UNSTEADY CONJUGATED HEAT-TRANSFER IN TURBULENT CHANNEL FLOWS WITH CONVECTION FROM THE AMBIENT

A numerical study is carried out to investigate the transient conjugat ed heat transfer in turbulent channel flows with convection from the a mbient. The solutions take wall conduction and heat capacity effects i nto consideration. Major nondimensional groups identified in this work are the wall-to-fluid conductivity ratio K, the wall-to-fluid thermal diffusivity ratio A, the dimensionless wail thickness beta, the Reyno lds number Re, the Prandtl number Pr, the outside Nusselt number Nu(o) and the dimensionless cooling length L. The influences of wall materi al, beta, Pr, Re and Nu(o) on the interfacial heat flux, outer wail te mperature and interfacial temperature are examined in detail. Results show that wall conduction plays a significant role in the transient co njugated heat transfer problem. In addition,the time required for heat transfer to reach the steady state condition is longer for systems wi th a larger beta or smaller A, Re and Nu(o).