透平机械空穴漏气非定常流动的数值模拟

为了解空穴漏气在透平中非定常流动,对某型带空穴漏气单级透平进行非定常数值模拟,计算格式采用包括LU-SGS-GE隐式格式和改良型高精度、高分辨率的MUSCL TVD格式的时间推进算法,非定常计算采用Jameson双时间步隐式迭代法.计算结果表明空穴漏气随着二次流的影响沿着动叶吸力面一侧向下游输运,输运过程中会不断沿径向向外迁移.由于空穴漏气的射人,非定常效应在动叶叶根处要比中间截面处明显,而且随着漏气向下游的迁移,非定常效应也逐渐削弱.

Numerical simulation against unsteady flow from cavity leakage of turbomachinery stage

An unsteady numerical simulation was performed for the effect of the unsteady flow from the cavity leakage on the turbine stage.LU-SGS-GE(lower upper symmetric Gauss Seidel Gaussian elimination method)implicit scheme and high precision high resolution MUSCL TVD(monotone upstream-centred scheme for conservation laws,total-variation-diminishing) scheme were used to solve 3-D Navier-Stokes equations.The dual-time step implicit scheme was used for unsteady calculation.The results show that the patch of the cavity leakage through the rotor passage is moved close to the suction surface owing to the effect of the secondary flow.As the path is convected downstream,it migrates radially towards midspan.With the leakage flow entering into the rotor,there is more unsteadiness on the root of the rotor than that of the mid-span,and the unsteadiness becomes weak as the leakage flow migrates downstream.