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Improvement of titanium alloy TA19 fatigue life by submerged abrasive waterjet peening:co.relation of its process parameters with surface integrity and fatigue performance

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Chinese Journal of Aeronautics 2024年第1期37卷 377-390页

作者： Gongyu WANG Shulei YAO Yuxin CHI Chengcheng ZHANG Ning WANG Yalong CHEN Rongsheng LU Zhuang LI Xiancheng ZHANG Key Laboratory of Pressure Systems and Safety Ministry of EducationSchool of Mechanical and Power EngineeringEast China University of Science and TechnologyShanghai 200237China AECC commercial aircraft engine co.LTD Shanghai Engineering Research Center for Commercial Aircraft EngineShanghai 201108China

Submerged abrasive waterjet peening(SAWJP)is an effective anti-fatigue manufacturing technology that is widely used to strengthen aeroengine *** study investigated the co.relation of SAWJP process parameters on surface integrity and fatigue life of titanium alloy *** with different water pressures and standoff distances(SoDs)was co.ducted on the TA19 *** surface integrity of the specimens before and after SAWJP with different process parameters was experimentally studied,including microstructure,surface roughness,microhardness,and co.pressive residual stress(CRS).Finally,fatigue tests of the specimens before and after SAWJP treatment with different process parameters were carried out at room *** results highlighted that the fatigue life of the TA19 specimen can be increased by 5.46,5.98,and 6.28 times under relatively optimal process parameters,which is mainly due to the improved surface integrity of the specimen after SAWJP ***,the fatigue life of specimens treated with improper process parameters is decreased by 0.55 to 0.69 times owing to the terrible surface roughness caused by the material *** work verifies that SAWJP can effectively improve the surface integrity and fatigue life of workpieces,and reveals the relationship between process parameters,surface integrity,and fatigue life,which provides support for the promotion of SAWJP in the manufacturing fields.

关键词： Fatigue testing Process parameters Submerged abrasive waterjet peening Surface integrity Surface treatment Titanium alloy TA19

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Dynamic analysis of C/C co.posite finger seal

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Chinese Journal of Aeronautics 2014年第3期27卷 745-758页

作者： Chen Guoding Wang Li’na Yu Qiangpeng Su Hua School of Mechanical engineering Northwestern Polytechnical University avic commercial aircraft engine co. Ltd

A seal device as an important co.ponent of aeroengines has decisive influence on per- formance, reliability, and working life of aeroengines. With the development of aeroengines, demands on the performance characteristics of seal devices are made strictly. Finger seal as a novel kind of sealing device, recently attracts more and more attentions in academic circles and engineer- ing fields at home and abroad. Research on finger seals has been extensively developed, especially on leakage and wear performances under dynamic co.ditions. However, it is a pity that the work on finger seals has been limited with a single approach that is improving the performance by structural optimization; in addition, the technology of dynamic analysis on finger seals is weak. Aiming at the problems mentioned above, a distributed mass equivalent dynamic model of finger seals co.sidering the co.pling effect of overlaid laminates is established in the present paper, the dynamic perfor- mance of 2.5 dimension C/C co.posite finger seal is analyzed with the model, and then the effects of fiber bundle density and fiber bundle preparation direction on finger seal＇s dynamic performance are discussed, as well as co.pared with those of co.based alloy finger seal. The current work is about dynamic analysis of finger seals and application of C/C co.posite in this paper may have much academic significance and many engineering values for improving research level of finger seal dynamics and exploring feasibility of C/C co.posite being used for finger seals.

关键词： Aeroengine C/C co.posite co.based alloy Equivalent dynamic model Finger seal

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Cutting force prediction for circular end milling process

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Chinese Journal of Aeronautics 2013年第4期26卷 1057-1063页

作者： Wu Baohai Yan Xue Luo Ming Gao Ge Key Laboratory of co.temporary Design and Integrated manufacturing Technology Ministry of Education Northwestern Polytechnical University avic commercial aircraft engine co. Ltd.

A deduced cutting force prediction model for circular end milling process is presented in this paper. Traditional researches on cutting force model usually focus on linear milling process which does not meet other cutting co.ditions, especially for circular milling process. This paper presents an improved cutting force model for circular end milling process based on the typical linear milling force model. The curvature effects of tool path on chip thickness as well as entry and exit angles are analyzed, and the cutting force model of linear milling process is then co.rected to fit circular end milling processes. Instantaneous cutting forces during circular end milling process are predicted acco.ding to the proposed model. The deduced cutting force model can be used for both linear and circular end milling processes. Finally, circular end milling experiments with co.stant and variable radial depth were carried out to verify the availability of the proposed method. Experiment results show that measured results and simulated results co.responds well with each other.

关键词： Chip thickness Circular end milling Cutting force Machining Radial depth Tool path curvature

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An approach for machining distortion measurements and evaluation of thin-walled blades with small datum

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Chinese Journal of Aeronautics 2016年第6期29卷 1806-1814页

作者： Yu Jianhua Chen Zhitong Jiang Zepeng School of Mechanical engineering and Automation Beihang UniversityBeijing 100083China avic commercial aircraft engine manufacturing co. Ltd.Shanghai 201306China co.Innovation Center for Advanced Aero-engine Beijing 100083China

Inspection techniques for aero-engine blades are a hot topic in industry. Since these blades have a sculptured surface and a small datum, measurement results may deviate from an actual position. There are few proper approaches co.pensating for non-uniform distribution errors that are within specified tolerance ranges. This study aimed to develop a meshing structure measuring approach for the distortion of blades via non-co.tact optical 3D scanning. A rough measurement and a registration procedure are initially adopted to rectify the co.rdinate system of a blade, which avoids the initial co.rdinate system errors caused by the small datum. A measurement path with meshing structure is then unfolded on the blade surface. For non-uniform distribution errors, the meshing structure measurement is more visual and clear than the traditional co.stant height curves method. All measuring points take only 7 min to co.plete, and the distribution of error is directly and accurately presented by the meshing structure. This study provides a basis for future research on distortion co.trol and error co.pensation.

关键词： Free surface Machining distortion Optical testing Thin-walled workpiece Turbine blades

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Research into co.figuration and Flow of Wall Oil Film in Bearing Chamber Based on Droplet Size Distribution

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Chinese Journal of Aeronautics 2011年第3期24卷 355-362页

作者： CHEN Guoding SUN Hengchao WANG Jun School of Mechanical engineering Northwestern Polytechnical University Xi 'an 710072 China avic commercial aircraft engine co. Ltd Shanghai 200030 China

The lubrication design and heat transfer determination of bearing chambers in aeroengine require a sufficient understanding of the oil droplet-film interaction and physical characteristic in an oil/air two-phase flow state. The analyses of oil droplet movement, mass and momentum transfer during the impingement of droplet/wall, as well as wall oil film thickness and flow velocity are very important for the bearing chamber lubrication and heat transfer calculation. An integrated model in co.bination with droplet movement, droplet/wall impact and film flow analysis is put forward initially based on the co.sideration of droplet size distribution. The model makes a co.tribution to provide more practical and feasible technical approach, which is not only for the study of droplet-film interaction and physical behavior in bearing chambers with oil/air two-phase flow phenomena, but also useful for an insight into the essence of physical co.rse through droplet movement and deposition, film formation and flow. The influences of chamber geometries and operating co.ditions on droplet deposition mass and momentum transfer, and wall film thickness and velocity distribution are discussed. The feasibility of the method by theoretical analysis is also verified by the ex- isting experimental data. The current work is co.ducive to expose the physical behavior of wall oil film co.figuration and flow in bearing chamber, and also significant for bearing chamber lubrication and heat transfer study under oil/air two-phase flow co.ditions.

关键词： bearing chamber droplet size film thickness oil/air two-phase aeroengine lubrication

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Precessing motion in stratified radial swirl flow

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Chinese Journal of Aeronautics 2016年第2期29卷 386-394页

作者： Qin Hao Lin Yuzhen Li Jibao National Key Laboratory of Science and Technology on Aero-engine Aero-thermodynamics School of Energy and Power Engineering Beihang University avic commercial aircraft engine co. Ltd.

Vortex/flame interaction is an important mechanism for unsteady co.bustion in a swirl co.bustion system. Technology of low emission stirred swirl （TeLESS）, which is characterized with stratified swirl flow, has been developed in Beihang University to reduce NOx emission. However, large-scale flow structure would be induced in strong swirl flow. Experiments and co.putational fluid dynamics （CFD） simulation were carried out to investigate the unsteady flow feature and its mechanism in TeLESS co.bustor. Hotwire was firstly applied to testing the unsteady flow feature and a distinct mode with 2244 Hz oscillation frequency occurred at the pilot swirl outlet. The flow mode amplitude decayed co.vectively. Large eddy simulation （LES） was then applied to predicting this flow mode and know about its mechanism. The deviation of mode prediction co.pared with hotwire test was 0.8%. The spiral isobaric structure in pilot flow passage indicates that precessing vortex co.e （PVC） existed. The velocity spectrum and phase lag analysis suggest that the periodic movement at the pilot outlet was dominated by precessing movement. Negative tangen- tial momentum gradient reflects that the swirl flow was unstable. Another phenomenon was found out that the PVC movement was intermittently rotated alon~ the symmetric axis.

关键词： Large eddy simulationPrecessing motion Stratified flow Swirl flow Unsteady flow

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CFD Study of NO_x Emissions in a Model commercial aircraft engine co.bustor

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Chinese Journal of Aeronautics 2012年第6期25卷 854-863页

作者： ZHANG Man FU Zhenbo LIN Yuzhen LI Jibao avic commercial aircraft engine co. Ltd. Shanghai 200241 China National Key Laboratory of Science and Technology on Aero-engine Aero-thermodynamics Beihang University Beijing 100191 China

Air worthiness requirements of the aircraft engine emission bring new challenges to the co.bustor research and design. With the motivation to design high performance and clean co.bustor, co.putational fluid dynamics （CFD） is utilized as the powerful design approach. In this paper, Reynolds averaged Navier-Stokes （RANS） equations of reactive two-phase flow in an experimental low emission co.bustor is performed. The numerical approach uses an implicit co.pressible gas solver together with a Lagrangian liquid-phase tracking method and the extended co.erent flamelet model for turbulence-co.bustion interaction. The NOx formation is modeled by the co.cept of post-processing, which resolves the NOx transport equation with the assumption of frozen temperature distribution. Both turbulence-co.bustion interaction model and NOx formation model are firstly evaluated by the co.parison of experimental data published in open literature of a lean direct injection （LDI） co.bustor. The test rig studied in this paper is called low emission stirred swirl （LESS） co.bustor, which is a two-stage model co.bustor, fueled with liquid kerosene （RP-3） and designed by Beihang University （BUAA）. The main stage of LESS co.bustor employs the principle of lean prevaporized and premixed （LPP） co.cept to reduce pollutant, and the pilot stage depends on a diffusion flame for flame stabili-zation. Detailed numerical results including species distribution, turbulence performance and burning performance are qualita-tively and quantitatively evaluated. Numerical prediction of NOx emission shows a good agreement with test data at both idle co.dition and full power co.dition of LESS co.bustor. Preliminary results of the flame structure are shown in this paper. The flame stabilization mechanism and NOx reduction effort are also discussed with in-depth analysis.

关键词： air worthiness co.putational fluid dynamics low emission co.bustor lean prevaporized and premixed NOx reduction

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Experimental research in rotating wedge-shaped co.ling channel with multiple non-equant holes lateral inlet

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Chinese Journal of Aeronautics 2018年第3期31卷 457-469页

作者： Huimin ZHOU Haiwang LI Zhi TAO Hongwu DENG Meisong YANG Shuqing TIAN National Key Laboratory of Science and Technology on Aero-engine Aero-Thermodynamics Beihang University co.laborative Innovation Center of Advanced Aero-engine Beihang University Research and Development Center AVIC Commercial Aircraft Engine Co. Ltd.

The heat transfer in a novel smooth wedge-shaped co.ling channel with lateral ejection of turbine blade trailing edge is experimentally investigated in both non-rotating and rotating *** the co.ventional inlet at the bottom of the channel, an extra co.lant injection from 8 lateral non-equant holes is introduced to improve the overall heat transfer. The total mass flow rate ratio（lateral mass flow rate/total mass flow rate） varies from 0 to 1.0. The major inlet Reynolds number and rotation number respectively vary from 10000 to 20000 and from 0 to 1.16. Experimental results show that the lateral inlet decreases local bulk temperature and increases local heat transfer at the middle and the top of the static channel. In rotating cases, the lateral inlet notably improves the heat transfer at the high-radius half channel and co.pensates the negative effects induced by the rotation. Both intensity and uniformity of heat transfer inside the channel are enhanced while flow resistance decreases with proper mass flow rate ratio of co.lant from two inlets. The most satisfactory total mass flow rate ratio is around 2/3. This new structural style of co.ling channel has huge potential and provides new direction of heat transfer of turbine blade trailing edge.

关键词： Heat transfer Lateral inlet Rotor blades trailing edge Rotating Wedge-shaped channel

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An innovative study on low surface energy micronano co.tings with multilevel structures for laminar flow design

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Chinese Journal of Aeronautics 2019年第3期32卷 577-584页

作者： Jun TAO Gang SUN Gang WU Liqiang GUO Yongjian ZHONG Meng WANG Bo YOU Department of Aeronautics & Astronautics Fudan University Department of Mechanical & Aerospace engineering University of CaliforniaIrvine Department of Material Science Fudan University AECC commercial aircraft engine co. Ltd. avic Aerodynamics Research Institute

Laminar flow design is one of the most effective ways to reduce the drag of a commercial aircraft by expanding the laminar flow region on the surface of the aircraft. As material science develops, the emergence of new materials such as low surface energy materials has offered new choices for laminar flow design of commercial aircraft. Different types of low surface energy micro-nano co.tings are prepared to verify the effects on the boundary layer transition position and the drag of the airfoil through wind tunnel tests. The infrared thermal imaging technology is adopted for measuring the boundary layer transition, while the momentum integral approach is employed to measure the drag co.fficient through a wake rake. Infrared thermal imaging results indicate that the co.tings are capable of moving backward the boundary layer transition position at both a low velocity of Mach number 0.15 and a high velocity of Mach number 0.785. Results of the momentum integral approach demonstrate that the drag co.fficients are reduced obviously within the cruising angle of attack range from 1° and 5° by introducing the low surface energy micro-nano co.ting technology.

关键词： co.ting techniques Drag reduction Laminar flow Surface energy Wind tunnel test

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Geometrical Scale-Sensitive Fatigue Properties of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si Alloys With α/β Lamellar Microstructures

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Journal of Materials Science & Technology 2014年第12期30卷 1284-1288页

作者： B.Zhang Z.M.Song L.M.Lei L.Kang G.P.Zhang Key Laboratory for Anisotropy and Texture of Materials Ministry of Education Northeastern University Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences avic commercial aircraft engine co. Ltd.

Fatigue properties of the Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy sheets co.taining different numbers of α/β Widmansttten co.onies in the thickness direction of the sheets were investigated by tensionetension fatigue testing. It is found that fatigue properties of the Ti alloy either in low- or high-stress amplitude regimes beco.e more sensitive to the sheet thickness of the Ti alloy as the sheet thickness is co.parable to the length scale of the Widmansttten co.onies. The basic mechanism of such length scale-sensitive fatigue properties in the Ti alloy was elucidated.

关键词： Fatigue Ti alloy Microstructure Size effect

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