2005 Vol. 20, No. 6

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Integral Inference Method for Multivariate Normal Distributions
FU Hui-min
2005, 20(6): 905-909.
Abstract PDF(861KB) icon1946 icon506
Abstract:
A integral inference method for multivariate normal distributions is presented.Combining the simulation results and the experiment data,it can totally infer the experiment data of the multivariate normal distributions in multi-state.Then it can establish the estimators of means and covariance matrix of the multivariate normal distribution,and estimate their confidence limits and intervals in each state.Compared with traditional methods,this method not only has higher precision but also solves the problem of reliability assessment with only one experiment datum of the multivariate normal distribution in a state.Besides,a method for testing simulation results of means and variances in multi-state is also presented with very small sample.
Method for Determining Covariance Functions of Time Series
FU Hui-min
2005, 20(6): 910-914.
Abstract PDF(961KB) icon1608 icon440
Abstract:
A method for determining covariance functions of time series is presented.First,it can construct a series of cross covariance,cross correlation,auto-covariance or auto-correlation function according to the time series.Then,it can determine the trend term of the cross covariance,the cross correlation,the auto-covariance or the auto-correlation function series,which obtains not only the periodic function of the trend term by the spectral analysis but also the nonperiodic function by multiple-point averaging,and synthesizes the integral function of the trend term.The functional form of the cross covariance,the cross correlation,the auto-covariance or the auto-correlation function can be derived from the trend function.Besides,its parameters are estimated by the least squares method.The presented method is credible and easily available for modeling,analysis and forecast of the covariance and the correlation function of time series.
Composite Mechanical Behavior with Weak Interfacial Bonding
SUN Zhi-gang, SONG Ying-dong, LIAN Ying-qi
2005, 20(6): 915-919.
Abstract PDF(389KB) icon2197 icon495
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The micromechanical finite element method and the nonlinear spring element for the interface were employed to predict the effective behavior of MMCs.The results indicate that weak interfacial bonding reduces the macro mechanical properties of MMCs.A weak interfacial bonding reduces the elastic modulus of MMCs.The Constant Compliant Interface(CCI) model included a finite interfacial strength for the interface.The stress-strain curve under transverse loading of MMCs has a corner point,associated with the initiation of interfacial de-bonding,which is determined by the interfacial bonding strength.The Evolving Complaint Interface(ECI) model allows unloading of interfacial stresses.The transverse loading stress-strain curve exists three-stage deformation process.
Fretting Fatigue Crack Detection Technique for Dovetail Attachment
XIA Qing-yuan, CUI Hai-tao, WEN Wei-dong
2005, 20(6): 920-924.
Abstract PDF(969KB) icon1889 icon467
Abstract:
The fretting fatigue crack detection system was developed.In the system,the areas where the fretting fatigue cracks would happen were predicted at first,the strain gauges were used to collect the strain signals around those areas.The signals were transmitted to the computer after A/D converters.Then the data could be analyzed to acquire the accurate time of the initiation of fretting fatigue crack,and observe the crack’s expanding process.The result of fretting fatigue experiment shows that the fretting fatigue crack detection system is easy to use and accurate to find out fatiguecrack.The system solves the problems during fatigue experiment,such as hard to observe the crack,difficult to get the right time that the crack happens,etc.
New Experimental Approach in Determining Creep/Fatigue Life of Directionally Solidified Alloy Turbine Blade
YAN Xiao-jun, NIE Jing-xu
2005, 20(6): 925-931.
Abstract PDF(1441KB) icon1960 icon456
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A new experimental method,in which the turbine blade was loaded by applying friction force and heated by eddy current induction,was proposed to study creep/fatigue life of directionally solidified alloy turbine blade.Design of the test devices,determination of blade’s key section and the equivalent accelerated test loading-spectrum,test data analysis etc.was described in detail.Test results show that the method can simulate turbine blade key section’s working "stress field" and temperature in the laboratory and give reasonable life data for turbine blade.The safe service life of aeroengine component determined by the component creep/fatigue tests will be more accurate than that obtained with the plain specimen.
Modal Experiment and Analysis of an Engine Casing Based on Stochastic Excitation
LIAO Qing-bin, LI Shun-ming, ZHU li-juan
2005, 20(6): 932-936.
Abstract PDF(388KB) icon1863 icon461
Abstract:
An engine casing modal experiment and modal parameters extraction have been introduced in the paper.In the power spectrum analysis,the effect of noise was considered.Power spectrum expression mixed with noise was proposed,and it was used to calculate the power spectrum function and finally modal parameters were extracted.The pre-experiment was introduced to determine the approximate scope of the modal frequency,so that we could determine the locations of transducers and excitation point of the vibro-machine.Considering the practical working condition,the white-noise stochastic excitation has been used to simulate the stochastic excitation during the modal experiment.Compared with the computational model,the means of extracting parameter with modal experiment can avoid complicated finite element modeling and simulation.Correlation function was used to checkout the reliability of the experimental data.Modal experiment shows that the parameters of the engine casing are of great importance in improving the structural design of the engine casing,vibration fault analysis,and fatigue life analysis and so on.
Analysis of Dynamic Load Sharing in a 2-Stage Planet Gear Train
BAO He-yun, ZHU Ru-peng
2005, 20(6): 937-943.
Abstract PDF(971KB) icon2000 icon492
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A dynamic analysis model was established for a 2-stage planet gear train in which manufacturing and assembly errors were considered.The load sharing coefficient of the gear train was formulated.The dynamic characteristics of sharing load were analyzed and some relations between errors and the load sharing coefficient were obtained.The effects of different kinds of error on dynamic load sharing were discussed.The results show that the run-out errors of the first stage planet gear and its bearing have the most significant effect on the load sharing coefficient.The errors have greater influences on the load sharing coefficient of the first stage than that of the second stage.The load sharing coefficients of the two stages are increased with the number of planet gears.
Fault Diagnosis of Rolling Bearings in a Gearbox
WANG Ping, LIAO Ming-fu
2005, 20(6): 944-950.
Abstract PDF(2108KB) icon1888 icon502
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A method for diagnosing the rolling bearing faults in a gearbox based on Adaptive Noise Canceling(ANC) and Demodulated Resonance Technique(DRT) was presented.The signals under normal condition were detected first,and then the continuously monitored signals of the rolling bearing were collected using the same sensor and measurement system at the same location of the gearbox.ANC processing was carried out using the signals under normal condition as the reference input and the monitored signals as the main input.Finally,DRT was applied to the noise-cancelled signals in order to realize feature extraction and fault diagnosis of the rolling bearing.The experimental results show that this method not only improves the signal-to-noise ratio of the measurements,but can also effectively diagnose the incipient faults of the rolling bearing in the gearbox.
A Probabilistic Model for Prediction of Life Based on Probabilistic Character of Defects in PM Alloys
WEI Da-sheng, YANG Xiao-guang, WANG Yan-rong
2005, 20(6): 951-957.
Abstract PDF(395KB) icon1848 icon504
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Due to manufacturing characteristic,the strength and life of powder metallurgy alloy are sensitive to micro defects,such as nonmetallic inclusion,pores,and nicks on the surface.A distinct character of failure of this kind of material is scatter,which makes life prediction more difficult.In this paper,based on the defect populations of domestic PM alloy and some probability failure methods established in reference ,definition of the probability for the presence of a defect inside the surface,sub-surface and internal region is given first,and then a probabilistic model is set up,which can calculate the failure probability caused by defects having different shapes and different sizes,being in different regions,and also can calculate the total failure probability.It is concluded that the method can describe the effect of probabilistic character of defects on the strength and life of PM alloy,and it is proved to be valid.
Tensile Behavior of a Single Crystal Ni-Base Superalloy at Different Temperatures
YU Hui-chen, LI Ying, LI Cheng, LI Jia-rong, WU Xue-ren
2005, 20(6): 958-963.
Abstract PDF(1527KB) icon1990 icon483
Abstract:
The tensile behavior at different temperatures of a single crystal Ni-base superalloy was studied.It was found that temperature and the crystal orientation has notable effect on the elastic properties of the alloy,and the elastic modulus of the alloy can be defined with a single variable,which is the three-dimensional crystal orientation parameter of the specimen.Moreover,the yield strength and the tensile strength of the alloy depend deeply on temperature and the crystal orientation index,the yield strength of orientation is higher than that of at room temperature,and shows the lowest yield strength at high temperature.
Implicit Euler Form of Chaboche Thermal Viscoplastic Model of IN738LC Material
WANG Qing-wu, YANG Xiao-guang, SHI Duo-qi
2005, 20(6): 964-968.
Abstract PDF(284KB) icon2622 icon534
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In order to improve the efficiency of numeric integral of Chaboche constitutive model,backward Euler integration method,which also called implicit Euler integration method,of Chaboche model was brought forward.As an example,material IN738LC was used.Based on the backward Euler integration equation,FORTRAN programming format was used.Such a program was linked with FEM by user’s program interface HYPELA2 in MSC.Marc of a general FEM software.As a result,backward Euler method applied to Chaboche model could be used for structural analysis.A numerical result was given.Comparison was made between the numerical result and the experimental one.Comparison between the result of backward Euler method and the one of forward Euler method was made,too.It is found that the backward Euler method is accurate and has better convergency than the forward one.
Discrete Particle Swarm Optimization Algorithm for Gearbox Fault Symptom Selection
WANG Xin-feng, QIU Jing, LIU Guan-jun
2005, 20(6): 969-972.
Abstract PDF(685KB) icon1777 icon497
Abstract:
Particle swarm optimization (PSO) has been developed rapidly and has been applied widely since it is easy to understand and realize.Aimed at mechanical fault symptom selection,the paper proposed a discrete Particle Swarm Optimization(PSO) algorithm.In order to improve the ability to escape from the local optimum,the mutation operator was added to the algorithm.The discrete PSO algorithm was applied to helicopter gearbox gear fault symptom selection.Symptom set extracted by wavelet packet transform method was presented by binary-coded particle.The accuracy evaluated by k-fold cross-validation of the SVM classifiers was used as the particle fitness.Experimental results indicate that the discrete PSO can get the same optimal symptom subset as that from genetic algorithm,and achieve the better diagnosis accuracy,but the compute time consumed is only 0.4 time that of genetic algorithm,so the discrete PSO is a more effective method for mechanical fault symptom selection problem.
Numerical Investigation on the Effects of Lobe Nozzle Geometric Parameters on Mixer-Ejector Performance
SHAN Yong, ZHANG Jing-zhou
2005, 20(6): 973-977.
Abstract PDF(903KB) icon2067 icon450
Abstract:
Based on three dimensional CFD of the lobed mixer-ejector,the effects of lobe nozzle geometric parameters on the lobed mixer-ejector performance were revealed.The results show that the increase of lobe width causes the rapid decrease of ejection ratio.The velocity circulation at lobe exit section and the thermal mixing efficiency decrease with the increase of lobe width,whereas the pressure recovery coefficient is improved by the increase of lobe width.The effect of lobe diffusion angle on the ejection ratio depends on the mixing duct diameter.For the case of small diameter mixing duct,the ejection ratio increases firstly and then decreases with the increase of lobe diffusion angle from 20 degrees to 90 degrees.For the case of large diameter mixing duct,the ejection ratio increases continuously with the increase of lobe diffusion angle.The increase of lobe diffusion angle results in the increase of velocity circulation at the lobe exit section,but it raises the mixing loss and lowers the pressure recovery coefficient.
Investigation on Ejecting and Mixing Characteristics of Lobed Nozzle with Curved Mixing Duct and Slot Exit
TANG Zheng-fu, ZHANG Jing-zhou, SHAN Yong
2005, 20(6): 978-982.
Abstract PDF(835KB) icon2036 icon497
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A combined experimental and computational study on ejecting and mixing characteristics of the lobed nozzle with curved mixing duct and slot exit was performed.The velocity fields,pressure fields and temperature fields,as well as the ejection coefficient and pressure recovery coefficient which reflect the overall characteristics of mixer-ejector system were obtained.It is indicated that the relative error between the computational and experimental results is about 15%.As the exit of the curved mixing duct is a narrow slot,the flow process inside mixing duct is affected by streamwise vortices and secondary circulation,which forms some special flow phenomena and features compared to common curved mixing duct with elliptical exit.Because of the existence of secondary flow caused by the curved duct,the streamwise vortices formed at the lobed nozzle trailing edge are strongly destroyed in the developing process,and the velocity and temperature distribution features are not similar to that in short curved mixing duct with elliptical exit.
Experimental Investigation on Thrust Augmentation of Pulsed Detonation Engine(PDE)
FAN Yu-xin, WANG Jia-hua, LI Jian-zhong, ZHANG Yi-ning
2005, 20(6): 983-988.
Abstract PDF(1076KB) icon1608 icon491
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A preliminary experimental investigation on the effect of thrust augmentation on Pulsed Detonation Engine(PDE) performance was performed.Two different thrust augmentation geometries were designed and tested.The results show that in average more than 50% thrust increment could be gained under rational construction parameters.Analysis of the mechanism of thrust augmentation and the influence of different construction parameters on thrust improvement was performed.These results offered basic reference for design optimization of the PDE thrust augmentation.
Disturber Affect on the characteristics of Detonation
HE Xiao-min, WANG Jia-hua
2005, 20(6): 989-993.
Abstract PDF(271KB) icon1834 icon450
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It is difficult to generate successfully multi-cycle liquid fuel detonation at ambient pressure and temperature conditiions.Using disturber is the simple and efficient way to promote detonation.In this paper,the experimental investigation was conducted at ambient pressure and temperature in the detonation tube(length of 2000mm and inner diameter of 40 mm) to acquire the relationship between the combustion wave pressure,flame velocity and structure parameters of the disturber,including number of disturber pieces(6～14),space(20～80 mm) and starting position(80～200 mm).The experimental results show:(1) it is helpful to promote detonation wave,while adopting more disturber pieces,farther space between disturber pieces and farther starting position of disturber;(2) the combustion wave pressure and the flame velocity will keep constant if the detonation wave is produced in the tube(maximal pressure>1.4 MPa and flame velocity>1 000 m/s).
Flamelet Modeling of a Pilot Methane/Air Jet Flame
HOU Ling-yun, ZHONG Bei-jing, JIANG Chang-qing
2005, 20(6): 994-999.
Abstract PDF(1084KB) icon1644 icon475
Abstract:
A methane turbulent non-premixed flame has been simulated numerically by the combination of laminar flamelet model and presumed probability density function(PDF).Steady flamelet structure was obtained from laminar flamelet library.Using the detailed chemical kinetics mechanism,the oxidation of methane and the generation of PAH and NO were described.Compared to the experimental data,it is shown that the numerical results agree well with the experiment and indicate that flamelet model approach is able to predict the major properties of the turbulent non-premixed flame.
Experimental Study on Impingement Cooling Characteristics of Synthetic Jet Flux Activated by Piezoelectricity
TAN Xiao-ming, ZHANG Jing-zhou
2005, 20(6): 1000-1004.
Abstract PDF(748KB) icon2235 icon517
Abstract:
Hot-wire anemoscope was used to measure the velocity and the turbulence intensity of a synthetic jet activated by piezoelectric actuator with a two-dimensional slot nozzle.The influences of the various voltages and frequencies imparting to the synthetic jet actuator were investigated and the best actuating parameters were obtained.The temperature distributions and convective heat transfer coefficients on the target surface cooled by synthetic jet were measured by an infrared camera.The results show that:(1) when the jet-to-surface spacing ratio is less than 20,the synthetic jet is in the formation process and the cooling effect is worse;(2) when the jet-to-surface spacing ratio is greater than 20,the synthetic jet is steady and fully developed,the cooling effect is better;(3) when the distance is too far away from the nozzle,the velocity of the synthetic jet decreases,and the heat transfer coefficient reached the highest when the jet-to-surface spacing ratio is 80.
Numerical Analysis of Heating Boundary Effect on the Characteristics of Rotational Sealing Labyrinth
WANG Suo-fang, LU Hai-feng
2005, 20(6): 1005-1009.
Abstract PDF(1181KB) icon1920 icon480
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The standard k-ε turbulence model,QUICK schemes,non-uniform grid and SIMPLE method were applied to the calculations of flow field characteristics for the modeled sealing labyrinth with heating boundaries.It is aimed at investigating the effect of heating boundary.The velocity,temperature and pressure fields were obtained and the flow characteristics were discussed.The computational results state that the leakage goes down as heat flux of the heating boundary rises,and thus the sealing effectiveness under different pressure ratios is enhanced.The results also show that the sealing effect and the heat flux are linearly related.The uneven distribution of the heat transfer causes to produce small eddy at the cavity of the labyrinth and an increase in the sealing effectiveness.The location and size of the small eddy depend on the heat flux on the wall of the heating boundary and the pressure ratio.
Numerical Simulation of Ice Accretion on Airfoils
CHEN Wei-jian, ZHANG Da-lin
2005, 20(6): 1010-1017.
Abstract PDF(1124KB) icon2135 icon525
Abstract:
A numerical simulation approach is presented to simulate the ice accretion on airfoil which can deal with the ice accretion under various atmospheric conditions.Incorporating the two-phase model of air supercooled droplets in the Eulerian coordinate,this approach was carried out to simulate the ice accretion on the NACA 0012 airfoil under different atmospheric conditions,and the final ice shapes(rime,mixed and glaze ice shapes) were predicted.The comparison between the results of this paper and the experimental data as well as other icing codes indicates that the current approach is applicable and effective.Also the effect of different ice shapes on lift and drag coefficient were assessed.The results indicate that the glaze ice has the most adverse impact on airfoil aerodynamic performance.
Rotating Stall Stability Theory of the Transonic Axial Compressors/Fans
YU Wei-wei, SUN Xiao-feng
2005, 20(6): 1018-1027.
Abstract PDF(1172KB) icon1749 icon448
Abstract:
One semi-actuator stability model for rotating stall considering in-passage shock wave was developed based on a three-dimensional compressible theory,and it was evaluated to be effective by comparing the results with experiments.Winding number integral method has been developed to solve the roots of complex functions for a long time,although it is not widely used,in some way,it is more stable than Newton-Raphson iteration method.The author used this approach to solve the eigen equation of the transonic stability model,and it is strongly recommended to extend its use in other fields because of its advantages over other methods.
Analysis of the Effects of Parameter Small Deviations on a High Thrust-Weight Ratio Aeroengine Performance
WU Xue-hui, LI Zhi-gang, TAO Zeng-yuan
2005, 20(6): 1028-1031.
Abstract PDF(596KB) icon1804 icon472
Abstract:
Based on method theory,considering the turbofan engine working characteristics,effects of the parameter small deviations on performance of a high thrust-weight ratio aeroengine were calculated and analyzed.This analysis included 14 engine working process parameters and coefficients assessing primary engine components.This research provides foundations of how to adjust parameter values to compensate effects of other parameter small deviations on aeroengine performance in the process of aeroengine design and also provides quantitative guidance for aeroengine technical development.
Exponent Extrapolation Method of Aero-Engine Turbomahinery Low State Characteristics
WANG Guang, LI Jun, MU Mu
2005, 20(6): 1032-1036.
Abstract PDF(805KB) icon1608 icon480
Abstract:
The exponential model that could extrapolate the Aero-engine turbomachinery low state characteristics was introduced.This model takes into account the influence of air compressibility.Applying the theory of similarity and considering the characteristics of aero-engine component performance,two exponent values can be obtained,and then the components low state characteristics can be deduced.The results show that the accuracy of this method is higher than that of numerical simulation.It is useful for the research of engine starting,especially for solving the start-up problem in plateau.
Design and Adjustment of Flow Duct Facility for Acoustic Liner Measurement
LI Xiao-feng, WANG Tong-qing, SHI Wei
2005, 20(6): 1037-1040.
Abstract PDF(529KB) icon1848 icon531
Abstract:
An important problem in the liAbstract:An important problem in liner optimization of ducted fan is to verify whether a designed liner construct possess the desired acoustical properties at presence of flow by experiment.The paper reviews the development of flow ducts facility,introduces the flow ducts facility built up in BUAA,and its configuration,operating principle and an initial test.It shows the flow is uniform in the test section,the sound field without inflow obey the rule of guided duct theory,all of that illustrate the facility satisfy the request for the device fundamentally.The test is only initial,further work for the impedance measurement of the terminals either with flow or without flow and other experimental research works about flow duct facility will be continued.
Influence of Inlet Water Ingestion on Aero-Engine Fan-Compressor Performance
LIU Bo, CAO Zhi-peng, GAO Song, JIN Jun, ZHOU Qiang
2005, 20(6): 1041-1047.
Abstract PDF(1054KB) icon1545 icon434
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Numerical simulation and twophase fluid flow theory were employed to calculate the characteristics of engine compressor with inlet water ingestion.Droplet model,loss and deviation model corrected by test data were used in the calculation.The investigation of water content,droplet size etc.,which would affect the compressor performance,shows that inlet water content and size of droplets have significant influence on compressor performance.In addition the results indicate that this method is effective and valuable in engineering application.
Applied Study on a Low Speed Axial Compressor with Wake Effects
JIN Liang, LI Zhi-ping, LU Ya-jun
2005, 20(6): 1048-1053.
Abstract PDF(1092KB) icon1753 icon444
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In this thesis,the blade number of wake effect disturbance coupling was changed in order to vary the exciting frequency of wake effect.In this way,the influence of exciting frequency on compressor steady state performance was studied.Through 12 wake effect disturbance coupling experiments,the stall margin was improved significantly at the wake effect frequencies of 2 000 Hz and 4 000 Hz,and the relative increase of surge margin reached 19.5% and 15.2% respectively.However,the exciting frequency of 1 000 Hz worsens compressor performance.The characteristic frequency of flow separation in rotors wake is about 2 000 Hz.That is,the optimal performance is achieved when the exciting frequency is exactly the characteristic frequency or its multiples.The performance is the worst when the exciting frequency is half of the characteristic frequency.Furthermore,the principle of wake effect,and the relation between stimulation frequency and the improvement of compressor performance was studied in a primary stage.This offers a new idea and method to the application of the conversion of two flow types in axis-flow compressor,especially to the matching in the design of multistage axis-flow compressor.
Application of CFD in the Investigation of the Secondary Flow in a High Speed Centrifugal Impeller
KANG Shun, CHEN Dang-hui
2005, 20(6): 1054-1060.
Abstract PDF(2139KB) icon1826 icon462
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High speed centrifugal compressors have been increasingly used in small aero-engines and gas turbine industries.However,knowledge of the 3D viscous flow in this kind of impeller flow passage is quite limited.Based on the CFD results validated previously with experimental data,this paper analyzed and discussed in detail the 3D flow within a high-speed centrifugal impeller at near-design condition in order to make deep understanding of the features of shock/boundary layer interaction and its secondary flow pattern.
Application of Internal Model Control System Based on Neural Network in Aeroengine
ZHANG Peng, HUANG Jin-quan
2005, 20(6): 1061-1065.
Abstract PDF(710KB) icon1697 icon462
Abstract:
The Internal Model Control(IMC) system based on recurrent neural network and its application to aeroengines were studied.An aeroengine multivariable control system was developed using neural network IMC method.Both the aeroengine internal model and the controller were constructed via Elman neural networks.A recurrent back-propagation algorithm was used to train the weights of the neural network and the control algorithm was analyzed.Numerical simulation results show the effectiveness of this method and self-learning ability of the system.
A Survey of Gas Turbine Control Technique
XUE Yin-chun, SUN Jian-guo
2005, 20(6): 1066-1071.
Abstract PDF(941KB) icon1930 icon546
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This paper surveyed the development of gas turbine control system,and briefed the scheme of some typical gas turbine control system.The development of overall structure,the design of digital controller,hydraulic actuator,control software,and the digital and semi-physical simulation in gas turbine control system was discussed.On this basis,the development trend of gas turbine control technique was provided.
Development of Field-Bus Technique in Gas Turbine Generator Sets Control
XUE Yin-chun, SUN Jian-guo
2005, 20(6): 1072-1077.
Abstract PDF(380KB) icon1351 icon425
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This paper surveyed the progress of field-bus technique in the gas turbine generator sets control,and pointed out the defects of traditional control design and the characteristics of field-bus control technique.The progress and application of field-bus and configuration software in gas turbine control were discussed.On this basis,suggestions to the application of field-bus technique to the control of gas turbine power engineering were provided.
Optimization Methodology of PI Controller Parameters for Aeroengines Based on Genetic Algorithm
SU Wei-sheng, LI Yue, SUN Jian-guo, ZHOU Wei
2005, 20(6): 1078-1082.
Abstract PDF(829KB) icon1930 icon432
Abstract:
Based on the mathematical model of aeroengine,an optimization methodology of the PI controller parameters with Genetic Algorithm(GA)was developed.This optimization methodology is a global optimization and has nothing to do with initial values.The fitting function used was based on the weighting combination of the system dynamic and steady state performance.The PI controller parameters of an aeroengine for both single-input single-output and two-input two-output were optimized with GA.The simulation results indicate that the optimization methodology of the aeroengine PI controller parameters developed in this paper is very effective.
Preliminary Investigation on Dynamic Characteristics of Swirl Injector
YANG Li-jun, GE Ming-he, ZHANG Xiang-yang
2005, 20(6): 1083-1087.
Abstract PDF(812KB) icon1743 icon458
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To investigate the dynamic characteristics of the swirling injector,an experimental system was built.High velocity photographic testing system has been used in the experiment.Original investigation of the velocity pulsation,breakup length and the wavelength of the liquid film in the spray field were tested.It can be concluded that effects of pressure drop and geometric characteristic coefficient of the injector on the axial velocity in the spray field and some parameters about swirling liquid film are significant.Pressure drop and pulsation of feed system will greatly affect the wavelength and the breakup length of the liquid film.Experimental system,testing device and method of the experiment can be used for the investigation of the dynamic characteristics of the injector.
Adaptive Threshold Algorithm Based on Autoregressive Model for Fault Detection of LRE in Ground Test
YANG Xue, ZHANG Zhen-peng, XIANG Shi-yong, ZHANG Qing-song
2005, 20(6): 1088-1092.
Abstract PDF(303KB) icon1747 icon468
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An adaptive threshold algorithm consisting of two stages based on autoregressive model was presented for monitoring the steady process of Liquid Propellant Rocket Engine(LRE) in ground test.For the first stage,the thresholds are calculated with the estimation values,standard deviation and band-width factors estimated by autoregressive model for steady parameter measurement values obtained from many different engine tests.Standard deviation and band-width factors which are trained by test data with the training algorithm are used at the beginning of the steady process of the engine test.For the second stage,the thresholds are calculated with the prediction values estimated using autoregressive model for steady parameter measurement mean values from many different engine tests.The standard deviation and band-width factors were used in the next steady process.The adaptive threshold algorithm based on autoregressive model was verified with the LRE ground test data.The results show that the approach can effectively and reliably monitor the LRE operation status.

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