Towards the concept of hydrodynamic cavitation control

1997 ◽  
Vol 332 ◽  
pp. 377-394 ◽  
Author(s):  
Dhiman Chatterjee ◽  
Vijay H. Arakeri
Keyword(s):  
Acoustic Field ◽  
Bubble Dynamics ◽  
Hydrodynamic Cavitation ◽  
Careful Study ◽  
Potential Control ◽  
Cavitation Phenomenon ◽  
Bubble Cavitation ◽  
First Results ◽  
Hydrodynamic Field ◽  
Pass Through

A careful study of the existing literature available in the field of cavitation reveals the potential of ultrasonics as a tool for controlling and, if possible, eliminating certain types of hydrodynamic cavitation through the manipulation of nuclei size present in a flow. A glass venturi is taken to be an ideal device to study the cavitation phenomenon at its throat and its potential control. A piezoelectric transducer, driven at the crystal resonant frequency, is used to generate an acoustic pressure field and is termed an ‘ultrasonic nuclei manipulator (UNM)'. Electrolysis bubbles serve as artificial nuclei to produce travelling bubble cavitation at the venturi throat in the absence of a UNM but this cavitation is completely eliminated when a UNM is operative. This is made possible because the nuclei, which pass through the acoustic field first, cavitate, collapse violently and perhaps fragment and go into dissolution before reaching the venturi throat. Thus, the potential nuclei for travelling bubble cavitation at the venturi throat seem to be systematically destroyed through acoustic cavitation near the UNM. From the solution to the bubble dynamics equation, it has been shown that the potential energy of a bubble at its maximum radius due to an acoustic field is negligible compared to that for the hydrodynamic field. Hence, even though the control of hydrodynamic macro cavitation achieved in this way is at the expense of acoustic micro cavitation, it can still be considered to be a significant gain. These are some of the first results in this direction.

Hemolytic Potential of Hydrodynamic Cavitation

2000 ◽  
Vol 122 (4) ◽  
pp. 321-326 ◽  
Author(s):  
Sean D. Chambers ◽  
Robert H. Bartlett ◽  
Steven L. Ceccio
Keyword(s):  
Analytical Model ◽  
Bubble Dynamics ◽  
Cavitation Number ◽  
Hydrodynamic Cavitation ◽  
Constant Flow ◽  
Free Hemoglobin ◽  
Constant Flow Rate ◽  
Recirculating Flow ◽  
Bubble Cavitation ◽  
Flow Apparatus

The purpose of this study was to determine the hemolytic potentials of discrete bubble cavitation and attached cavitation. To generate controlled cavitation events, a venturi-geometry hydrodynamic device, called a Cavitation Susceptibility Meter (CSM), was constructed. A comparison between the hemolytic potential of discrete bubble cavitation and attached cavitation was investigated with a single-pass flow apparatus and a recirculating flow apparatus, both utilizing the CSM. An analytical model, based on spherical bubble dynamics, was developed for predicting the hemolysis caused by discrete bubble cavitation. Experimentally, discrete bubble cavitation did not correlate with a measurable increase in plasma-free hemoglobin (PFHb), as predicted by the analytical model. However, attached cavitation did result in significant PFHb generation. The rate of PFHb generation scaled inversely with the Cavitation number at a constant flow rate, suggesting that the size of the attached cavity was the dominant hemolytic factor. [S0148-0731(00)00404-0]

Innovative Technique for the Closure of Rectovaginal Fistula Using Amplatzer™ Septal Occluder

2021 ◽  
Vol 10 (29) ◽  
pp. 2225-2227
Author(s):  
Omer Alabaz ◽  
Ugur Topal
Keyword(s):  
Rectovaginal Fistula ◽  
Vascular Tissue ◽  
Surgical Flaps ◽  
Severe Infection ◽  
Poor Quality ◽  
Pelvic Cavity ◽  
First Results ◽  
Standardized Treatment ◽  
Pass Through ◽  
Tissue Flaps

Rectovaginal fistulas (RVF) result from an abnormal epithelial connection between the vagina and the rectum, allowing the intestinal contents to pass through the vagina.1 Patients may clinically present with vaginal faeces or gas discharge in addition to inflammation in the pelvic cavity, which may lead to severe infection and poor quality of life.2 RVF is seen in women who previously received treatment for a malignant disease in the pelvic region. The malignancies in the pelvic area are often treated with radiotherapy. This treatment results in tissue damage and poor healing.3 Management of postoperative RVF is difficult and the results are often unsatisfactory. Currently there is no widely accepted and standardized treatment for RVF.3, 4 In the treatment of RVF, various surgical flaps (endorectal or vaginal), vascular tissue flaps (Martius, gracilis), grafts or biomaterials have been used.3,5,6 This case shows the first results using the Amplatzer™ Septal Occluder for the closure of rectovaginal fistula.

Thermal Bubble Dynamics Under the Effect of Acoustic Vibration

2009 ◽  
Author(s):  
Xiaopeng Qu ◽  
Huihe Qiu
Keyword(s):  
Heat Transfer ◽  
Acoustic Field ◽  
Vapor Bubble ◽  
Boiling Heat Transfer ◽  
High Speed ◽  
Bubble Dynamics ◽  
Acoustic Vibration ◽  
Micro Electro Mechanical System ◽  
Mems Technology ◽  
Enhanced Boiling

The effect of acoustic field on the dynamics of micro thermal bubble is investigated in this paper. The micro thermal bubbles were generated by a micro heater which was fabricated by standard Micro-Electro-Mechanical-System (MEMS) technology and integrated into a mini chamber. The acoustic field formed in the mini chamber was generated by a piezoelectric plate which was adhered on the top side of the chamber’s wall. The dynamics and related heat transfer induced by the micro heater generated vapor bubble with and without the existing of acoustic field were characterized by a high speed photograph system and a micro temperature sensor. Through the experiments, it was found that in two different conditions, the temperature changing induced by the micro heater generated vapor bubble was significantly different. From the analysis of the high speed photograph results, the acoustic force induced micro thermal bubble movements, such as forcibly removing, collapsing and sweeping, were the main effects of acoustic enhanced boiling heat transfer. The experimental results and theoretical analysis were helpful for understanding of the mechanisms of acoustic enhanced boiling heat transfer and development of novel micro cooling devices.

A semianalytical approach to calculate the reflected wave of an eccentric source in a borehole

Geophysics ◽  
2019 ◽  
Vol 84 (1) ◽  
pp. D1-D9
Author(s):  
Feilong Xu ◽  
Hengshan Hu
Keyword(s):  
Acoustic Field ◽  
Fourier Transforms ◽  
Acoustic Source ◽  
Reflection And Transmission ◽  
Reflected Wave ◽  
Reflection And Transmission Coefficient ◽  
Simulation Error ◽  
Pass Through ◽  
Coefficient Method ◽  
Cased Borehole

The acoustic field in a borehole is usually simulated under axisymmetric conditions. When the acoustic source deviates from the borehole axis, the field loses the axial symmetry property. We have developed a semianalytical approach to calculate the acoustic field excited by an eccentric source of limited size. The eccentric source is first decomposed into infinitely long multipole cylinder sources whose center axes pass through the eccentric point. Then, by applying the continuity of displacement and stress on the interfaces, we derive reflection coefficients by the generalized reflection and transmission coefficient method. Finally, the reflected wave is obtained after dual inverse Fourier transforms with respect to time and wavenumber. Numerical tests based on the reciprocity theorem are performed to validate this approach. The results indicate that the simulation error in every reciprocal model is negligible even if the eccentric distance of the acoustic source reaches two thirds of the radius of the borehole wall. We apply this semianalytical approach to simulate the reflected wave of an eccentric directional beam in a cased borehole.

New approach of suppressing cavitation in water hydraulic components

2016 ◽  
Vol 231 (21) ◽  
pp. 4022-4034 ◽  
Author(s):  
Zhang Zuti ◽  
Cao Shuping ◽  
Luo Xiaohui ◽  
Shi Weijie ◽  
Zhu Yuquan
Keyword(s):  
Pressure Distribution ◽  
Bubble Dynamics ◽  
Cloud Model ◽  
The Novel ◽  
Outlet Pressure ◽  
Cavitation Phenomenon ◽  
Throttle Valve ◽  
Novel Approach ◽  
Cavitation Intensity ◽  
Water Hydraulic

Cavitation frequently appears in high pressure water hydraulic components and leads to serious hydraulic erosions and horrible hydrodynamic noises. In this paper, a novel approach of suppressing cavitation was proposed, inducing the outlet pressure back to the orifice to improve the pressure distribution of throttle valves. In order to realize this approach, an optimized throttle valve chamber structure was designed. After that, the anticavitation performance of the valve was investigated. A theoretical cavitation cloud model was built based on bubble dynamics. In order to solve the mathematic cavitation model, the velocity field and pressure distribution of the novel throttle valve were simulated through Computational Fluid Dynamics(CFD). Combining the simulation results, the mathematic cavitation cloud model was solved through numerical calculations. Moreover, new indexes estimating cavitation intensity were proposed scientifically to investigate cavitation phenomenon. Then, the comparison of the novel throttle valve (with an innovative valve chamber) and traditional throttle valve in anticavitation performance was conducted under different conditions. Finally, the experiment about anticavitation performance was completed on the test rig. The calculation and experiment results indicated that the approach, inducing the outlet pressure back to the orifice, was effective in suppressing cavitation.

scholarly journals Linear and weakly nonlinear instability of a premixed curved flame under the influence of its spontaneous acoustic field

2014 ◽  
Vol 758 ◽  
pp. 180-220 ◽  
Author(s):  
Raphaël C. Assier ◽  
Xuesong Wu
Keyword(s):  
Acoustic Field ◽  
Numerical Solutions ◽  
Parametric Instability ◽  
Linear Instability ◽  
Weakly Nonlinear ◽  
Observed Behaviour ◽  
Hydrodynamic Field ◽  
The Stability ◽  
Sivashinsky Equation ◽  
Asymptotic Formulation

AbstractThe stability of premixed flames in a duct is investigated using an asymptotic formulation, which is derived from first principles and based on high-activation-energy and low-Mach-number assumptions (Wu et al., J. Fluid Mech., vol. 497, 2003, pp. 23–53). The present approach takes into account the dynamic coupling between the flame and its spontaneous acoustic field, as well as the interactions between the hydrodynamic field and the flame. The focus is on the fundamental mechanisms of combustion instability. To this end, a linear stability analysis of some steady curved flames is undertaken. These steady flames are known to be stable when the spontaneous acoustic perturbations are ignored. However, we demonstrate that they are actually unstable when the latter effect is included. In order to corroborate this result, and also to provide a relatively simple model guiding active control, we derived an extended Michelson–Sivashinsky equation, which governs the linear and weakly nonlinear evolution of a perturbed flame under the influence of its spontaneous sound. Numerical solutions to the initial-value problem confirm the linear instability result, and show how the flame evolves nonlinearly with time. They also indicate that in certain parameter regimes the spontaneous sound can induce a strong secondary subharmonic parametric instability. This behaviour is explained and justified mathematically by resorting to Floquet theory. Finally we compare our theoretical results with experimental observations, showing that our model captures some of the observed behaviour of propagating flames.

The Influence of Acoustic Cavitation to Microscopic Material Removal in Polishing Process Based on Vibration of Liquid: A Numerical Study

2006 ◽  
Vol 532-533 ◽  
pp. 301-304 ◽  
Author(s):  
Zhong Ning Guo ◽  
Zhi Gang Huang ◽  
Xin Chen
Keyword(s):  
Material Removal ◽  
High Speed ◽  
Bubble Dynamics ◽  
Numerical Study ◽  
Dissipative Particle Dynamics ◽  
Thermal Conditions ◽  
Acoustic Cavitation ◽  
Ultrasonic Frequency ◽  
Polishing Process ◽  
Cavitation Phenomenon

In Polishing Process based on Vibration of Liquid (PVL), abrasive particles driven by polishing liquid will brush and etch workpiece to achieve material removal. Because the liquid is vibrated in ultrasonic frequency, polishing process will be greatly affected by cavitation phenomenon. The critical thermal conditions and high-speed liquid jet produced by bubble dynamics may damage workpiece. A refined Dissipative Particle Dynamics method is applied to study the effect of acoustic cavitation on PVL. Validity of the numerical simulation is tested according to experimental results.

Effect of Surfactant in Gas Dissolved Cleaning Solutions on Acoustic Bubble Dynamics

2021 ◽  
Vol 314 ◽  
pp. 197-201
Author(s):  
So Young Han ◽  
Nagendra Prasad Yerriboina ◽  
Bichitra Nanda Sahoo ◽  
Bong Kyun Kang ◽  
Andreas Klipp ◽  
...  
Keyword(s):  
Sodium Dodecyl Sulfate ◽  
Anionic Surfactant ◽  
High Speed ◽  
Bubble Dynamics ◽  
Sodium Dodecyl ◽  
High Speed Camera ◽  
Semiconductor Processing ◽  
Megasonic Cleaning ◽  
Bubble Cavitation ◽  
Bubble Characteristics

Megasonic cleaning is one of the promising technologies to remove the particles during semiconductor processing. Acoustic bubble cavitation plays a key role in removing the particles. In this work, the effect of an anionic surfactant sodium dodecyl sulfate (SDS) on a bubble in the presence of hydrogen dissolved DIW water was studied. The bubble dynamics were observed using a high-speed camera. It was found that with the increase of surfactant the bubble characteristics were changed very significantly. Several parameters affecting the bubble dynamics were investigated.

Direct numerical simulation of three-dimensional dynamics of compressible bubbles in acoustic field using boundary element method

2014 ◽  
Vol 10 ◽  
pp. 59-65
Author(s):  
Yu.A. Itkulova ◽  
O.A. Abramova ◽  
N.A. Gumerov ◽  
I.Sh. Akhatov
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Acoustic Field ◽  
Bubble Dynamics ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Numerical Approach ◽  
Low Reynolds Numbers ◽  
Dimensional Simulation ◽  
Element Method

In the present work the dynamics of bubbles containing compressible gas is studied in the presence of an acoustic field at low Reynolds numbers. The numerical approach is based on the boundary element method (BEM), which is effective for three-dimensional simulation. The application of the standard BEM to the compressible bubble dynamics faces the problem of the degeneracy of the algebraic system. To solve this problem, additional relationships based on the Lorentz reciprocity principle are used. Test calculations of the dynamics of one and several bubbles in an acoustic field are presented.

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