Experimenial data and correlations on heat transfer were obtained for vertical array of three horizontal cylinders under high Rayleigh number conditions. For S/D < 2, Contrary to the diminishing effect on heat transfer for upper rows in lower Rayleigh number conditions asreported in the literature, an intensive effect on heat transfer for the upper rows was revealed for Ra = 4 ×107 ～ 1 ×108.
