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超声空化场分布的动力学机理研究 被引量:2
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作者 杨芬 张明铎 +1 位作者 何倩 谭安乾 《西北大学学报(自然科学版)》 CAS CSCD 北大核心 2018年第1期37-40,共4页
超声技术在机械制造中获得了广泛的应用,其应用与声场分布有着密切的关系,精细准确地描述声场分布则是超声技术更广泛地投入实际应用中的关键。该文基于声波叠加原理和牛顿第二定律,分析了染色法生成声像图的物理原因。结果表明,在声场... 超声技术在机械制造中获得了广泛的应用,其应用与声场分布有着密切的关系,精细准确地描述声场分布则是超声技术更广泛地投入实际应用中的关键。该文基于声波叠加原理和牛顿第二定律,分析了染色法生成声像图的物理原因。结果表明,在声场力的作用下,声场中的亚甲基蓝悬浮粒子总是背离声压波节(力的波腹)而向其波腹(力的波节)聚集。在声压波腹附近,超声空化效应导致原本光洁的铜版纸面变得粗糙,使得汇聚到声压波腹附近的悬浮粒子易于附着在纸面;而在声压波节附近,悬浮粒子几乎不会附着在纸面。因而铜版纸被染色的程度呈现出的"声像"形象地反映了声场强弱的分布。 展开更多
关键词 驻波场 声压 波腹 波节 声场力 染色法
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Effect of applied pressure and ultrasonic vibration on microstructure and microhardness of Al-5.0Cu alloy
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作者 张杨 李风雷 +3 位作者 罗执 赵愈亮 夏伟 张卫文 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2016年第9期2296-2303,共8页
The squeeze pressure field and power ultrasonic field were applied during the conventional casting process of Al-5.0Cu alloy simultaneously. The effects of individual squeeze pressure or power ultrasonic and their cou... The squeeze pressure field and power ultrasonic field were applied during the conventional casting process of Al-5.0Cu alloy simultaneously. The effects of individual squeeze pressure or power ultrasonic and their coupling on the microstructures and microhardness of Al-5.0Cu alloy were studied by optical microscopy, scanning electron microscopy, image analysis and micro Vickers hardness test. The results show that compared with the conventional casting, refined microstructures, homogeneous distribution of α(Al) and θ(Al2Cu) and improved microhardness can be obtained when squeeze pressure or power ultrasonic is applied individually. For the case of combined fields, both the treated region and the improvement of microstructure and properties can be enhanced. 展开更多
关键词 Al-Cu alloy squeeze pressure field power ultrasonic field combined field MICROSTRUCTURE MICROHARDNESS
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Analyzing gravity anomaly variations before the 2016 Ms6.4 earthquake in Menyuan,Qinghai with an interpolation/cutting potential field separation technique 被引量:1
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作者 Liu Jin-Zhao Wang Tong-Qing +3 位作者 Chen Zhao-Hui Zhang Pin Zhu Chuan-Dong and Zhang Shuang-Xi 《Applied Geophysics》 SCIE CSCD 2018年第1期137-146,150,共11页
We evaluated 2011-2015 mobile relative gravity data from the Hexi monitoring network that covers the epicenter of the 2016 Menyuan Ms6.4 earthquake, Qinghai Province, China and examined the spatiotemporal characterist... We evaluated 2011-2015 mobile relative gravity data from the Hexi monitoring network that covers the epicenter of the 2016 Menyuan Ms6.4 earthquake, Qinghai Province, China and examined the spatiotemporal characteristics of the gravity field at the focal depth. In addition, we assessed the regional gravity field and its variation the half-year before the earthquake. We use first different interpolation algorithms to build a grid for the gravity data and then introduce potential field interpolation-cutting separation techniques and adaptive noise filtering. The results suggest that the gravity filed at the focal depth of 11.12 km separated from the total gravity field at about -400-150 ×10^-8 m/s^2 in the second half of 2015, which is larger than that in the same period in 2011 to 2014 (±30×10^-8 m/s^2). Moreover, at the same time, the gravity field changed fast from September 2014 to May 2015 and May 2015 to September 2015, reflecting to some extent material migration deep in the crust before the Menyuan earthquake. 展开更多
关键词 Menyuan EARTHQUAKE GRIDDING DENOISING potential field separation
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The Influence of an Acoustic Field on the Bed Expansion of Fine Particles
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作者 Akash M. Langde R.L.Sonolikar 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2011年第4期649-655,共7页
Fine particles are difficult to fluidize due to strong interparticle attraction.An attempt has been made to study the bed expansion of silica gel(dp=25μm) powder in presence of an acoustic field.A 135 mm diameter flu... Fine particles are difficult to fluidize due to strong interparticle attraction.An attempt has been made to study the bed expansion of silica gel(dp=25μm) powder in presence of an acoustic field.A 135 mm diameter fluidized bed activated by an acoustic field with sound intensity up to 145 dB and frequency from 90 Hz to 170 Hz was studied.The effects of sound pressure level,sound frequency and particle loading on the bed expansion were investigated.Experimental results showed that,bed expansion was good in presence of acoustic field of particular frequency.In addition,it was observed that in presence of acoustic field the bed collapses slowly. 展开更多
关键词 acoustic field FREQUENCY VIBRATION fluidized bed fine powder EXPANSION
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Effect of high-intensity ultrasonic field on process of semi-continuous casting for AZ80 magnesium alloy billets 被引量:2
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作者 张志强 乐启炽 崔建忠 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2010年第B07期376-381,共6页
Under the high-intensity ultrasonic field,AZ80 magnesium alloy was semi-continuously cast.The effects of ultrasonic intensity on the as-cast microstructures and mechanical properties were investigated.The results show... Under the high-intensity ultrasonic field,AZ80 magnesium alloy was semi-continuously cast.The effects of ultrasonic intensity on the as-cast microstructures and mechanical properties were investigated.The results show that the microstructures of the alloy cast under high-intensity ultrasonic field are fine and uniform,and the grains are equiaxed,rose-shaped or globular with an average size of 257μm.High-intensity field significantly decreases the grain size,changes the morphologies of theβ-Mg17Al12 phases and reduces their area fraction.It is also shown that a proper increase in ultrasonic intensity is helpful to obtain fine,uniform and equiaxed as-cast microstructures.The optimum ultrasonic parameters are that frequency is 20 kHz and ultrasonic intensity is 1 368 W.The mechanical tests show that the mechanical properties of the as-cast AZ80 magnesium alloy billets cast under ultrasonic field are greatly improved,and with increasing the ultrasonic intensity,the mechanical properties of the entire alloy billets are much higher and more uniform than those of the alloy without ultrasonic field. 展开更多
关键词 magnesium alloy ultrasonic field semi-continuous casting MICROSTRUCTURE mechanical properties
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Patch nearfield acoustic holography combined with sound field separation technique applied to a non-free field 被引量:2
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作者 BI ChuanXing ING WenQian +1 位作者 ZHANG YongBin XU Liang 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2015年第2期33-41,共9页
The conventional nearfield acoustic holography(NAH) is usually based on the assumption of free-field conditions, and it also requires that the measurement aperture should be larger than the actual source. This paper i... The conventional nearfield acoustic holography(NAH) is usually based on the assumption of free-field conditions, and it also requires that the measurement aperture should be larger than the actual source. This paper is to focus on the problem that neither of the above-mentioned requirements can be met, and to examine the feasibility of reconstructing the sound field radiated by partial source, based on double-layer pressure measurements made in a non-free field by using patch NAH combined with sound field separation technique. And also, the sensitivity of the reconstructed result to the measurement error is analyzed in detail. Two experiments involving two speakers in an exterior space and one speaker inside a car cabin are presented. The experimental results demonstrate that the patch NAH based on single-layer pressure measurement cannot obtain a satisfied result due to the influences of disturbing sources and reflections, while the patch NAH based on double-layer pressure measurements can successfully remove these influences and reconstruct the patch sound field effectively. 展开更多
关键词 nearfield acoustic holography sound field separation equivalent source method
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Underwater moving noise source identification based on hybrid near-field acoustical holography 被引量:2
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作者 HU Bo YANG DeSen +1 位作者 SHI ShengGuo SUN Yu 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2011年第9期1570-1578,共9页
Near-field acoustical holography (NAH) is a powerful tool for identifying noise sources and visualizing acoustic field. By recording the acoustic pressures in the near-field, the acoustic quantities in the whole 3-D f... Near-field acoustical holography (NAH) is a powerful tool for identifying noise sources and visualizing acoustic field. By recording the acoustic pressures in the near-field, the acoustic quantities in the whole 3-D field can be reconstructed and predicted. However, the current theory of NAH is not applicable to tracking large scale moving noise sources. Therefore, the hybrid near-field acoustical holography is developed for reconstructing acoustic radiation, which is derived from statistically optimized near-field acoustical holography (SONAH) and moving frame acoustical holography (MFAH). The theoretical formulation is systematically addressed. This method enables us to visualize the noise generated by moving noise sources and the measurement array can be smaller than the source, which improves the practicability and efficiency of this technology. Numerical simulations are presented to demonstrate the advantages of hybrid NAH. Then, two experiments have been carried out with a line array of hydrophones. The results of simulations and experiments support the proposed theory, which shows the advantage of hybrid NAH in the reconstruction of an acoustic field in an underwater holographic measurement. 展开更多
关键词 near-field acoustical holography statistically optimized moving noise source
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Experimental Study of Effects of Tip Geometry on the Flow Field in a Turbine Cascade Passage 被引量:7
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作者 MA Hongwei WANG Lixiang 《Journal of Thermal Science》 SCIE EI CAS CSCD 2015年第1期1-9,共9页
This study investigates the effects of blade tip geometry on the flow field of a turbine cascade at the incidence angle of 0 degree experimentally. The tests were performed in a low-speed turbine cascade wind tunnel. ... This study investigates the effects of blade tip geometry on the flow field of a turbine cascade at the incidence angle of 0 degree experimentally. The tests were performed in a low-speed turbine cascade wind tunnel. The Reynolds number based on the blade chord was about 172300 at the exit. Traverses of the exit flow field were made in order to measure the overall performance. The effects of using fiat tip and grooved tip with a chord-wise channel were studied. The case with the flat tip is referenced as the baseline. The tip clearances are all 1 mm measuring 0.84 percent of the blade span. The depth of channel is 2mm.The flow field at 10% chord downstream from the cascade trailing edge was measured at 38 span-wise positions and 26 pitch-wise positions using a mini five-hole pressure probe. The static pressure distribution on the tip end wall is measured at 16 pitch-wise stations and 17 chord-wise stations. Results show that there exists great pressure gradient in the pressure side for the fiat tip and the pressure side squealer tip, which means strong leakage flow. The pressure gradient from the pressure side to the suction side is greatly decreased for the grooved tip, and the resulting leakage flow is weaker. The core of the leakage vortex moves closer to the suction side for the pressure side squealer tip and farther away from the suction side for the suction side squealer tip. The pressure side squealer has little advantages over the fiat tip in improving the flow capacity and reducing the overall losses. The suction side squealer tip and grooved tip can effectively decrease the intensity of the tip leakage vortex, improve the flow capacity and reduce loss of the turbine cascade passage and the grooved tip performs the best. 展开更多
关键词 blade tip geometry turbine cascade flow field EFFECT
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