J051033 Unsteady Internal Flow in Rotors of Contra-Rotating Small-Sized Axial Fan

Small-sized axial fan is used as air cooler for electric equipments. But there is demand for higher power of fan according to the increase of quantity of heat from electric device. Therefore, higher rotational speed design is necessary but it causes the deterioration of efficiency and increases the noise. Contra-rotating axial fan is smaller than single axial fan under the same rotational speed, and is effective for lower rotational speed design under the same diameter. In addition, contra-rotating small-sized axial fan is higher efficiency compared with single small-sized axial fan. Then, the adoption of contra-rotating rotor for small-sized fan was proposed for the improvement of performance. In the present paper, the internal flow of contra-rotating small-sized axial fan with 100mm diameter obtained by the numerical analysis is shown. Furthermore, flow condition at inlet of rear rotor influenced by the wake of front rotor which is characteristic unsteady flow condition of contra-rotating rotors and flow condition at outlet of rear rotor is mentioned by the results.