均匀流场中含自由液面的陷落腔脉动压力分布研究

Research on Fluctuating Pressure Distribution on Inside Wall of Cave-in Cavity with Free Surface under Uniform Fluid Condition

在有自由液面的情况下，针对横剖面为圆形的陷落腔模型，在均匀流场条件下，开展水动力实验研究，模拟了大量的工况，测量了腔体壁面的流体脉动压力。本文分析了模型所受的脉动压力随傅汝德数在不同腔体位置的变化趋势，并讨论了晃荡现象对压力分布的影响。实验时发现，傅汝德数小于0．35的工况有明显的晃荡现象发生，而傅汝德数小于0．35的工况的脉动压力系数也明显大于其他工况，且变化剧烈。本文认为，流体剪切层自持振荡与腔内液体深度驻波振荡共振是产生晃荡现象的原因，本文实验中Fr〈0．35的工况对应的流速正是达到以上两种振荡频率耦合所需要的流速。本文对工程应用中的腔体尺度和形式的设计有一定的指导意义。

The hydrodynamic experiment of the cave-in cavity model is carried out under the condition of uniform fluid. A large numbers of work conditions have been simulated, and the fluctuating pressure of the fluid acted on the inside wall of the cavity is measured. The trend of the fluctuating pressure coefficient in different position of the cavity is analyzed, and the influence of the sloshing phenomena on the pressure distribution is discussed. It is found that in the experiment, when the Froude number is less than 0.35, the sloshing phenomena will happen, and in these conditions, the fluctuating pressure coefficients are much larger than other conditions and change intensively. The result of the experiment indicates that, the resonance of the cut layer＇s self-sustain vibration and the liquid＇s depth stationary wave vibration is the reason of the sloshing phenomena. The velocity of the fluid in the conditions when the Froude number is less than 0.35 has reached the demanded velocity to generate interaction between the two kind of vibrations mentioned above.This paper is instructive to the optimization of the cross section, especially to the design of the cave-in cavity with better hydrodynamic performance.