This may be caused by the side wall boundary layer and prismatic wave on the surface of the flow.

研究表明，溢流坝反弧段内流动存在着微弱的三维结构，流的三维性主要由侧壁边界层及表面棱形波造成。

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A hammer frame board is changed into a single layer prismatic shape or an I shape to save steels of the rotor part of the crusher 30%, and thus the cost is lowered.

将锤架板改为单层棱形或工字形，使粉碎机转子部分节省钢材30%，降低了成本。

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