Single-bubble sonoluminescence(SBSL)occurs when a tiny bubble with an extremely small volume,isolated within a liquid,periodically compresses and expands in response to a strong ultrasonic field,emitting a brief burst...Single-bubble sonoluminescence(SBSL)occurs when a tiny bubble with an extremely small volume,isolated within a liquid,periodically compresses and expands in response to a strong ultrasonic field,emitting a brief burst of bright light.Sonoluminescence spectroscopy serves as a powerful tool for analyzing the material structure and physical state of these bubbles.Recent experimental results have demonstrated that the sonoluminescence spectra of moving single bubbles exhibit the characteristic spectra of divalent europium ions[Eu(Ⅱ)]in solutions containing europium chloride(EuCl_(2)).To elucidate the radiation mechanism of the characteristic spectra of Eu(Ⅱ)ions during sonoluminescence,we combined fluid mechanics,the Keller-Miksis(KM)equation,and spectral equations to calculate the spectral intensity and radiation power of SBSL in EuCl_(2)solutions,as well as the spatial distributions of temperature,pressure,particle number density,ionization energy,ionization degree and opacity within bubbles.The results indicate that the characteristic spectra of Eu(Ⅱ)ions may arise from the transition radiation excited under a localized environment of high temperature,pressure,and density within bubbles.These findings could enhance our understanding of the mechanisms underlying sonoluminescence and potentially aid in the development of advanced diagnostic tools for analyzing high-energy processes in fluids.展开更多
In this paper,an axial dispersion mathematical model is developed to simulate a three-phase slurry bubble column reactor for direct synthesis of dimethyl ether（DME） from syngas.This large-scale reactor is modeled us...In this paper,an axial dispersion mathematical model is developed to simulate a three-phase slurry bubble column reactor for direct synthesis of dimethyl ether（DME） from syngas.This large-scale reactor is modeled using mass and energy balances,catalyst sedimentation andsingle-bubble as well as two-bubbles class flow hydrodynamics.A comparison between the two hydrodynamic models through pilot plantexperimental data from the literature shows that heterogeneous two-bubbles flow model is in better agreement with the experimental data thanhomogeneous single-bubble gas flow model.Also,by investigating the heterogeneous gas flow and axial dispersion model for small bubblesas well as the large bubbles and slurry（i.e.including paraffins and the catalyst） phase,the temperature profile along the reactor is obtained.Acomparison between isothermal and non-isothermal reactors reveals no obvious performance difference between them.The optimum values ofreactor diameter and height were obtained at 7 m and 50 m,respectively.The effects of operating variables on the axial catalyst distribution,DME productivity and CO conversion are also investigated in this research.展开更多
This paper is the third in a series published in this journal during 2017-2018. These three papers present various stages in the development of the PeTa model for phenomena of the same physical nature: cavitational lu...This paper is the third in a series published in this journal during 2017-2018. These three papers present various stages in the development of the PeTa model for phenomena of the same physical nature: cavitational luminescence (CL), multi-bubble sonoluminescence (MBSL), single-bubble sonoluminescence (SBSL), and laser-induced bubble luminescence (LIBL). The basis of this model is the PeTa (Perel’man-Tatartchenko) effect—a nonequilibrium characteristic radiation under first-order phase transitions, for instance, vapour condensation. The third iteration of this model “Vapour bubble luminescence” (VBL) is presented in this paper. The essence of this model is as follows: with a local decrease of pressure or an increase of temperature in a tiny volume of the liquid, one or several bubbles filled with vapour will appear. Subsequently, a very rapid increase in pressure or a decrease in temperature of the bubble leads to super-saturation of the vapour inside the bubble, followed by its instantaneous condensation with the emission of condensation energy (this is the PeTa effect). A sharp decrease in pressure causes the collapse of the bubble accompanied by a shock wave in the liquid. VBL model is conveniently represented on the solid-liquid-vapour phase diagram. A better understanding of the physical nature of the phenomena under consideration could help to find their useful applications. To develop this idea further, we propose a design of a cavity-free pulsed laser on the basis of CL/MBSL/SBSL. An analysis of LIBL in cryogenic liquids is also given in this paper.展开更多
We use the phase field method to track the gas-liquid interface based on the gas-liquid two-phase flow in the pool boiling process,and study the bubble nucleation,growth,deformation,departure and other dynamic behavio...We use the phase field method to track the gas-liquid interface based on the gas-liquid two-phase flow in the pool boiling process,and study the bubble nucleation,growth,deformation,departure and other dynamic behaviors on the heating surface under microgravity.By simulating the correlation between liquid undercooling and bubble dynamics,we find that the bubble growth time increases with the increase of liquid undercooling,but the effect of liquid undercooling on bubble height is not significant.Meanwhile,the gas-liquid-solid three-phase contact angle and the gravity level will also have an effect on the bubble growth time and bubble height.With the increase of the contact angle,the bubble growth time and bubble height when the bubble departs also increase.While the effect of gravity level is on the contrary,the smaller the gravity level is,the larger the bubble height and bubble growth time when the bubble separates.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12264008,11864007,and 12204119)the Basic Research Program of Guizhou Province,China(Natural Science)(Grant No.QKHJCZK[2024]ZD054)。
文摘Single-bubble sonoluminescence(SBSL)occurs when a tiny bubble with an extremely small volume,isolated within a liquid,periodically compresses and expands in response to a strong ultrasonic field,emitting a brief burst of bright light.Sonoluminescence spectroscopy serves as a powerful tool for analyzing the material structure and physical state of these bubbles.Recent experimental results have demonstrated that the sonoluminescence spectra of moving single bubbles exhibit the characteristic spectra of divalent europium ions[Eu(Ⅱ)]in solutions containing europium chloride(EuCl_(2)).To elucidate the radiation mechanism of the characteristic spectra of Eu(Ⅱ)ions during sonoluminescence,we combined fluid mechanics,the Keller-Miksis(KM)equation,and spectral equations to calculate the spectral intensity and radiation power of SBSL in EuCl_(2)solutions,as well as the spatial distributions of temperature,pressure,particle number density,ionization energy,ionization degree and opacity within bubbles.The results indicate that the characteristic spectra of Eu(Ⅱ)ions may arise from the transition radiation excited under a localized environment of high temperature,pressure,and density within bubbles.These findings could enhance our understanding of the mechanisms underlying sonoluminescence and potentially aid in the development of advanced diagnostic tools for analyzing high-energy processes in fluids.
文摘In this paper,an axial dispersion mathematical model is developed to simulate a three-phase slurry bubble column reactor for direct synthesis of dimethyl ether（DME） from syngas.This large-scale reactor is modeled using mass and energy balances,catalyst sedimentation andsingle-bubble as well as two-bubbles class flow hydrodynamics.A comparison between the two hydrodynamic models through pilot plantexperimental data from the literature shows that heterogeneous two-bubbles flow model is in better agreement with the experimental data thanhomogeneous single-bubble gas flow model.Also,by investigating the heterogeneous gas flow and axial dispersion model for small bubblesas well as the large bubbles and slurry（i.e.including paraffins and the catalyst） phase,the temperature profile along the reactor is obtained.Acomparison between isothermal and non-isothermal reactors reveals no obvious performance difference between them.The optimum values ofreactor diameter and height were obtained at 7 m and 50 m,respectively.The effects of operating variables on the axial catalyst distribution,DME productivity and CO conversion are also investigated in this research.
文摘This paper is the third in a series published in this journal during 2017-2018. These three papers present various stages in the development of the PeTa model for phenomena of the same physical nature: cavitational luminescence (CL), multi-bubble sonoluminescence (MBSL), single-bubble sonoluminescence (SBSL), and laser-induced bubble luminescence (LIBL). The basis of this model is the PeTa (Perel’man-Tatartchenko) effect—a nonequilibrium characteristic radiation under first-order phase transitions, for instance, vapour condensation. The third iteration of this model “Vapour bubble luminescence” (VBL) is presented in this paper. The essence of this model is as follows: with a local decrease of pressure or an increase of temperature in a tiny volume of the liquid, one or several bubbles filled with vapour will appear. Subsequently, a very rapid increase in pressure or a decrease in temperature of the bubble leads to super-saturation of the vapour inside the bubble, followed by its instantaneous condensation with the emission of condensation energy (this is the PeTa effect). A sharp decrease in pressure causes the collapse of the bubble accompanied by a shock wave in the liquid. VBL model is conveniently represented on the solid-liquid-vapour phase diagram. A better understanding of the physical nature of the phenomena under consideration could help to find their useful applications. To develop this idea further, we propose a design of a cavity-free pulsed laser on the basis of CL/MBSL/SBSL. An analysis of LIBL in cryogenic liquids is also given in this paper.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.52161002,51661020,and11364024)the Postdoctoral Science Foundation of China(Grant No.2014M560371)the Funds for Distinguished Young Scientists of Lanzhou University of Technology of China(Grant No.J201304)。
文摘We use the phase field method to track the gas-liquid interface based on the gas-liquid two-phase flow in the pool boiling process,and study the bubble nucleation,growth,deformation,departure and other dynamic behaviors on the heating surface under microgravity.By simulating the correlation between liquid undercooling and bubble dynamics,we find that the bubble growth time increases with the increase of liquid undercooling,but the effect of liquid undercooling on bubble height is not significant.Meanwhile,the gas-liquid-solid three-phase contact angle and the gravity level will also have an effect on the bubble growth time and bubble height.With the increase of the contact angle,the bubble growth time and bubble height when the bubble departs also increase.While the effect of gravity level is on the contrary,the smaller the gravity level is,the larger the bubble height and bubble growth time when the bubble separates.
