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阐述了砾卵石均匀沙的运动机理,通过对附加质量力和床面颗粒相对暴露度参数的引入,推得了均匀沙起动无因次拖曳力公式,并对公式中的系数进行了计算。结果表明,在起动状态一定时,该系数并非为一个常量,而是介于某个区间,且随颗粒在床面上的相对暴露度的变化而变。通过转化推得了散粒体均匀沙起动流速公式,同时考虑了砾卵石扁度的影响,其系数同样不是一个常量,同学者们的公式相对照较为合理,该系数包含了其它公式的系数。结论部分可以解释为何不同的作者通过实验所拟合的系数各异,且差别较大,说明文中公式基本能反映均匀沙的起动特性。
The movement mechanism of uniform sand in gravel cobblestone is expounded. By introducing the additional mass force and the relative exposure parameters of bed particles, the non-dimensional drag force formula of uniform sand start is deduced and the coefficients in the formula are calculated. The results show that the coefficient is not a constant at a certain start-up state, but rather ranges somewhere and varies with the relative degree of particle exposure on the bed surface. Through the transformation, we get the formula of uniform sand starting velocity of the granular material, taking into account the influence of the flatness of the gravel. The coefficient is also not a constant. The formula of the students is relatively reasonable, which contains the coefficients of other formulas. The conclusion part can explain why different authors fit different coefficients through experiments, and the difference is large, indicating that the formula in the paper can basically reflect the starting characteristic of uniform sand.