1999 Vol. 14, No. 4

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A STUDY ON CAUSE FOR SOME GEAR FAILURES
Yan Litang, Ren Guangming
1999, 14(4): 337-342.
Abstract PDF(380KB) icon1576 icon519
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There were several gear failures,in which the gear was broken into two,one of which is only a little smaller than one quarter of the gear.Several researchers had studied the cause of such gear failures and concluded that it was resonant vibrations.However the conclusion was not yet completely acceptable.In order to further ascertain the cause of such gear failures,the self-exciting vibration and instabilities were analyzed.The vibration instability of the disk-shaped plain gear was studied with the multiple scale's method of nonlinear perturbation method.The vibration response of a disk-shaped bevel gear was measured on a test rig.Both theoretical and experimental investigations show that there exist self-exciting vibrations on the gears with traveling wave vibration.Under certain conditions the forward traveling wave vibration of the driving gear and the backward traveling wave vibration of the driven gear are instable and cause the gear failures mentioned above.
EXTRACTION OF SHOCK CHARACTER FROM HARMONIC SIGNAL BASED ON WAVELET
Yang Jianguo, Xia Songbo, Xu Genfa
1999, 14(4): 343-347.
Abstract PDF(320KB) icon1589 icon410
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Wavelet transformation has very good characteristics of time-frequency analysis,and is very effective to extract the small instantaneous shock from harmonic signal.An improved fast algorithm is proposed to avoid frequency aliasing,which exists in the Mallat algorithm.The incipient fault character of the bearing in one aeroengine is extracted successfully by the wavelet transformations.
A FRACTIONARY DIMENSION IDENTIFICATION METHOD OF CRITICAL BIFURCATED PARAMETERS
Zhao Yucheng, Zhang Yulian, Xu Qingyu
1999, 14(4): 348-352.
Abstract PDF(368KB) icon1682 icon476
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The nonlinear behaviors of rotor systems set high requirements to the designing of motor system:Such as to take nonlinear elements into account;to avoid the unstable parameter points or regions where will appear nonlinear phenomena.For this purpose,from studying a typical fractional model-May model and Jeffcott rotor system,the map of the fractional dimension of time-serial vs the parameter is obtained,which can identify critical bifurcated parameters of nonlinear dynamical system quite well.
BIFURCATIONS OF NONLINEAR ROTOR—SFD SUPPORTING SYSTEM
Zhao Yonghui, Zou Jingxiang
1999, 14(4): 353-356.
Abstract PDF(295KB) icon1414 icon396
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Periodic solutions of nonlinear rotor-SFD supporting system are calculated by using Newton-Fox shooting method and pseudo-arc length continuation procedure.According to multi-variable Floquet theory,bifurcations and stability of the system are analyzed.Bifurcation diagrams of the system are obtained from on Poincaré map.The results show that the motion of the rotor system undergoes nonlinear dynamics phenomena,such as period doubling bifurcation,tangent bifurcation and so on.
RESEARCH ON UNIFIED VISCOPLASTIC DAMAGE RELATIONSHIP OF ANISOTROPIC MATERIALS
Zhou Baizhuo, Nie Jingxu, Yang Shijie
1999, 14(4): 357-360.
Abstract PDF(516KB) icon1900 icon399
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With the help of combining continuum damage mechanics and viscoplastic theory,the unified viscoplastic constitutive model [1] developed by authors is modified.A unified viscoplastic constitutive damage model of anisotropic materials under the alternative effect of creep and fatigue load is established.The creep and fatigue property as well as their damages for monocrystalline alloys DD3 have been predicted according to this model.The durability and damage under the alternative effect of the creep and fatigue load for the material under cyclic loading.The predicted results are compared with test data.
AN EXPERIMENTAL STUDY ON LOW CYCLE FATIGUE LIFE OF 1ST TURBINE DISK IN AEROENGINE
Gong Mengxian, Huang Qingdong, Xiao Yuxiang, Gu Yuanxing, Zhao Xingming, Cao Fenglan
1999, 14(4): 361-365.
Abstract PDF(745KB) icon2319 icon511
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According to the standard load cycle spectrum,a stress analysis of 1st turbine disk in an aeroengine was completed to determine its useful life.The places,where the centre hole came across the pin holes,were the dangerous points (so called check points).An experimental rotor of the 1st turbine disk had been designed to model the stress spectrum on the check points.The high temperature LCF(low cycle fatigue)test of an old disk was also conducted at SB804-the disk LCF tester in GTE(Gas Turbine Establishment).The test indicated that cracks emerged on the check points of 5 from all of 16 pin holes on the old disk as the 6047th cycle was completed and the crack extended life is 2886 cycles.The comparative analysis of the test results of the old and new disks indicates that LCF crack growth life and fault life with reliability 99 87% and degree of confidence 95% for the 1st turbine disk are 1132 cycles and 2072 cycles respectively.
A STUDY ON FATIGUE PROPERTY OF AUSTENITIC WELDED JOINTS IN STATE OF DEFORMING RECRYSTALLIZATION
Ruan Miqing, Fan Yinhe
1999, 14(4): 366-370.
Abstract PDF(360KB) icon1537 icon467
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The post weld heat-treatment cannot obviously improve the heterogeneity of microstructure and mechanical property in 1Cr18Ni9Ti welded joints,in particnlar for increasing their fatigue property,because there is no allotropic modification in 1Cr18Ni9Ti alloy,an austenitic stainless steel.Deforming recrystallization can be used to better the microstructure and mechanical properties of austenitic welded joints,and then to enhance their fatigue resistance remarkably.This paper mainly discusses the improvement of the microstructure and fatigue property in 1Cr18Ni9Ti welded joints,and verifies it by the low-cycle fatigue tests.
DYNAMIC BEHAVIOUR INVESTIGATION OF TAPER BEAM WITH SIDEWISE CRACK
Xing Deshun
1999, 14(4): 371-374.
Abstract PDF(287KB) icon1623 icon372
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Emergence of crack causes local flexibility variation of the component.A linear elasticity theory of fracture mechanics is applied to deriving the strain energy released by the crack.According to Castigliano theorem,elements of local flexibility matrix are obtained,which can correct the stiffness matrix of the taper beam.The dynamic behaviour of the taper beam has been found out by means of finite element method.The effects of relative depth of crack,crack location,ratios of length to width and width to taper thickness on natural frequency have been numerically investigated and the relevant experiments have been conducted to testify the calculation results.
FATIGUE LIFE PREDICTION OF TENONS IN AEROENGINE COLD-SECTION DISCS BASED ON SMALL CRACK GROWTH
Liu Shaolun, Wu Xueren, Huang Hongfa, Liu Jianzhong, Ding Chuanfu, Han Xipeng, Yang Shijie, Wei Duokui
1999, 14(4): 375-381.
Abstract PDF(2141KB) icon1699 icon518
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Tests for small and large crack growth were conducted on substructure model of tenon in the aeroengine cold section disc which was made of Titanium alloy TC11.Stress intensity factor solution of the substructure was obtained by FEM and its weight functions were analyzed.Plasticity introduced Newman Crack Closure model was used to predict the total fatigue life of the substructure,in which small crack was initiated from swallow-tailed groove bottom.Prediction results are in good agreement with tested results.
ANALYTICAL PART-LOAD PERFORMANCE OF SINGLE SHAFT SMALL GAS TURBINE AND ITS COGENERATION
Zhang Na, Cai Ruixian
1999, 14(4): 382-386.
Abstract PDF(297KB) icon2127 icon399
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The typical analytical part-load performances of constant speed single shaft small gas turbine with centrifugal compressor and its cogeneration are given.The influence of gas turbine design parameters and steam side design parameters are thoroughly investigated.The typical efficiency curve and statistical formula obtained for this type gas turbine are consistent with the practical data.The part-load performance of cogeneration is studied with saturated steam supply.It is pointed out that the approaching temperature difference may be negative in low load condition with high steam parameter and low ambient temperature.Some other part-load performances and quantitative rules are summarized as well.
AN EXPERIMENTAL INVESTIGATION ON COMPRESSOR ROTOR-STATOR INTERACTION
Hu Jun, Tang Guocai
1999, 14(4): 387-392.
Abstract PDF(965KB) icon1729 icon475
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An experimental investigation on the effect of the rotor wake on unsteady loading of downstream stator has been carried out in a low speed single stage axial compressor.The unsteady pressure distribution along the stator blade was measured,and the effects of axial gap between rotor and stator,operating rotation speed and mass flow of the compressor were investigated in detail.The experimental results show that all these factors have a great effect on the rotor-stator interaction.The incidence change caused by the velocity defect in the rotor wake has a major impact on the unsteady pressure distribution and lift of the stator blade.The amplitude of the pressure fluctuation reaches maximum at the blade leading edge and decays rapidly towards the trailing edge on the pressure side.The interaction intensifies with the decrease in the mass flow or the increase in the rotation speed.The results of the investigation on the influence of axial gap between rotor and stator (l) show that,the unsteady pressure distribution and the lift of the stator blade fluctuate strongly as l<0 4,and the fluctuation intensity decreases quickly as lincreasses.
SIMULATION OF VORTEX STRUCTURE IN BOWED BLADE CHANNEL
Wang Songtao, Wang Zhongqi, Yuan ning, Feng Guotai
1999, 14(4): 393-396.
Abstract PDF(280KB) icon1792 icon473
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Flow fields in a bowed and a straight turbine blade channels were simulated with 3D N-S solver.Generation and development of horse vortex and passage vortex were also considered in detail.There is distinguished difference between topological structure of passage vortex in the bowed blade and that in the straight blade.The passage vortex core is changed from unsteady focus point in the straight blade channel to steady focus point in the bowed blade channel in the most part of the domain.The effect of the topological structure flow pattern difference on energy loss was also analyzed.The steady passage vortex core not only makes passage vortex more tight,but also is beneficial to wrap low energy fluid cumulating in corner into passage vortex to reduce the energy loss of the secondary flow.
A 3-D VISCOUS NUMERICAL SIMULATION FOR STATIC COMPRESSOR CASCADE
Yan Ming, Peng Zeyan
1999, 14(4): 397-400.
Abstract PDF(290KB) icon1916 icon391
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A 3-D viscous numerical simulation was completed for the plane cascade flow fields of end-bend and original blade with the helps of pressure-based method of N-S equations and a K-ε two equations model.In the case of using simple stagger grid,by the way of velocity modification for calculating flux of a control volume,the well-known problem of checkerboard distribution of pressure and velocity fields in the pressure-based method is well settled.The accuracy and reliability of this numerical simulation are verified with the experimental data.
AN EXPERIMENTAL INVESTIGATION OF PIT-ARRAY-PLATE COMPRESSOR CASCADE
Zhang Shunong, Yan Ming, Ren LiYun, Peng Zeyan
1999, 14(4): 401-404.
Abstract PDF(1377KB) icon1833 icon391
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An experimental investigation of end wall flow control for pit-array cascade plate in a compressor cascade wind tunnel has been completed.The experimental comparison of pit-array-plate with original cascade plate shows that:(1)The movement of flow along pitchwise could be obstructed.It delays the formulation or reduces the intensity of passage-vortex;(2)The flow mixing around the end wall region of the cascade could be moderately increased.The accumulation of lower-level-energy air in the corner may be reduced.(3)The flux across cascade increases obviously at a higher incidence.It is beneficial to improve compressor characteristic map and engine performance.
2-D MODEL FOR INFLUENCE OF TRAILING EDGE EJECTION ON AERODYNAMIC PERFORMANCE OF A TURBINE CASCADE
Gao Limin, Wang Shangjin, Liu Bo
1999, 14(4): 405-408.
Abstract PDF(201KB) icon1856 icon497
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In accordance to analysis of interaction mechanism between the ejection and the main flow,a 2-D compressible model of the turbine blade trailing edge ejection has been improved,which uses energy loss coefficient for representing the effect of the ejection on the aerodynamics of the main flow.The aerodynamical loss after the ejection has been analyzed through correlation of the model with the numerical calculation of the cascade main flow field and boundary layer parameters.The comparison between calculation results and experimental data shows that the improved model can exactly describe the mixing process between the main flow and the ejection,and predict the energy loss coefficient for the ejection on the pressure side near the trailing edge and through the trailing edge holes.
A STUDY ON BREAKUP AND ATOMIZATION OF HIGH PRESSURE LIQUID JETS
Zhang Yurong, Jin Zhiming, Yu Yonggang
1999, 14(4): 409-412.
Abstract PDF(319KB) icon1913 icon485
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In order to find an exact description of jet formation process for the high pressure liquid injection,it is difficult to photograph the mechanism of the liquid jet breakup in the vicinity of the nozzle,because the jet core is hidden behind a curtain of spray cloud.The system built by authors uses flash X-rays to study the liquid jet breakup processes.Radiography can hardly resolve the spray cloud,but it is capable of recording the full jet structure and allows to determine the intact core.As examples some liquid jet radiographs have been taken at different fluid pressures and nozzles.The point of cylindrical jet disintegration and the point of annular jet coalescence shift to the nozzle orifice with increasing prepressure.
A METHOD FOR CONSTRUCTING TWO-DIMENSIONAL DELAUNAY TRIANGULATION OF COMBUSTOR FLUID
Yin He, Chang Lina, Yan Chuanjun
1999, 14(4): 413-416.
Abstract PDF(293KB) icon1527 icon383
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A method is presented here for constructing two-dimensional Delaunay triangulation with a new automatic point creation technique.This technique is based on the idea of advancing-front method to achieve good geometry flexibility.The main steps are as follows:The initial triangulation is generated first,according to the given border set.In the initial triangulation usually there are lots of triangles with very small minimum angles which will seriously decrease computational accuracy.The new nodes are introduced with advancing-front method,and added into the existing mesh according to Bowyer-Watson algorithm simultaneously.The procedure is repeated until no more improvement of the grid can be achieved by inserting the new nodes.Its application to triangulating combustor fluid shows that the resulted grids have great regularity and boundary quality.
A STUDY OF COMPUTER AIDED TESTING TECHNIQUE FOR AEROENGINE
Chen Guiying, Li Bin, Lei Yong, Wu Zhizhen
1999, 14(4): 417-420.
Abstract PDF(269KB) icon1695 icon486
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A system engineering method for development of the Computer Aided Testing (CAT) technique was discussed in the light of a comprehensive review of CAT technique,and investigation of CAT Systems.The application of digital filtering to the Aeroengine Test was also introducted.The focus was put on the achievements of multi-signal acquisition,processing and displaying according to Virtual Instrument conception.The necessity and trend of a man-machine harmonious information environment development with supporting of database system in the aeroengine Test field were considered.
A STUDY OF OBJECT-ORIENTED APPROACH FOR AEROENGINE PERFORMANCE SIMULATION
Tang Hailong, Zhang Jin
1999, 14(4): 421-424.
Abstract PDF(459KB) icon2375 icon516
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This paper discusses how to create an extensible,flexible,reliable aeroengine simulation program.An effective areoengine simulation program on the basis of object-oriented areoengine fundament class library (an areoengine application framework),can be easily built for a specified type of areoengine or a specified intention of study,an Exception handlers are integrated to the framework to make the debug of the simulation software easy and improve its reliability.A two-spool turbofan engine and a turboshaft engine simulation programs are provided as examples to illustrate the flexibility and specificity of the framework.
A STUDY ON SYSTEM RESPONSE FOR LIQUID PROPELLANT STAGED COMBUSTION CYCLE ROCKET ENGINE
Zhang Lihui, Zhang Zhenpeng
1999, 14(4): 425-428.
Abstract PDF(284KB) icon1745 icon506
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A feeding system of a pump-fed Liquid Propellant Staged Combustion Cycle Rocket Engine (LPSCCRE) is taken as a research object.Its system physical model is constructed,and its nonlinear mathematical model is established.The nonlinear dynamic response of LPSCCRE is simulated with adaptive Runge-Kutta algorithm on the conditions of parameter variation and working regime regulation in wide range.Comparison of the obtained results with the test data shows that:The mathematical model is quite valid and calculation method meets the simulation requirements.
LEAK FAULT DETECTION OF LIQUID ROCKET ENGINE BASED ON K-L INFORMATION DISTANCE
Wang Jianbo, Yu Daren, Wang Guangxiong
1999, 14(4): 429-432.
Abstract PDF(290KB) icon1631 icon476
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The leak of Liquid Rocket Engine (LRE) is very common and dangerous.It is important to research a fast and effective approach for leak detection.In accordance to the measured monitor state parameters of LRE,the AR model is established and the time series analysis is completed.K-L information distance is taken as discriminant function to detect the leak fault of LRE.The simulation results show the leak fault detection algorithm is feasible.
ANALYTICAL REDUNDANCY BASED ON AUTOASSOCIATIVE NEURAL NETWORK FOR AEROENGINE SENSORS
Huang Xianghua, Sun Jianguo, Ilyasov B.G., Vasilyev V.I.
1999, 14(4): 433-436.
Abstract PDF(342KB) icon1669 icon458
Abstract:
Analytical redundancy technology based on autoassociative neural network is presented for aeroengine sensors.It doesn't depend on model and needs only the sample net of measurement data without sensor fault to train the network.Then it can work on-line.Estimation Feedback Scheme is developed and can meet the real-time requirements.If there has been performance degeneration of aeroengines,a compensation algorithm can be used automatically.Sensor fault analytical redundancy is accomplished by integrating the network estimation and fault detection logic.The results of theoretical analysis and simulation show that the provided scheme has the ability of distinguishing performance degeneration and sensor faults,and it also can detect soft faults of sensors.
ROBUST INTEGRATED FLIGHT/PROPULSION CONTROL DESIGN FOR A STOL AIRCRAFT
Wang Tao, Meng Qingming
1999, 14(4): 437-439.
Abstract PDF(230KB) icon1816 icon381
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An application of robust LQG/LTR control design methodology to a centralized integrated flight/propulsion control (IFPC) system design for STOL/MTD aircraft is presented.The emphasis is put on formulating the Robust Servo LQR (RSLQR)control synthesis problem.A conversion parameter is introduced in controller design to improve the comparability of the system parameters.A detailed evaluation is completed for a controller obtained from RSLQR control design.The results indicate that a RSLQR control design meets the IFPC control system with thrust vectoring.
ADAPTIVE MODELLING TECHNIQUE FOR AEROENGINE
Duan Shoufu, Qi Wenkai, Gao Deping
1999, 14(4): 440-442.
Abstract PDF(283KB) icon1989 icon416
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An adaptive method for aeroengine modelling is introduced on the basis of an established original model.A weighing function and a series of correction factors are adopted.The value of the weighing function will be minimized when the correction factors are optimized so that the adaptive correction of the model and the part characteristics is accomplished.In order to validate the feasibility of this method,the test data of a given engine are used to revise its mathematical model and the part characteristics with the method.
BISTABLE STATE OCCURRENCE OF SYMMETRIC SFD—FLEXIBLE ROTOR SYSTEM
Chen Zhaobo, Jiao Yinghou, Xia Songbo, Liu Zhansheng, Jiang Shuyun
1999, 14(4): 443-445.
Abstract PDF(652KB) icon1737 icon471
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The bistable state occurrence has been investigated theoretically for squeeze film damper(SFD) supported flexible rotor system.The bistable state calculation method of the system is presented in detail.The bearing parameter B ,stiffness ratio f and unbalance U are chosen to analyze the bistable state performance,and a domain of U(B,f ) is obtained.The results show that the bistable state phenomenon can be avoided as long as the value of U beyond the above mentioned domain.This makes it convenient to optimize the SFD design parameters.
DIGITAL SIMULATION OF POST-STALL BEHAVIORS OF A COMPRESSION SYSTEM
Cheng Bangqin, Li Jun, Tao Zengyuan
1999, 14(4): 446-448.
Abstract PDF(235KB) icon1690 icon373
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The post-stall behaviors,such as surge and rotating stall,of a three-st age compressor are simulat ed based on an one-dimensional unsteady model for the dynamic response of compression system.The variations of the annular average parameters, i.e.velocity,pressure,temperature and flow coefficient,can be obtained from the simulation. The stall types can be identified by these parameters vs.time.In addition,the effect of parameter"B",proposed by E.M.Greitzer,is analyzed.

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