超超临界机组中压阀门扩散器共轭换热分析

Analysis on Conjugate Heat Transfer of Medium Pressure Valve Diffuser for USC Units

某引进型1 000MW超超临界汽轮机中压阀门扩散器是对称布置的,在运行一个大修周期后,多台机组均出现了不对称开裂的情况。采用计算流体力学的方法对扩散器所处腔室进行了共轭换热分析,得到了扩散器在不同工况下的温度场分布,揭示了可能导致扩散器不对称开裂的原因,并将共轭换热方法与传统换热公式法得出的温度场分布进行了对比,分析了二者的优劣。研究成果可为复杂流动区域温度场计算提供参考。

The medium pressure valve diffuser of a certain type of imported 1 000 MW ultra supercritical(USC) steam turbine is symmetrically arranged, and there exist asymmetric cracks in many units after running for a period of overhaul. The method of computational fluid dynamics was used to analyze the conjugate heat transfer of the chamber where the diffuser was located. The distribution of the temperature field of the diffuser under different working conditions was obtained, and the possible causes of the asymmetric cracking of the diffuser were revealed. The temperature field distribution obtained using the conjugate heat transfer method and the traditional heat transfer formula method was compared, and the advantages and disadvantages of both methods were analyzed. The research results can provide reference for the temperature field calculation of complex flow areas.