Experimental determination of the speed of sound in cavitating flows

Shamsborhan, Hiva; Coutier-Delgosha, Olivier; Caignaert, Guy; Nour, Fadi Abdel

doi:10.1007/s00348-010-0880-6

Cited by 64 publications

(40 citation statements)

References 13 publications

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“…The speed of sound in the bubbly mixture upstream of the shock High void fractions within the partial cavities leads to reduced sound speeds of the bubbly mixture that can fall below that of the inlet flow speed. Shamsborhan et al (2010) confirmed that the sound speed of a cavitating bubbly flow at an ambient pressure p can be approximated by the relationship of Brennen (2005) for a twocomponent mixture:…”

Section: Shock Formation and The Cavity Mach Numbermentioning

confidence: 63%

“…Based on the void-fraction measurements it was found that averaged void fraction in the cavity ranged from less than 5 % at higher cavitation numbers to values exceeding 50 % under shedding conditions. It is well known that the sound speed of high-void-fraction cavitation bubbly mixtures is greatly reduced compared to that of the constituent water, air and vapour (Shamsborhan et al 2010). This makes such mixtures compressible and susceptible to shocking under certain flow conditions.…”

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confidence: 99%

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Bubbly shock propagation as a mechanism for sheet-to-cloud transition of partial cavities

2016

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Partial cavitation in the separated region forming from the apex of a wedge is examined to reveal the flow mechanism responsible for the transition from stable sheet cavity to periodically shedding cloud cavitation. High-speed visualization and time-resolved X-ray densitometry measurements are used to examine the cavity dynamics, including the time-resolved void-fraction fields within the cavity. The experimentally observed time-averaged void-fraction profiles are compared to an analytical model employing free-streamline theory. From the instantaneous void-fraction flow fields, two distinct shedding mechanisms are identified. The classically described re-entrant flow in the cavity closure is confirmed as a mechanism for vapour entrainment and detachment that leads to intermittent shedding of smaller-scale cavities. But, with a sufficient reduction in cavitation number, large-scale periodic cloud shedding is associated with the formation and propagation of a bubbly shock within the high void-fraction bubbly mixture in the separated cavity flow. When the shock front impinges on flow at the wedge apex, a large cloud is pinched off. For periodic shedding, the speed of the front in the laboratory frame is of the order of half the free-stream speed. The features of the observed condensation shocks are related to the average and dynamic pressure and void fraction using classical one-dimensional jump conditions. The sound speed of the bubbly mixture is estimated to determine the Mach number of the cavity flow. The transition from intermittent to transitional to strongly periodic shedding occurs when the average Mach number of the cavity flow exceeds that required for the generation of strong shocks.

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Section: Shock Formation and The Cavity Mach Numbermentioning

confidence: 63%

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confidence: 99%

Bubbly shock propagation as a mechanism for sheet-to-cloud transition of partial cavities

2016

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“…The sound speed in pure water is close to 1500 m/s, is on the order of 400 m/s in vapor, and even lower for liquid/vapor mixture [23]. A stainless steel rectangular tank model is partially filled with water and sound speed is measured when the half cosine mode is excited by an earphone as shown in Fig.…”

Section: Experiments Of Rectangular Tankmentioning

confidence: 99%

Study on Piston Slap Induced Liner Cavitation

Wang

Ohta

2015

Journal of Vibration and Acoustics

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Liner cavitation induced by piston slap in a diesel engine is caused by water pressure fluctuation when the pressure of coolant falls below saturated vapor pressure. Cavitation erosion of cylinder liners is thought to be generated by the impulsive pressure or jet flow impingement following the collapse of cavitation bubbles. In this study, a numerical method to predict the water pressure fluctuation in water coolant passage induced by piston slap impact force is developed. In complimentary impact vibration experiments, high frequency components of the water pressure fluctuation can be seen just after the pressure reaches the saturated vapor pressure level or less. These high frequency components seem to show the occurrence of cavitation. A finite element acoustic model of the water coolant passage in an actual engine block is created and its validity is confirmed by the acoustic vibration tests in air. Then, the coupled vibration characteristics of the water acoustic field and engine block structure are determined, and water pressure waveform induced by piston slap is predicted.

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“…On the other hand, experimental information on the speed of sound in a bubbly liquid where the bubbles contain an appreciable amount of vapour is very sparse at best. The latest study is a paper by Shamsborhan et al [12] which is, however, somewhat inconclusive. Surprisingly (but see below in §4.1), the dependence of the data on the bubble volume fraction is in reasonable agreement with the classic Wood formula [14,15] which, in principle, should only apply to bubbles containing a permanent gas rather than a vapour.…”

Section: Introductionmentioning

confidence: 99%

“…No consensus currently exists on the correct value of c min or, more generally, on the dependence of the speed of sound on bubble volume fraction, composition, frequency and others (e.g. [12]). …”

Section: Introductionmentioning

confidence: 99%

The speed of sound in a gas–vapour bubbly liquid

Prosperetti

2015

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In addition to the vapour of the liquid, bubbles in cavitating flows usually contain also a certain amount of permanent gas that diffuses out of the liquid as they grow. This paper presents a simplified linear model for the propagation of monochromatic pressure waves in a bubbly liquid with these characteristics. Phase change effects are included in detail, while the gas is assumed to follow a polytropic law. It is shown that even a small amount of permanent gas can have a major effect on the behaviour of the system. Particular attention is paid to the low-frequency range, which is of special concern in flow cavitation. Numerical results for water and liquid oxygen illustrate the implications of the model.

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Experimental determination of the speed of sound in cavitating flows

Cited by 64 publications

References 13 publications

Bubbly shock propagation as a mechanism for sheet-to-cloud transition of partial cavities

Bubbly shock propagation as a mechanism for sheet-to-cloud transition of partial cavities

Study on Piston Slap Induced Liner Cavitation

The speed of sound in a gas–vapour bubbly liquid

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