鄱阳湖洪水要素演变特征分析

大倾角、大收缩角泄槽收缩段水流特性与Ippen冲击波理论假定的平底、小收缩角收缩段水流特性有明显的差异，目前对大倾角、大收缩角收缩段水流特性还缺乏系统的研究。为了研究大倾角、大收缩角收缩段水流特性以及倾角和收缩角对水流特性的影响，依托FLUENT软件，采用基于RSM湍流模型的三维湍流数值模拟方法，系统分析底坡倾角、边墙收缩角以及来流弗劳德数Fr0对陡坡收缩段水流特性的影响。研究表明：在大倾角、大收缩角条件下，边墙收缩产生的冲击波主要是向下游传播，横向影响范围很小；水流在与边墙交汇时发生碰撞、跃起，并沿收缩边墙向下游流动，先与边墙交汇碰撞跃起的水流位于上部，后与边墙碰撞跃起的水流位于下部，水流分层明显，边墙处沿程水面线呈现出“先快速升高，后逐渐平稳”的趋势；底坡倾角、边墙收缩角和来流弗劳德数的改变对边墙处沿程水面线影响较大，而对收缩段中线处沿程水面线影响较小。

Analysis on the evolution characteristics of flood elements in Xingzi station of Poyang Lake

The flow characteristics in the contraction section of large inclination and large contraction angle chute are significantly different from those in the flat bottom and small contraction section assumed by Ippen shock wave theory.At present,there is still a lack of systematic research on the flow characteristics in the contraction section of large inclination and large contraction angle chute.In order to study the flow characteristics of the contraction section with large inclination angle and large contraction angle,and the influence of inclination angle and contraction angle on the flow characteristics,based on FLUENT,the three-dimensional turbulent numerical simulation method based on RSM turbulence model was used to systematically analyze the influence of the inclination angle of the bottom slope,and the contraction angle of the side wall and the inflow Froude number Fr0on the flow characteristics of the contraction section of the steep slope.The research shows that under the conditions of large inclination angle and large contraction angle,the shock wave generated by the contraction of the sidewall mainly propagates downstream,and the lateral influence range is limited.The water flow collides and jumps when it intersects with the side wall,flowing downstream along the contraction side wall.The water flow initially colliding with the side wall is located at the upper part,and subsequently colliding with the side wall is located at the lower part,whose stratification is obvious.The water surface line along the side wall starts with a rapidly rising trend and then gradually stays stable.The changes of inclination angle of bottom slope,contraction angle of side wall and Froude number of incoming flow have great influence on the water surface line along the side wall,but have less influence on the water surface line along the middle line of contraction section.