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Interface settling property of clay floc suspension

粘土絮体悬浮液的界面沉降特性

基本信息

批准号：
21580292
负责人：
NAKAISHI Katsuya
金额：
$ 3.16万
依托单位：
Ibaraki University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2009
资助国家：
日本
起止时间：
2009 至 2011
项目状态：
已结题

项目摘要

The settling velocity of flocculated suspensions is determined as a function of effective floc volume fraction that is believed to be proportional to the solid volume fraction. However, flocs are very fragile and have an extended structure in suspensions so the effective volume changes easily. Therefore, a new method to determine effective volume from sediment volume was proposed and the effective volume was found to not be proportional to the solid volume. By using the measured effective volume, network formation was clarified to occur at an effective volume fraction over 0.25-0.30. Self-similar properties of floc structure were introduced for the analysis of settling velocity, and with the help of the relationship between settling velocity and effective volume fraction, fractal dimension was determined to be 2.35. On the other hand, at high volume fractions, many vertical channels were formed through the sediment and settling velocity tremendously increased. The flow rate in the channel was comparative to the computed maximum viscous-flow rate.

絮凝悬浮液的沉降速度被确定为有效絮凝体体积分数的函数，被认为是成比例的固体体积分数。然而，絮体是非常脆弱的，并且在悬浮液中具有延伸结构，因此有效体积容易变化。因此，提出了一种由泥沙体积确定有效体积的新方法，并发现有效体积与固体体积不成正比。通过使用测量的有效体积，网络形成被澄清为在有效体积分数超过0.25-0.30时发生。将絮体结构的自相似性引入到沉降速度的分析中，利用沉降速度与有效体积分数的关系，确定了絮体结构的分形维数为2.35。另一方面，在高体积分数，许多垂直通道形成通过沉积物和沉降速度大大增加。通道中的流速与计算的最大粘性流速相当。