| 摘要 |
The device comprises several blades (3) mounted on a helical hub (2). Each paddle has at its free end a rotating collar (23) for suppressing turbulence. A divergent casing (6,8) joins the circular inlet to the exit. The rotating collar does not project into the conduit but is preceded by surfaces which have a shape which lead the air naturally towards the internal surface. These shapes can be part of the inlet mouth (5) or be connected pieces. The mouth and the hub are made of materials (10,12) which absorb acoustic emissions.
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