小型軸流ファンへの二重反転形羽根車の採用について The Adoption of Contra-Rotating Rotors for Small-Sized Axial Flow Fan

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 the efficiency and the increase of noise. Then, the adoption of contra-rotating rotors for the small-sized axial fan is proposed for the improvement of performance. In the present paper, the experimental results of a conventional small-sized axial fan with 100 mm diameter are shown and the important points to adopt the contra-rotating rotors are considered with these results. Furthermore, the performance and the flow field of the contra-rotating smallsized axial fan are clarified by the numerical analysis results and the advantages of the adoption of the contra-rotating rotors for the small-sized axial fan are discussed.