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在工程实际或水力模型实验中均末曾发现过深水平面闸门仅因水流作用而产生自激振动现象。这是由于平面闸门刚度摩阻力较大,而且振动所引起的相互作用力随作用于闸门上水头的增加而减少的缘故。因此深水平面闸门的振动属于强迫振动性质。根据实验资科,在一般条件下由于紊动旋涡所引起的脉动压力较小,不足引起强烈的强迫振动。然而当运动狀态急剧改变时,例如气蚀、明喑流交替、旋涡区破坏等将使水流搅动外力加大甚多。同时,因具体闸门构造特点而引起的水流搅动亦可能远大于一般条件下的脉动压力。因此,必须结合闸门具体情况,按照危险振动型与危险外力的不利组合,研究深水平面闸门的振动向题。引起闸门振动的外力具有随机变化的性质,以往常用简谐变化外力代替,近似地计算最大应变。我们用水力模型与电模型对这二种性质的外力进行了比较,发现在计算最大应变时,不可能用一种谐变化外力代替一种随机变化外力。从而说明了以往的近似的计算方法不可能有一个统一的标准,而且将引起较大的计算误差。合理的近似计算方法,必须重整研究。同时,对记录资料长度亦进行了统计分析,我们初步认为记录资料的单波数不宜少于700—800。结合深水平面闸门的可能振型,本文从理论上证明当水流条件接近势流时,动水对闸门振动的惯性影响与同样边界条件下静水的影响相同,与稳定流速无关。并从实验论证了旋涡区水体对闸门振动的惯性影响与静水差别甚大。
In the engineering practice or hydraulic model experiment, it has been found that deep-water level gate produces self-excited vibration only due to water flow. This is due to the greater frictional resistance of the planar gate and the reduction of the interaction force caused by the vibration as the head on the gate increases. Therefore, the vibration of the deep horizontal gate belongs to forced vibration. According to the experimental data, the pulsating pressure caused by turbulent vortices under normal conditions is small and insufficient, causing strong forced vibration. However, when the state of the sport changes drastically, such as cavitation, alternation of Mingliu flow, destruction of the vortex zone, etc., the external force will aggravate greatly. At the same time, due to the characteristics of the gate structure caused by the water flow may also be far greater than the general conditions of the pulsating pressure. Therefore, it is necessary to study the vibration problem of the deep water level gate according to the specific conditions of the gate and according to the unfavorable combination of dangerous vibration type and dangerous external force. The external force that causes gate vibration has the property of random change. In the past, the external force of simple harmonic change is often used instead of calculating the maximum strain approximately. We compare the external forces of these two properties with hydraulic and electric models and find it impossible to replace a randomly varying external force with a harmonic external force in calculating the maximum strain. This shows that the conventional approximate calculation method can not have a uniform standard, and will cause a large calculation error. Reasonable approximate calculation method, you must re-study. At the same time, statistical analysis of the length of recorded data was also conducted. We initially thought that the single wave number of recorded data should not be less than 700-800. Combined with the possible vibration modes of the deep-water gate, this paper theoretically proves that when the water flow conditions close to the potential flow, the influence of hydrodynamic water on the gate vibration is the same as that of the static water under the same boundary conditions, and has nothing to do with the stable flow rate. The experiment also proves that the influence of water body in swirl zone on gate vibration is very different from that of static water.