DES和LES在被动旋转叶轮机械中的数值计算适用性分析

Applicability Analysis of Numerical Calculation of DES and LES in Passive Rotating Turbomachinery

以静止固体边界(表壳及其附属调节装置)、过渡域(表壳内叶轮旋转区外的流体域)和与固体边界存在相互作用的被动旋转域(叶轮)为分析主体,求解分析在进水口固定流速为2 500 L/h、20 L/h、12.5 L/h条件下的两种湍流模型所对应的流体速度分布及叶轮被动旋转情况。结果显示,在高雷诺数入射流边界条件下,大涡算法所得的叶轮转速要高于分离涡算法的计算结果,且更接近于实测数据。而在低雷诺数入射流边界条件下,两者的计算结果非常接近,在低雷诺数边界条件下,LES的结果无论从流场分布来看还是最终叶轮转速都没有明显优于DES的表现。

The static solid boundary(the watch case and its auxiliary regulating device), the transition domain(the fluid domain outside the impeller rotation region in the watch case) and the passive rotation domain(impeller) interacting with the solid boundary are analyzed. The fluid velocity distribution and the passive rotation of the impeller corresponding to the two turbulence models are calculated when the inlet fixed velocity is 2 500 L/h, 20 L/h and 12.5 L/h. The results show that under the condition of high Reynolds number incident flow, the impeller speed obtained by large eddy algorithm is higher than that obtained by separated vortex algorithm, which is closer to the measured data. In the case of low Reynolds number inlet velocity, these two calculation results are very close. Under the low Reynolds number boundary condition, the results of LES are not significantly better than DES in terms of flow field distribution and final impeller speed.