Heat Transfer Characterisics And Fluid Dynamics Around 3×3 Prisms

This dissertation investigated the heat transfer characteristics and fluid dynamics around 9 square prisms,which are in a 3 × 3 configuration and the middle prism is isothermal using a simulated method,based on the Re = 150,Pr = 0.74 and the spacing ratio L/D varying from 1.2 to 7(L is the center to center length of any two adjacent prisms,D is the side length of any prism).The principal focus of research is on the variation of vortex shedding frequency St,the time-averaged drag coefficient (?),the fluctuating drag coefficient (?) and the lift coefficient (?),the recirculation length on the front and rear surface of the heated prism (?),the time-and-surface-averaged Nusselt Number Nu,the formation length L*_f,wake width w* and the heat flux characteristics in the near wake of nine square prism with L/D.The flow behaviors can be classified into five distinct flow patterns.They are single bluff body flow(flow pattern A: L/D < 1.5),reattachment flow(flow pattern B: 1.5 < L/D < 3.2),lateral-interaction induced co-shedding flow(flow pattern C: 3.2 < L/D < 4.0),reattachment + co-shedding flow(flow pattern D: 4.0 < L/D < 4.5)and coshedding flow(flow pattern E: 4.5 < L/D < 7.0).When L/D = 3.5,the time-averaged drag coefficient (?) and Nusselt Number Nu reach its maximum value,which illustrates that the wind load is the biggest and the heat transfer effect is the best.When L/D is less than 3.5,and Nu on the front surface show the same tendency with increasing L/D,and Nu on the rear surface increase with L/D(L/D < 3.5 and L/D > 4.8),while the tendency is adverse for the other ranges.Future the correlation between the bubble length and Nusselt number can be found.In the near wake region,the affected range of each flow pattern,the heat transfer direction and range of influence of the transverse heat flux are very different.From above all,the spacing ratio L/D significantly affected the flow mechanism and heat transfer characteristics of each flow pattern.