دوستان کسی میتونه مفهوم متن زیر رو بهم بگه...قسمت قرمز رنگ برام مهمتره:
Internal flow of the centrifugal pump impellers are made up of low velocity wakes zone and free
viscosity jets zone [5-7]. Figure 1 shows that the flow near the boundary layer has generated backflow
and stall because of the flow in impellers passageway getting the work from the blade no uniform by the
action of adverse pressure gradient. The wider wakes areas that are close to the front shroud of impellers
and suction surface are, the thinner the shear layer between jets and wakes is, and the velocity gradient
between them is bigger. For the sewage pumps it should consider the effecting of stratified fluid and
stratified solid. The speed of the particles is excessive or not enough, which will cause additional
centrifugal and Coriolis forces. The slow speed particles have a tendency to moveto the suction side, and
the fast particles tend to move to the pressure side.
But then layered effect is related to the velocity of the
suction side and pressure side, that also is related to the blade loading, so to reduce the layered effect must
reduce the blade loading. To enable the high passing capacity the number of sewage pump blade is less,
which increases the blade loading. In order to reduce the effect of layer, it should extend the flow
passageway that reduces the blade loading at unit length. So less blade number and large blade wrap
angle need using the small blade exit angle B
با تشکر
