来流条件对排汽缸内非轴对称流动的影响

Influence of Entering Flow Conditions on the Non-axial Symmetric Flow in Exhaust Hoods

研究了大功率汽轮机低压缸排汽在不同气流角及不同总压分布下的流场,以模型为对象进行了三维流场的数值模拟。结果表明:排汽缸入口较大的旋流角会恶化排汽缸性能,而总压沿径向变化梯度为负时则有利于改善排汽缸气动性能。基于这一结果提出了通过改变总压分布抑制由于来流方向对排汽缸性能产生的负面影响的方法。

The complex 3-D flow in a large capacity steam turbine＇s exhaust hood model, under different incident flow angles and different inlet total pressure conditions, has been simulated and analyzed, for the purpose of studying the influence of entrance flow conditions on the aerodynamic performance and flow field in exhaust hoods. Results indicated that a relatively large inlet tangential flow angle, at the hub of inlet annuls has an unfavorable effect on the exhaust hood＇ s performance, while a negative radial total pressure distribution gradient helps to improve the exhaust hood＇s aerodynamic properties. According to these results, a method is suggested, with which the negative influnce of entering flow direction on the exhust hood＇s performance is repressed,by changing the distributiion of total pressure.