搅拌槽内三维流动场的RNG k-ε数值模拟

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

RNGk 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 :RNGk 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 。

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 C * 1 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.