共查询到17条相似文献,搜索用时 140 毫秒
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超声空化在许多不同的学科和工业生产中有着广泛的应用。超声空化的应用与声场的分布及空化的机理密切相关,精准地反映空化场和空化机理是超声空化技术实际应用的关键。该文通过分析采集的声信号和金属箔膜空蚀法对空化区域随液位发生变化的现象进行研究,并利用Matlab对金属箔膜空蚀程度量化。实验发现,超声波会在液面与实验箱体底部形成驻波场。在某一液体温度下,随着液位高度的变化,超声空化现象的出现具有周期性。并且,在同一液位下,当超声功率改变时,空化区域强度分布情况随之改变。小功率时各空化区域空化强度分布均匀,当功率增大到一定时,会出现空化屏蔽现象。该研究为超声清洗设备的改良提供了借鉴,对进一步认识和利用超声空化效应具有重要意义。 相似文献
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为了探究超声搅拌磁流变抛光液的制备及优化工艺,利用多物理场数值计算方法,建立了超声搅拌磁流变抛光液的声场仿真模型,并进行了频域分析。研究了不同液位深度、超声变幅杆探入深度,不同功率下磁流变抛光液的声场分布。通过测量磁流变抛光液的声场强度对声场仿真进行了验证。结果表明:随着距变幅杆距离的增加,声强逐渐减弱,高声强区域主要分布在换能器轴线附近。声强在距变幅杆20mm范围内急剧衰减,变幅杆最佳探入深度为10mm,增大功率有助于空化区域的扩大。声场仿真结果与实验测量结果基本一致,对磁流变抛光液的制备提供了数值计算基础。 相似文献
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驻波和换能器指向性等影响声场均匀性,造成清洗死角,影响清洗效果。采用COMSOL仿真软件建立了单个换能器位于底部的三维模型,通过染色法实验结果验证模型的有效性。研究了换能器同时位于底部和侧面、多排换能器位于底部时的声场,用声压幅值相对标准差来量化均匀性,发现该两种换能器分布方式能够有效优化声场均匀性。通过调节频率研究频率对声场的影响,进一步优化声场均匀性。对声源分布的确定、频率的选择以满足声场均匀化需求有指导意义。 相似文献
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本文叙述了医用超声功率的常规测量方法的原理和已达到的水平之后,讨论了医用超声场的声强的使用范围和安全性问题,着重阐明了使用PVDF压电薄膜水听器扫描超声场,记录脉冲超声场的声压波形分布并计算I_(SPTP)、I_(SPTA)、I_(SATA)和I_(SAPA)的方法。给出了计算公式和实验结果,并对A型和B型超声诊断仪的典型测量数据和声强分布特征进行了讨论与比较。 相似文献
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对于线性单频混响声场的统计特性的研究人们曾做了许多工作,建立了均方根声压和平均声能密度统计分布理论。本文在此基础上推导出声压级统计分布函数,并把处理方法推广到混响室内在强大声源激发下的非线性单频混响声场,求得各谐波声场和总声场的统计分布函数。本文实验采用数字测量技术,对混响声场进行了大量的测量,得到的实验结果与理论符合良好。 相似文献
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本文研究了超声场对Ti/SnO2 Sb2O3/PbO2电极电化学氧化Cr3 过程的影响,探讨了在不同的操作电流密度、反应温度、硫酸浓度及Cr3 浓度下,超声场对硫酸介质中Cr3 电化学氧化生成Cr2O72-过程中的电流效率的影响,并用扫描电镜对有无超声场时不同反应时间下的电极形貌进行了分析。实验结果表明:在相同的反应条件下,有超声场作用时Cr3 电化学氧化过程的电流效率明显高于无超声场时的电流效率。扫描电镜测定发现,有超声场作用时不同反应时间下电极的形貌有明显的变化。 相似文献
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为了简便、直观地测量功率超声珩磨磨削区的空化声场强度及分布情况,提出了利用弱酸PH试纸测量磨削区空化声场的方法。利用超声空化效应产生的弱酸空化泡在PH试纸表面溃灭后,形成深浅和分布不同的变色区域,间接地表征油石表面空化声场的强弱和分布规律。通过对比不同超声频率、测试距离和时间,得出了最佳测试距离和时间。结果表明,当超声频率为18.6 kHz,距离为10 mm时,测得油石表面的空化声场强度和分布最佳。该方法可形象地评价功率超声珩磨磨削区空化声场的强度和分布情况,具有一定的实际应用价值。 相似文献
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《中国物理 B》2021,30(10):104302-104302
The present study analyzes the effect of stirring on ultrasonic degradation experiments through acoustic field distribution, which provides a guidance for further improvement of the degradation rate of organic solutions. It is known that in order to eliminate the standing wave field formed by ultrasonic radiation in the water tank, the liquid in the water tank needs to be stirred and the corresponding distribution of acoustic field is simulated by using the finite element method(FEM).The standing wave leads to an uneven distribution of the acoustic field when it is not stirred, and disappears after being stirred, which increases the cavitation area in the ultrasonic cleaning tank. Then, the degradation experiment with agitation is carried out. The experimental results show that the degradation rate of the solution is higher than that when there is no agitation, which confirms the importance of the acoustic field distribution to ultrasonic degradation. In addition, it is clear that with the increase of the stirring speed, the degradation rate increases first and reaches a maximum at 600 rpm before decreasing. Finally, the distribution of flow field is simulated and analyzed. 相似文献
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《Ultrasonics sonochemistry》2014,21(2):566-571
Cavitation is a complex physical phenomenon affected by many factors, one of which is the gas dissolved in the medium. Researchers have given some efforts to the influence of gas content on sonoluminescence or some specific chemical reactions in and around the bubble, but limited work has been reported about the influence on the ultrasonic cavitation field distribution. In this work, the intensity distribution of the ultrasound field in a cleaning tank has been measured with the hydrophone. After analysed and visualised by MATLAB software, it was found that the cavitation intensity distribution in degassed water was much better than that in tap water. And further study proved that degassing process can improve the cavitation effect dramatically both in intensity and scope. Finally, the cavitation fields in mediums with different gas content were measured and the specific influence of air content on cavitation field was discussed. 相似文献
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Studies of a novel sensor for assessing the spatial distribution of cavitation activity within ultrasonic cleaning vessels 总被引:5,自引:0,他引:5
This paper describes investigations of the spatial distribution of cavitation activity generated within an ultrasonic cleaning vessel, undertaken using a novel cavitation sensor concept. The new sensor monitors high frequency acoustic emissions (>1 MHz) generated by micron-sized bubbles driven into acoustic cavitation by the applied acoustic field. Novel design features of the sensor, including its hollow, cylindrical shape, provide the sensor with spatial resolution, enabling it to associate the megahertz acoustic emissions produced by the cavitating bubbles with specific regions of space within the vessel. The performance of the new sensor has been tested using a 40 kHz ultrasonic cleaner employing four transducers and operating at a nominal electrical power of 140 W under controlled conditions. The results demonstrate the ability of the sensors to identify 'hot-spots' and 'cold-spots' in cavitation activity within the vessel, and show good qualitative agreement with an assessment of the spatial distribution of cavitation determined through erosion monitoring of thin sheets of aluminium foil. The implications of the studies for the development of reliable methods of quantifying the performance of cleaning vessels are discussed in detail. 相似文献
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The dynamic actions of cavitation bubbles in ultrasonic fields can clean surfaces. Gas and vapor cavitation bubbles exhibit different dynamic behaviors in ultrasonic fields, yet little attention has been given to the distinctive cleaning effects of gas and vapor bubbles. We present an experimental investigation of surface cleaning by gas and vapor bubbles in an ultrasonic field. Using high-speed videography, we found that the primary motions of gas and vapor bubbles responsible for surface cleaning differ. Our cleaning tests under different contamination conditions in terms of contaminant adhesion strength and surface wettability reveal that vapor and gas bubbles are more effective at removing contaminants with strong and weak adhesion, respectively, and furthermore that hydrophobic substrates are better cleaned by vapor bubbles. Our study not only provides a better physical understanding of the ultrasonic cleaning process, but also proposes novel techniques to improve ultrasonic cleaning by selectively employing gas and vapor bubbles depending on the characteristics of the surface to be cleaned. 相似文献