| 摘要 |
A low noise axial flow impeller has a multi cellular form of construction comprising a multiplicity of individual axial flow channels disposed in a circumferential and radial array with respect to the axis of rotation. This increases the “blade passing frequency” as compared to a conventional impeller and since higher frequencies have lower energy for a given flow output the total amplitude of the noise generated can be reduced. For high total flow area coupled with low structural weight the channels are arranged in tessellating rings of equal numbers of channels, with channel cross sections based on hexagons (or truncated hexagons in the case of the channels in the innermost and outermost rings). In another embodiment each channel also extends from a respective channel inlet to a respective channel outlet which is offset from the respective inlet in the radial direction of the impeller, and involves an increase in the internal dimension of the respective channel in the direction radial to the axis of rotation, thus assisting deceleration and compression of the air or other medium being conveyed as it flows through the channels. |
