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针对某600 MW机组高压缸冲动式级的模拟透平级在隔板汽封一定的条件下,通过改变平衡孔的孔径及总面积,对模拟透平级进行数值计算分析,研究平衡孔面积的变化对透平级效率和气动性能的影响,并与试验结果进行了分析比较.结果表明:叶轮上开平衡孔有利于改善级间根部流动,提高了透平级效率;与无平衡孔透平级相比,随着平衡孔面积的增大,级效率逐渐提高;但面积增大至一定值后,级效率变化不明显;在叶轮结构和强度许可的条件下,设计时平衡孔面积可尽量取大一些,以保证设计工况时级间根部保持不吸不漏或少量漏气状态;平衡孔面积较大,也有利于减小隔板漏气量增加对级效率的影响作用;对于反动度较小的冲动级,要获得最佳级间漏气工况(相对漏气量约-1%)是不太可能的.
Aimed at the impulse level analog cylinder stage of a high pressure cylinder of a 600 MW unit, the numerical simulation analysis of the simulated turbine stage was carried out by changing the aperture and the total area of the balance hole under the certain condition of the diaphragm seal. The results show that the opening hole of the impeller can improve the flow at the root level and improve the efficiency of the turbine stage. Compared with the unbalanced hole turbine Compared with the balanced hole area, the stage efficiency gradually increases. However, when the area increases to a certain value, the level efficiency does not change obviously. Under the condition of the impeller structure and strength permitting, the balance hole area can be designed as much as possible Whichever is larger, to ensure that the roots at the design stage remain non-aspirated or with a small amount of air leakage; the larger the balance hole area is also beneficial to reducing the influence of the increased amount of air leakage on the stage efficiency; To a lesser degree of impulse, it is not possible to get the best interstage air leaks (about -1% relative air leakage).