非牛顿流体充填料浆的管输摩擦阻力预测

在矿山充填采矿中,充填料浆在管道输送中的阻力损失计算是一重要环节.为探索采用摩擦阻力系数模型简单高效地预测充填料浆管输阻力损失的方法,按照流态分类,总结了7种常用的非牛顿流体的摩擦阻力系数模型,结合一个具体案例分析讨论了模型的正确使用.结果显示,选取模型时必须先考虑工程实际的流体类型和流态;对于最常见的宾汉塑性体的层流运动,使用Darby-Melson模型和Swamee-Aggarwal方程可近似替代Buckingham-Reiner方程,其预测的沿程阻力损失与实际监测十分吻合,是宾汉塑性体层流流动首选的阻力预测模型,而Danish-Kumar模型则过低估计阻力值,适合赫德数较大的流体.实际监测中的速度、沿程阻力波动原因与料浆配比的波动、骨料变异性、料浆非均匀性和充填采场倍线大小等因素密切相关且不可避免.对于层流紊流过渡区流体的沿程阻力预测仍是工程难题.

Prediction of Friction Pressure for Non-Newtonian Backfilling Pipe-flow Slurry

In mine backfilling, it is of great significance to calculate the slurry pressure loss in the pipeline transportation. In order to seek a simple and efficient method to predict the pressure loss through applying the friction factor correlations, this paper summarized seven friction factor correction models for non-Newtonian flow according to the flow state classication. After that, details on how to utilize the models to predict the pressure loss through a case study were presented. The results show that choosing a proper model is very important, where the practical flow type and conditions should be considered. For Bingham plastic laminar flow, the Darby-Melson and Swamee-Aggarwal model, which are approximations of the Buckingham-Reiner equation, are the first choices since their prediction results are in good agreement with the actual monitoring results of the pressure loss. However, the Danish-Kumar model underestimates the pressure drop and is suitable for flow with a large Hedstrom Number. Besides, monitoring fluctuations for the velocity and pressure loss in practice can be observed due to the slightly changeable slurry mixing proportion, the variability of the aggregate, the particle settling and mild segregation of the slurry during transportation, and the change of the stowing gradient. Finally, the pressure loss prediction for the transition flow region is still an engineering challenge.