Hydraulic valve block balance weight piston sleeve has thin wall, high precision of geometry dimension and strict roughness, and its quality determines the lifetime of balance weight directly.
缸块平衡块的活塞套壁薄，几何尺寸精度要求高，粗糙度要求严格，其质量好坏直接决定平衡块的寿命。
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Because of the differences of the roughness, the interflow, the soil moisture and the rainfall intensity, the pipe flow process shows different hydraulic graph.
It has been verified in this paper, by theoretical analysis with two-phase fluid mechanics and hydraulic tests, that decreasing surface roughness in a wade stack can not increase critical discharge.