自動車用送風機シャッタに関する研究

（送風機性能向上に向けたシャッタ形状の提案）

抄録

The common purpose for vehicle development has always been lowest fuel consumption. Automotive cooling fan shutter reduces the air resistance of the vehicle by controlling the amount of the air flow through the vehicle cooling system. The shutter proposed in this study consists of a diffuser and a stage of stator cascade with variable stagger angle of the blades, settled in the downstream of a fan rotor. An adequate stagger angle may improve the fan performance, due to the diffuser effects through the diffuser and the stator cascade. With large stagger angle of the stator, the cascade can be used as a shutter for the cooling system. The present paper reports the improvement method of the shutter shape, in order to increase the fan efficiency. The prototype shutter decreases the efficiency in the high flow rate range, although it increases the efficiency at the design point. The cause of the efficiency decrease has been investigated by the visualization test, and a new shape of the shutter has been designed with the help of CFD analysis. The validity of the shape improvement has been confirmed by the experiments.