Circulation Fan

FIG. 1 is a perspective view of a circulation fan showing our new design; FIG. 2 is another perspective view thereof; FIG. 3 is a front elevational view thereof; FIG. 4 is a rear elevational view thereof; FIG. 5 is a left side elevational view thereof; FIG. 6 is a right side elevational view thereof; FIG. 7 is a top plan view thereof; FIG. 8 is a bottom plan view thereof; and, FIG. 9 is an enlarged view of portion 9 shown in FIG. 2 . The dash-dash broken lines in the drawings depict portions of the circulation fan that form no part of the claimed design. The dot-dash broken lines in FIGS. 2 and 9 represent boundaries of the enlarged portion and form no part of the claimed design.