【摘要】 应用非定常不可压缩流体N-S控制方程和大涡模拟动态亚格子湍流模型,基于混合网格技术,采用SIMPLEC算法实现速度、压力变量的分离求解,得到了型号为A55x的某试验模型水轮机活动导叶全流道速度场、压力场以及涡量场分布。计算结果表明,活动导叶绕流形成的涡带向下游进一步发展,造成转轮进口速度及压力分布的不均匀,直接影响转轮内的流动状态。同时还研究了导叶后不均匀流场的动态特性,发现越靠近下游时间平均的压力和速度不均匀度越来越小,但各断面的瞬时不均匀度值相差较大,提出寻找叶后时间平均上始终处于最小速度不均匀度的断面应成为未来水轮机水力设计的重要设计指标。更多还原

【Abstract】 By using the N-S control equation of a nonsteady uncompressible fluid and the dynamic sub-grid turbulence model of a large eddy simulation,and based on mixed grid techniques,the authors have employed SIMPLEC algorithm to seek separate solutions to velocity and pressure variables.As a result,obtained were the distribution of velocity field,pressure field and vorticity field in the whole flow passages of the movable guide vanes of an A55x type test-model water turbine.The calculation results show that the eddy belt formed by the stream encircling the movable guide vanes further develops downstream,leading to a nonuniform velocity and pressure distribution at the inlet of the rotating wheel and exercising a direct influence on the flow state inside the wheel.In the meanwhile,studied were the dynamic characteristics of the nonuniform flow field after the guide vanes.It has been found that the closer to the downstream,the smaller the time-averaged pressure and speed nonuniformity.However,the values of transient nonuniformity at various cross sections have a relatively big difference.It is proposed that to identify the cross section,which always has the minimum time-averaged speed nonuniformity after the blades,should become an important design effort and index for the hydraulic design of future water turbines.更多还原