It is shown that the 「damping」 effect mainly exists in the zone of 0.5d from the impingement wall, and there are positive as well as adverse pressure gradient in the radial direction.
表明壁面的「阻尼」影响主要集中在近壁面0 . 5D以内,在径向上流动既有顺压梯度,又有逆压梯度。
In zero pressure gradient flow, this local momentum loss is Minost an additive constant quantity. On the other hand, adverse pressure gradient results in amplification of this momentum loss.
在零压力梯度下,这个局部的动量损失几乎是一个附加的常量,而逆压梯度则会扩大这种动量损失。
The high head produced by the impeller means high adverse pressure gradient within blade passage and because of this the flow often separates from the blade surfaces even at the design point.