k－ε－PDF两相湍流模型和台阶后方气粒两相流动的模拟

A k-ε-PDF TWO-PHASE TURBULENCE MODEL FOR SIMULATING GAS-PARTICLE FLOWS BEHIND A BACKWARD-FACING STEP

本文提出了两相湍流的ｋ－ε－ＰＤＦ模型。ＰＤＦ模型所得的湍流两相流动的统计平均方程，与雷诺时均方程有相似的形式，但ＰＤＦ模型可精确计算出颗粒相各方程的脉动关联项。本文将该模型用于预报台阶后方湍流两相流动，与ｋ－ε－ｋｐ模型相比，它可以更合理地预报出颗粒湍流的各向异性。

A k-ε-PDF model based on a statistical theory for turbulent gas-particle flows is proposed.The obtained statistically averaged equations have samilar form as that of the equations obtained by using the Reynolds averaging. Using the k-ε-PDF model (PDF particle turbulence model combined with the k-εgas turbulence model), many terms,such as the diffusion term in particle Reynolds Stress equations, can be exactly calculated.The k-ε-PDF model is used to simulate gas-particle flows behind a backward-facing step.Comparison of the predictions using both k-ε-PDF and the k-ε- kp models with experimental results shows that the k-ε-PDF model gives more reasonable non--isotropic Features of particle turbulence.