Abstract
The main purpose of this study was to shed light on the unsteady cavitating flow and corresponding wall-pressure fluctuation characteristic. A simultaneous sampling technique is used to synchronize the observations of cavitation images and the measurements of wall-pressure signals in a convergent–divergent channel. The results show that, with the decreasing cavitation number, cavitating flows in a convergent–divergent channel display several types of cavitation behavior, such as cavitation inception, sheet cavitation, and sheet/cloud cavitation. The intensity of the pressure fluctuation increases with the decrease in cavitation number. However, with decreasing cavitation number, the dominant frequency of the unsteady pressure fluctuation decreases significantly, and for sheet/cloud cavitation, the dominant frequency of pressure fluctuation is consistent with that of global cavitation area fluctuation. A typical quasi-periodic sheet/cavitation development cycle is characterized by three stages such as: (1) the growth of attached cavity, (2) the shedding of attached cavity, and (3) the development and collapse of detached cavities. In the stage one, the magnitude of pressure fluctuations under the attached cavity is small; however, it is large in the closure region of attached cavity, especially when attached cavity obtains its maximum length. In the stage two, the attached cavity begins to shed and some small detached cavities are observed, and small local pressure fluctuations with higher frequency are detected. In the stage three, a large detached cavity is formed in the rear of attached cavity. When the detached cavity collapses rapidly in the downstream region, pressure pulses with the magnitude of the order of several atmospheres are detected. The propagation speeds of pressure pulses in different cavitation regions are found to be related with the bubble density in the flow field. It is also found that the pressure impulse in the region covered by attached cavity is much lower than that in the attached cavity closure area.
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References
Arndt REA (2012) Some remarks on hydrofoil cavitation. J Hydrodyn 24(3):305–314
Brennen CE (1995) Cavitation and bubble dynamics. Oxford engineering and sciences series 44. Oxford University Press, Oxford
Callenaere M, Franc JP, Michel J (2001) The cavitation instability induced by the development of a re-entrant jet. J Fluid Mech 444:223–256
Coutier-Delgosha O, Stutz B, Vabre A, Legoupil S (2007) Analysis of cavitating flow structure by experimental and numerical investigations. J Fluid Mech 578:171–222
De Lange DF, de Bruin GJ, van Wijngaarden L (1994) On the mechanism of cloud cavitation-experiment and modelling. The 2nd international symposium on cavitation, Tokyo, Japan, pp 45–49
Dular M, Stoffel B, Sirok B (2006) Development of a cavitation erosion model. Wear 261(5–6):642–655
Dular M, Khlifa I, Fuzier S et al (2012) Scale effect on unsteady cloud cavitation. Exp Fluids 53(5):1233–1250
Foeth EJ (2008) The structure of three-dimensional sheet cavitation. Ph.D. thesis, Delft University of Technology, The Netherlands
Foeth EJ, Van Terwisga T, Van Doorne C (2008) On the collapse structure of an attached cavity on a three-dimensional hydrofoil. J Fluids Eng 130(7):071303
Huang B, Young YL, Wang GY et al (2013) Combined experimental and computational investigation of unsteady structure of sheet/cloud cavitation. J Fluids Eng 135(7):071301
Ji B, Luo XW, Peng XX et al (2012) Numerical analysis of cavitation evolution and excited pressure fluctuation around a propeller in non-uniform wake. Int J Multiph Flow 43:13–21
Ji B, Luo XW, Wu YL et al (2013) Numerical analysis of unsteady cavitating turbulent flow and shedding horse-shoe vortex structure around a twisted hydrofoil. Int J Multiph Flow 51:33–43
Ji B, Luo XW, Arndt REA, Wu YL (2014) Numerical simulation of three dimensional cavitation shedding dynamics with special emphasis on cavitation–vortex interaction. Ocean Eng 87:64–77
Ji B, Luo XW, Arndt REA, Peng XX, Wu YL (2015) Large eddy simulation and theoretical investigations of the transient cavitating vortical flow structure around a NACA66 hydrofoil. Int J Multiph Flow 68:121–134
Joussellin F, Delannoy Y, Sauvage-Boutar E, Goirand B (1991) Experimental investigations on unsteady attached cavities. AMSE-FED 116:61–66
Kehr YZ, Kao JH (2011) Underwater acoustic field and pressure fluctuation on ship hull due to unsteady propeller sheet cavitation. J Mar Sci Technol 16(3):241–253
Kubota A, Kato H, Yamaguchi H, Maeda M (1989) Unsteady structure measurement of cloud cavitation on a foil section using conditional sampling technique. J Fluids Eng 111:204–210
Le Q, Franc JP, Michel JM (1993) Partial cavities: global behavior and mean pressure distribution. J Fluids Eng 115:243–248
Leroux JB, Astolfi JA, Billard Y (2004) An experimental study of unsteady partial cavitation. J Fluids Eng 126:94–101
Leroux JB, Coutier-Delgosha O, Astolfi JA (2005) A joint experimental and numerical analysis of mechanisms associated to unsteady partial cavitation. Phys Fluids 17(5):052101
Luo XW, Ji B, Peng XX et al (2012a) Numerical simulation of cavity shedding from a three-dimensional twisted hydrofoil and induced pressure fluctuation by large-eddy simulation. J Fluids Eng 134(4):041202
Luo XW, Ji B, Zhang Y et al (2012b) Cavitating flow over a mini hydrofoil. Chin Phys Lett 29(1):016401
Lush PA, Peters PI (1982) Visualisation of the cavitating flow in a Venturi type duct using high speed cine photography. In: Proceedings of IAHR conference on operating problems of pump stations and power plants, Vol 1, No. 5
Petkovsek M, Dular M (2013) Simultaneous observation of cavitation structures and cavitation erosion. Wear 300:55–64
Pham TM, Larrarte F, Fruman DH (1999) Investigation of unsteady sheet cavitation and cloud cavitation mechanisms. J Fluids Eng 121:289–296
Reisman GE (1997) Dynamics, acoustics and control of cloud cavitation on hydrofoils. Ph.D. thesis, California Institute of Technology
Reisman GE, Wang C, Brennen CE (1998) Observation of shock waves in cloud cavitation. J Fluids Mech 355:255–283
Soyama H, Kato H, Oba R (1992) Cavitation observations of severely erosive vortex cavitation arising in a centrifugal pump. In: Proceedings of the third IMechE international conference on cavitation
Stutz B, Reboud JL (1997a) Experiments on unsteady cavitation. Exp Fluids 22:191–198
Stutz B, Reboud JL (1997b) Two-phase flow structure of sheet cavitation. Phys Fluids 9(12):3678–3686
Van Rijsbergen M, Foeth EJ, Fitzsimmns P et al. (2012) A High speed video observations and acoustic impact measurements on a NACA 0015 foil. In: Proceedings of 8th international symposium on cavitation, Singapore
Wang GY, Senocak I, Shyy W et al (2001) Dynamics of attached turbulent cavitating flows. Prog Aerosp Sci 37:551–581
Zhang MD, Song XF, Wang GY et al (2006) Design and application of cavitation flow image programs. Trans Bei**g Inst Technol 26:980–986
Acknowledgments
This work was financially supported by the National Natural Science Foundation of China (NSFC, Grant Nos.: 11172040, 51239005, 51479002, and 51306020).
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Chen, G.H., Wang, G.Y., Hu, C.L. et al. Observations and measurements on unsteady cavitating flows using a simultaneous sampling approach. Exp Fluids 56, 32 (2015). https://doi.org/10.1007/s00348-015-1896-8
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DOI: https://doi.org/10.1007/s00348-015-1896-8