2003 Vol. 18, No. 4

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Linear Regression Analysis Method for Censored Data
HUANG Wei, FU Hui min
2003, 18(4): 465-469.
Abstract PDF(758KB) icon1792 icon444
Abstract:
A new regression analysis method is presented and the regression equation for censored data is established. The best unbiased integral estimators for the regression parameters,the standard deviation and their covariance are also given.The confidence limits of the regression curve and the confidence intervals of percentiles for normal distributions are discussed in detail.The traditional regression analysis is only suitable to complete data from normal distribution.In engineering,censored data is analyzed by group test method that requires a large number of samples.The present method extends traditional regression analysis to not only censored data but also extreme distribution and Weibull distribution.Compared with traditional method,the present method can reach a higher precision and a great number of specimens can be saved.
Analysis Method for Correlation Coefficient Stationary Series with Unequally Spaced Data
MA Xiao bing, FU Hui min
2003, 18(4): 470-476.
Abstract PDF(1012KB) icon1586 icon433
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The idea of correlation coefficient stationary series with unequally spaced data is presented and the pth order autoregressive model for the correlation coefficient stationary series with unequally spaced data is established.The exact maximum likelihood estimations and the conditional maximum likelihood estimations of their parameters are given in detail.Unequally spaced time series is common in engineering when the observation is irregular. The traditional time series analysis method is only suitable to equally spaced data and the approximate analysis methods for unequally spaced data, such as interpolation method,may cause big error.By employing the present method, the mean function,the variance function and the correlation coefficient function of unequally spaced time series can be calculated with high precision.
Influence of Deviation and Randomness of Crystallographic Orientations on the Strength and Life of Nickel-Base Single Crystal Superalloy Turbine Blades
YUE Zhu feng, LU Zhen zhou, YANG Zhi guo, CHENG Xiao ming, YIN Ze yong
2003, 18(4): 477-480.
Abstract PDF(352KB) icon1971 icon446
Abstract:
A two damage variable creep constitutive model has been presented for the strength and life of nickel base single crystal superalloy turbine blades.Uniaxial creep experiments for different orientations and stress levels have been conducted and validated for the model parameters.Modeling creep blades and double shear creep specimens were tested experimentally.The model has been validated by the uniaxial stress state and multiaxial stress state specimens.With the increase in deviation of the axial crystallographic orientations of the blade,the deviation of the strength increases,by the name of resolved shear stress of the slip systems.The randomness of the two uncontrolled crystallographic orientations of the blades results in a 15% deviation of the strength.The life deviation increases with the increasing deviation of axial crystallographic orientation.If there is a 15° deviation of the axial orientation,the life will have a deviation of factor 6.The randomness of the two uncontrolled orientations reduces 50% deviation of life.The study shows that the blade crystallographic orientations should be optimized for a better conjunction of strength and creep life.
The Study of Layout Method for 3D Engine Accessories
LUO Qiang, CHEN Zhi ying
2003, 18(4): 481-484.
Abstract PDF(643KB) icon1722 icon431
Abstract:
The 3D auto layout method is studied that is based on the numeric model for engine and it's accessories.The 2D LSI (Large Scale Integration) layout arithmetic is uesd for reference.The 3D minimum distance is changed into 2D using the method of "2D sector projection distance" according to the structure.This method simulates the real situation of the pipe connection of all the accessories well.It is developed that the software of 3D automatic layout is combined with the optimizing arithmetic and the rules of realities that have been summarized.So that the layout for 3D engine accessorise is realized.14 accessories have been placed as an example in this thesis.It takes nearly 20 minutes to complete it.
Experimental Study of Low Leakage and High Endurance Brush Seals
GUO Lin, KANG Ning
2003, 18(4): 485-487.
Abstract PDF(283KB) icon1928 icon393
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On the basis of the similarity theory,a new style of brush seals with low leakage and high endurance was studied experimentally in this paper.The brush seal structure was evaluated according to the measured experimental results.The results showed that:the leakage of the new brush seals was smaller than that of the old brush seals;the leakage difference between the two brush seals became larger with the increase of the pressure difference.
Variable-Dimension Construction in the Axial Arrangement of Finger Seal Mechanism
CHEN Guo ding, SU Hua, ZHANG Yong hong
2003, 18(4): 488-491.
Abstract PDF(617KB) icon1564 icon449
Abstract:
Based on Ansys FEM method,the Influences of the axial dimensional disposition of sealing pieces in the axial arrangement,under the conditions of different pressure differentials,on the hysteresis and contact pressure of finger seal mechanism have been studied in the current work.A sandwichlike axial arrangement form which has relatively advantageous matching relationship between hysteresis and contact pressure has been shown.The research work here shows that the axial arrangement has quite consideralle influence upon the performance and service life of finger seal mechanism,and therefore the optimization of axial arrangement should be taken into consideration in the optimized design of finger seal construction.
A Preliminary Study of NOX Emission of staging/Premixed and Prevaporized Lean Combustion Low Emission Combustor Scheme
LIN Yu zhen, PENG Yun hui, LIU Gao en
2003, 18(4): 492-497.
Abstract PDF(764KB) icon1943 icon482
Abstract:
Preliminary research results of NOX emission are presented for a scheme of staging/lean premixed and prevaporized (LPP) combustion.Conventional swirl cup with direct injection nozzle is employed for the primary stage, while a prefilm airblast atomizer with premixed prevaporized duct is equipped for the main stage.In addition,a dome swirler is fitted at the end of the duct for flame stabilizing.The main purpose of the study is to investigate the low emission capability of the premixed prevaporized lean combustion main stage. The properties of the fuel used in the test is RP 3 which is similar to JET A fuel.A single dome combustor was fabricated and NOX emission investigation was carried out under operating conditions:high inlet temperature (800 K),inlet velocity and overall fuel/air ratio at the design point.The inlet air pressure is atmospheric.The results demonstrated that the NOX emissions are reduced by 60% and the fuel staging ratio exerted significant influence on NOX emission reduction.
Experimental Investigation of Flow and Heat Transfer About the Thermal Driving of R12 in Rotating Small-Size Circular Enclosures
MAO Jun kui, CHANG Hai ping, FANG Li
2003, 18(4): 498-501.
Abstract PDF(259KB) icon1639 icon463
Abstract:
With the development of the aero engine,the temperature before turbine is increasing greatly and it becomes more and more important to study new cooling technology and equipment.Experiments have been carried out to investigate a new cooling technology which used the thermal driving of fluid in small size circular enclosure to enhance the heat transfer rate.In this paper,the characteristics of flow and heat transfer of the thermal driving of R12 varying with the rotating speed were investigated.All the results show that the characteristics are similar with those in gravity;and the average temperature,the gradients of temperature of the heated wall decrease when the rotating speed increases;and at the same time,the average heat transfer rate is enhanced greatly.When the rotating speed reaches 1140 r/min,the rate will go to 1550 W/m2·K.
The Interior Heat Transfer Characteristics of Gas Turbine Blade Due to Sparse Film Cooling Holes
ZHANG Jing yu, CHANG Hai ping
2003, 18(4): 502-506.
Abstract PDF(382KB) icon1563 icon446
Abstract:
The film cooling technique is one of the useful cooling methods.At present,the sparse film cooling technique is alaiays employed for the midchord region of gas turbine blade in aeroengine,and the impingement cooling technique is also used at the same time.So the interior heat transfer characteristics about an inner side of blade due to sparse film cooling holes have become a very complicated and interesting problem.In this paper,the heat transfer characteristics have been investigated experimentally whether there is impingement cooling fluid or not.Through lots of experimental data,the effect of flow parameters and geometric parameters on heat transfer characteristics has been studied.Besides that,the correlation equation for the interior heat transfer characteristics to the parameters is finally formulated,and the comparison shows that the correlation results are in good agreement with the experimental data.
Discharge Coefficient Measurements of Film Cooling Holes on Blade Surface in a Turbine Cascade
XIANG An ding, ZHU Hui ren, LIU Song ling, XU Du chun, GUO Wen
2003, 18(4): 507-511.
Abstract PDF(791KB) icon1602 icon471
Abstract:
Discharge coefficients of film cooling holes on the turbine blade surface were measured in a large scale low speed turbine cascade.Discharge coefficients of coolant injection were obtained in the region of Re∞=250,000～450,000,and BR=0.5～2.5.The influences of Reynolds numbers and blowing ratios on discharge coefficients were investigated.The results show that turbine blade surface film hole discharge coefficients are different greatly for different hole array positions.The distribution of discharge coefficients is mainly determined by blowing ratio for the same geometry.Film hole discharge coefficients were increased obviously with blowing ratio in the case of low blowing ratio.In the case of high blowing ratio,the discharge coefficients became a constant.
Experimental Study of a ZS195 Direct-Injection Diesel Engine Fueled with DimethylEther (DME)
LIU Xiang yun
2003, 18(4): 512-514.
Abstract PDF(282KB) icon1568 icon498
Abstract:
The performance of a diesel engine with Dimethyl Ether (DME) Diesel mixed fuel was experimentally studied in this paper.Tests were conducted under the principle of minimum engine alteration.Results show that the exhaust emission is much lower with the mixed fuel while the output power of the engine could be kept little changed with the choice of different mixing ratios.Dimethyl Ether is proved to be very promising as an alternative fuel for diesel engines.
The Interior Heat Transfer Characteristics of Gas Turbine Blade Due to Sparse Film Cooling Holes
ZHANG Jing yu, CHANG Hai ping
2003, 18(4): 515-518.
Abstract PDF(641KB) icon1543 icon451
Abstract:
The film cooling technique is one of the useful cooling methods.At present,the sparse film cooling technique is alaiays employed for the midchord region of gas turbine blade in aeroengine,and the impingement cooling technique is also used at the same time.So the interior heat transfer characteristics about an inner side of blade due to sparse film cooling holes have become a very complicated and interesting problem.In this paper,the heat transfer characteristics have been investigated experimentally whether there is impingement cooling fluid or not.Through lots of experimental data,the effect of flow parameters and geometric parameters on heat transfer characteristics has been studied.Besides that,the correlation equation for the interior heat transfer characteristics to the parameters is finally formulated,and the comparison shows that the correlation results are in good agreement with the experimental data.
Design Investigation and Application of an Aeroengine Gas Temperature Control System
JIANG Cai hong
2003, 18(4): 519-523.
Abstract PDF(287KB) icon1832 icon420
Abstract:
An engine gas temperature control system is presented in this paper.It has been applied to a supersonic fighter engine successfully.Its characteristics such as good control quality,high reliability and excellent maintainability have been demonstrated in the evaluation flight test throughout flight envelope.Its application can not only decrease the life cycle cost by preventing engines from overheating due to high gas temperature,but also provide carefree handling for the pilot with the result of lightening pilot's workload.
The Integrated Flight/Propulsion H∞ Controller Design for a New Fighter
GUO Ying qing, TIAN Tong jun
2003, 18(4): 524-529.
Abstract PDF(346KB) icon1662 icon483
Abstract:
The integrated flight/propulsion control system of a new fighter and its new turbofan engine are studied in this paper.Firstly,the models for the flight sub system and propulsion sub system are proposed,and then the model for integrated flight/propulsion system is set up.Secondly,the integrated flight/propulsion controller is designed based on the hybrid sensitivity approach;some key problems in controller design are discussed.Finally,the simulation results indicate that the designed integrated controller has good performances.
2003, 18(4): 529-529.
Abstract PDF(123KB) icon1370 icon75
Abstract:
Simulation of Dynamic Performance of a Turbofan Engine
QU Yu an, XIE Shou sheng, SONG Zhi ping
2003, 18(4): 530-533.
Abstract PDF(298KB) icon1721 icon479
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The dynamic model for turbofan engine accelerating process was presented by utilizing component characteristics.The performance of accelerating process was studied under varied fuel supply plan.The surge range of high pressure and the effect of nozzle throat area are also considered.The results show the model accords better with the true situation.It can be used as a model for engine accelerating control.
Study of Adjusting Aeroengine Starting Fuel Supply in the Plateau Area
QIAO Hong xin, XIA Ai guo, YANG Li
2003, 18(4): 534-537.
Abstract PDF(588KB) icon1877 icon525
Abstract:
It is very difficult to estimate adjusting discipline of areoengine starting fuel supply in plateau area.A new method is presented to resolve it in the paper.This method applyies TRAINBR training arithmetic of artificial neural net to estimation for adjusting discipline of areoengine starting fuel supply in plateau area,based on adjusting discipline of starting fuel supply obtained by testing in ground test bed.Through further research,matching and practical adjusting methods for fuel supplement valve adjusting screw,starting automat adjusting screw and airbleed orifice are suggested.As the experiments have showed,the benefit acquired by this adjusting method is prominent.It makes certain that areoengine can be not only started safely and reliably but also adjusted rapidly in plateau area.
Multivariable Fuzzy-PID Control for Aeroengine
DONG Jin, HUANG Jin quan
2003, 18(4): 538-541.
Abstract PDF(679KB) icon2094 icon492
Abstract:
Due to its simplicity,utility and easy application,PID controller is used largely in classical automation systems.However,the performance of the controller can not satisfy complicated nonlinear systems such as aircraft engines.This problem can be solved on the basis of the fuzzy control theory.It is very difficult to formulate accurate models for aircraft engines.In consideration of this difficulty,a parameter self adapting fuzzy PID controller is put forward for aircraft engines.The full envelope simulation results indicate that not only the fuzzy PID controller does not rely on the precisely accurate models but also possesses favorable dynamic and static control performances.
A Mass Addition Approach to the Bypass Turbomachine Through Flow Inverse Design Problem
SHAN Peng, LIU Xi yang
2003, 18(4): 542-545.
Abstract PDF(761KB) icon2253 icon460
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In the design of a low bypass ratio fan stage,this paper links the through flow inverse problem of the fan rotor,the core channel fan stator and the bypass channel fan stator together,as an organic whole,with the splitter aerodynamic design problem.It forms thus a unified through flow inverse problem for two channel turbomachines.After an overall quasi radial equilibrium is iteratively achieved among four parts-the streamlines of the core channel fan stator,the bypass channel fan stator,the splitter and the position of the splitter,the blading processes for one fan blade,two fan vanes and one splitter are performed.This method designs in one pass a fan stage and a splitter with a precise value of bypass ratio.Its primary and key approach scheme is the introduction of a mass addition half way through the through flow streamline development.This scheme can serve as a new feature which can be inserted into existing through flow programs.When subtracting mass flow after adding a mass flow,alternatively,this scheme can also be used to treat the problem of inverse design of fan/compressor rotor blades with part span shrouds.
An Averaged Numerical Difference Method for Detection of Stall Inception
ZHANG Pu, ZHU Xue ping, LI Ying hong
2003, 18(4): 546-548.
Abstract PDF(256KB) icon1978 icon456
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To detect stall inception signal before the whole compressor running into deep rotating stall,a method based on averaged numerical difference is developed to detect short length scale disturbance.While the method is used to analyze measured pressure data of certain axial flow compressor, corresponding analysis results demonstrate that the method can detect stall inception signal of the compressor 0.02～0.05 second before the start of deep rotating stall,and that the method has certain engineering application value.
Method for Quantification of Aeroengine Performance Tendency Monitoring
WANG Ying jun, XIE Shou sheng
2003, 18(4): 549-553.
Abstract PDF(992KB) icon1700 icon448
Abstract:
The application of data acquired from a certain engine to the performance tendency monitoring of aeroengine is studied in depth.The approach to obtaining integrative parameter from these data is demonstrated.The integrative parameter,in turn,can be employed as a quantitative criterion for judging the engine performances on which basis engine early warning signal system can thus be established.Finally,the method was verified by real engine data.
Matching Test of an Aircraft Inlet and Engine on the Ground
JIANG Yong, TAO Zeng yuan, ZHANG Fa qi, SANG Zeng chan, KONG Wei dong, ZHANG Bai ling
2003, 18(4): 554-557.
Abstract PDF(682KB) icon1635 icon511
Abstract:
Matching tests of an aircraft inlet and engine on the ground in our test cell have been performed.By means of the measuring rake/ring device which consists of 40 total pressure probes and 20 circumferentially located bundles of three tube probes,the total pressure distribution and the airflow speed distribution at the exit plane of the inlet were obtained.On the basis of the test data, we computed the stable pressure distortions in circumferential and diametric directions.The regular changing patterns of these distortions with the variations of the airflow rate into the engine were thus obtained.The circumferential rotational flow and pair whirls at the exit of the inlet were also found,and subsequently,the causes were analyzed.In addition,main performance parameters of the engine were measured,such as thrust,exhaust gas temperature and their changes after the inlet of the aircraft was installed.The causes of the changes were also analyzed.
Numerical Method for Coolant Mixing in Turbine Cascade Flow Field
WANG Song tao, YAN Pei gang, SUN Xi miao, HAN Wan jin, WANG Zhong qi
2003, 18(4): 558-562.
Abstract PDF(1387KB) icon1424 icon482
Abstract:
Three dimensional N S equation is discretized by a finite difference scheme with three order TVD property.Arbitrarily curved surface generation technique and multi block method are employed to simulate the film cooling flow field in a turbine cascade with arbitrary numbers of coolant holes.The development of counter rotating vortices in coolant mixing flow field is expounded,including its origination,disappearing and the distribution of temperature near coolant trajectory.The result shows that the solver with domains arbitrarily decomposed developed in this paper can simulate the flow field well,and the description of coolant jet flow field in the turbine cascade is reasonable.
Dynamic Response Study of Flexible Nozzle in a Solid Rocket Motor
SHI Hong bin, GUAN Zheng xi, HOU Xiao
2003, 18(4): 563-569.
Abstract PDF(888KB) icon1841 icon448
Abstract:
Based on the dynamic finite element method of structures,the response analysis of a flexible nozzle having a cone cylinder shaped divergent section is presented.The flexible joint is simply treated as a distributed spring and to which the Newmark difference method is applied.The numerical results are obtained when triangular wave excitation,sine wave excitation and arcsine wave excitation are exerted correspondingly.
Investigation of Resonance Characteristics of Conical Resonance Tube
TONG Xiao yan, LANG Guo zhu, ZHANG Guo zhou
2003, 18(4): 570-573.
Abstract PDF(352KB) icon1633 icon411
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Because the gas at the end of a conical resonance tube can be heated to a higher temperature more quickly than at the end of a cylindrical resonance tube,researchers pay more attention to the conical resonance tube in the engineering field of the gas dynamic resonance ignition technique of liquid propellant rocket engine.By using Whitham rule,this paper analyzes the characteristics of pressure and temperature of the oscillating gas in the conical resonance tube theoretically and explains why the conical resonance tube can reach higher temperatures than the cylindrical resonance tube.Because the conical resonance tube can enhance shock waves,the gas at the end of the conical resonance tube has higher pressure oscillation amplitudes and higher temperatures and heating rates than that at the end of the cylindrical resonance tube.
Anechoic Chamber in the Inlet Room of Transonic Compressor Rig in Beijing University of Aeronautics and Astronautics
WANG Tong qing, BAO Guo liang, SHI Wei
2003, 18(4): 574-576.
Abstract PDF(357KB) icon1623 icon450
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The paper briefly introduces an anechoic chamber setup recently in the inlet room of transonic compressor rig of Beijing University of Aeronautics and Astronautics. A preliminary acoustic experiment had been performed in it,and the comparisons with the similar facilities abroad were mentioned.

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