稠密栅元不同子通道内湍流流动的RANS和URANS模拟

RANS and URANS Simulations of Turbulent Flow Inside Different Subchannels in Tight Lattice Bundle

本工作采用RANS和非稳态雷诺平均纳维斯托克斯模拟(URANS)方法对稠密栅元内典型子通道——中心通道和壁面通道内的湍流流动进行CFD模拟。研究分析了稠密栅元子通道内的不同周向角度的主流速度、壁面剪应力、湍动能等参数。将模拟计算结果和实验测量结果进行对比,结果表明:RANS模拟在采用各向异性的湍流模型的情况下能较好地模拟P/D较大的稠密栅元通道,但对于P/D较小(P/D<1.1)的稠密栅元通道,CFD结果和实验数据存在较大差距。相比之下,URANS方法可模拟紧密栅元子通道间隙区的大尺度、准周期的流动振动,从而和实验数据拟合良好。推荐采用雷诺应力湍流模型(SSG,ORS)进行RANS模拟,而采用SAS湍流模型进行URANS模拟。

Both steady and unsteady Reynolds averaged Navier stokes（URANS） methods were applied to the prediction of turbulent flow inside different subchannels in tight lattice bundle.Two typical configurations of subchannels（i.e.,wall subchannel and center subchannel） were chosen to be investigated.The validity of the method was assessed by comparing computational results of axial velocity,wall shear stress and turbulent intensity distributions inside various bundle configurations with the experimental data.The results show that RANS simulations with anisotropic turbulent model produce excellent agreement with experiment,whereas it fails to predict the flow behavior accurately in the case of tightly packed geometries（P/D〈1.1）.On the other hand,the URANS simulations are in good agreement with the results in tightly packed geometries due to reproducing the flow oscillation in the gap region.Reynolds stress turbulence model（SSG,ORS） are proposed for RANS and SAS turbulence model for URANS simulation.