1992 Vol. 7, No. 1

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A LARGE-SCALE AXIAL FLOW COMPRESSOR FACILITY AND DYNAMIC MEASUREMENT TECHNIQUES FOR ROTOR FLOW STUDY
Jiang Haokang, Li Yuchun, Zhang Hong, Xiong Zhang, Xu Lipin, Cheng Maozhang
1992, 7(1): 1-8,95.
Abstract PDF(861KB) icon3117 icon504
Abstract:
A large scale axial flow compressor research facility designed for relative flow measurements is presented.With the test section outer diameter of one meter and hub/tip ratio of 0 6,the facility has a unique rotating probe traversing mechanism downstream the rotor blade row and inside the hub,which is capable of traversing five hole pressure probe,hot wire and other probes across the rotor blade passage.The precise null,tangential,radial and axial motions of the probes are entirely electrical and controlled by an online 386 microcomputer.The data transmission system which transmits signals from rotating frame to stationary frame of reference consists of rotating Kulite pressure transducers and a multi channel slip ring.In stationary reference frame,where the velocity and pressure at the rotor exit are unsteady with both periodic and random components,high response probes fixed on stationary probe traverse mechanisms are used for rotor exit flow measurements.Two high frequency pressure probes(a two inclined hole probe and a four hole conic probe)have been developed and two hot wire techniques(a single slant hot wire and a two inclined hot wire sensor)have been improved.A self made computer controlled 16 channel parallel data acquisition and processing system with the maximum sampling frequency of 100KHz per channel,accompanied with a phase locked ensemble averaging technique,is used for acquiring the data measured by high response probes.Typical data on the three dimensional flow structure at the rotor exit and inlet with fine resolution by various probes are presented.
3D LDA MEASUREMENT IN AN AXIAL FAN ROTOR
Wang Xiaoyu, Xu Liping, Chen Yuanzhong, Zhu Yan
1992, 7(1): 9-13,95.
Abstract PDF(337KB) icon1763 icon452
Abstract:
A stacked three dimensional Laser Doppler Anemometer(LDA)system has been developed on the basis of a one demensional and a two demensional LDA systems.This system was successfully used in the measurement of the rotational flow field inside a small axial fan rotor.The measurements reveal rich and complex flow structures near the blade tip region,in particular fine helical vortex structures are obtained,which prove the system a useful tool in turbomachinery flow measurement.
A RANDOM VORTEX METHOD FOR PREDICTION OF MAXIMUN INSTANTANEOUS INLET TOTAL PRESSURE DISTORTION
Wu Hu, Cheng Fuqun
1992, 7(1): 14-16,100.
Abstract PDF(255KB) icon1480 icon465
Abstract:
An improved random vortex model for predicting maximum instantaneous pressure distortion is presented based on the statistical behavior of turbulence type dynamic inlet total field generated by plate type turbulence generator.A new statistical method is put forward for determining the vortex core size.The numerical results show good accuracy of the prediction.This method also decreases the dynamic inlet pressure measurements.The effectiveness of the method in decreasing both cost and time is proved well.
QUASI-STATIC ANALYSIS OF ROLLER BEARING
Lin Guochang, Xu Congru, Lin Jishu
1992, 7(1): 17-21,96.
Abstract PDF(346KB) icon1771 icon625
Abstract:
The quasi static analysis of radial cylindrical roller bearing is introduced.The influences of the out of round raceway,the relative inclination of the roller and race,and flexible deformation of the bearing housing on bearing performance are taken into consideration.The calculation of out of round raceway and the counter rotating intershaft support bearing characteristics are studied.The precise determination of roller loading in an inclined inner race is presented,and the calculation of contact force on the inclined roller is carried out by means of the transverse“slicing”technique.The maximum stress of roller are calculated with the flexible two dimensional contact variational method.The thermal effects of oil in Hertzian zone and the entry region and the oil starvation influence are also taken into account in the lubrication model.The main bearing in an aeroengine was calculated with the quasi static analysis program on the M 150H computer.The agreement of calculated and experimental results is quite good.
QUASI-KINETICS OF FOLLOWING TEETH TRANSMISSION
Zuo Hongfu, Zhou Youqiang
1992, 7(1): 22-26,96.
Abstract PDF(342KB) icon1296 icon345
Abstract:
The quasi kinetics and load characteristics of Following Teeth Transmission(FTT)are researched all sidedly in accordance with its fundamental structure models.In the meantime the interactions of elastic deformations,manufacture errors,lubricating film and so on,are taken into consideration simulataneous of a number of teeth.According to the loading a centralized regressive loading formula is proposed.The concept about skidding coefficient of FTT is firstly introduced.Since there are local freedoms at the following rollers and the outer ring of eccentric bearing,the skidding states of FTT are brought to light.The conclusions were verified by the methods of photo elastic analysis and high speed photography was taken during authors′ experiments and the test results support the conclusions of the paper satisfactorily.
AN OPTIMAL DESIGN TECHNIQUE FOR CROWNED TEETH OF HELICAL GEAR
Fang Zongde, Shen Yunwen
1992, 7(1): 27-30,96.
Abstract PDF(296KB) icon1736 icon498
Abstract:
An optimal design technique for crowned teeth of helical gear is presented,which includes 3 D finit element method,flexibility matrix and mathematical programming.In the calculation the manufacturing and assembling errors,the deformations of gears and supporting structure are taken into account.For the objective function to uniform the load distribution under the two limited error conditions,a quadratic program is automatically formed and solved by computer.Thus an optimal longitudinal modification with crowning is obtained,which has a comprehensive effect on decreasing the sensitivity to the errors and uniforming the load distribution.Comparison of this modification with the traditional ones demonstrates the advantages of this method in accuracy and effectiveness.
COMPREHENSIVE CONDITION MONITORING OF GEAR OPERATION
Wang Tong, Gao Xueguan, Qiu Liangheng
1992, 7(1): 31-34,97.
Abstract PDF(282KB) icon1246 icon372
Abstract:
The comprehensive condition monitoring has been proposed by the anthors with six kinds of condition monitoring methods:temperature,vibration,noise,ferrography,infrared spectrum and surface roughness.The research on combined application of these methods has been conducted on a gear test machine(Type CL 100)to develop the technique,method,theory and application of the comprehensive condition monitoring.The comprehensive condition monitoring research is integreted with the pull life experiment.Some of primary experiemental results given in this paper show that the comprehensive condition monitoring with the various methods is much better than that only with one or two methods,especially for monitoring all forms of machine component surface damage such as pitting,wearing and so on.
AN EQUIVALENT WEIBULL DISTRIBUTION METHOD FOR MECHANICAL RELIABILITY ANALYSIS
Wu Liyan, Liu Geng, Wang Buying
1992, 7(1): 35-38,97.
Abstract PDF(285KB) icon1464 icon471
Abstract:
A new reliability analysis method is presented which is called quasi pure probabilistic method(QPPM).On the basis of the present method,equivalent Weibull distribution method(EWM)is established for the reliability analysis of machine elements.Weibull distribution can express different distribution forms,so it is a more suitable method to describe random parameters with different distribution forms in mechanical reliability analysis.The calculation accuracy of the EWM is higher than that of the equivalent normal distribution mehtod(ENM)in reliability prediction.The present method is intelligible in concept,convenient in use,and has more important significance for reliability prediction of mechanical products with higher reliability requirements.
PREDICATION OF FASTENNING CAPACITY OF SCREWED JOINT STRUCTURE WITH CONE ASSEMBLY
Dong Benhan, Gao Pengfei
1992, 7(1): 39-42,97-98.
Abstract PDF(340KB) icon1883 icon464
Abstract:
Assembly and cone assemble are employed between jointed pants for meeting the requirement of self centring.The fastenning capacity of rotator screwed joint with cone assembly can not be calculated according to traditional method,because it is not only related to elastical deformation of jointed parts but also to friction condition and slide condition between contact cone surface under simulation conditions of the geometry and assembly technique.A model test has been conducted to research the mechanical behaviour of the jointed parts in assembling and loading process.The load deformation relation of jointed parts reveals the difference between the plane assembly and the cone assembly.The relation of the former is linear and that of the latter nonlinear.In this research the loose condition of joint structure was defined experimentally as that the strain of cone parts equals to zero and the correlated load is named for loose load(or bearing capacity).Based on the test results the cone assembly jointed structure increases loose load owing to the friction factor.We have been predicted loose load of real jointed structure in an aeroengine by means of the model test and investigated the factors which have influence on bearing capacity.
NUMERICAL MODELLING FOR GAS DUCT IN TUBOANNULAR COMBUSTOR
Li Changlin, Yao Jixian, Liu Wei
1992, 7(1): 43-46,98.
Abstract PDF(289KB) icon1583 icon382
Abstract:
A numerical approach to modelling of hot gas duct in tuboannular combustor is suggested.The modelling scheme is based on five controlling rules:top and bottom curves on central profile,radii of top and bottom arcs of cross sections,and area of cross sections.A three dimensional hot gas duct is regarded as a stacking of finite two dimensional cross sections constrained by the rules.A brief analysis of computed rules is presented as well.As an example the hot gas duct of SPEY engine is computed by using this method.Comparison between the computed cross sections and real ones obtained from SPEY technical drawings shows that the method is effective and practicable.
STUDY ON RELIABILITY DESIGN OF TURBINE BLADE
Shi Jinyuan
1992, 7(1): 47-50,98.
Abstract PDF(371KB) icon1789 icon382
Abstract:
A reliability design method is presented for fatigue strength of turbine blades.The method considers static stresses,dynamic stresses and the blade endurance strength as random variables.The scatter effects of the centrifugal tensile stress,the centrifugal bending stress and the gas bending stress are taken into consideration when the distribution parameters of static stresses are determined.The scatter effects of the static natural frequency,the dynamic natural frequency,the stimulus and the amplification factor are considered as the distribution parameters of dynamic stresses are determined.The distribution parameters of the blade endurance strength are determined under the condition that the scatter effects of the corrosion correction factor,the surface quality correction factor,the stress concentration correction factor,the dimension correction factor and the material fatigue limit are taken into account.The distribution parameters of the fatigue stress and the fatigue strength for turbine blades are obtained by the plotting method from the blade endurance strength graphs.The reliability of turbine blades can be estimated in the designing stage by use of interference models for fatigue stress distribution and fatigue strength distribution,which provides a scientific basis for designers to analyze and improve reliability of the turbine blades.
EFFECT OF SOME LOAD FACTORS OF BIRD IMPACT ON BLADE RESPONSE
Yin Jing
1992, 7(1): 51-54,98-99.
Abstract PDF(330KB) icon1676 icon369
Abstract:
The effect of some load factors of bird impact on blade response is analysed in this paper.These factors include momentum transfer,load duration,loading location,and spatial distribution of loads.The finite element method is used to compute the nonlinear transient response of the blade by means of simulating a real blade with a rectangular cantilever plate and simulating bird impact loads with shock loads.By computing and comparing the response of the cantilever plate to various load factors,the following conclusions can be obtained:The local and total deflection of the blade are directly proportional to momentum transfer to the blade.The load duration affects directly the deformation and stress states of the blade too.So the two parameters must be accurately predicted when a load model is developed.It is also very important to correctly predict the load location on the blade because the eccentric loads cause the greater deflection and twisting.The spatial distribution forms for distributed loads seem to have a little effect on blade response.The work which is conducted in this paper can provide the basis for the development of the bird impact load model.
STRATEGIES FOR OPTIMAL DESIGN OF GAS TURBINE DISKS
Zhang Dongxu, Cheng Gengdong, Sui Yongkong, Shong Limin, Liu Xiangsheng, Chen Junyue
1992, 7(1): 55-56,99.
Abstract PDF(200KB) icon1796 icon428
Abstract:
A number of strategies for optimal design of the gas turbine disks are proposed,which include separation of tenons design from disk design,rational simplification of structural model,check on local constraints,optimal design based on elastic analysis and further check based on elastoplastic analysis,multi level optimization by grouping design variables.According to the strategies a computer program TDSOS is developed for practical use.By applying the strategies and the program TDSOS,shape optimization of gas turbine disk with light mass and low stress level can be obtained and the contradiction among high performance index,reliability and long life expectation is better solved.
A NEW FORM OF NUSSELT′S DIMENSIONLESS EQUATION
Wang Feng, Hang Zhenxing, Xing Yuming
1992, 7(1): 57-60,99.
Abstract PDF(306KB) icon1426 icon387
Abstract:
It is expounded theoretically that C and m of the dimensionless equation Nu=CRe Pr m,which is in common use,should not be constant.This simple dimensionless equation is unable to reflect accurately the heat transfer when Prandle number equals 0 001～7500.The authors made use of integral equations to solve the laminar flow heat transfer problem of various field flow fields around a plate of Prandtl number 0 001 to 7500.Another form of dimensionless equation is recommended which can describe the functional relationship among Nusselt number,Raynolds number and Prandtl number more accurately.
STUDY ON SECONDARY ATOMIZATION OF LIQUID FUEL AT THE LIP OF THE FLAMEHOLDER
Yang Maolin, Huang Yong, Gu Shanjiang, Zhang Yingnian
1992, 7(1): 61-64,99-100.
Abstract PDF(340KB) icon1515 icon384
Abstract:
An experimental investigation of secondary atomization of liquid fuel at the lip of the flameholder has been completed by means of Malvern Particle Sizer.This secondary atomization has several features:Fine droplets occur in the high speed air flow side,while gross droplets occur in the recirculation zone side;the velocity of air flow(V a)has a predominant influence on the mean drop size(MMD)of the spray,the effect may be expressed quantitatively as MMD∝V -1 75 a.The mechanism of the secondary atomization may be described as follows:Some of the liquid drops in the spray are gathered by the flameholder and form a fuel film in its surface,the air flow forces the wavy film to move forward to the lip of the flameholder,further the fuel film breaks up at flameholder lip under a pincer attack of high speed turbulent flow and low speed recirculation flow.
THE EXPERIMENTAL STUDY ON THE PERFORMANCE OF EVAPORATOR MODEL
Wang Hongming, Zhu Zhiwei, Chang Shunong
1992, 7(1): 65-68,100.
Abstract PDF(289KB) icon1667 icon467
Abstract:
An evaporator fitted on a model combustor is investigated to provide uniform circumferential gas temperature profile.It is shown that less fuel vapor exhausts from the primary holes with uniform outlet area along the evaporator,so that the lower gas temperature is behind these holes,and the more vapor from the final holes makes the gas temperature higher.The vapor flow is proportional to the outlet area as the evaporativity is 100% for the final holes.Uniform vapor flow and uniform circumferential temperature profile can be achieved with larger primary outlet holes and even final holes.
THE JET SCREEN IGNITION SCHEME AND ITS EXPERIMENTAL VERIFICATION
Yin Qun
1992, 7(1): 69-71,100.
Abstract PDF(240KB) icon1209 icon374
Abstract:
A jet screen ignition scheme has been developed based on the investigation of the ignition environment of the burning zone in the high speed flow combustor.It features a short time change of the flow pattern in the high speed flow near the wall during the ignition period,which is caused by a thin and bend high speed gas jet.A specially designed ignition experiment on a model of an aerogasturbine combustor verified success of the proposed scheme and showed its potentiality in enlarging the ignition range of the high speed flow combustor.
TRIPLE COUNTRA-ROTATING TURBINE AND ITS BASIC ANALYSIS
Cai Ruixian, Wei Xinglu
1992, 7(1): 72-76101.
Abstract PDF(333KB) icon1898 icon411
Abstract:
A comprehensive basic analysis for various triple countra roating turbines is given with the blade element stage assumption.The appropriate independent variables and evaluation criteria of the triple countra rotating turbine stages are first presented by analogy with the classical analysis of conventional turbine stages.Then three typical kinds of rotating blade rows are defined and all possible typical schemes of such stages are enumerated.Their characteristics of specific work and load distribution of the triple countra rotating shafts are presented in a very simple form.The typical triple countra rotating turbine stages suitable to the three shaft gas turbine power plants are analysed and given.From the analysis results it is concluded that the load capacity per unit engine length of the triple countra rotating turbines can be much higher than that of the conventional turbines.
OPTIMIZATION OF MULTISTAGE AXIAL-FLOW COMPRESSOR VANE SETTING
Wang Yongming
1992, 7(1): 77-80,101.
Abstract PDF(281KB) icon1884 icon404
Abstract:
A methodology has been developed for calculating optimum stagger angles of vanes for the axial flow compressor performance adjustment tests.The methodology uses a square Taylor series as an approximate optimization model,determines initial vane angle changements of the axial flow compressor tests by means of the compressor performance prediction model and abtains direction and steps for vane adjustment by the digital optimization technology.This methodology has the advantages of fast convergence,less iteration and suitability for the test data calculation with measuring errors.Compared with the existing methods it can reduce the period and times of compressor performance tests.
AEROENGINE SENSOR FAILURE DETECTION BY BAYESIAN MULTIPE HYPOTHESIS TESTING
Jian Dazhong, Wang Xiaokui
1992, 7(1): 81-84,101.
Abstract PDF(294KB) icon1416 icon449
Abstract:
Analytical redundancy of the advanced sensor failure detection isolation and fault sensor output reconstruction obviously enhance the reliability of aircraft engine controls.The Bayesian multiple hypothesis testing is applied to detection isolation and accommodation of the hard failure.The hypothesis conditioned errors,the covariance matrices of the cost function and the optimal estimate are obtained from a bank of Kalman filters.The example using the microcomputer based simulation indicates that the detective rate,the accuracy of output reconstruction and the detectable minimum range and so on has the advantage over the Kalman filter residual in hard failure.
1992, 7(1): 84-84.
Abstract PDF(87KB) icon1533 icon360
Abstract:
FAILURE DETECTION OF ENGINE SENSORS WITH A BANK OF KALMAN FILTERS
Wang Shengyuan
1992, 7(1): 85-88,102.
Abstract PDF(280KB) icon1702 icon413
Abstract:
A detection method is presented for sensor failures in FADEC engine.In order to avoid that the output of a fault sensor affects other system states through state feadback,we use a bank of Kalman filters in which different combinations of sensor outputs as inputs of the filters are fed to each filter.According to the characteristics of innovation sequences of each filter,the failure can be detected and isolated.The sample frequencis are different in feedback control path and computation of innovation sequences.When a failure has occured in one sensor but before the failure affects other system states,the failure can be detected and isolated effectively.Therefore,the effects of failure on the outputs of other sensors are avoided.A digital simulation has been made for a rotational speed and temperature control system of a twin spool turbine engine.The simulation results show that this failire detection and isolation method is effective.
1992, 7(1): 88-88.
Abstract PDF(88KB) icon1259 icon472
Abstract:
STUDY ON THE RELIABILITY EVALUATION OF ENGINE FUEL ACCESSORIES
Xue Jianhua, Ai Xianfeng, Liu Yiyu
1992, 7(1): 89-91,102.
Abstract PDF(682KB) icon1253 icon389
Abstract:
Application of Bayes method to the reliability analysis of mechanical products is considered.The key to the application of Bayes statistics selection of prior probability has been solved by means of comparison and discrimination.Bayes statistics is of universal significance for the reliability analysis of complicated mechanical products.Satisfactory results can be achieved if the proper selection of prior probability is made.
A SIMPLIFIED METHOD OF TRANSIENT MATHEMATICAL MODEL FOR NON-AUGMENTATION ENGINE
Yu Weifeng, Zhang Shaoji
1992, 7(1): 92-94,102.
Abstract PDF(299KB) icon1952 icon440
Abstract:
A simplified method of transient mathematical model for non augmentation engine is presented,which is used in real time simulation for developing engine control system.Two spool inertias are considered in the simplified model,which are the main factors for engine transient performance.

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