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利用能量耗散率计算管流的平均剪切率 被引量:23
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作者 张劲军 严大凡 《石油学报》 EI CAS CSCD 北大核心 2002年第5期88-90,共3页
含蜡原油的流变性与其所经历的剪切历史有关。以往用截面平均剪切率或湍流时的管壁剪切率衡量流体管流的剪切历史 ,有不当之处。根据能量耗散率与剪切率的关系 ,提出了按流体的体积平均能量耗散率计算流体平均剪切率的方法 ,即可根据流... 含蜡原油的流变性与其所经历的剪切历史有关。以往用截面平均剪切率或湍流时的管壁剪切率衡量流体管流的剪切历史 ,有不当之处。根据能量耗散率与剪切率的关系 ,提出了按流体的体积平均能量耗散率计算流体平均剪切率的方法 ,即可根据流体的密度、平均流速、管道直径、流动的摩擦因子或摩阻压降以及流变参数计算牛顿流体和幂律流体管流的平均剪切率。对于湍流 ,按本方法计算的平均剪切率能合理地度量流体的平均剪切历史。在原油管道正常运行的雷诺数范围内 ,按截面平均方法计算的湍流剪切率比按体积平均能量耗散率计算的结果约偏低 2 0 %~ 40 %。 展开更多
关键词 原油 能量耗散 计算 管流 平均剪切率 石蜡基原油 剪切历史 湍流
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Average cluster sizes and cluster size distributions of superfine nickel particles in light media
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作者 李敬生 杜飞虎 王娟 《Journal of Central South University》 SCIE EI CAS 2009年第3期399-404,共6页
Effects of shear rates on average cluster sizes (ACSs) and cluster size distributions (CSDs) in uni- and bi-systems of partly charged superfine nickel particles were investigated by Brownian dynamics, and clustering p... Effects of shear rates on average cluster sizes (ACSs) and cluster size distributions (CSDs) in uni- and bi-systems of partly charged superfine nickel particles were investigated by Brownian dynamics, and clustering properties in these systems were compared with those in non-polar systems. The results show that the ACSs in bi-polar systems are larger than those in the non-polar systems. In uni-polar systems the behavior of clustering property differs: at the lower ionic concentration (10%), repulsive force is not strong enough to break clusters, but may greatly weaken them. The clusters are eventually cracked into smaller ones only when concentration of uni-polar charged particles is large enough. In this work, the ionic concentration is 20%. The relationship between ACS and shear rates follows power law in a exponent range of 0.176-0.276. This range is in a good agreement with the range of experimental data, but it is biased towards the lower limit slightly. 展开更多
关键词 ionic concentration average cluster sizes cluster size distribution power law
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