浓度对水煤浆壁面滑移和流变特性的影响

在中试规模水煤浆输送试验装置上，采用直径25、32、40和50 mm的直管系统地考察了浓度对水煤浆壁面滑移流动特性的影响。联合采用经典Mooney滑移修正方法和Tikhonov 正则化数值计算方法，确定了水煤浆的真实流变特性和壁面滑移特性。结果表明，在低浓度区，滑移速度随浓度增加而增加；在高浓度区，滑移速度随浓度增加而降低。管内流动存在临界剪切应力，只有壁面剪切应力高于临界剪切应力时才产生壁面滑移现象；临界剪切应力和屈服应力随浓度增加有相同的变化趋势，2者相对大小不同，导致滑移贡献率随壁面剪切应力的变化呈现2种相反的趋势。浓度越高，真实剪切粘度越大，非牛顿流体特性越显著。

Effects of Concentration on Wall Slip Behavior and Rheological Characteristics of Coal Water Slurry

Experimental researches were carried out on a pilot-scale slurry transportation apparatus to investigate effects of volume concentration on slip flow of coal water slurry (CWS) in pipes with different diameters of 25, 32, 40 and 50 mm. A procedure combining traditional Mooney method for wall slip correction with numerical technique based on Tikhonov regularization was applied to determine true rheology of CWS and wall slip behavior. The results suggested that slip velocity increases with increasing concentration in the low range of concentration. While in the range of high concentration, slip velocity decreases with increasing concentration. Critical wall shear stresses were observed beyond which slip phenomenon occurs. With the increasing of concentration, there are similar trends in variations of critical wall shear stress and yield stress. Depending on difference between the value of yield stress and that of critical wall shear stress, slippage contributions exhibit opposite trends with increasing wall shear stress. The true shear viscosity and non-Newtonian behavior increase when concentration is promoted.