Combined with the relationship between the time averaged parameters of flow field and the inter-subchannel transverse turbulent mixing velocity, a method for solving the mixing velocity between adjacent subchannels is presented in this paper. Then an anisotropic mixing model, which is based on subchannel-wise inhomogeneous turbulent mixing, is presented to reflect the three-dimensional mixing effect in rod bundle with spacer grid. By comparing the anisotropic mixing model with isotropic mixing model, it is found that the anisotropic mixing model agrees well with the experimental data from literature. In addition, based on the anisotropic mixing model, analysis on the subchannels with different spacer grids is also performed, including configurations with or without the mixing vanes and different arrangements of mixing vanes. It is found that the forced mixing effect between subchannels is mainly caused by the mixing vanes of the spacer grid. Besides, the continuous change of the flow and temperature fields is also caused by mixing vanes, which improves the Departure from Nucleate Boiling Ratio (DNBR) of the rod bundle channel. Also, the effect of different mixing vane arrangements on flow and heat transfer in the rod bundle is analyzed in detail.

结合流场的时间平均参数与子通道间横向湍流混合速度之间的关系，提出了一种求解相邻子通道间混合速度的方法。然后提出了一种基于子通道不均匀湍流混合的各向异性混合模型，以反映带间隔栅的棒束中的三维混合效果。通过将各向异性混合模型与各向同性混合模型进行比较，发现各向异性混合模型与文献中的实验数据吻合良好。另外，基于各向异性混合模型，还对具有不同间隔栅的子通道进行了分析，包括具有或不具有混合叶片的配置以及混合叶片的不同布置。发现子通道之间的强制混合效果主要是由间隔栅的混合叶片引起的。此外，混合叶片也引起流场和温度场的连续变化，从而改善了棒束通道的核沸腾比（DNBR）。同样，详细分析了不同混合叶片布置对棒束中流动和传热的影响。