| 摘要 |
<p>A jet fan arrangement (1) for ventilating tunnels etc. in which the axis (8-8) of the fan is at an angle (a) to the supporting surface (4) so as to blow air away from the supporting surface and when the flow of air through the fan (1) is reversed the angle (b) of inclination of the axis (8-8) of the fan is automatically changed so that the direction of flow of air remains away from the supporting surface (4).</p> |
