摘要
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.
Keeping the gland seal gap constant,a numerical simulation has been carried out to a simulated turbine stage of a 600 MW unit with its high-pressure cylinder of the impulse type,so as to study the influence of the area of balance hole on the stage efficiency and aerodynamic performance,by varying the size of balance hole and total area.Comparison results between simulation and experiment show that tapping holes on the impeller is beneficial to flow improvement at the root,and hence the stage efficiency is raised;with the rise of hole area,the stage efficiency increases at first,and then remains basically unchanged;if permitted by impeller structure and strength,the balance hole is recommended to be designed as large as possible,so as to guarantee the root area to be in the no suction,no leakage or less leakage state under design conditions;bigger balance hole area will result in reducing the influence of gas leakage on the stage efficiency.For impulse stage with small degree of reaction,it seems impossible to obtain an optimum working condition with a relative gas leakage rate of-1%.
出处
《动力工程学报》
CAS
CSCD
北大核心
2011年第8期575-578,610,共5页
Journal of Chinese Society of Power Engineering
关键词
汽轮机
冲动级
级平衡孔
隔板汽封
级效率
turbine
impulse stage
balance hole
clapboard seal
stage efficiency
