突扩突缩式内流消能工的数值模拟研究

Numerical simulation of turbulent flow in throat type energy dissipators

本文采用轴对称k～ε紊流模型对收缩比0 4～0 7的突扩突缩式内流消能工进行数值模拟研究。用PISO方法来解决速度场和压力场的耦合问题,得到了消能区压力特性、流场特性和紊动能耗散率等分布规律,详细地分析了收缩比对消能及空化特性的影响。计算的压力分布、回流区长度与试验结果吻合良好。分析了突缩比ζ和收缩段相对长度η对消能的影响。研究表明,与孔板式消能工比较,洞塞式消能工能够显著增加消能率并具有良好的抗空化性能,同时,显示了数值研究省时、节约经费和直观的优越性。

The axis-symmetrical k-ε turbulence model is applied to simulate the flow in a throat type energy dissipator.The PISO method is used to solve the problem of coupling velocity field with pressure field.The flow characteristics and pressure distributions as well as the turbulent energy dissipation rate of the dissipator are analyzed.The validity of the calculated eddy length and pressure distribution is verified by physical model test. It is found that the contraction ratio and the relative length of throat are the major factors influencing the energy dissipation rate of the dissipator.The energy dissipation rate decreases with the increase of the contraction ratio, but it increases with the increase of relative length of throat.The higher ratio of contraction is in favor of preventing the dissipator from cavitation erosion.