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为准确捕捉小开度流动的瞬态湍流特性,充分了解流场结构,采用滑移网格技术以及基于Vreman亚格子模型的全局动态大涡模拟方法,不仅得到混流式水轮机全流道内速度、压力以及涡量的分布,同时捕捉到了活动导叶周围独特的流动形式和叶道涡的时空演化。计算结果表明:当高转速、小开度工况时,流道内流体的圆周速度占有绝对优势,加强了导叶后尾迹涡的相互影响,致使流道中发生更为剧烈和复杂的漩涡、脱流等各种水力不稳定现象。从蜗壳到转轮室的压力脉动均以低频为主,主要的频率能量成分基本相同,说明小开度低频异常振动与压力波的传递有关。叶道涡是致使叶片疲劳破坏的主要因素。
In order to accurately capture the transient turbulent flow characteristics of small opening flow, fully understand the flow field structure, using slip mesh technology and global dynamic large eddy simulation based on Vreman sub-lattice model not only get the velocity, pressure As well as the distribution of vorticity, while capturing the unique flow patterns around the vanes and the spatial and temporal evolution of the vortex vortex. The calculation results show that the circumferential velocity of the fluid in the flow channel occupies an absolutely dominant position at high speed and small opening conditions, which enhances the interaction between the wake vortices of the guide vanes and causes more violent and complex eddies in the flow channel. Other kinds of hydraulic instability. The pressure pulsations from the volute to the runner chamber are dominated by low frequency, and the main frequency energy components are basically the same, which shows that the low frequency anomalous vibration with small opening is related to the transmission of pressure wave. Leaf vortex is the main factor leading to leaf fatigue damage.