Analysis of Influence Factors on Sludge Wall Slip

Wall slip behavior of sludge was studied experimentally by using a rotational rhehometer with parallel plate fixtures and checking the possible influence factors on sludge wall slip based on the gap dependence of the stress/ strain data. In the steady shearing flow it was found that there seems to be no critical shear stress for the onset of slip of sludge, while concentration is the important influence factor to sludge wall slip. In the oscillatory shear flow experiments, we analyze the total wave. While strain γ₀=0.68, stress amplitude decreases with the time, while strain γ₀=0.1, the stress amplitude remains constant. The stress sweep under the three gaps was done on the sludge of different angular frequency and temperature. In the previous stage, shear stress coincides better under the different angular frequency in the linear region and nonlinear region, somewhere in the nonlinear area it appears bifurcation, but the shear stress and strain are not constant in the bifurcation point. In a certain temperature range, gap dependence occurs, but the bifurcation point is almost same. It indicates that the wall slip relates to strain, angular frequency and other factor, the temperature of its impact is negligible.