水工弧形钢闸门振动的负阻尼

Negative Damping Ratio Due to Tainter Gate Vibration

引入了弧形闸门小开度切向振动时因流量随时变化产生的水力负阻尼的表达式,定义了因压杆纵向恒定力及交变力引起的参数共振相应的负阻尼·对弧门振动的不同情况简化为两端铰支承和一端铰支一端弹性支承两种端点条件不同的压杆,并给出了相应的第一欧拉临界力的计算式·由动力方程给出了杆端纵向力的近似算式,根据实验资料给出了作用在支铰上的脉动压力的参考值,为讨论可能出现动力失稳的典型情况奠定了基础·

A hydraulic expression of negative damping ratio of a tainter gate when a tangential vibration resulting from changing waterflow takes place on such a rigid body is introduced to define the negative damping ratio corresponding to the parametric resonance condition caused by the longitudinal constant force of compressional members and alternating force. Various types of vibration of the tainter gate are simplified into two kinds of compressional members, i.e., two simply supported ends and one simply supported end with one elastically supported end, and the relevant formula of Euler critical load of 1st kind is given. A formula of longitudinal force at member end is thus given approximately through kinetic equation. The reference values of pulsating pressure acting on supporting hinges are also given according to experiments, which will lay a foundation for discussing further the typical case of dynamic instability.