TITLE:
Unsteady Flow Condition between Front and Rear Rotor of Contra-Rotating Small Sized Axial Fan
AUTHORS:
Toru Shigemitsu, Hiroaki Fukuda, Katsuhiko Hirosawa
KEYWORDS:
Turbomachinery, Contra-Rotating Axial Flow Fan, Leakage Flow, Wake
JOURNAL NAME:
Open Journal of Fluid Dynamics,
Vol.7 No.3,
September
26,
2017
ABSTRACT: Contra-rotating small-sized axial fans are used as cooling fans for electric
equipment. In the case of the contra-rotating rotors, the blade row distance
between front and rear rotors is a key parameter for the performance and stable
operation. The wake and potential interference occur between the front
and rear rotors and leakage flow from the front rotor tip influences on the
flow condition of the rear rotor near the shroud when the blade row distance
is small. Therefore, it is important to clarify the flow condition between front
and rear rotors. The fan static pressure curves were obtained by the experimental
apparatus and the numerical analysis was also conducted to investigate
the internal flow between front and rear rotors. The leakage flow from the
front rotor tip reaches the leading edge of the rear rotor when the blade row
distance is small as L = 10 mm and the pressure fluctuations at the leading
edge of the rear rotor tip becomes larger than those at other radial positions.
In the present paper, the vorticity contour between front and rear rotors is
shown and pressure fluctuations related to the leakage flow from the front rotor
is investigated using the numerical analysis result. Then, suitable blade
row distance for the contra-rotating small sized axial fan is discussed based on
the internal flow condition.