液—液旋流分离管中强旋湍流的RNGk-ε数值模拟

Numerical Simulation of Strongly Swirlling Turbulent Flows in Liquid liquid Hydrocyclones Using RNG k ε Model

在高雷诺数时， Ｒ Ｎ Ｇ ｋε模型在形式上与标准ｋε模型基本相同，其区别主要是在 ε方程中增加了一个附加生成项。当流动快速畸变时该项迅速增大，由此改善了对旋转流、浮力流等较复杂湍流的预报能力。本文应用该模型对液—液旋流分离管中强旋湍流场的数值计算结果表明，其结果虽较标准ｋε模型有所改善，但同实际值间仍存在定性上的不合理性，因此，要在更大程度上改进对液—液旋流分离管中强旋湍流的预报，必须放弃基于各向同性假设的湍流模型，转而采用能够反映各向异性特性的高级模型如代数应力模型或雷诺应力模型等。

A k ε model based on the renormalization group theory ( RNG k ε model )is used to predict the turbulent flow field in a liquid liquid hydrocyclone in this work. The new model just has the same form as the standard k ε model, but it includes an extra term that describes the effect of large distortion (shear rate) and incorporates some anisotropy effect.So it can resolve fine details of the flow field better than previous models. The results show that some improvement has been made in prediction of the liquid liquid hydrocyclone, but it is not remarkable. The work indicates that in order to obtain a reasonably accurate flow description for the geometry of liquid liquid hydrocyclone, an anisotropy turbulence model should be employed such as Algebraic Stress Model or Reynolds Stress Differential Equation Model.