轴向间距对涡轮损失影响的非定常数值研究

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气动损失、非定常性的影响.结果表明,随着轴向间距的减小,涡轮级内流动的非定常性增大,流动的不均匀性更为强烈.大轴向间距方案的尾迹同主流区域的流体掺混距离较长,表现出大的总压损失系数的分布.小轴向间距下流动的不均匀性非常强烈,因而也表现出较高的损失分布.存在一个最优的轴向间距使得气动损失最小. 

Unsteady numerical investigation of the influence of axial gap on the turbine loss

The unsteady flowfield of the turbine stage was investigated numerically under different axial gaps,and the influences of the axial gap on the aerodynamic loss and the flow unsteadiness were discussed.Results show that the flow unsteadiness in the turbine stage becomes stronger with the reduction of the axial gap,and the corresponding flow becomes non-uniform.The total pressure loss coefficient of the turbine with the larger axial gap is bigger than that with the design axial gap.The reason is that the mixing distance between the wake and the main flow becomes much larger.Due to the much stronger flow unsteadiness under the smaller axial gap,the corresponding aerodynamic loss of the turbine stage is larger.There exists an optimum axial gap to minimize the aerodynamic loss.