不同湍流模型在混流泵数值模拟中的应用与评价

Application of different turbulence models in numerical simulation of mixed-flow pump and its evaluation

为了评价不同湍流模型在混流泵性能预测中的精度,以某比转速为511的混流泵模型作为研究对象,分别选取3种湍流模型:标准k-ε模型、RNGk-ε模型和SSTk-ω模型,基于SIMPLEC算法和混合网格技术,进行混流泵性能预测和全流场数值模拟,并以试验结果作为基准对预测扬程和效率进行误差分析.研究结果表明,网格密度对模拟结果具有较大影响,较疏的网格导致性能预测精度降低;当流量系数大于0.8时,3种湍流模型预测精度较高,都可以满足工程应用需要,当流量系数小于0.8时,只有RNGk-ε和SSTk-ω模型能较好地使数值预测和实验数据相一致,可以预测出流量扬程曲线中的正斜率特性.该结论将为混流泵性能预测的可靠性提供参考.

In order to evaluate the accuracy of turbulence model used for performance prediction of mixedflow pump,three kinds of turbulence model such as standard k-ε,RNGk-ε,and SSTk-ωare selected and a mixed-flow pump with specific speed of 511 is taken as investigation object.Numerical simulation of its performance prediction and full flow field is performed based on SIMPLEC algorithm and hybrid mesh.The error analysis of simulated head and efficiency is conducted on the basis of experimental results.The investigation result showed that simulation result would be greatly affected by the mesh density;a sparse mesh would make the accuracy of prediction decreased.All three models would give satisfactory prediction when the flow coefficient is greater than 0.8,so that could meet the needs of engineering applications,However,when the flow coefficient is less than 0.8,agood agreement between numerical predictions and experimental data could be obtained only by using RNGk-εand SSTk-ωturbulence models,which could make the slope characteristic of head-capacity curve positive.This conclusion will provide a reference for the reliability of performance prediction of mixed-flow pumps.