跌坎型底流消能工冲击区时均动水压强分布与抗冲磨强度确定.doc

跌坎型底流消能工冲击区时均动水压强分布与抗冲磨强度确定 　　摘要：在跌坎型底流消能工消力池内水流流态分区的基础上，根据自由紊动射流理论，得出不同入射角度下冲击区时均动水压强半经验公式。利用冲击区底板时均动水压强分布图，在角度和流量不变的工况下，跌坎的变化对底板时均动水压强的影响，以及角度跌坎不变的工况下，流量的变化对底板时均动水压强的影响，显示出冲击区最易遭受冲磨与破坏的区域。以某水库工程为例，由实测数据推求经验公式相关参数，验证经验公式的可行性，进一步结合临底流速求出消力池底板混凝土抗冲磨强度分布图，对底板分区，为合理确定消力池底板混凝土强度等级提供参考。 　　关键词：时均动水压强；跌坎型底流消能工；抗冲磨强度；水力学试验 　　中图分类号：TV653 文献标志码：A 文章编号：1672-1683（2015）06-1118-06 　　Abstract：On the basis of creating water flow regime partitions in the impact zone of bottom-flow dissipation with step-down floor and the theory of free turbulent jet flow，an empirical formula of time-averaged dynamic water pressure in the impact zone was obtained under different incident angles.The distribution diagram of dynamic water pressure in the impact zone was analyzed using matlab.The effects of step-down floor on the dynamic water pressure under the same incident angle and flow rate，and the effects of incident flow rate on the dynamic water pressure under the same incident angle and step-down floor were investigated，and the most vulnerable area to damage and abrasion in the impact zone was determined.A reservoir project was selected as the case study.The relevant parameters of the empirical formula were deduced based on the measured data to verify the feasibility of the empirical formula.With the knowledge of the bottom velocity，the abrasion resistance strength of concrete floor in the impact zone of bottom-flow dissipation was obtained.The research can provide reference for the strength classification of concrete floor of bottom-flow dissipation. 　　Key words：time-averaged dynamic water pressure；bottom-flow dissipation with step-down floor；abrasion resistance strength；hydraulic test 　　跌坎型底流消能工建立在常规底流消能工基础上，在消力池进口处将消力池底板向下开挖形成跌坎，构成跌坎型消力池。跌坎的存在使水流以淹没射流形式进入消力池水体，在主流上下形成漩涡和强剪切紊动进行消能，水流沿程有一定扩散，降低水力学指标。在高水头大流量条件下，在泄水建筑物泄流的混凝土表面上的破坏形式主要有空蚀、冲磨和水力冲刷。在一定条件下冲磨破坏又会诱发空蚀破坏，因此抗冲磨研究具有非常重要的意义。 　　本文通过水力学模型试验研究了15 °、30 °和45 °入射角度下不同跌坎深度、不同水头冲击区时均动水压强分布规律，分析时均动水压强分布图。通过对数据的处理和曲线拟合，得出以入射角度为控制变量的经验公式参数