| 摘要 |
Gas flow is controlled by two concentric, cylinders, having slots at different angles. The slots intersect along a spiral or stepped duct. The inner and outer cylinders are coupled to drivers rotating at different speeds. - The spiral or stepped duct is built up of cells which are open at the side facing the gas flow controller. At least one other side of each cell is provided with openings. In some cases, gas flow guide elements are also provided. |
