FIV2018 Paper Management System, FIV2018 Conference

Font Size: 
EFFECT OF ROUNDING-OFF THE CAVITY EDGES ON FLUID-RESONANT OSCILLATIONS OF A SHALLOW CAVITY IN A PIPE-LINE
Saber Mohamed, Samir Ziada

Last modified: 2018-06-28

Abstract


The effect of rounding-off the cavity edges on the fluid-resonance oscillations generated by fully developed pipe flow through an axisymmetric shallow cavity is investigated experimentally for the case of acoustic resonance of longitudinal pipe modes. Different locations of the curved edge (upstream, downstream, or both cavity corners) and different sizes of curvature are examined. The self-excited acoustic resonance is investigated by using a short piping system which is carefully designed to generate self-excited resonances within a suitable flow velocity range and to reduce the viscous losses to promote the occurrence of acoustic resonances. The acoustic amplitude is found to be NOT significantly affected by rounding-off the cavity edges, except for a relatively large radius. This finding is different from published results on the effects of edge curvature for other flow-sound interaction patterns. This difference in trend is due to the fact that the spatial distribution of the shear layer aeroacoustic sources in the present case is different from those observed during trapped-mode resonances in shallow cavities and in closed side-branches. In the present case, acoustic sources do exist at both the upstream and downstream corners of the cavity, whereas in the previously investigated flow geometries, an acoustic sink existed at the upstream corner and a source at the downstream corner.

Keywords


Shallow cavity, Fluid-Resonance, Edge effect, Aeroacoustics

Full Text: PDF