摘要
以水煤浆的流动特性(壁面滑移特性和流变特性)研究为基础,在中试规模的浆体输送装置上研究水煤浆流经90°弯管、突缩管和突扩管的阻力损失。以表征浆体流动特性的广义Reynolds数(Reg)作为参数,建立了局部阻力系数关联式;考察了弯径比、管径和Reg对弯管阻力损失的影响,分析了浆体流动特性对突缩管和突扩管阻力损失的影响。结果表明:除突缩管外,采用Reg作为入口流动状态参数可使流动特性不同的浆体的局部阻力系数试验数据一致;不同弯管的阻力系数随Reg的增加具有相似的变化趋势,在弯管的流动阻力损失方面不存在动力学相似性。当Reg<350,突扩管的阻力系数随Reg的增加迅速降低;当Reg>350,突扩管的阻力系数达到稳定值。在高Reynolds数下,突缩管的阻力系数与浆体的流动特性之间存在显著的相关性,即阻力系数随浓度的增加而增加。
Experimental investigations were carried out on a pilot scale slurry transport apparatus to evaluate the friction losses across 90° bends, sudden contraction and sudden expansion for coal-water slurries with the presence of wall-slip behavior. The flow behavior （wall-slip behavior and theological properties） of these slurries flowing in a straight pipe was determined to use as the baseline. Local resistance coefficients versus generalized Reynolds number correlations were established, in which the generalized Reynolds number （Reg） well accounted for the wall-slip behavior and theological properties of these slurries. Local energy losses in a series of bends were investigated as a function of ratio of bend to diameter, pipe diameter and generalized Reynolds number. For sudden expansion and sudden contraction, the effects of the flow behavior of the test slurries on local energy losses were determined. When Reg was used as a parameter to represent the flow status, a high degree of overlap in local resistance coefficients of various slurries was observed for all test fittings except for sudden contraction. The trends of change in local resistance coefficients with Reg showed obvious similarity for different bends. The measurements established that dynamic similarity could not be achieved in bends. With increasing Reg , the resistance coefficients for sudden expansion decreased rapidly when Reg〈350 and leveled off when Reg〉350. At a high generalized Reynolds number, the resistance coefficient for sudden contraction became closely related to the flow behavior of the test slurries and increased with increasing solid concentration.
出处
《化工学报》
EI
CAS
CSCD
北大核心
2009年第12期2981-2989,共9页
CIESC Journal
基金
国家重点基础研究发展计划项目(2010CB227001)~~
关键词
水煤浆
壁面滑移
非牛顿流体
弯管
突缩管
突扩管
局部阻力系数
coal-water slurry
wall-slip
non-Newtonian fluid
bend
sudden contraction
sudden expansion
local resistance coefficient
