J055022 Influence of Blade Row Distance of Contra-Rotating Small-Sized Axial Fan on Performance and Internal Flow Condition

Small-sized axial fan is used as air cooler for electric equipments. But there is strong demand for higher power of fan according to the increase of quantity of heat from electric devices. Therefore, higher rotational speed design is necessary, however it causes the deterioration of efficiency and increases the noise. Contra-rotating axial fan is smaller than conventional axial fan under the same rotational speed, and is effective for lower rotational speed design under the same diameter. Then, contra-rotating rotors were proposed for the improvement of the performance of small-sized axial fans and the advantages of it on the point of view of the performance were confirmed. In the present paper, the performance curves and internal flow of the contra-rotating small-sized axial fan with 100mm diameter obtained by the experimental and numerical analysis results are shown and the pressure distribution and attack angle of rear rotor at the design flow rate are clarified. Furthermore, the influence of the blade row distance on the performance and internal flow condition is clarified and higher performance design of the contra-rotating small-sized axial fan are discussed.