In this paper we describe the effect of spacing between two adjoining circular cylinders on flow around three rows of two-dimensional circular cylinder bundles supported by wires. The experiment was carried out in an N.P.L. blow-down-type wind tunnel with a working section of 500mm×500mm / 2000mm and with the Reynolds number of 9.4×103. The frequency of shedding vortices from the circular cylinder, displacement of the vibrating circular cylinder, and the time mean and fluctuating surface pressure distributions on the circular cylinder were measured. And the results were compared with those for the case of fixed support. Consequently it was found that (i) shedding vortices from circular cylinders exist in the range of spacing ratio S/D≥3 for the first row, S/D≥2.3 for the second row and S/D≥2.0 for the third row, (ii) the fluid elastic vibration occurs in the range of S/D<2.O for the first row and S/D<2.3 for the second row, though it does not occur for the third row, and (iii) the variation of fluctuating drag coefficient and fluctuating lift coefficient corresponds to that of displacement of a vibrating cylinder.
