Imaging of the Self-Excited Oscillation of Flow Past a Cavity During Generation of a Flow Tone
Flow through a pipeline-cavity system can give rise to pronounced flow tones, even when the inflow boundary layer is fully turbulent. Such tones arise from the coupling between the inherent instability of the shear flow past the cavity and a resonant acoustic mode of the system. A technique of high-image-density particle image velocimetry is employed in conjunction with a special test section, which allows effective laser illumination and digital acquisition of patterns of particle images. This approach leads to patterns of velocity, vorticity, streamline topology and hydrodynamic contributions to the acoustic power integral. Comparison of global, instantaneous images with time- and phase-averaged representations provides insight into the small-scale and large-scale concentrations of vorticity, and their consequences on the topological features of Streamline patterns, as well as the streamwise and transverse projections of the hydrodynamic contribution to the acoustic power integral. Furthermore, these global approaches allow the definition of effective wavelengths and phase speeds of the vortical structures, which can lead to guidance for physical models of the dimensionless frequency of oscillation.
- Research Organization:
- Lockheed Martin Corporation, Schenectady, NY 12301 (US)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC12-00SN39357
- OSTI ID:
- 821957
- Report Number(s):
- LM-02K040; TRN: US200412%%297
- Resource Relation:
- Other Information: PBD: 21 May 2002
- Country of Publication:
- United States
- Language:
- English
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