We have been using the method of tube-arrest as a means of producing transient single cavitation bubble. In the present paper we seek to comprehend the mechanism of production and inquire into the structure of the ab ...We have been using the method of tube-arrest as a means of producing transient single cavitation bubble. In the present paper we seek to comprehend the mechanism of production and inquire into the structure of the ab initio pressure field in the arrested liquid column. The generated pressure wave is shown by combining the theoretical analysis with the experimental observation to be a slightly varied version of water hammer. With relatively clean liquid, the magnitude of the tension peak generating the TSB is likely to reach of several millions Pa. It is also shown that the so generated cavitation bubble originating from the gas-containing bulk liquid is in ‘violent’ motion.展开更多
Our earlier paper has identified a wave of Type 1 that is the pressure wave generated in the liquid-filled glass tube through the tube-arrest method by pulling and arresting the tube,when cavitation is prohibited. If ...Our earlier paper has identified a wave of Type 1 that is the pressure wave generated in the liquid-filled glass tube through the tube-arrest method by pulling and arresting the tube,when cavitation is prohibited. If cavitation is produced,a wave of Type 2 generally appears. The present paper takes the transition between wave types as indication of cavitation onset,and looks for a liquid parameter which controls the onset. One such an attempt shows the concentration of a dissolved gas in the liquid is the controlling factor with the result that the threshold of cavitation onset decreases with the increase of the concentration. Then a specially designed experiment reveals that possibly the mobility of the gas molecules (and also that of the liquid molecules) transiently affects the threshold so as to induce a large rise and fall in time of hours. The threshold finally settles down to some stable value under atmospheric pressure.展开更多
乌兰察布地区某变电站220 k V侧V相避雷器炸裂。对故障避雷器进行现场解体检查和试验分析,同时排查乌兰察布地区相同型号、批次、制造工艺的110 k V避雷器,对其进行解体检查及试验分析后,发现由于避雷器采用热缩管材质及制造工艺不良造...乌兰察布地区某变电站220 k V侧V相避雷器炸裂。对故障避雷器进行现场解体检查和试验分析,同时排查乌兰察布地区相同型号、批次、制造工艺的110 k V避雷器,对其进行解体检查及试验分析后,发现由于避雷器采用热缩管材质及制造工艺不良造成挥发物残留在热缩管内部,导致芯柱沿面绝缘强度下降,最终发展为避雷器整体贯穿性导通或击穿。提出了加强设备选型、完善红外诊断依据、细化相关标准的措施及建议。展开更多
基金supported by the National Natural Science Foundation of China (Grant No 10434070)
文摘We have been using the method of tube-arrest as a means of producing transient single cavitation bubble. In the present paper we seek to comprehend the mechanism of production and inquire into the structure of the ab initio pressure field in the arrested liquid column. The generated pressure wave is shown by combining the theoretical analysis with the experimental observation to be a slightly varied version of water hammer. With relatively clean liquid, the magnitude of the tension peak generating the TSB is likely to reach of several millions Pa. It is also shown that the so generated cavitation bubble originating from the gas-containing bulk liquid is in ‘violent’ motion.
基金supported by the National Natural Science Foundation of China (Grant No. 10434070)
文摘Our earlier paper has identified a wave of Type 1 that is the pressure wave generated in the liquid-filled glass tube through the tube-arrest method by pulling and arresting the tube,when cavitation is prohibited. If cavitation is produced,a wave of Type 2 generally appears. The present paper takes the transition between wave types as indication of cavitation onset,and looks for a liquid parameter which controls the onset. One such an attempt shows the concentration of a dissolved gas in the liquid is the controlling factor with the result that the threshold of cavitation onset decreases with the increase of the concentration. Then a specially designed experiment reveals that possibly the mobility of the gas molecules (and also that of the liquid molecules) transiently affects the threshold so as to induce a large rise and fall in time of hours. The threshold finally settles down to some stable value under atmospheric pressure.
文摘乌兰察布地区某变电站220 k V侧V相避雷器炸裂。对故障避雷器进行现场解体检查和试验分析,同时排查乌兰察布地区相同型号、批次、制造工艺的110 k V避雷器,对其进行解体检查及试验分析后,发现由于避雷器采用热缩管材质及制造工艺不良造成挥发物残留在热缩管内部,导致芯柱沿面绝缘强度下降,最终发展为避雷器整体贯穿性导通或击穿。提出了加强设备选型、完善红外诊断依据、细化相关标准的措施及建议。
