轴流泵内部流动数值模拟及PIV试验

Numerical simulation and PIV experiment of flow field in axial flow pump

为了研究轴流泵内部流动数值模拟中不同湍流模型的适用性,分别采用standard k-ε模型、RNG k-ε模型、SST k-ω模型以及大涡模拟(LES)方法,基于结构化网格与网格滑移技术,对叶轮直径为200 mm、名义比转数ns为700的模型轴流泵进行了性能预测和全流场数值模拟;计算了水泵的扬程和效率,并与在水泵试验台上测试得到的外特性结果进行了对比和分析.结果表明,在最优工况附近,standard k-ε模型、RNG k-ε模型和SST k-ω模型都能较精确地预测轴流泵的外特性,基于RNG k-ε湍流模型的扬程和效率误差相对较小;在非设计工况下,不同湍流模型具有不同的特性.在0.8Qopt,1.0Qopt和1.2Qopt工况下,针对叶轮与导叶间的轴向间隙处进行了PIV内部流场测试;将各个湍流模型下的数值模拟结果与PIV的测量结果进行比较,发现基于雷诺时均方程的3种湍流模型的内流场流线与PIV的测量结果进行比较,发现基于雷诺时均方程的3种湍流模型的内流场流线与PIV的试验结果具有基本相同的趋势性,从而证明了数值模拟计算的可靠性和有效性;而采用LES计算得到的流场与PIV测量结果产生一定的偏差.同时,对轴流泵在不同流量工况下内流场的流动结构进行了分析.

In order to study the applicability of turbulence models of an axial flow pump,the standard k-ε,RNG k-ε,SST k-ω models and large eddy simulation（LES） method were used.Based on the structured hexahedral and mesh slip technology,the performance prediction and numerical simulation of model axial flow pump with impeller diameter of 200 mm and rated specific speed of ns= 700 were carried out.The obtained head and efficiency of pump were calculated and compared with the experimental results.The results show that the three models can give satisfactory predictions of overall characteristics at the operating condition and the result of RNG k-ε is relatively ideal,but different models have different characteristics at off-design conditions.PIV measurement was carried out for the axial clearance between the impeller and guide vane at 0.8Qopt,1.0Qoptand 1.2Qopt.Numerical simula-tion results for the four models were compared with those from PIV measurement in the same areas.The streamlines for the three models based on Reynolds time-averaged equations are in a good agreement with PIV results,indicating the accuracy and validity of the numerical simulation.However,there is a certain deviation between the calculation results of LES and PIV results.Moreover,the flow features at different flow rates were analyzed.