Noise generated by cavitating single-hole and multi-hole orifices in a water pipe |
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| Institution: | 1. Laboratoire de Mécanique des Structures Industrielles Durables, UMR CNRS-EDF 2832, 1 Avenue du Général De Gaulle, F-92141 Clamart, France;2. Fluid Dynamics Laboratory, Department of Applied Physics, Technische Universiteit Eindhoven, P.O. Box 513, 5600 MB Eindhoven, The Netherlands;3. Laboratoire d’Acoustique de l’Université du Maine, UMR CNRS 6613, Avenue Olivier Messiaen, F-72085 Le Mans Cedex 9, France;1. Eindhoven University of Technology, Department of Mechanical Engineering, Eindhoven, The Netherlands;2. Siemens Industry Software, Researchpark 1237, Interleuvenlaan 68, 3001 Leuven, Belgium;3. KU Leuven, Department of Mechanical Engineering, Celestijnenlaan 300B, 3001 Leuven, Belgium;4. KTH Royal Institute of Technology, Department of Aeronautical and Vehicle Engineering, Stockholm, Sweden;5. Eindhoven University of Technology, Department of Applied Physics, Eindhoven, The Netherlands;1. DICA, Politecnico di Milano, Piazza Leonardo da Vinci, 32–20133 Milano, Italy;2. DICATECh, Politecnico di Bari, Via Orabona, 4–70125 Bari, Italy |
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| Abstract: | This paper presents an experimental study of the acoustical effects of cavitation caused by a water flow through an orifice. A circular-centered single-hole orifice and a multi-hole orifice are tested. Experiments are performed under industrial conditions: the pressure drop across the orifice varies from 3 to 30 bar, corresponding to cavitation numbers from 0.74 to 0.03. Two regimes of cavitation are discerned. In each regime, the broadband noise spectra obtained far downstream of the orifice are presented. A nondimensional representation is proposed: in the intermediate ‘developed cavitation’ regime, spectra collapse reasonably well; in the more intense ‘super cavitation’ regime, spectra depend strongly on the quantity of air remaining in the water downstream of the orifice, which is revealed by the measure of the speed of sound at the downstream transducers. In the ‘developed cavitation’ regime, whistling associated with periodic vortex shedding is observed. The corresponding Strouhal number agrees reasonably well with literature for single-phase flows. In the 'super cavitation’ regime, the whistling disappears. |
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