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Axial-flow fans have been used in various applications such as thermal control and ventilation. Fans are often used in narrow spaces around obstacles such as electric parts, areas near clogged of fan filters, and walls. These obstacles lead to decreased performance and increased noise and vibration in electric devices. This study attempts to experimentally clarify the influences of upstream/downstream-mounted blockage disks on the flow characteristics of an axial-flow fan. The important results are summarized as follows: (1) For the same relative distance, the pressure performance and efficiency curves of the fan owing to the upstream-mounted blockage disk completely differ from those owing to the downstream-mounted blockage disk. (2) For a small relative distance, the pressure coefficient owing to the upstream and downstream-mounted blockage disks decreases and increases, respectively. (3) The efficiency of the fan owing to the upstream-mounted blockage disk decreases. However, the efficiency owing to the downstream-mounted blockage disk increases for specific conditions.

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