搅拌槽内三维流动场的RNG k-ε数值模拟

RNG k-ε模型在耗散率方程中通过系数C*1引入描述流场畸变效应的附加源项后,在一定程度上会改善对旋转流、浮力流等较复杂湍流的预报能力.本文应用该模型对六直叶涡轮搅拌桨的三维流动场进行了数值模拟,并将计算结果与实验数据进行了比较.计算结果表明:RNG k-ε模型对桨叶附近速度场的预报较k-ε模型有一定程度改善,但对湍流动能的预报却要比k-ε模型差.若要进一步改进对桨叶附近流动场的预报,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的模型或采用先进的计算方法.

Numerical simulation of three dimensional flow field in a stirred tank using RNG k-ε model

A k-ε model based on the renormalization group theory (RNG k-ε model) has the same form as the standard k-ε model , but it includes an extra term in the dissipation rate equation through C₁* that describes the effect of large distortion and incorporates some anisotropic effects. To some extent , better results can be got for complex flows , such as rotating flow , buoyancy flow , etc. This model was used in the numerical simulation of three dimensional flow of Rushton turbine in a stirred tank. The results were compared with experimental data and show that some improvements are made in prediction of velocity distribution , but the prediction of turbulent kinetic energy is worse than that by the k-ε model. The work indicates that in order to obtain more accurate results an anisotropic turbulence model or more advanced methodes should be employed.