Affiliations: Product Development Center, Toyo Radiator Co., LTD.
4-14 Shioya-cho, Minami-ku, Nagoya, 457-8560, Japan | Department of Mechanical Engineering, School of
Engineering, Tokai University, 1117 Kitakaname, Hiratsuka, Kanagawa 259-1292,
Japan
Abstract: This paper discusses the straight-through type labyrinth seal. This
labyrinth seal is used for axial flow fans, which have an outer ring at the
blade tip to seal the clearance between the ring tip and the fan shroud, in
order to prevent the reverse flow or leakage. These fans are used for the
cooling of automobile radiators. In these cases, the labyrinth seal is used in
an extremely low static pressure difference and a large clearance. A
significant decrease of the leakage rate was reported even when the labyrinth
seal rotated in comparatively low speed in this unique condition according to
the authors' former report. However, this phenomenon is different from past
research. Furthermore the cause of this phenomenon has not been determined.
Therefore, the internal flow was depicted with Computational Fluid Dynamics
(CFD) in order to clarify the cause of this phenomenon. The results of CFD show
that the leakage rate decreases significantly because the carry-over flow is
intercepted in the expansion groove. This is the newly discovered phenomenon
which occurs under the unique condition of an extremely low differential
pressure. It has not been pointed out before as the reason why the rotation
decreases the leakage rate.
Keywords: Fan, Tip clearance, Labyrinth seal, Visualization, CFD
