离心泵边界层网格的实现及应用评价

    Realization and application evaluation of near-wall mesh in centrifugal pumps

    • 摘要: 为了定量研究网格质量对离心泵数值模拟计算精度的影响,以结构化网格为例,从网格数量、近壁区网格加密和网格拓扑块生成方法3个方面系统研究了离心泵边界层网格的构建和应用评价过程。在网格数量无关性分析的基础上,生成了3套不同质量的边界层网格,并分别采用标准k-ε模型、RNG k-ε模型、标准k-ω模型和SST k-ω模型模拟了比转速为103的单级单吸离心泵的内外特性。将数值模拟结果和试验结果对比,发现具有边界层网格的模拟结果与试验值更为吻合,设计工况下,粗边界层网格基于标准k-ε模型的扬程预测精度比无边界层网格的模拟结果提高了1.19%。评估了边界层网格质量与湍流模型的关系,发现湍流模型的选择和边界层网格的质量密切相关,网格节点到壁面的最近距离Y+在200左右基本能满足k-ε湍流模型对近壁区网格质量要求,而选用k-ω模型时,至少保证Y+≤100。

       

      Abstract: To investigate effects of grid quality on the calculation accuracy for flow field simulation in centrifugal pumps, taking structured grid as research objects, the near-wall mesh of centrifugal pumps were constructed and evaluated in three aspects from the number of gird, subdivision of near-wall mesh and blocking strategies. Based on the grid independence analysis, the standard k-ε model, RNG k-ε model, standard k-ω model and SST k-ω model were used to simulate the flows in the centrifugal pump with ns=103 respectively. Compared to the measured values, the prediction accuracy of numerical results obtained by coarse grid and fine grid were higher than the grid without near-wall mesh. The results showed that when near-wall mesh was added, the prediction accuracy of the pump head increased by 1.19%. The relationship between the near-wall mesh and the turbulence models were also analyzed to find a reliable and feasibility numerical method for the centrifugal pump. To accommodate the use of k-ε model based scalable wall function, grid near-wall points were established at locations yielding dimensionless, grid wall spacing of Y+<200 was appropriate, while Y+≤100 was a must for the k-ω model with automatic wall function.

       

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