论文部分内容阅读
在有限宽的弯曲河渠中,例如曲线形排淤渠,主流速分布受到螺旋运动和既定宽深比的影响。本文提出了描述主流速垂向分布的一种改进型对数律,它适用于最大主流速发生在水面以下的情况。利用该对数律,并假定紊流主切应力为非线性分布,就可以导出径向流速在垂向的分布,从而反映宽深比的影响。本文还提出能反映河床糙率和宽深比影响的水流对河床偏离角的表达式。分析结果表明,不但河床糙率,而且宽深比也同样对河床偏离角和径向流速分布有着显著的作用。计算值和实测值吻合良好。试验研究限于流速及切应力的垂向变化,其横向变化未予孝虑。
In a limited width of curved channel, such as curvilinear drainage channels, the main velocity distribution is affected by the spiral motion and the established aspect ratio. In this paper, we propose an improved logarithmic law that describes the vertical velocity distribution of the main flow, which is suitable for situations where the maximum main velocity occurs below the surface of the water. Using this logarithmic law, and assuming that the principal turbulence stress is nonlinear, the radial velocity distribution in the vertical can be derived to reflect the effect of aspect ratio. In this paper, we also present an expression of river flow off-angle that can reflect the effects of river bed roughness and aspect ratio. The analysis results show that not only the roughness of the riverbed but also the width-depth ratio also play a significant role in the deviation of the riverbed and the radial velocity distribution. Calculated and measured values agree well. The experimental study is limited to the vertical variation of flow rate and shear stress, and its horizontal variation is not obliged.