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4.低流阻气道使气体以一定速度通过气门座区所需的压差在很大程度上影响着气道流动阻力。此外,还有气道方向的变化(弯道)和摩擦等影响因素。任何降低气道流阻的努力,首先应是力图在气门座区保持较低的动能并在气道出口前使压力损失有所回收。当气流均速地充满流通截面时,即可得到较低的动能。为此,需要一个到气门座的圆滑过渡。气门座前的气道截面应避免气流分离。这可通过逐渐减小流通面积和适当的弯曲半径来达到。
4. Low flow resistance Gas passage to gas at a certain speed through the valve seat area required for the pressure difference to a large extent affect the airway flow resistance. In addition, there are airway changes in the direction (corners) and friction and other factors. Any attempt to reduce airway resistance should try first to maintain lower kinetic energy in the seat area and to recover the pressure loss before the airway exits. When the air flow velocity is full of flow cross-section, you can get lower kinetic energy. For this purpose, a smooth transition to the valve seat is required. Airway cross-section in front of valve seat should avoid airflow separation. This can be achieved by tapering the flow area and the appropriate bend radius.