水力发电学报2013，Vol.32Issue(4)：88-93,152,7.
相对粗糙度和雷诺数对90°弯管局部阻力系数的影响
Influence of relative roughness and Reynolds number on local resistance coefficient of 90°-bend pipeline
摘要
Abstract
Local resistance coefficients of bend pipeline in engineering hydraulic calculation are usually empirical values and they vary greatly due to different sources.This directly lowers the accuracy of hydraulic losses calculation and project cost estimation.In this work,a numerical model was developed for 90°-bend pipeline,and three k-ε models adopted in this model were verified using the test results for steel bends of different wall roughness.The resistance coefficients of the bends were simulated for over 200 test conditions at different combinations of relative roughness ranged from 0 to 0.002 and Reynolds number Re ranged from 3.2 ×104 to 3.2 × 107.The results show that the variation of this coefficient can be divided into smooth region,transition region and rough region,similar to those of friction resistance coefficient.In smooth region,the coefficient decreases with Re in power function; in transition region,it depends on both Re and relative roughness; in rough region,it is only positively correlated with relative roughness.Effect length of local resistance in smooth region increases nonlinearly with increase of Re,and beyond smooth region,it decreases in the forepartand then tends to a stable value with increase of Re and is negatively correlated with relative roughness.Local resistance coefficient has a functional relationship with friction resistance coefficient,and the coefficients of this functional equation only depend on relative roughness.The results offer an improved calculation method of pipeline local losses.关键词
水力学/局部阻力系数/相对粗糙度/影响长度/数值模拟Key words
hydraulics/ local resistance coefficient/ relative roughness/ effect length/ numerical simulation分类
建筑与水利引用本文复制引用
张昕,纪昌知,姜敏,姬艳君..相对粗糙度和雷诺数对90°弯管局部阻力系数的影响[J].水力发电学报,2013,32(4):88-93,152,7.基金项目
国家自然科学基金(51079150) （51079150）
水利部公益性行业科研专项(201301016-02) （201301016-02）
