TY - JOUR
TI - Research on heat transfer characteristics of fractal-generated turbulence based on large eddy simulation
AU - Duan Chengdong
AU - Jiang Yuncong
AU - Wu Nannan
AU - Xu Qiwen
AU - Wang Lijun
JN - Thermal Science
PY - 2019
VL - 23
IS - 6
SP - 3993
EP - 4004
PT - Article
AB - Turbulence plays an important role in the fields of heat and mass transfer  and enhanced chemical reaction. 
In order to explore the effect of  grid-generated turbulence on flow heat transfer, in this paper, three  different fractal grid structures with the same blocking ratio σ, effective  mesh size Meff and thickness ratio tr=tmax/tmin (case1: The grid  cross-section is a triangle, case2: the grid cross-section is an inverted  triangle,case3:the grid cross-section is square ,case4:no grid) and without  the grid were simulated based on large eddy simulation(LES). The aim of this  simulation is to explain the evolution characteristics and heat transfer  mechanism of turbulent flow field under the four cases. The results show  that，in the same initial condition, case 2 can generate the highest  turbulence intensity and the feature of heat transfer on the cylindrical  surface is more uniform. In case3, the boundary layer in the flow field is  separated earlier, and more vortices are excited to enhance the heat  transfer than other cases in the boundary layer region. The surface average  Nusselt number is 1.3 times than that of case4.