润滑脂在钢管中流动的壁滑移实验和研究

根据Mooney方法按边界层理论建立了研究管道流动的两个基本公式:壁滑移速度是由管壁的粗糙度和材料决定,不随管径变化;扣除壁滑移后的真实流变模型与管径无关.研究了润滑脂粘弹性、触变性、壁滑移等因素对流变特性的影响,研制了适宜壁滑移研究的高精度管流流变仪,制定了合理的实验步骤和测试方法,尽量消除其他因素的影响,分离壁滑移流动;在3种直径的钢管中进行流变试验,验证了两个基本公式,建立了适应任一管径流动阻力方程,计算各种管路的压降;证实了管径越小减阻效果越好,但管径小流动阻力大,应合理选择管径;减阻效果还与壁滑移速度成正比,提出了研究管壁与壁滑移速度关系的新课题.为在润滑脂集中润滑系统中研究管道输送特性提供了理论和实验基础.

Experiment and study on wall slip of lubricating grease flowing in tube

Based on the theory of boundary layer,two basic formulas for studying flowing in tubes were established according to Mooney method.One is that wall slip speed is determined by roughness and material of tube wall,and it does not change with the tube diameter.And the other is that real rheological model deducted wall slip is independent of the tube diameter.The effects of many factors on the rheological property were studied,such as viscoelasticity,thixotropic property and wall slip of lubricating grease.High accurate tube rheometer was developed for the study on wall slip.Reasonable experimental steps and testing measures were adopted in order to remove the effects of other factors and to separate the wall slip flowing.The two basic formulas were validated through rheological experiments in steel tube with three different diameters.A flowing resistance formula suitable for any tube diameter was developed to calculate the pressure decrease of all sorts of pipelines.It was proved that the smaller the tube diameter was,the better the effect of drag reduction would be.However,tube diameter should be properly chosen for small tube diameter may cause larger flowing resistance.At the same time,the effect of drag reduction was directly proportional to the wall slip speed.New study on the relationship between tube wall and wall slip speed was put forward.The paper established theoretical and experimental foundation for pipeline transport property of centralized grease lubrication systems.