孔板泄洪洞宣泄含沙水流脉动壁压特性研究

Characteristics of Fluctuating Wall-Pressure when Discharging Silty Flow in a Tunnel with Orifices

通过模型试验的方法研究了在不同含沙量下孔板泄洪洞脉动壁压的幅值特性、时空相关特性和频域特性.试验结果表明,脉压均方根在不同含沙量下的沿程分布规律相似,含沙量及水流来流条件均对脉压强度的大小产生重要影响,存在临界含沙量使脉压强度变化趋势发生改变;水流含沙后,时间和空间相关系数均比清水时降低,说明泥沙的加入使得水流大涡旋平均尺度有所减小;在各含沙量条件下脉动壁压的优势频率均属低频范畴,含沙水流归一化功率谱密度曲线存在其他频率的峰值,进一步验证了漩涡平均尺度的减小.

The characteristics of amplitude value, time-scale correlation and spectrum of fluctuating wall-pressure are given by means of model test. The results show that the distribution pattern of standard deviation of pressure is similar under different sediment concentrations. Both the sediment concentration and flow condition play important roles in am- plitude value. There is a critical sand content which can cause a change in the trend of fluctuating pressure intensity. The time-scale correlation is decreased with the sediment in water, indicating that the average scale of large vortex is reduced. The dominant ~equency of fluctuating wall-pressure is very low regardless of sediment concentration. The other peaks in the normalized power spectral density curves of silty flow also verify the reduction of vortex scale.