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颗粒间碰撞对槽道湍流中颗粒聚集效应的影响研究
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作者 崔元凯 张欢 《力学学报》 EI CAS CSCD 北大核心 2024年第2期365-376,共12页
颗粒两相湍流广泛存在于自然现象和工业流动中,与人们的生活和生产活动息息相关.通常情况下,当颗粒的体积分数小于O(10^(-4))时,颗粒间的碰撞效应被忽略.一些研究发现,在颗粒两相壁湍流中,即使在低体积分数情况下,由于湍泳和倾向性聚集... 颗粒两相湍流广泛存在于自然现象和工业流动中,与人们的生活和生产活动息息相关.通常情况下,当颗粒的体积分数小于O(10^(-4))时,颗粒间的碰撞效应被忽略.一些研究发现,在颗粒两相壁湍流中,即使在低体积分数情况下,由于湍泳和倾向性聚集会导致颗粒局部浓度较高,颗粒间的碰撞频繁发生.然而,已有结果大多针对均匀各向同性湍流或采用大涡模拟的研究手段,尚缺少关于颗粒两相槽道湍流的直接数值模拟研究,颗粒间碰撞对颗粒聚集程度和形态影响的定量规律仍不清楚.文章基于欧拉-拉格朗日点颗粒框架,在摩擦雷诺数为Re_(τ)=180的条件下,采用直接数值模拟探讨了有/无颗粒间碰撞时水平槽道湍流中双分散颗粒聚集模式的差异.算例的颗粒平均质量分数为Φm~O(1),因此模型中还考虑了颗粒对流场的反馈作用.研究发现,颗粒间碰撞驱使近壁颗粒向槽道中心迁移,导致颗粒平均浓度的壁法向廓线变得十分平坦,抑制了壁湍流中颗粒的湍泳现象.同时,颗粒间碰撞导致颗粒在与壁面平行的水平薄层内更加均匀地分布.特别是在黏性底层内,各向异性的颗粒条带结构完全消失.这些结果表明,颗粒间碰撞显著抑制了水平槽道湍流中颗粒的湍泳和近壁区的倾向性聚集现象. 展开更多
关键词 颗粒两相湍流 槽道湍流 颗粒聚集 颗粒间碰撞 直接数值模拟
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Abrasion characteristic analyses of solid-liquid two-phase centrifugal pump 被引量:23
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作者 LI Yi ZHU Zuchao +1 位作者 HE Zhaohui HE Weiqiang 《Journal of Thermal Science》 SCIE EI CAS CSCD 2011年第3期283-287,共5页
Based on the solid-liquid two-phase mixture transportation test, the renormalization group (RNG) k-e turbulent model was utilized to simulate the solid-liquid two-phase turbulent flow in a centrifugal pump. By compari... Based on the solid-liquid two-phase mixture transportation test, the renormalization group (RNG) k-e turbulent model was utilized to simulate the solid-liquid two-phase turbulent flow in a centrifugal pump. By comparing the simulated and experimental results, inner flow features were revealed to improve the abrasion characteristic of the solid-liquid two-phase centrifugal pump. The influence of the solid phase on centrifugal pump abrasive performance is small when the particle volume fraction is less than 2.5%. The aggregation degree of the solid particles is enhanced as the particle diameter increases from 0.1 to 1 mm; however, the mixture density on the pressure side is reduced when the particle diameter increases to 1 mm for the impact of inertia. The wear on the hub is most severe for the shear stress on this position; it is also the largest. The wear characteristic is affected greatly by the parameters of the solid phase. The wear chracteristic can be optimized by decreasing the blade outlet angle. In the modified design, the blade angle is different, whereas the other geometric dimensions remain the same. The improved pump is simulated to contrast with the original pump. The results show that the values of mixture density and shear stress both decrease. The wear condition of the blade is improved to a certain extent. 展开更多
关键词 SOLID-LIQUID centrifugal pump numerical simulation abrasive experiment
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