Numerical Analysis of Developing Turbulent Structure in Triangular Array Rod Bundles.

Abstract

Numerical analysis has been performed on developing turbulent flow in triangular array rod bundles. The ratio of pitch represented by two rod centers to rod diameter is 1.2 and Reynolds number is 4.9×104. In calculation, an algebraic stress model was adopted in order to predict Reynolds stresses precisely, and a boundary-fitted coordinate system was introduced to set boundary conditions easily. Calculated results were compared with the experimental data. The calculated profiles of secondary flow and Reynolds stresses in rod bundles are shown in this study. As a result of this calculation, it was found that the calculated intensity of the secondary flow is about 0.6% of bulk velocity. This calculated intensity of secondary flow coincides with the evaluated value from the experimental data measured by several researchers. Judging from this calculated value, it is very difficult to measure the secondary flow in rod bundles. The present method predicts larger the turbulent enregy and primary velocity fluctuation in the vicinity of the wall than the experimental data.