工况变化对贯流式水轮机叶顶间隙流态的影响

贯流式水轮机是低水头水能资源开发的主力机型之一,而转轮叶片叶顶间隙流动特性是影响其空化、稳定性能的关键因素.基于数值模拟的方法,本文研究了工况变化引发转轮叶片叶顶间隙泄漏涡初生位置、形态变化的机理,分析了间隙泄漏涡形态改变对水轮机空化、稳定性的影响规律.主要结果表明:工况变化必然伴随导叶开度变化,导叶开度的改变使得转轮...

Effect of operating condition variations on tip clearance flow characteristics of tubular turbines

The tubular turbine is a main type of the hydraulic turbines for low head hydropower development,but its tip clearance flow is the key factor controlling its cavitation and stability performances.Using CFD simulations,this paper examines the mechanism of the initial location variation and shape variation of the tip leakage vortices(TLVs)that are induced by a variation in the operating condition,and evaluates the vortices’influence on the cavitation and stability of the turbine.Results support the major conclusion that a variation in guide vane opening alters the angle of attack at the leading edge of runner blades and further affects the initial locations and three-dimensional shapes of TLVs.And we find these variations are the cause of variations in runner cavitation performance,and verify TLVs can increase the amplitude of pressure fluctuations over the regions they swept,leading to the amplitudes doubled or more.