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System Life and Reliability Modeling of a Multiple Power Takeoffs Accessory Gearbox Transmission

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Journal of Shanghai Jiaotong university(Science) 2022年第6期27卷 855-866页

作者：汪凯王宪良朱加赞欧代松潘代锋 aecc sichuan gas turbine establishment Chengdu 610500China

A mathematical model for system life and reliability of a multiple power takeoffs aeroengine accessory gearbox transmission is presented.The geometry model of gear train is distributed into several subsystems by different transmitted powers.The lives of each component are combined to determine the units,subsystems and entire system lives sequentially according to a strict series probability model.The unit and subsystem interface models are defined to dispose the loads of common components.The algorithm verification is presented and a numerical example is given to illustrate the use of this program.The initial design could not fulfill the life requirement.A design modification shows that the gear train has a more balanced life distribution by strengthening the weak parts,and the overall life of entire system is increased above the design requirement.This program can help the designer to approach an optimal accessory gearbox transmission design efficiently.

关键词： aeroengine accessory gearbox power takeoff gear train life model reliability numerical program

Comparison of Flow Mechanism of Blade Sweep between a Transonic Single Rotor and a Rotor in Stage Environment

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Journal of Thermal Science 2022年第5期31卷 1804-1819页

作者： CAO Zhiyuan GAO Xi LIANG Yuyuan HUANG Ping LEI Peng LIU Bo School of Power and Energy Northwestern Polytechnical UniversityXi’an710072China AECC Sichuan Gas Turbine Research Establishment Chengdu610599China

In order to reveal the different effect mechanisms of blade sweep on the aerodynamic performance when a transonic rotor operates alone or in fan stage environment,two series of forward and backward swept rotors were designed and utilized in the first stage of the dual-stage NASA CR-120859 fan.Results show that,the influence of sweep on the single rotor and the whole stage is different,indicating swept designs for rotor alone may not be suitable for the stage operations.The distinct effect of sweep is account for the difference of the flow field characteristic and stall mechanism of the single rotor and the rotor in the stage environment.The single rotor is tip limited and its stall mechanism is shock/tip leakage vortex(TLV)interaction,whereas the fan stage is hub limited and its stall mechanism is the severe corner separation at stage hub region.For the single rotor,forward sweep increases the stall margin(SM)for all sweep schemes,while backward sweep reduces it in general.For the fan stage,however,backward swept rotor significantly increases stall margin and the stall mechanism is changed to shock/TLV interaction.On the contrary,forward sweep reduces stall margin in general.The flow mechanism is that forward sweep reduces blade loading at tip region near leading edge(LE)and causes the shock to move downstream.Both the variations improve flow field at tip region,while backward sweep exerts an opposite effect.At hub region,backward sweep reduces radial flow tendency by varying radial pressure gradient,causing reduction of corner separation at rotor hub,while forward sweep enhances corner separation.Moreover,with increasing of swept height and swept angle,the chock mass flow,peak efficiency and total pressure ratio of forward sweep are reduced in general,while an opposite effect can be found for backward sweep.

关键词： sweep tip leakage flow shock corner separation transonic fan

Experimental and Numerical Investigation of Non-synchronous Blade Vibration Excitation in a Transonic Axial Compressor

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Journal of Thermal Science 2024年第2期33卷 602-610页

作者： WANG Songbai WU Yadong CHEN Yong CAO Zhipeng School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai200240China aecc sichuan gas turbine establishment Chengdu610500China

The complex flow phenomenon of rotating instability(RI) and its induced non-synchronous vibration(NSV) have become a significant challenge as they continuously increase aerodynamic load.This study aims to provide an understanding of the non-synchronous blade vibration phenomenon caused by the rotating instability of a transonic axial compressor rotor.In this case,blade vibrations and non-synchronous excitation are captured by strain gauges and unsteady wall pressure transducer sensors.Unsteady numerical simulations for a full-annulus configuration are used to obtain the non-synchronous flow excitation.The results show that the first-stage rotor blade exhibits an NSV close to the first bending mode;NSV is accompanied by a sharp increase in pressure pulsation;amplitude can reach 20%,and unsteady aerodynamic frequency will lock in a structural mode frequency when the blade vibrates in a large-amplitude motion.The predicted NSV frequency aligns well with the experimental results.The dominant mode of circumferential instability flow structure is approximately 47% of the number blades,and the cell size occupies 2-3 pitches in the circumferential direction.The full-annulus unsteady simulations demonstrate that the streamwise oscillation of the shedding and reattachment vortex structure is the main cause of NSV owing to the strong interaction between the tip leakage and separation vortices near the suction surface.

关键词： non-synchronous vibration transonic axial compressor rotor blade rotating instabilities unsteady flow

Variable Importance Measure System Based on Advanced Random Forest

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Computer Modeling in Engineering & Sciences 2021年第7期128卷 65-85页

作者： Shufang Song Ruyang He Zhaoyin Shi Weiya Zhang School of Aeronautics Northwestern Polytechnical UniversityXi’an710072China aecc sichuan gas turbine establishment Mianyang621700China

The variable importance measure(VIM)can be implemented to rank or select important variables,which can effectively reduce the variable dimension and shorten the computational time.Random forest(RF)is an ensemble learning method by constructing multiple decision trees.In order to improve the prediction accuracy of random forest,advanced random forest is presented by using Kriging models as the models of leaf nodes in all the decision trees.Referring to the Mean Decrease Accuracy(MDA)index based on Out-of-Bag(OOB)data,the single variable,group variables and correlated variables importance measures are proposed to establish a complete VIM system on the basis of advanced random forest.The link of MDA and variance-based sensitivity total index is explored,and then the corresponding relationship of proposed VIM indices and variance-based global sensitivity indices are constructed,which gives a novel way to solve variance-based global sensitivity.Finally,several numerical and engineering examples are given to verify the effectiveness of proposed VIM system and the validity of the established relationship.

关键词： Variable importance measure random forest variance-based global sensitivity Kriging model

基于声发射信号频谱特征的2D C/SiC复合材料损伤模式实时分析

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Acta Mechanica Sinica 2022年第10期38卷 107-124页

作者：曾翔龙邵红艳潘容王波邓琼张程煜索涛 School of Aeronautics Northwestern Polytechnical UniversityXi’an710072China AECC Sichuan Gas Turbine Research Establishment Chengdu610500China School of Materials Science and Engineering Northwestern Polytechnical UniversityXi’an710072China

本研究将无监督模式识别与有监督模式识别相结合,实现对材料健康状况的实时监测.常温下完成拉伸试验后,采用无监督识别(k-mean++)标记声发射(AE)信号的频谱特征.以800和1000°C面内拉伸为实施例,采用有监督识别(K近邻(KNN))对损伤模式... 详细信息

本研究将无监督模式识别与有监督模式识别相结合,实现对材料健康状况的实时监测.常温下完成拉伸试验后,采用无监督识别(k-mean++)标记声发射(AE)信号的频谱特征.以800和1000°C面内拉伸为实施例,采用有监督识别(K近邻(KNN))对损伤模式进行实时识别.根据损伤识别结果,确定了二维C/SiC复合材料的4种主要拉伸损伤模式:基体开裂(122.6~201 kHz)、界面脱粘(201~294.4 kHz)、界面滑移(20.6~122.6 kHz)和纤维断裂(294.4~1000 kHz).根据二维C/SiC复合材料在常温和高温拉伸过程中的声发射能量积累曲线特征,分析其损伤演化机制.同时,利用谐波小波包精确计算了各损伤模式的损伤能量和损伤程度.识别结果表明,与以往研究相比,采用本声发射分析方法,具有更高的损伤识别灵敏度和准确性.

关键词： C/SiC复合材料纤维断裂损伤模式频谱特征损伤识别实时分析基体开裂声发射信号

High temperature creep mechanisms of a single crystal superalloy: A phasefield simulation and microstructure characterization

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Progress in Natural Science:Materials International 2020年第3期30卷 366-370页

作者： Ronghai Wu Yunsong Zhao Yanfei Liu Xing Ai School of Mechanics Civil Engineering and Architecture Northwestern Polytechnical University Beijing Institute of Aeronautical Materials aecc sichuan gas turbine establishment aecc Hunan Aviation Power Plant research Institute

The high temperature creep behavior of a single crystal Ni-based superalloy was studied by combined experimental and numerical methods. The creep test results showed that the creep curves exhibited a three-stage feature. The qualitative explanations for each stage of the creep curves were carried out based on the microstructure characterizations of γ/γ′ phases and dislocations. An elastoplasticity incorporated phase-field model was developed to provide quantitative understanding on directional coarsening(rafting) of γ′ phase. The simulation results showed that the directionality of γ′ coarsening was induced by both dislocation activity in γchannels and elastic inhomogeneity between γ and γ’ phases, therein the dislocation activity played a major role.This findings provide new insights into the design of novel single crystal superalloys with improved creep properties.

关键词： Creep mechanism Dislocation activity Phase-field method Single crystal superalloy

PPB structure elimination,DRX nucleation mechanisms and grain growth behavior of the3rd-generation PM superalloy for manufacturing aviation components

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Chinese Journal of Aeronautics 2024年第1期37卷 325-344页

作者： Baoyun ZHANG Yongquan NING Zhaotian WANG Qiaomu LIU School of Materials Science and Engineering Northwestern Polytechnical UniversityXi’an 710072China aecc sichuan gas turbine establishment Chengdu 610500China

Previous Particle Boundary(PPB),as the detrimental structure in Powder Metallurgy(PM)components,should be eliminated by subsequent hot process to improve the mechanical properties.The objective is to investigate the Dynamic Recrystallization(DRX)nucleation mechanisms and grain growth behavior of the 3rd-generation PM superalloy with PPB structure.Microstructure observation reveals that PPB decorated with(Ti,Ta,Nb)C carbides belongs to the discontinuous chain-like structure.The elimination of PPB networks can be achieved effectively via hot deformation due to the occurrence of DRX.Four different DRX nucleation mechanisms were proposed and discussed in detail according to the special microstructure characteristics of the PM superalloy.Firstly,local lattice rotations can be detected in the vicinity of(Ti,Ta,Nb)C carbides during hot deformation and thus PPB structure serves as the preferential nucleation sites for DRX grains via Particle-Stimulated Nucleation(PSN).Then,Discontinuous-DRX(DDRX)characterized by grain boundary bulging dominates the microstructure refinement and Continuous-DRX(CDRX)operated by subgrain rotation can be regarded as an important assistant mechanism.At last,the initial Σ3 boundaries would lose their twin characteristics owing to the crystal rotation and then transform into the general High Angle Grain Boundaries(HAGBs).The distorted twins provide additional DRX nucleation sites,viz.,twin-assisted nucleation.Particular attention was focused on the grain growth behavior of the PM superalloy in subsequent annealing process.The recrystallization temperature was determined to be about 1110.C and 1140.C can be considered as the critical temperature for grain growth.The findings would provide theoretical support for microstructure refinement of the 3rd-generation PM superalloy,which is of pivotal significance for improving the mechanical properties of aviation components.

关键词： PM superalloy Previous Particle Boundary(PPB) DRX nucleation Grain growth Microstructure refinement

Experimental Study on the Film Cooling Characteristics of Three Complex Tip Structures

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Journal of Thermal Science 2023年第4期32卷 1378-1392页

作者： LIN Juqiang LI Haiwang YOU Ruquan LIU Runzhou TAO Zhi LIU Song School of Energy and Power Engineering Beihang UniversityBeijing100191China research Institute for Aero-Engines Beihang UniversityBeijing100191China National Key Laboratory of Science and Technology on Aero Engines Aero-thermodynamics Beijing100191China aecc sichuan gas turbine establishment Sichuan610500China

The turbine blades of aircrafts must be properly cooled to prevent engine failure.Thus,to investigate the influence of the tip structure on the film cooling effect,pressure-sensitive paint test technology was used to determine the adiabatic film cooling effectiveness in this study.The experiment was completed in a cascade comprising three straight blades.The effects of the blowing ratio,density ratio,tip clearance,and tip structure on film cooling efficiency were analyzed.The experimental results demonstrated that,as the blowing ratio increased,the film coverage area and film cooling efficiency increased under most experimental conditions.However,the film cooling efficiency was found to initially increase,and subsequently decrease,as the blowing ratio increased.The respective influences of the density ratio and tip clearance on the film cooling efficiency were found to be significant.The density ratio experiments revealed that a high-density ratio can result in better film coverage than the low-density-ratio air.The tip clearance experimental results indicated that a small tip clearance promotes an increase in film cooling efficiency;this is because the small tip clearance negatively affects the main stream leakage flow,which can reduce the film coverage area.Under the conditions of the Base case 2 configuration,a blowing ratio of 2.1,and a tip clearance of 0.6%h,the average film cooling efficiency of the blade tip was 0.22.Among the three blade tip structures applied in this study,Base case 2 demonstrated higher film cooling efficiency than the other two blade tip structures under the conditions of the same blowing ratio,tip clearance,and density ratio.

关键词： film cooling tip structure pressure-sensitive paint leakage flow

Real-time modular dynamic modeling for compression system of altitude ground test facilities

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Chinese Journal of Aeronautics 2023年第5期36卷 202-211页

作者： Yang SU Xuejiang CHEN Xin WANG Xiaodong LI Xiaoming LIU School of Energy and Power Engineering Xi’an Jiaotong UniversityXi’an 710049China aecc sichuan gas turbine establishment Mianyang 621703China State Key Laboratory of Compressor Technology(Compressor Technology Laboratory of Anhui Province) Hefei 230031China

Modeling of a centrifugal compressor is of great significance to surge characteristics and fluid dynamics in the Altitude Ground Test Facilities(AGTF).Real-time Modular Dynamic System Greitzer(MDSG)modeling for dynamic response and simulation of the compression system is introduced.The centrifugal compressor,pipeline network,and valve are divided into pressure output type and mass flow output type for module modeling,and the two types of components alternate when the system is established.The pressure loss and thermodynamics of the system are considered.An air supply compression system of AGTF is modeled and simulated by the MDSG model.The simulation results of mass flow,pressure,and temperature are compared with the experimental results,and the error is less than 5%,which demonstrates the reliability,practicability,and universality of the MDSG model.

关键词： Altitude Ground Test Facilities(AGTF) Compression modeling Dynamic simulation Real-time modelling Modular Dynamic System Greitzer(MDSG)modeling