Numerical simulation on fluid flow and heat transfer in the disk MHD generator of the closed loop experimental facility

摘要

Time dependent r-z two-dimensional large eddy simulation has been carried out in order to clarify the performance, flow behavior and heat transfer across the downstream duct walls of the disk MHD generator region installed in a closed loop experimental facility at the Tokyo Institute of Technology. The numerical region is not limited to only the MHD generator channel, but it also includes the inlet duct, a downstream 90°-bend diffuser, and the outlet cylindrical duct. Both the fluid flow and heat transfer across the bend diffuser and the cylindrical duct walls are simulated simultaneously, solving the conjugate heat transfer problem. The results, obtained for realistic working conditions, show that boundary layer separation occurs in the generator channel for both no-MHD and MHD flow regimes. In particular, the separation of the boundary layer in the generator influences negatively the performance because of weak plasma ionization in the separated flow regions. The heat flux at the downstream walls is not constant, but has maximum and minimum values depending on the flow behavior in the channel.