2001 Vol. 16, No. 4

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Display Method:
A Durability and Damage Tolerance Centered Approach to Life Control of In-Service Engines
ZHAO Fu-xing
2001, 16(4): 305-308.
Abstract PDF(509KB) icon1595 icon480
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On the basis of the life control methods in common use for aircraft engines and structures,a durability and damage tolerance centered approach is presented for the life control of in-service aircraft engines in consideration of the reality in China.It is pointed out that the focus of interests for the life of non-modular engines should be put on the time between overhaul (TBO) rather than on the total life,with special emphasis on the role of the concept and practical experience of damage tolerance in the analysis.The technical difficulties in assessing durability and damage tolerance are briefly considered.It is expected that this paper will facilitate the application of damage tolerance assessments to the life control of in-service engines.
Stress Analysis for Single Crystal Blade and Application
YANG Zhi-guo, CHENG Xiao-ming, YIN Ze-yong
2001, 16(4): 309-311,315.
Abstract PDF(246KB) icon1645 icon436
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In this paper,based on the mechanism of crystal slip and considering the lattice rotation and finite deformation,the crystallographic constitutive model for the plastic and creep behavior was established,a new finite element formulation was given.As an example of application,the stress and creep deformation analysis was carried out for the single crystal blade of a certain aeroengine.The application has shown the effectiveness of this new method.
A Study on Useful Life of LPT Disk
CAO Feng-lan, WANG Lu-sheng, HUANG Qing-dong, QING Hua, HE Yun, WU Chang-bo, GONG Meng-xian
2001, 16(4): 312-315.
Abstract PDF(781KB) icon1888 icon495
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This paper studies useful life of an areoengine's LPT (Low Pressure Turbine) disk by analysis and experiment.Stress calculation and life prediction are performed to choose the critical location where cracks likely occur.Experiment equipments,specimens and parameters on the basis of equivalent damage principles are introduced.In this paper test results of two specimens are presented,which are used to determine the standard cycles and average flying hours of the disk in accordance with related literature.Test research provided experimental basis for useful life assessment and prolongation of disk.
Debris Analysis Technology and its Application to Aeroengine Fault Diagnosis Field
WU Zhen-feng, ZUO Hong-fu, SUN You-chao
2001, 16(4): 316-322.
Abstract PDF(417KB) icon1855 icon456
Abstract:
The debris microanalysis technology based on the micromorphology and artificial intelligence techniques is one of the new feasible measure of aeroengine wearing faults diagnosis in recent years.By means of morphological analysis,a set of micro-characteristic parameters of wear particles is put forward.By taking this as the basic information,the wear particles can be identified automatically and truly in virtue of the BP neural network and the other AI techniques.Based on the Particle Tribology theory and the analytical results of the debris sampled in the aeroengine lubricating oil,it is easy to evaluate the wear state of contacting parts and components in aeroengine well and truly,thereby the wear faults of aeroengine are diagnosied or predicted.In addition,this analytical technology has the potential application to the field of wear faults diagnosis of aeroengine gas pass.
Research on Experimental Technique for Fatigue-Creep Life of the Turbine Blade in Aeroengine
LI Wei, SHI Hai-qiu
2001, 16(4): 323-326.
Abstract PDF(652KB) icon2325 icon510
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Turbine blades of aeroengine are one kind of component parts working in the most severe conditions.They have the most complex structure,and are apt to fracture.The turbine blades endure the compound loads at high temperature all the time when the engine is working.Therefore,to determine the working life of the blade,the creep and fatigue life cannot be separately considered.On the contrary,the mutual effects of fatigue and creep must be fully considered.At present the method for predicting the fatigue-creep life of structure is imperfect in theory,so experimental research for the fatigue-creep life of the turbine blade is an important procedure in the design and life determination of the blade.This paper has a general discussion on the technique of fatigue-creep experiment of turbine blade.The determination of the experimental load spectrum and the key technical procedure of designing the testing blade sample are emphasized.This paper also introduces a synthetical testbed,whose loading system is based on the electric-mechanical servo device and which is especially suitable for blade fatigue-creep experiment.
Fracture Analysis of the 2nd Stage Compressor Blade in an Aeroengine
YANG Xing-yu, GENG Zhong-xing, CAI Xiang-hui, SHI Hai-qiu
2001, 16(4): 327-330.
Abstract PDF(664KB) icon2107 icon449
Abstract:
The blades on the 2nd stage compressor of one kind of aeroengine are frequently damaged components.Recently a fault of blade body fracture happened,which is different from the usual blade corner fracture.Judging from the shape of the fractured blade,it is a new type of fault,which is different from the corner fracture caused by the 2nd twist vibration.The fatigue started from the upper middle of the blade.The resulted crack expanded vertically up and down,and then turned horizontally in different directions.Finally,the upper part of the blade flew away.The flown part is about one third of the whole blade and the fracture shape is of "S" form.This paper provides an analytical conclusion drawn from the research work including:metallographic analysis of the blade fracture,scanning electron microscope analysis,computation and analysis of the vibration characteristics,the measurement of the static frequency and vibration mode of the blade,the test of fatigue breach,the measurement of the 10th relative vibration stress,and estimating of the fatigue life-time of the blade.The paper concludes that the mechanism of this new type fault is the 10th vibration of the blade,which occurred at 0 8 rating rotation of the aeroengine and the basic cause is the resonance and the flaw of the blade basin surface.
A Study of Probability Distribution of Multiparameter Load Spectrum Combination
SONG Ying-dong, WEN Wei-dong, GAO De-ping, ZHANG Yong
2001, 16(4): 331-334,339.
Abstract PDF(738KB) icon1650 icon430
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A method of multiparameter load spectrum formulation for aeroengine is provides.Firstly,according to the loading condition of the engine component,a parameter is selected as the norm.Secondly,the biparameter tables from the initial multiparameter load-time histories are made.Thirdly,by performing a statistical analysis of biparameter table data,the dependency relationships and interval spaces among the parameters can be obtained,and the pseudo-parameters are determined.Fourthly,the pseudo-biparameter tables are deduced from the initial multiparameter load-time histories,and the marginal and conditional probability distributions of the concerned parameters can then be estimated.Finally,based on probability theory the joint probabilities of any parameter combinations are calculated.Using this method,the paper deals with the multiparameter load spectrum of a fighter engine,and provides the joint probabilities of the combination between three directional overload coefficients and the engine rotational speed.
FEA Method for the Critical Buckling Load of Aeroengine Composite Case
QI Hong-yu, WEN Wei-dong, QI Hong-yuan, WANG Lin-jiang
2001, 16(4): 335-339.
Abstract PDF(857KB) icon2343 icon432
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The advanced composite material as a new material has been developed since 1960′s.Now laminated continuous fiber-reinforced composite materials are being used in some primary components in aircraft structures.Using linear shell and buckling theory and modeling finite element,this paper analyses the buckling of laminated plate and composite aeroengine case.At the same time some advice on engineering design is given.
Discussion on the Instantaneous Viewpoint About the Flame Stability Mechanism of Flameholder
YUE Lian-jie, YANG Mao-lin
2001, 16(4): 340-344.
Abstract PDF(721KB) icon1757 icon445
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The detailed near-wake flow behind the EBMC flameholder and V-gutter flameholder was measured by using 2D cross-correlation on-line PIV in a low speed wind tunnel.On the basis of the research on the instantaneous flow,the instantaneous viewpoint about the flame stability mechanism is put forward.Alternative formation and shedding of vortices in the near-wake flow structure have important effect on the flame stability.Large scale vortex provides essential condition for flame spreading as ignition source.And it transfers the energy and radicals to the forming vortex which becomes the ignition source as its development.So the source is handed on with the alternative formation and shedding of vortices.The larger is the scale of vortices and the more stable are the vortices, the better is the flame stability.
Research on Combustion Performance of the Edge Blowing Mixture Curtain Flameholder
YUE Lian-jie, XIONG Jian-qiu, FAN Wei-jun, YANG Mao-lin
2001, 16(4): 345-349.
Abstract PDF(289KB) icon1789 icon428
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On the basis of elementary research,the geometry structure of the edge blowing mixture curtain (EBMC) flameholder was improved and the experimental study on the combustion performance of the EBMC flameholder was carried out in 2D afterburning test rig.The flame stability,the influence of jet velocity and fuel supply at the trail edge on the combustion performance and the performance difference between fuel supply from the frontal injector and jet curtain were analyzed.At the same time,V-gutter flameholder was used to compare with the new type flameholder.The results show that the new type flameholder is a controllable flameholder,that can work stably with higher efficiency and lower pressure loss.It is expected to be used in future aero-engine,especially its by-pass afterburner.
Numerical Study of Two-Phase Reacting Flow in Annual Reversed Combustor
LEI Yu-bing, HU Hao-sheng, ZHAO Jian-xing
2001, 16(4): 350-354.
Abstract PDF(383KB) icon1651 icon447
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A zone data transmit method has been developed for simulating the two-phase reacting flowfield of the whole annual reversed combustor including the cooling passages in an arbitrary curvilinear coordinates.The gas phase is treated with Eulerian method by adopting the k-ε two-equation turbulent model,EBU-Arrhenius turbulent combustion model and six-flux radiation model,and the liquid phase is treated with Lagrangian method.The gas phase is solved with SIMPLE algorithm in non-staggered grid system,and the liquid phase is solved with PSIC algorithm by adopting the particle trajectory model.The calculation results of the flowfield under four different conditions are reasonable.It is shown that the numerical study of the combustor as a whole can reflect flowfield heat transfer and combustion comprehensively and provide useful information for the engineering research and optimization of the combustor.
Narrow Band Model Parameters of High Temperature Radiation for Carbon Dioxide of Combustion Products
DONG Shi-kui, YU Qi-zheng, TAN He-ping, HE Zhi-hong
2001, 16(4): 355-359.
Abstract PDF(341KB) icon1856 icon435
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CG approximation and LS approximation associated with narrow band model can be utilized to deal with radiation heat transfer problem in non-gray,non-isothermal and inhomogeneous media.Therefore,they are broadly adopted in studying high-temperature gas radiation transfer problem in engine combustor and plume of high speed flying vehicles.Carbon dioxide is a primary combustion product of carbonaceous propellant and the close attention has been paid on studying its radiative properties.But some of today's narrow band model parameters are obtained by fitting to experimental data and the spectral resolution is too low;some could not overlay near,middle and far infrared spectral region,or precision of some parameters is too bad;particularly high temperature data of over 2000 K are lacking.In this paper,by making use of the up-to-date high resolution and high temperature flame gas spectral database-HITEMP (serial number:3153),and parameters such as line strength,self-broaded half-width,and air-broaded half-width in HITEMP database being extrapolated to 300～3000 K,new carbon dioxide parameters,such as mean absorption coefficient,line density and mean half-width are obtained.Based on these parameters and narrow band model,the emissivity and transmissivity are evaluated under different temperature,pressure and optical path conditions.Results show a good agreement with Scutaru,Ferriso,Ludwig's experimental values.
Effects of Film Cooling Hole Shape on Heat Transfer
ZHU Hui-ren, XU Du-chun, LIU Song-lin
2001, 16(4): 360-364.
Abstract PDF(1008KB) icon1598 icon436
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The Effects of hole shapes,secondary flow Reynolds numbers,and blowing ratio on the heat transfer downstream of film cooling holes have been investigated.Experiments on dust-pan shaped holes,cone-shaped holes and round holes have been conducted with secondary flow Reynolds number ranging from 10,000 to 25,000 and blowing rate ranging from 0 3 to 2 0.Measurements are taken for 26 conditions.Results show that the critical blowing ratio is 1 3 for the dust-pan shaped holes and cone-shaped holes,0 7 for the round holes.The turbulence provided by jet from round holes is greater than that from dust-pan shaped holes and cone-shaped holes.
Investigation of Heat Transfer Inside Inclined Multihole in the Impingement/Inclined Multihole Double Wall
YU Wen-li, LIN Yu-zhen, LIU Gao-en
2001, 16(4): 365-369.
Abstract PDF(288KB) icon1654 icon457
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The local and overall heat transfer inside inclined multihole has been investigated experimentally with two types of hole distributions and different locations in the impingement/inclined multihole double wall of aeroengine combustor liner under the guidance of similarity method.The results demonstrated that the heat transfer near the entrance was enhanced greatly with the local heat transfer coefficients,and the average heat transfer coefficients were related closely with the impingement.The heat transfer coefficients vary greatly in the region of entrance due to the influence of impingement.The influencial area can reach down to some where X/D being equal to 3 0,but vary little in the region far from the entrance.
Coupled Radiation and Convection Heat Transfer in High Temperature Heated/Cooled Tubes with Inside Participating Medium Flowing
XIA Xin-lin, HUANG Yong, LIU Shun-long, TAN He-ping
2001, 16(4): 370-375.
Abstract PDF(1253KB) icon1761 icon477
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The coupled radiation and convection heat transfer in high temperature heated/cooled tubes with inside participating medium flowing is investigated by numerical simulation.The laminar flow is developed with a Poiseuille velocity distribution but thermal status is developing.By the discrete ordinate method,the nonlinear integrodifferential radiative transfer equation in cylindrical coordinate system is solved to obtain the radiative source term in the energy equation.And the energy equation for the coupled heat transfer is discretized by the finite difference approximation.The local Nusselt number and wall heat flux for convection and the total wall heat flux for coupled heat transfer are used to evaluate the influence of radiation on convection.The effects of the medium thermal conductivity,scattering albedo and phase function as well as the wall emissivity are discussed based on the calculated results.The analysis shows that the effect of radiation weakens convection heat transfer,but compared with the simplex convection,the coupled heat transfer accelerates the development of temperature field and significantly shortens the tube length with obvious heated/cooled effect.Difference appears between the two cases of coupled heat transfer in heated/cooled tubes even though the medium property parameters keep constant.The wall emissivity,the medium thermal conductivity and scattering albedo have great influences on the coupled heat transfer,while the effect of the medium scattering phase function is small.
Aerodynamic Performance Investigation of Exhaust Nozzles with Ejector Pumping and Cooling on Divergent Wall
ERI Qi-tai, WANG Qiang, WU Shou-sheng, WEI Fu-qing
2001, 16(4): 376-380.
Abstract PDF(562KB) icon1480 icon392
Abstract:
The aerodynamic performance of an axisymmetric convergent-divergent exhaust pumping nozzle with cooling on divergent wall was investigated.The three cooling schemes were adopted,such as slot film cooling,discrete hole film cooling and impact-film cooling.The influences of cooling air flowrate on thrust coefficients,distribution of wall pressure and pumping characteristics of nozzles for every scheme were also investigated.Compared with conventional axisymmetric nozzle,some thrust gain was obtained on the nozzle with pumping and cooling.The different cooling methods have significant effects on the distribution of wall pressure in the nozzle supersonic section.The pumping performance of the nozzle with slot cooling is best,the followed is a nozzle with impact-film cooling.Experimental results show that the proposed ejector pumping nozzle concept is superior to baseline nozzle in thrust characteristics and pumping performance .
Performance Investigation of Multi-Slot Ejector Nozzles for High Speed Exhaust System
WANG Qiang, ERI Qi-tai, WANG Hong-bo, ZHANG Jing
2001, 16(4): 381-385.
Abstract PDF(1034KB) icon1700 icon387
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A computer program,so-called the Ejector Nozzle Sizing and Analysis Program (ENSAAP),has been developed for ejector nozzle sizing and analysis.It was applied to the required ejector slot heights by using models of the slot pumping,secondary air induction system,engine cycle and slot cooling effectiveness.For an example,an engine cycle and aircraft mission has been used to demonstrate the inlet/ejector sizing process,as well as the performance sensitivities to an ejector installation.This program provides an approach to the optimization of advanced aircraft performance with reduced IR signature.
Experimental Investigation on Impingement Heat Transfer from Rib Roughened Surface
ZHANG Jing-yu, CHANG Hai-ping
2001, 16(4): 386-389,393.
Abstract PDF(858KB) icon1765 icon423
Abstract:
Impingement heat transfer is one of the useful cooling methods for high temperature gas turbine blades and/or guide vanes in aeroengines.After the cooling jet impinges on the leading edge of the turbine blade and/or guide vane,it flows downstream and turns to be the initial crossflow for the aft row of impinging jet.The process of impingement heat transfer is quite complicated, especially when the target surface is rib roughened.In this paper,Impingement heat transfer from rib roughened surface with two-dimensioned arrays of circular jet with initial crossflow has been investigated experimentally.Through the thousands of experimental data,the effect of the several flow parameters ( Re j=7000～15000,G c/Gj =0～0 5) and geometric parameters ( Xn=5～15,Zn=1 5～5,p/e=5～12,e/d =0 5～1 5) on heat transfer characteristics has been studied.It would be useful for the cooling analysis and design of gas turbine hot section.
A Study of Enlarging Surge Margin and Optimization of Variable Geometry for Afterburning Turbofan Engines
WU Hu, LIAN Xiao-chun, SHEN Shao-ying
2001, 16(4): 390-393.
Abstract PDF(249KB) icon1678 icon447
Abstract:
A general model for predicting the thermodynamic performance of variable geometry axial compressors has been developed,based on stage-stacking model.The model is combined with the method,with which off-design operating points of gas turbine engines can be predicted.The simulation program is established for predicting variations in engine surge margins.An example on the use of the model and method is given to prove their validity.The optimization is obtained to predict the effects of combined variable geometry of fan inlet guide vane,mixer and nozzle area on the performances and surge margins of the engine.
Numerical Simulation of Static Internal Performance for an Axisymmetric Vectoring Exhaust Nozzle (AVEN)
JIN Jie, WANG Qiang
2001, 16(4): 394-397.
Abstract PDF(251KB) icon1739 icon402
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The numerical simulation of static internal performance for an axisymmetric vectoring exhaust nozzle (AVEN) has been conducted with solving 3-D N-S equations by means of finite volume method with separation of vector flux and B-L turbulent model as well as technologies of TTM grids generation and compact local grids.The results of computation have been compared with that of scale model experiments.The investigation results indicated that during nozzle vectoring the relative tolerance of wall static pressure distribution is less than 13%,the relative tolerance of resultant vector angle is less than 10% and the relative tolerance of thrust coefficient is less than 2%.
Numerical Simulation of Secondary Flow in Compressor Cascade
ZHONG Jing-jun, WANG Hui-she, JIA Jian-bo, WANG Zhong-qi
2001, 16(4): 398-401.
Abstract PDF(269KB) icon2309 icon405
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The numerical simulation has been carried out to investigate the secondary flow in compressor cascade.The method of the pseudo-compressibility was used and the incompressible Navier-Stokes equations were solved with Beam-warming's implicit approximate factorization algorithm and the MML turbulence model.It is shown that there are several vortices in the cascade under the given condition.In addition to the passage vortices,the horseshoe vortices,the corner vortices and the wall vortices induced by the strong separation in the corner of suction surface are found very close to the suction surface and become new vortex couples.The development and interaction of these vortices have a great influence on the energy loss.The agreement of calculated results with the experimental data is favorable.
Nonlinear Dynamic Modeling and Dynamic Tooth Loads Analysis of Star Gearing System
SUN Zhi-min, SHEN Yun-wen, WANG San-min, HOU Yu
2001, 16(4): 402-407.
Abstract PDF(1033KB) icon1793 icon473
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A torsional and translational nonlinear vibration mathematical model was established to predict the dynamic characteristics of the star gearing system.The time-varying mesh stiffness,gear composite errors,run-out errors and gear backlashes were considered.A numerical method was applied to solving the large parametrically excited nonlinear multi-DOF dynamic system.A numerical example was also presented.From the results,the influences of the time-varying meshing stiffness,run-out errors and backlashes on the dynamic responses and dynamic gear tooth loads were investigated respectively.The dynamic load equalizations among star gears were also analyzed under the existence of gear run-out errors.In comparison with some calculated results from the literature ,the numerical results presented show a good agreement.
Stability Robustness Bounds for H∞ State Feedback Control of Aeroengine
WANG Xi, ZENG Qing-fu
2001, 16(4): 408-410.
Abstract PDF(294KB) icon1239 icon439
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The uncertainty system with the structured parameter of aeroengine was investigated,according to T.Shen's conception of the negative margin of algebraic Riccati inequality.The criterions of defining stability robustness bounds for designing the H∞ state feedback controller were provided,based on the nominal model,and its scan-searching algorithm was given.

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