Periodic cavitation shedding in a cylindrical orifice

Stanley, Cameron; Barber, Tracie; Milton, B. E.; Rosengarten, Gary

doi:10.1007/s00348-011-1138-7

Cited by 35 publications

(26 citation statements)

References 23 publications

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“…where l cav the length of the main cavity, here evaluated in the time series. The values obtained are Str ≈ 0.3 (see Table 2) and compare well with experimental values for cylindrical orifices with Str = 0.3 -0.5 (Sato and Saito, 2002;Stanley et al, 2011;Sugimoto and Sato, 2009). As can be seen in the time series (Fig.…”

Section: Characterization Of the Shedding Processessupporting

confidence: 84%

“…The vapor sheet is not a coherent vapor cavity, as often shown schematically (Callenaere et al, 2001;Franc and Michel, 2005;Le et al, 1993), but is a two-phase mixture of vapor bubbles and liquid, which also has been observed in experimental investigations (Kubota et al, 1989;Stanley et al, 2014). Furthermore, in most cases the vapor sheet is not attached to the nozzle wall but separated from the wall by a liquid film with an upstream velocity, as also reported by Stanley et al (2011Stanley et al ( , 2014.…”

Section: Developing Cavitation and Mainly Re-entrant Jet Initiated Shmentioning

confidence: 57%

“…Based on the above mentioned studies, two cavitation regimes can be identified. The first regime involves developing cavitation, where cavitation is initiated in the shear layer close to the nozzle inlet and the cavity length reaches about half of the nozzle length (Sou et al, 2007;Stanley et al, 2011). In the separated shear layer at the nozzle inlet, cavitating spanwise vortices form, coalesce, and pair in a rotational motion to larger clouds (Saito and Sato, 2003;Sato and Saito, 2002).…”

Section: Introductionmentioning

confidence: 99%

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Investigation of condensation shocks and re-entrant jet dynamics in a cavitating nozzle flow by Large-Eddy Simulation

Trummler

Schmidt

Adams

2020

International Journal of Multiphase Flow

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Cloud cavitation is related to an intrinsic instability where clouds are shed periodically. The shedding process is initiated either by the motion of a liquid re-entrant jet or a condensation shock. Cloud cavitation in nozzles interacts with the flow field in the nozzle, the mass flow and the spray break-up, and causes erosion damage. For nozzle geometries cloud shedding and the associated processes have not yet been studied in detail.In this paper, we investigate the process of cloud cavitation shedding, the re-entrant jet and condensation shocks in a scaled-up generic step nozzle with injection into gas using implicit Large-Eddy Simulations (LES). For modeling of the cavitating liquid we employ a barotropic equilibrium cavitation model, embedded in a homogeneous multi-component mixture model. Full compressibility of all components is taken into account to resolve the effects of collapsing vapor structures.We carry out simulations of two operating points exhibiting different cavitation regimes. The time-resolved, three-dimensional simulation results cover several shedding cycles and provide deeper insight into the flow field. Our results show that at lower cavitation numbers, shedding is initiated by condensation shocks, which has not yet been reported for nozzle flows with a constant crosssection. We analyze the cavitation dynamics and the shedding cycles of both operating points. Based on our observations we propose modifications to established schematics of the cloud shedding process. Additionally, we analyze the near-wall upstream flow in and underneath the vapor sheet and possible driving mechanism behind the formation of the re-entrant jet.

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Section: Characterization Of the Shedding Processessupporting

confidence: 84%

Section: Developing Cavitation and Mainly Re-entrant Jet Initiated Shmentioning

confidence: 57%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Investigation of condensation shocks and re-entrant jet dynamics in a cavitating nozzle flow by Large-Eddy Simulation

Trummler

Schmidt

Adams

2020

International Journal of Multiphase Flow

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“…34 As shown in Figure 11(b), the cavity attaching to the wall of passage is named as fixed cavity (partial cavitation), which has a clear liquid–gas interface named as glassy surface. 35 The laminar boundary layer in the fluid prevents the fixed cavity swept away by the oncoming flow at upstream. 36 A further decrease of cavitation number makes the fixed cavities to spread up to the outlet (Figure 11(c)).…”

Section: Resultsmentioning

confidence: 99%

Interactions between poppet vibration and cavitation in relief valve

Zou

et al. 2014

Proceedings of the Institution of Mechanical Engineers, Part C:

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Poppet vibration and cavitation, two representative phenomena in relief valves, are considered as the roots of the violent noise, erosion, and structure damage. In this paper, the interactions between the poppet vibration characteristics and cavitation property in relief valves with the unconfined poppet are investigated experimentally. Tests have been performed in stable and unstable valves under cavitation and noncavitation conditions. The valve housing is fabricated by Perspex for flow visualization. As for the influence of cavitation on vibration characteristics, it is found that the generated cavitation bubbles in the downstream circuit decrease the flow coefficient and fluid viscosity, and decrease the hydrodynamic spring in turn. The location of cavitating flow, characterized by the low local pressure, changes the thrust on poppet and poppet lift, affecting the radial stiffnesses of mechanical spring and hydrodynamic spring, respectively. On the other hand, as for the influence of vibration on cavitation property, it is found that the poppet vibration leads to a dramatic increase of the noise comparing to the fixed poppet conditions. Spectrum analysis shows that augmented noise in unstable valves mainly comes from the intensification of cavitation noise. A reason for this is that the vibration of poppet leads to a quick and violent collapse of large amount of cavities developed from the throttling region, which should be performed as attached cavities and avoided from collapse in the stable poppet conditions.

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“…From engineering viewpoints such as the design of a water jet nozzle suitable for washing and cutting as well as a diesel injector nozzle for atomizing [14], it is important to make clear the mechanism of periodic cavitation behavior to apply the high-intensive impact and the mixing action through the controlling of cavitation clouds.…”

Section: Introductionmentioning

confidence: 99%

Unsteady Behavior of Cavitating Waterjet in an Axisymmetric Convergent-Divergent Nozzle: High Speed Observation and Image Analysis Based on Frame Difference Method

Hayashi¹,

Sato²

2014

JFCMV

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Although it is well known that cloud cavitation shows unsteady behavior with the growing motion of an attached cavity, the shedding motion of a cloud, the collapsing motion of the cloud shed downstream and a reentrant motion in flow fields such as on a 2-D hydrofoil and in a convergentdivergent channel with a rectangular cross-section, observations for the periodic behavior of cloud cavitation in a cylindrical nozzle with a convergent-divergent part, which is mainly used in an industrial field, have hardly been conducted. From engineering viewpoints, it is important to elucidate the mechanism of periodic cavitation behavior in a cylindrical nozzle. In this study, a high-speed observation technique with an image analysis technique was applied to the cloud cavitation behavior in the nozzle to make clear the mechanism of unsteady behavior. As a result, it was observed in the nozzle that the periodic behavior occurs in the cloud cavitation and pressure waves form at the collapse of clouds shed downstream. Also, it was found through the image analysis based on the present technique that the pressure wave plays a role as a trigger mechanism to cause a reentrant motion at the downstream end of an attached cavity.

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Periodic cavitation shedding in a cylindrical orifice

Cited by 35 publications

References 23 publications

Investigation of condensation shocks and re-entrant jet dynamics in a cavitating nozzle flow by Large-Eddy Simulation

Investigation of condensation shocks and re-entrant jet dynamics in a cavitating nozzle flow by Large-Eddy Simulation

Interactions between poppet vibration and cavitation in relief valve

Unsteady Behavior of Cavitating Waterjet in an Axisymmetric Convergent-Divergent Nozzle: High Speed Observation and Image Analysis Based on Frame Difference Method

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