A local maximum appears in the distribution of Nusselt numbers of the axisymmetric confined jet with a cylindrical ring. It has been confirmed by flow visualization and the measurements of velocity fluctuation and its spectrum that the large-scale vortices shedding from the ring bring about heat transfer enhancement at some downstream region of the ring. In the cases of the velocity ratio of the jet and circumferencial flows Uj/Us≤1.5, the periodically shed vortices attach directly to the pipe wall. On the other hand, the vortices are entrained into the jet due to the intense shear rate in the case of larger velocity ratio, and the high-intensity turbulence produced during the collapse of the vortices can be considered to increase the heat transfer coefficient.