不同轴向间距下涡轮级内非定常流场的数值研究

Numerical investigation on the unsteady flowfield of the turbine stage under different axial gaps

针对不同轴向间距下涡轮级内非定常流动进行了数值研究.讨论了非定常条件下轴向间距变化对非定常性及流场分布的影响,探讨了转子和静子叶片之间的非定常相干的机理.结果表明,轴向间距L对转子内流动的非定常性有着强烈的影响.随着轴向间距的减小,静叶尾迹的强度及影响范围增加,静叶尾迹对动叶的周期性非定常影响还是主要出现在前缘附近.由于静叶尾迹的恢复效应与来流尾迹强度成正比,50%轴向间距下动叶出口流场的湍动能在动叶通道中央区域最小.

The unsteady flowfield of the turbine stage were investigated numerically under different axial gaps, and the influence of the axial gap on the flow unsteadiness and the flowfield was discussed. Results show the axial gap L has great influence on the flow unsteadiness in the rotor. The intensity of the stator wake and its influence range increase with the reduction of the axial gap, and the unsteady influence of the stator wake mainly occurs near the leading edge of the rotor. The turbulent kinetic energy of the rotor outlet is minimum under the half of the design axial gap because the recovery effect of the stator wake is directly proportional to the wake intensity of the incoming flow.