偏工况下壁面粗糙度对泵腔内流动规律的影响

Impact of Wall Roughness on the Flow Law in Chamber of a Centrifugal Pump at Off-Design Operating Condition

本文将结合雷诺时均方程、RNG k-ε湍流模型和等效沙粒粗糙度模型,研究一离心泵泵腔内的流动规律与壁面粗糙度和运行工况的关系。研究表明:壁面粗糙度对离心泵外特性的影响存在一个峰值,此时绝对粗糙度的值为0.2mm;随着流量的增加,壁面粗糙度对叶轮前、后盖板所受扭矩的影响增加、对离心泵轴功率的影响减小。设计工况下,前泵腔中存在无量纲切向速度α值不变的核心流动区域。在核心流动区域内,随着粗糙度的增加,α值先减小,达到极小值后趋于稳定,稳定值为0.51。在前盖板附近,极小值往粗糙度较大的方向移动。小流量工况下,湍流核心区域消失,动、静壁面附近α值随流量的变化规律相反。大流量工况下,湍流核心区域减小,且更加靠近静壁面。

The relation of inner flow with wall roughness is studied when a centrifugal pump is operating at off conditions. This study is conducted with the method of simulation, considering the RNG k - e turbulence model and equivalent sand-grain roughness model The research shows that a peak value of roughness appears which has significant impact on the performance of the centrifugal pump and the peak value is 0.2 ram. The wall roughness＇ influence on the front and rear shroud torque becomes greater with the increasing of flux, while its impact on shaft power is opposite. There is a core flow region where the dimensionless tangential velocity a is invariant. If the wall roughness value increases, the value of a decreases firstly and then it becomes a stable value when reaching the minimum, which is about 0.51. The minimum value moves toward the larger roughness value nearby the front shroud. Under the smaller flux conditions the core flow region disappears and the law between a and flux near the moving and static wall is opposite. The core flow region decreases and becomes more closer to the static wall under lager flux conditions.