Study of the Cavitating Instability on a Grooved Venturi Profile

Danlos, Amélie; Mehal, Jean-Elie; Ravelet, Florent; Coutier-Delgosha, Olivier; Bakir, Farid

doi:10.1115/1.4027472

Cited by 37 publications

(12 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Grooves were found to suppress cloud cavitation instabilities. 148 Liu and Tan 134,149 studied grooves' effects on suppressing tip vortices, which are precursor to cavitation inception. The analysis confirmed the ability of grooves to suppress the leakage vortices near the leading-edge of the hydrofoil subject to careful positioning.…”

Section: Groovesmentioning

confidence: 99%

Cavitation control using passive flow control techniques

et al. 2021

Self Cite

View full text Add to dashboard Cite

Passive flow control techniques, and particularly vortex generators have been used successfully in a broad range of aero-and hydrodynamics applications to alter the characteristics of boundary layer separation. This study aims to review how such techniques can mitigate the extent and impact of cavitation in incompressible flows. This review focuses first on vortex generators to characterize key physical principles. It then considers the complete range of passive flow control technologies, including surface conditioning and roughness, geometry modification, grooves, discharge, injection, obstacles, vortex generators, and bubble generators. The passive flow control techniques reviewed typically delay and suppress boundary layer separation by decreasing the pressure gradient at the separation point. The literature also identifies streamwise vortices that result in the transfer of momentum from the free stream to near-wall low energy flow regions. The area of interest concerns hydraulic machinery, whose performance and life span are particularly susceptible to cavitation. The impact on performance includes a reduction in efficiency and fluctuations in discharge pressure and flow, while cavitation can greatly increase wear of bearings, wearing rings, seals, and impeller surfaces due to excessive vibration and surface erosion. In that context, few studies have also shown the positive effects that passive controls can have on the hydraulic performance of centrifugal pumps, such as total head and efficiency. It is conceivable that a new generation of design in hydraulic systems may be possible if simple design features can be conceived to maximize power transfer and minimize losses and cavitation. There are still, however, significant research gaps in understanding a range of impact factors such as manufacturing processes, lifetime, and durability, and essentially how a static design can be optimized to deliver improved performance over a realistic range of operating conditions.

show abstract

Section: Groovesmentioning

confidence: 99%

Cavitation control using passive flow control techniques

et al. 2021

Self Cite

View full text Add to dashboard Cite

show abstract

“…As a result, a control of the cavitation behavior can lead to a stable regime instead of having an unsteady damaging one. Some passive control methods based on surface roughness have been studied by Danlos et al (2014a).…”

Section: Sheet Cavity Dynamicsmentioning

confidence: 99%

Experimental study of aerated cavitation in a horizontal venturi nozzle

Tomov

Khelladi

Ravelet

et al. 2016

Experimental Thermal and Fluid Science

View full text Add to dashboard Cite

The injection of bubbles into an already cavitating flow is a way of influencing the typical cavitating behavior. The present article deals with experiments on aerated and non-aerated cavitation in a transparent horizontal venturi nozzle. The observations are done by means of a high-speed camera. In such a way the extremely rapid cavitation and cavitationaeration flows are captured and further analysed. The post-processing techniques is based on the detection of the grey level on the series of images. As a result, three different regimes are identified: sheet cavitation, cloud cavitation and "supercavitation". Those regimes are further aerated by injecting air bubbles. Standard deviations, time-space diagrams and frequency spectrum based on the vertical distribution of the grey level along a monitored line are plotted for all of the observed regimes. In the pure cavitation cases we obtain statistically symmetrical structures with characteristic lengths and frequencies. On the other hand, with aeration present, the symmetry is broken and characteristic lengths and frequencies are deeply modified, until a complete disappearance when "supercavitation" is reached.

show abstract

“…Classically the cavity closure length, which correspond to the place where most of the shedding processes take place, is detected with the maximum of standard deviation on a sequence of images 11 . In the present study the region of interest is divided in two in order to investigate the symmetry of the different cavities.…”

Section: Grey Level Detectionmentioning

confidence: 99%

“…Partial cavity shedding phenomenon has been widely investigated in the past decades about different geometries such as hydrofoil profiles [2][3][4][5][6][7] , spheres 8 or Venturi nozzles [9][10][11][12] . As a consequence, a dynamical feature has been clearly consisting of a frothy re-entrant jet reaching back the vapor cavity and eventually cutting it in two, the second "cloud" cavity being advected downstream.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Two Mechanisms Governing Cloud Cavitation Shedding: Experimental Study and Numerical Highlight

Croci

Tomov

Ravelet

et al. 2016

Volume 7: Fluids Engineering

Self Cite

View full text Add to dashboard Cite

Cavitation is a phenomenon of classical interest which can be observed in various applications. It consists in a transition of phase due to a pressure drop under the saturation pressure of a liquid. The unsteady behavior of this phenomenon leads to generate some issues such as erosion, noise or vibrations: as a result the comprehension of the cavity dynamics remains of crucial importance. Unsteady cavitation has been investigated in numerous studies and a mechanism of re-entrant jet has been firstly identified as responsible of the cavity shedding process. Recently, a second shedding mechanism, induced by a shock wave propagation due to the condensation of vapor structures, has been experimentally highlighted with X-ray measurements [1]. The present paper focuses on the experimental detection, with a wavelet method, of these two shedding features on 2D image sequences recorded with a high-speed camera about a double transparent horizontal Venturi nozzle with 18°/8° convergent/divergent angles respectively. A compressible two-phase flow numerical 3D model is performed in complement in order to illustrate some phenomena hardly perceptible experimentally.

show abstract

Study of the Cavitating Instability on a Grooved Venturi Profile

Cited by 37 publications

References 19 publications

Cavitation control using passive flow control techniques

Cavitation control using passive flow control techniques

Experimental study of aerated cavitation in a horizontal venturi nozzle

Investigation of Two Mechanisms Governing Cloud Cavitation Shedding: Experimental Study and Numerical Highlight

Contact Info

Product

Resources

About