| 摘要 |
PURPOSE:To prevent the generation of counterflow and metallic noise by installing a counterflow preventing plate formed by bending the edge part on the wind upstream side towards the shaft center side of a Sirocco fan in close to the inner peripheral surface of the vane of the fan on the periphery of the throat part formed at the effluence port of a fan casing. CONSTITUTION:Air is inhaled from an inflow port 3 by the blower action of a Sirocco fan 1 and sent outside the system from an effluence port 4. A low pressure is generated inside the fan 1, and a high pressure is generated outside, and the pressure difference is made max. on the periphery 5 of the throat of a fan casing 2. However, the counterflow from outside the fan 1 to the inside of the fan 1 is prevented by the action of a counterflow preventing plate 6 formed by bending the edge part on the wind upstream side towards the shaft center side of the fan 1 in close to the inner peripheral surface of the fan 1 on the above-described periphery 5. Though a pressure difference is generated between the front and the back surfaces of a vane, and a pulsation flow is generated, the pressure impact onto the counterflow preventing plate 6 is lightened by the bent part 7, and the generation of the metallic noise by the counterflow preventing plate 6 is prevented.
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