不同湍流模型对射流泵内部流场模拟的影响

为研究不同湍流模型和壁面边界处理方法对射流泵性能和内部流场模拟的影响,尝试寻找一种能够准确预测射流泵性能和内部流场的湍流模型与相应壁面处理方法的组合．将6种湍流模型(即3种k-ε模型,标准和SST k-ω模型以及RSM模型)和2种壁面处理方法(标准壁面函数和增强壁面处理方法)进行搭配．3种k-ε模型和RSM模型分别采用2种壁面处理方法,2种k-ω模型作为低雷诺数模型使用,不采用壁面处理方法,由此共得到10种组合．以某射流泵为例,将其壁面静压分布和性能试验数据作为参考来验证这10种组合的效果．结果表明:当流量比较小时,10种组合均与试验结果吻合较好；当流量比较大时,10种组合的模拟误差均大于10％.通过修正湍流模型常数,部分组合的模拟结果与试验数据之间的误差可以降低到5％以内.模型常数C2ε比σε对计算结果影响更大.湍动能的最大值随着C2ε或σε值的减小而减小,而湍动能的分布区域却相应的增大．

Influence of different turbulence models on simulation of internal flow field of jet pump

To study the effect of different turbulence models and related wall boundary treatment me thods on the simulation of the performance and internal flow field of a jet pump, and to find their good combination, six turbulence models (namely, three k-ε models, standard and SST k-ω models and Reynolds stress models) and two wall treatment methods (standard wall functions and enhanced wall treatment) were combined in different ways. Standard wall functions and enhanced wall treatment were respectively applied to three k-ε models and RSM model. Both k-ω models were used as low Reynolds number models without applying any wall treatment methods. Ten combinations were thus obtained. The data of the performance and the static wall pressure distribution of a jet pump were employed as the criteria to validate the simulation results. The results show that all the ten combinations agree well with the experiment data when the volumetric flow ratio is relatively low, and all simulation errors of the ten combinations are greater than 10% when working at relatively high flow ratio. After adjusting constants of the turbulent model, for some combinations, the difference between the errors of the predicted results and the experiment data were lowered to be less than 5%. The model constant C2ε has a greater influence than σε on the calculation; and the maximum turbulence energy decreases as  C2ε or σε decreases, but the distribution region of turbulence energy expands correspondingly.