| 摘要 |
<p>A plate (10) supports a venturi (11) within a conduit (20) and divides the fluid flow stream into a first stream which flows through the venturi tube (11) and a second stream which bypasses the venturi tube (11). A variety of adjusting mechanisms are disclosed for varying the cross-sectional area of the bypass flow. The apparatus is adapted to allow the back pressure within the venturi tube (11) to force an increasing proportion of the flow stream to bypass the venturi tube (11) in order to maintain a relatively constant aspiration rate within the venturi tube. The adjustment mechanisms disclosed include a second plate (12), similar to the first plate (10), which is manually rotated and a blocking ring (60) which moves responsive to changes in rate of flow of the fluid flow stream. Helical passages (605) may also be provided at the outlet to promote mixing.</p> |
