管道内均匀与非均匀PEO溶液湍流减阻特性研究

在自制重力式循环水槽中(最高试验Re数可达105),测试分析了管道内均匀与非均匀聚氧化乙烯(PEO)溶液的湍流减阻规律。结果表明,均匀PEO溶液减阻率(DR)随Re数和浓度增加而提高(最大减阻率>70%),但浓度大于临界浓度(100p.p.m)后DR不再增加;而相同浓度均匀PEO溶液的减阻效果随时间逐渐减弱,且Re数越大,剪切破坏越严重,DR下降越明显。与均匀PEO溶液不同,非均匀PEO溶液(从管壁狭缝向内喷射PEO溶液所得)不受剪切破坏影响,减阻效果更稳定,且药品使用量小;同时通过增大喷射速率、Re数和喷射液浓度,可提高减阻率(最大减阻率>50%)。对比可见,喷射减阻方式仅需消耗少量药剂,就能实现显著、稳定减阻,有望用于水下航行体湍流减阻。

Study of the turbulent flow drag reduction characteristics of homogeneous and inhomogeneous PEO solution in pipeline flow

In a self-made gravity circulating water tank(the maximum experimental Reynolds number Re is up to 105),the turbulent drag reduction pattern of homogeneous and inhomogeneous polyethylene oxide(PEO)solution in pipeline was measured and analyzed.Results show that drag reduction rate(DR)of homogeneous PEO solution increases with the increase of Re(the maximum DR>70%),but when concentration is higher than critical concentration(100 p.p.m),drag reduction rate no longer increases.However,the drag reduction effect of homogeneous PEO solution with the same concentration(75 p.p.m)decreases gradually with time,and the larger the Re number is,the more serious the shear failure,and the more obvious the decrease of DR.Different from homogeneous PEO solution,inhomogeneous PEO solution(obtained by injecting PEO solution from narrow slit of tube wall)is not affected by shear failure,the drag reduction effect is more stable,and the dosage of drugs is small.At the same time,by increasing the injection rate,Re number and injection concentration,drag reduction rate can be increased(maximum drag reduction rate >50%)The comparison between the two kinds of solution reveals that the injection can obtain more significant and stable DReffect with fewer additives,which may be valuable for realizing long-time drag reduction for underwater vehicles.