The ornamental design for a spiraltowerfan, as shown and described.
FIG. 1 is a front left perspective view of the spiral tower fan;
FIG. 2 is a rear perspective view of the spiral tower fan of FIG. 1;
FIG. 3 is a front elevation view of the spiral tower fan of FIG. 1;
FIG. 4 is a rear elevation view of the spiral tower fan of FIG.;
FIG. 5 is a left elevation view of the spiral tower fan of FIG. 1;
FIG. 6 is a right elevation view of the spiral tower fan of FIG. 1;
FIG. 7 is a top plan view of the spiral tower fan of FIG. 1; and,
FIG. 8 is a bottom plan view of the spiral tower fan of FIG. 1.
The broken line showing of portions of the spiral tower fan is included for the purpose of illustrating environmental structure and forms no part of the claimed design.