Affiliations: Product Development Center, Toyo Radiator Co., LTD.
937 Soya, Hadano, Kanagawa, 257-0031, Japan | Department of Mechanical Engineering, School of
Engineering, Tokai University, 1117 Kitakaname, hiratsuka, Kanagawa 259-1292,
Japan
Abstract: The low pressure axial flow fans with an outer ring, used for
cooling automobile radiators, have a significantly large tip clearance between
the ring tip and the fan shroud. It has been found that the turbulent reverse
flow, or leakage flow, which occurs at the tip clearance, greatly affects the
fan performance and noise level. Therefore, in order to improve the fan
performance and noise level it is important to decrease the effect of leakage
at the tip clearance. The authors investigated the performance of the
straight-through type of labyrinth seal which operates in an extremely low
static pressure difference with a large clearance. It was hoped that by sealing
this clearance with the labyrinth seal the performance would be improved. It
was verified that the labyrinth seal satisfied almost the same performance as
that predicted by the previous theory. This theory was established by
experimental studies in the condition of quite high static pressure difference
when the labyrinth is stationary. However, it was later discovered that the
leakage rate decreased significantly even though there was far lower ring speed
in comparison to past research results where the ring rotated. This phenomenon
is conspicuous in a lower differential pressure. However, the cause of this
phenomenon has not been determined.
Keywords: Fan, Tip clearance, Labyrinth seal, Visualization
