| 摘要 |
<p>Air is sucked through a conduit (4) connected to a double walled cap (1) of which the inner wall is perforated. The air inlet cross-section is adjustable by means of an inflatable hose (7) connected to a pear (8). The inflation of the hose and the suction flow rate are adjusted so that the air pressure under the cap is lower by 0.5-60 cm of water than the atmospheric pressure and the air flow rate is comprised between 1 and 4 m3/min. A fraction of sucked air passes on an electric heating resistance (6).</p> |
