Analysis of the influences of variable physical parameters on coherent structure in rod bundle lattice

The study of the flow and heat transfer characteristics in heat exchanger equipment has been a major of engineering research. The discovery of the coherent structure provided a new direction for this field research. Based on the classic turbulent model of the Unsteady Reynolds-Averaged Navier-Stokes (URANS) method, the flow, heat transfer characteristics and the coherent structure in 7-rod bundle lattice. The influences of variable physical parameters were analyzed. It was revealed that: (1) The coherent structure period was shorter but the intensity was stronger when the physical parameters were variable. Meanwhile, the starting points of coherent structure were backer than these when the physical parameters were unchangeable. (2) The distribution nonuniform of velocity when the physical parameters were variable was greater than that when the physical parameters were unchangeable. The coherent structure was related to the velocity discrepancy on both sides of the gap region. (3) The distribution nonuniform of temperature was also greater when the physical parameters were variable. (authors)