共查询到15条相似文献,搜索用时 92 毫秒
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基于空泡生长和溃灭理论分析不同环境压强对空泡膨胀的最大泡半径、收缩的最小泡半径、膨胀与收缩速度的影响.同时,利用高功率激光与液体物质相互作用产生空泡,采用高速照相机、高频测量水听器实验研究不同环境压强下液体中空泡运动规律,并将实验结果与计算结果进行对比.结果表明:环境压强对空泡脉动特性有较大影响.相同激光能量击穿液体介质时,随着外界环境压强的增加,空泡脉动周期呈现递减趋势;空泡第一次脉动的最大泡半径同脉动周期的变化趋势一致,且数值由快到慢递减;随着外界压强的增加,空泡溃灭的速度越快.随着压强的增大,空泡膨胀与收缩更为剧烈,持续时间更短. 相似文献
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通过自行研制的光偏转测试系统对黏性液体中激光空泡脉动特性进行了实验,获得了激光等离子体空泡前两次脉动全过程,从而判定了空泡在脉动过程中对应的最大和最小泡半径;并将不同黏性系数下空泡脉动结果与基于空泡溃灭理论的计算结果进行了对比.结果表明:液体黏性对空泡生存周期、空泡半径,以及泡壁的运动速度等均有影响.受液体黏性影响,空泡膨胀或收缩过程明显变缓,其相应的生存周期也越长.这一研究结果不仅可促进空化研究的深入,也可为合理利用空化现象提供参考.
关键词:
激光泡
脉动特性
黏性
光纤传感器 相似文献
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表面张力是影响空泡脉动及空蚀的一个重要因素.对五种不同表面张力液体中空泡脉动(膨胀和收缩)过程进行了研究,并将实验结果与基于空泡生长和溃灭理论的计算结果进行了对比.实验中,用激光作为测试光源,采用光偏转测试系统研究了不同表面张力液体中空泡泡壁运动规律及泡壁速度的变化.结果表明:表面张力对空泡膨胀过程起抑制作用,故液体表面张力愈大,空泡能达到的最大直径越小;表面张力对空泡的收缩过程则起加速作用,液体表面张力愈大,收缩越迅速,空泡泡壁运动速度越大,其所产生的瞬时溃灭压强越大,空化效果越好.
关键词:
表面张力
空泡
光偏转 相似文献
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《中国光学与应用光学文摘》2006,(6)
TN241 2006064910液体物质中的空化现象实验研究=Experimental research on cavitation bubble in water[刊,中]/赵瑞(南京理工大学应用物理系.江苏,南京(210094)),徐荣青…//光电子·激光.—2006.17(5).—629—633采用自行研制的光偏转测试系统对强激光诱导液体物质的空化现象进行了实验研究,实验得到了激光等离子体冲击波传播规律和空泡的动力学特性。结果表明,激光等离子体冲击波在其传播过程中迅速衰减为声波;激光空泡的最大泡径随脉动次数增加依次减小,而收缩的最小泡径则由腔内含气量决定。图7参11(严寒) 相似文献
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Comprehensive numerical and experimental analyses of the effect of viscosity on cavitation oscillations are performed. This numerical approach is based on the Rayleigh-Plesset equation. The model predictions are compared with experimental results obtained by using a fibre-optic diagnostic technique based on optical beam deflection (OBD). The maximum and minimum bubble radii as well as the oscillation times for each oscillation cycle are determined according to the characteristic signals. It is observed that the increasing of viscosity decreases the maximum bubble radii but increases the minimum bubble radii and the oscillation time. These experimental results are consistent with numerical results. 相似文献
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To investigate the energy partitioning up to the fourth oscillation of a millimeter-scale spherical cavitation bubble induced by laser, we used nanosecond laser pulses to generate highly spherical cavitation bubbles and shadowgraphs to measure the radius-time curve. Using the extended Gilmore model and considering the continuous condensation of the vapor in the bubble, the time evolution of the bubble radius, bubble wall velocity, and pressure in the bubble is calculated till the 4th oscillation. Using Kirkwood-Bethe hypothesis, the evolution of velocity and pressure of shock wave at the optical breakdown, the first and second collapses are calculated. The shock wave energy at the breakdown and bubble collapse is directly calculated by numerical method. We found the simulated radius-time curve fits well with experimental data for the first four oscillations. The energy partition at the breakdown is the same as that in previous studies, the ratio of shock wave energy to bubble energy is about 2:1. In the first collapse and the second collapse, the ratio of shock wave energy to bubble energy is 14.54:1 and 2.81:1 respectively. In the third and fourth collapses, the ratio is less, namely than 1.5:1 and 0.42:1 respectively. The formation mechanism of the shock wave at the collapse is analyzed. The breakdown shock wave is mainly driven by the expansion of the supercritical liquid resulting from the thermalization of the energy of the free electrons in the plasma, and the collapse shock wave is mainly driven by the compressed liquid around the bubble. 相似文献
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为了揭示刚性界面附近气泡空化参数与微射流的相互关系, 从两气泡控制方程出发, 利用镜像原理, 建立了考虑刚性壁面作用的空化泡动力学模型. 数值对比了刚性界面与自由界面下气泡的运动特性, 并分析了气泡初始半径、气泡到固壁面的距离、声压幅值和超声频率对气泡溃灭的影响. 在此基础上, 建立了气泡溃灭速度和微射流的相互关系. 结果表明: 刚性界面对气泡振动主要起到抑制作用; 气泡溃灭的剧烈程度随气泡初始半径和超声频率的增加而降低, 随着气泡到固壁面距离的增加而增加; 声压幅值存在最优值, 固壁面附近的气泡在该最优值下气泡溃灭最为剧烈; 通过研究气泡溃灭速度和微射流的关系发现, 调节气泡溃灭速度可以达到间接控制微射流的目的. 相似文献
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Experimental investigation of the collapse of laser-generated cavitation bubbles near a solid boundary 总被引:4,自引:0,他引:4
Rui Zhao Rong-qing Xu Zhong-hua Shen Jian Lu Xiao-wu Ni 《Optics & Laser Technology》2007,39(5):968-972
The oscillation of a laser-generated single cavitation bubble near a solid boundary is investigated by a fiber-optic diagnostic technique based on optical beam deflection (OBD). The maximum bubble radii and collapse time for each oscillation cycle are determined from a sequence of bubble oscillations. Furthermore, by combining the revised Rayleigh theory, the prolongation factor κ at different dimensionless parameter γ (γ=L/Rmax, where Rmax is the maximum bubble radius and L is the distance of a cavity inception point from a boundary) is obtained. In addition, the prolongation factor of the collapse time versus laser energy is also derived, which are valuable in the fields of hydraulic cavitation, laser lithotripsy and laser ophthalmology. 相似文献