude. The measurements also indicate that the boundary layer upstream of the leading edge pulsates considerably.
π SIMILAR VOLUMES
Di!erent procedures for estimating steady #ow rate during "eld application of the Guelph permeameter method were compared in terms of "eld-saturated hydraulic conductivity K DQ and equilibration time t Q estimates. The steady #ow rate was evaluated by the slope of the linear portion of the cumulativ