Gas Bubble Collapse in liquid
The Experimental Study of Dynamics of Scaled Gas-Filled Bubble Collapse in Liquid
Tech Area / Field
- PHY-NGD/Fluid Mechanics and Gas Dynamics/Physics
- PHY-PLS/Plasma Physics/Physics
8 Project completed
Senior Project Manager
Melnikov V G
VNIITF, Russia, Chelyabinsk reg., Snezhinsk
- Lawrence Livermore National Laboratory, USA, CA, Livermore\nState University of New York at Stony Brook, USA, NY, Stony Brook
In 1990 a new exceptional discovery – a Single Bubble Sonoluminescence (SBSL) – was made. A main point of this phenomenon is not understandable up to now and consists in the following. It was turned out that in a liquid (water), which was under normal conditions (atmospheric pressure P0 and room temperature), gaseous micro bubbles of initial radius of 3 – 5 m was arising under the action of acoustic (sound) fields (the composition of the gas in the bubbles is permanently discussed). These bubbles pass the stage of expanding, the stage of compressing, and the stage of a high intensity collapse followed by an intensity light flash. In the result of the collapse, the gas inside the bubble heats up the temperature of 1 – 2 eV and compresses up the density of 1 g/cm3. Exceptionality of this phenomenon is that, that among the all known phenomena of the impulse cumulation of energy the maximum increase of the energy density in comparison with the initial density of energy of acoustic (sound) field achieves in the SBSL (the coefficient of cumulation achieves value of K = 109 – 1011).
Many technical devices with high degree of energy cumulation, in which energy cumulation produces with using high explosives, laser squeezing of spherical targets (in ICF-problem), magnetic cumulation (compressing gas-filled targets by high-intensity magnetic fields), and so on, are well investigated up to now. In the all these devices the energy density increase is much less than in the SBSL, and the coefficient of cumulation achieves value of K = 104.
At present, a large coefficient of cumulation in the SBSL generated a lot of proposals regarding to using this phenomenon in practice. For example, a proposal regarding to realization the SBSL in a liquid preliminary saturated with deuterium and tritium with the aim of producing of a great neutron yield at the stage of a gas bubble collapse.
All existing proposals proceed from the following assumptions:
2. Hydrodynamic instabilities and turbulent mixing, which arise at all the stages of the gas bubble evolution, do not essentially decrease the coefficient of cumulation K.
3. It can be succeeded in forming a gas media in the bubble with known concentrations of gas components at initial moment of time at the stage of expansion.
All these assumptions need experimental and theoretical examine and basing.
In connection with these, the goals of the present Project are:
1. Experimental study of possibility of increase of the SBSL-phenomenon scale by more a factor than 100 by means of increase of initial pressure in a liquid medium up to 102 P0 and increase of an acoustic (sound) field amplitude more than by a factor of 100.
2. Carrying out of experimental and theoretical study of hydrodynamic instabilities and turbulent mixing at spherical contact boundaries between gas and liquid. First of all to study the Rayleigh-Taylor instability and the turbulent mixing caused by this instability and to reveal the coefficient cumulation K reduction degree conditioned by the instability and turbulent mixing processes evolution.
3. Experimental study of possibility of generating of initial spherically symmetrical gas bubbles with known initial conditions (bubble radius, density and temperature, composition and concentration of gas components and so on).
Such the bubbles suppose to use in the experiments.
The Project tasks are:
1. Choice and substantiation of the physical scheme of the experimental facility, design and optimization of its construction, manufacture of the experimental facility and its start.
2. Development and arrangement of the measuring techniques for registration of parameters instability and turbulence, bubbles dynamics, parameters of high compressed plasma, and for both parameters and modes of operation diagnostics of the experimental facility.
3. Carrying out of experimental study of the instability and turbulence at spherical contact boundaries, dynamics of the bubble collapse at different values of ambient pressure, different values of variable pressure amplitude, different radiuses of gas-filled bubbles, and different compositions of the gas.
4. Development of turbulent mixing models of the second level of closing with taking into account of spherical geometry of contact boundaries movement.
5. Study of possibilities of using of developed technology for obtaining information about properties of strongly coupled plasma.
6. Expansion of theoretical investigations regarding to using of the phenomenon of the scaled acoustic collapse of a bubble in liquid.
In the result of the Project fulfillment:
1. It will be developed a technique, an appropriate experimental facility will be produced, and study of evolution of a gas-filled bubble in liquid at increased pressure and under action of variable acoustic fields will be carried out.
2. Parameters of the Rayleigh-Taylor instability and the turbulent mixing caused by this instability at spherical boundary gas – liquid at expansion and next collapse of the gas bubble will be studied.
3. The values of compressed gas density up to 110 g/cm3 and temperature up to 2 10 eV will be achieved, and mass of high compressed substance will be increased by a factor of 102 103 and even more that is essentially above the values achieved in the SBSL-phenomenon. Obtained data will be used for developing of models of strongly coupled plasma.
4. A model of turbulent mixing of the second level of closing with taking into account of spherical geometry of contact boundary movement will be developed.
Developed experimental approach and theoretical results will be a basis for future study of fundamental problems such as instability and mixing at the gas-liquid interface, properties of high compressed and heated substances, physical and chemical processes in them. A mass increase of compressed substance opens some perspectives for finding of applied uses of the controlled phenomenon of collapse, for example, for realization of difficult produced reactions of disintegration or fusion.
In RFNC-VNIITF there are favorable conditions for fulfilling this project. The experimental work will be carried out in the laboratory having developed infrastructure (installations EKAP, SOM, OSA, and MST) and many-years experience of study of the processes of instability and mixing of gases and liquids. The theoretical work will be carried out by a group of theorists and mathematicians, who have gained a great experience in developing of models of high intensity and high-speed physical processes and producing of corresponding numerical basis.
The authors of the Project are looking forward to collaboration with Dr. O. Schilling, Dr. T. Peyser, Dr. E. Chandler, and Dr. W. Moss from Lawrence Livermore National Laboratory (USA), Professor J. Glimm from the State University of Stony Brook (USA), and Professor J. Jacobs from the University of Arizona (USA).
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