气膜孔对DD6镍基单晶高温合金高周疲劳强度的影响研究  

Effects of film cooling holes on high cycle fatigue strength of DD6 Ni-based single-crystal superalloy

作　　者：卢绪平 王跃 陈墨 江荣 何云 宋迎东[2] LU Xuping;WANG Yue;CHEN Mo;JIANG Rong;HE Yun;SONG Yingdong(AECC Sichuan Gas Turbine Establishment,Chengdu 610500,China;College of Energy and Power,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China)

机构地区：[1]中国航发四川燃气涡轮研究院,四川成都610500 [2]南京航空航天大学能源与动力学院,江苏南京210016

出　　处：《推进技术》2024年第8期198-206,共9页Journal of Propulsion Technology

基　　金：航空发动机及燃气轮机基础科学中心重大项目(P2022-A-III-003-001);南京航空航天大学研究生科研与实践创新计划项目(xcxjh20220205)。

摘　　要：气膜孔因其特殊的几何构型,在提升涡轮叶片冷却效率的同时,孔边往往存在较为明显的应力集中现象,导致叶片的高周疲劳(High Cycle Fatigue,HCF)失效。因此,本文开展了900℃下振动疲劳试验,以评估圆柱型和簸箕型气膜孔对DD6镍基单晶高温合金高周疲劳强度的影响,并通过扫描电子显微镜(Scanning Electron Microscope,SEM)和能谱仪(Energy Dispersive Spectroscopy,EDS)分析气膜孔模拟件HCF失效机理。研究发现孔边氧化层在交替载荷作用下存在均布开裂现象,形成尖角,最终导致裂纹萌生,并沿着{111}滑移面扩展。通过有限元仿真分析了孔边应力应变分布,结合临界距离理论,建立了气膜孔高周疲劳强度评估方法和基于疲劳缺口系数经验公式的气膜孔高周疲劳强度预测方法。结果表明:簸箕型气膜孔的高周疲劳强度为298.03 MPa,圆柱型气膜孔高周疲劳强度为321.35 MPa;气膜孔高周疲劳强度预测误差在10%以内。所建立的含异型气膜孔的DD6单晶高温合金高周疲劳强度评估、预测方法可为航空发动机涡轮叶片膜冷却结构疲劳性能的设计和评估提供技术支持。The film cooling holes(FCHs)used to increase the cooling efficiency of turbine blades usually cause high cycle fatigue(HCF)of turbine blades due to the stress concentration around the holes,because of the geometry discontinuity.In this study,HCF strength of DD6 Ni-based single crystal superalloy with cylindrical and dustpan film cooling holes was evaluated at 900°C by vibration fatigue test,and the HCF failure mechanism of specimens with FCHs was investigated by scanning electron microscope(SEM)and energy dispersive spectros⁃copy(EDS).The results show that the oxide layer of the hole edge is partially cracked subjected to the alternating loading,forming a sharp angle,which eventually leads to crack initiation,and then the crack propagates along the{111}slip plane.Moreover,stress-strain distribution around the holes was analyzed by finite element,a HCF strength evaluation method based on the theory of critical distance and a FCHs’HCF strength prediction method based on the fatigue notched coefficient was established,the HCF strength of the FCHs were obtained.The results show that the HCF strength of dustpan FCHs is 298.03 MPa,and the HCF strength of cylindrical FCHs is 321.35 MPa.The prediction error of HCF strength of the FCHs is within 10%.The established FCHs strength evaluation method for DD6 single crystal superalloy with FCHs can provide technical support to design and evaluate fatigue performance of film cooling structure of aero-engine turbine blades.

关 键 词：单晶高温合金 气膜孔 应力集中 高周疲劳 疲劳强度预测 

分 类 号：V231.95[航空宇航科学与技术—航空宇航推进理论与工程]