水力发电引水系统水体共振的数值模拟

分析了某水力发电厂水轮机组在紧急关机试验过程中出现的异常强烈的振动现象。考虑水为可压缩黏性流体，采用瞬态动力响应仿真软件，按照原型参数对水体共振进行数值模拟。研究了冲击载荷引起的水体自由振荡信号，得到水体振荡主频率。在引水管末端用平板的横向振动引入压强扰动，观察到强迫振动频率接近水体主频率时发生共振，而且在整个引水管内的水体都有较强烈响应，证实了水体共振发生的可能性。对共振发生时的压强信号进行小波分解，发现引水系统的压强信号中响应幅度最大的小波分量的频率低于强迫振动频率。计算结果还表明水的黏性和壁面粘附条

Numerical simulation of water body resonance in penstock of hydropower station

The strong resonance happened to the penstock in the process of emergent turning off turbine unit in a hydropower station is studied by numerical simulation.The water is regarded as compressible and viscous fluid and the dynamic response simulation software is applied.The main natural oscillation frequency of the water body system under the action of impacting load is calculated.The oscillation of the system due to the forced vibration of a plate at the terminal of the penstock is investigated and found that resonance will occur when the frequency of forced vibration is approximately equal to the main natural oscillation frequency and strong response of the whole system will take place.The wavelet decomposing analysis of the pressure signal during resonance shows that the frequency of wavelet component having the largest response amplitude is lower than the forced vibration frequency.The results also reveal that the viscosity of water and the non-slip condition of the penstock wall have little influence on the response frequency,but they can reduce the amplitude of the response of forced vibration.