基于网格数值耗散修正的圆湍射流模型

Turbulence Model for Round Jet Flow Based on Modification of Grid Numerical Dissipation

基于民用机舱内个性通风口,以圆湍射流作为研究对象,以标准κ-ε湍流模型较精细数值模拟与实验对比结果为出发点,通过对粗网格下数值结果的分析,针对网格尺度增大导致计算中数值耗散相应增大、射流速度沿轴向和径向衰减过快问题,从湍流耗散率方程出发,对影响湍流耗散的生成项和耗散项进行修正,平衡因网格尺度产生流动衰减过快的因素,进而提出了耗散率修正的κ-ε湍流模型.采用该修正模型验证了不同雷诺数和非等温条件下射流的适用性.应用修正的湍流模型可以避免机舱内大尺度空间流动对网格的苛刻要求,明显减少网格总数,同时达到对舱内复杂结构和边界条件下流场特征的正确模拟.

Based on the personalized vents in aircraft cabin,the turbent flow of round jet was studied. The results of the numerical simulation using the standard κ-εturbulence model with fine gird were compared with those of the ex-periment. Taking those comparison results as a point of departure,the analysis on the simulation results with coarse grids revealed that an increase in gird scale caused significant increase of dissipation and decline of velocity in jet flow along the axial and radial directions. This excessive decay of jet flow with coarse grids was resolved by modifying the turbulent dissipation rate of the generation and dissipation terms. The factors that cause an excessive decay were bal-anced. The modified dissipation rateκ-ε turbulent model was presented in this paper. The applicability of the modified model under different Reynolds numbers and non-isothermal conditions was also studied. The modified turbulence model was found to be capable of avoiding the demanding grid requirements for aircraft cabins and reducing total grid number significantly. The flow characteristics inside the cabin with complex structures and boundary conditions could be accurately simulated as well.