Small-sized axial fans are used as air cooler for electric equipments. But there is a strong demand for
higher power of fan according to the increase of quantity of heat from electric devices. Therefore, higher
rotational speed design is conducted although, it causes the deterioration of efficiency and the increase
of noise. Then the adoption of contra-rotating rotors for small-sized fan was proposed for the
improvement of performance.
In the present paper, the performance and internal flow condition of a small-sized axial fan with
100mm diameter are shown as a first step of the research for the contra-rotating small-sized axial fan and
the similarity law of this small-sized axial fan is discussed. Furthermore, the numerical flow simulation
was conducted to investigate the performance of the contra-rotating small-sized axial fan and internal
flow field and pressure distributions were clarified and the effect of contra-rotating rotors would be
considered
