Decaying swirl flow and its heat transfer enhancement in a pipe

The local maximum tangential velocity, the local friction factor and the local Nusselt number of the decaying swirl flow in a pipe are calculated theoretically in this paper. Comparison shows that the theoretical values are in reasonable agreement with the experimental data. The experimental results of the inlet axial vane swirlers are presented to show that for the same pump power and the same heat transfer area, the heat transfer quantity, Q, of the decaying swirl flow in a pipe is higher than that of the axial flow in a pipe, Qs, and the value of Q/Qs is influenced by the swirler construction parameters.