2003 Vol. 18, No. 2

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Analysis Method of Correlation Coefficient ARMA(p,q) Series
FU Hui-min, LIU Cheng-rui
2003, 18(2): 161-166.
Abstract PDF(995KB) icon1712 icon463
Abstract:
The correlation coefficient ARMA(p,q)series of which mean and variance may vary with time is widely used in engineering,such as pattern recognition,fault diagnosis,signal processing,automatic control,structure response analysis and so on.The traditional correlation function stationary ARMA(p,q) model is just a special case of that.The conditional maximum likelihood estimation (MLE) and exact MLE for the correlation coefficient ARMA(p,q) series are established in this paper,which can obtain its mean function,variance function and correlation coefficient function with high precision.The conditional MLE is simple and convenient for engineering application when the sample is large enough,and the exact MLE is still precise in the case of small sample. Base on analyzing in time domain,the spectral analysis of correlation coefficient ARMA(p,q) series can be done.
The Theory of Confidence Tests
FU Hui-min, LIANG Zhao-hu
2003, 18(2): 167-174.
Abstract PDF(1371KB) icon1250 icon480
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The concept of confidence distribution of population characteristic is presented in this paper.Based on the confidence distribution,a new theory of confidence tests is established,which includes three kinds of tests:strong test,weak test and weak strong test.The confidence tests are based on The Law of Small Probability, while the significance hypothesis tests are based on The Law of Large Probability.Compared with hypothesis tests,the confidence tests can inspect and control the quality of products with higher precision,and overcome the disadvantage that to accept a null hypothesis may simply mean that it is not rejected by significance hypothesis tests.In addition,the application of the confidence tests can greatly improve the test precision and bring more convenience in engineering.
Development and Application of a High Load and High Throughflow Transonic Compressor
WANG Hua-qing, CHEN Mao-zhang
2003, 18(2): 175-180.
Abstract PDF(882KB) icon1654 icon468
Abstract:
The average loading coefficient of the 3 stage LP compressor is 0.319.The mass flow rate per front area is 191.0 kg/m2s.The average axial Mach number is 0.676.Efficiency is 0.82.Rotor inlet hub/tip radius ratio is less than 0.35.The surge margin is 20.67%.The engine thrust is increased by 14.3%.The engine has been experienced conventional ground test,high altitude testbed test and flight test.Extensive application shows that the layout option, gasdynamic design and structural design are very successful.
Effect of Downstream Pylon on Flow Field and Performance of Compressor
ZHANG Hui, ZHANG Yong-xin, LIU Huo-xing, JIANG Hao-kang
2003, 18(2): 181-185.
Abstract PDF(383KB) icon1674 icon442
Abstract:
Flow fields in a low speed large scale axial compressor were measured with and without pylon in design condition and near stall condition.The 2 D calculations showed good agreement with the experiment results.The measurement and calculation results show that the flow circumferential non uniformity caused by the pylon is the main reason influencing the efficiency and stall margin.2 D numerical simulation for restaggered vane has been performed,and preliminary results indicate that proper restaggering of vane can reduce the effect of pylon on the flow field.
Thermal Fatigue Analysis to Nozzle Guide Vanes
QIAN Hui-hua, LI Hai, CHENG Tao, ZHANG Jin
2003, 18(2): 186-190.
Abstract PDF(759KB) icon1622 icon475
Abstract:
On the basis of malfunction detection,the calculation method for the transient thermal field of the nozzle guide vanes for a turbofan engine has been derived,and the transient thermal field analysed in a numerical way.Moreover,the calculation results of the transient thermal stress and the thermal fatigue life were obtained.In this paper,further investigation of the nozzle guide vane failure is performed in detail.
Research on Reliability Design Method of Structural Vibration
WANG Yan-rong, TIAN Ai-mei
2003, 18(2): 191-194.
Abstract PDF(599KB) icon1620 icon506
Abstract:
Based on the conventional design methods of structural vibration,a method is presented to evaluate the reliability of structural vibration.By use of the interference theory of stress and strengh,an interference probability model of the exciting frequency and the natural frequency of a structure has been developed,and a vibration reliability model has been established.The reliability computation formula and its application conditions for the forced resonant response that can damage the structure have also been presented.In general,this method can be applied to the structural components,for which the modal frequencies are not populated densely,such as the blades in turbomachinery.
An Experimental Study of Oxidation and Thermal Fatigue of TBC
YANG Xiao-guang, GENG rui, ZHOU Yan-pei
2003, 18(2): 195-200.
Abstract PDF(728KB) icon1966 icon497
Abstract:
The research results presented here are first part of the oxidation and thermal fatigue research of TBC (Thermal Barrier Coatings),which was mainly concerned with the experiments of oxidation and thermal fatigue for two types of TBC:plasma sprayed and electrical beam physical vapor deposition coatings,and prepared for further modeling of fatigue life prediction of TBC.At first,whole research work focuses on designing a set of suitable experiment methods for evaluating the failure characteristics and modes of oxidation and thermal fatigue of TBC at current domestic spray technique level.The failure mechanisms of oxidation and thermal fatigue of TBC are investigated with the aid of SEM.The project includes the TBC oxidation experiment and TBC thermal cyclic experiments.Both gain of oxidized weight and thickness of oxidized layer were measured during oxidation experiments,and used for modeling evolution of oxidation.Thermal cyclic fatigue experiments included the fatigue mainly induced by thermal cyclic mismatched stress and thermal cyclic fatigue with hold time at peak temperature.All experiments included the effect of pre oxidation.
A Study of Thermal Fatigue Life Prediction of TBC
YANG Xiao-guang, GENG Rui, ZHOU Yan-pei
2003, 18(2): 201-205.
Abstract PDF(770KB) icon1997 icon505
Abstract:
The research results presented here are the second part of the oxidation and thermal fatigue research of TBC (Thermal Barrier Coatings).Based on the previous experimental research,the life prediction model of thermal fatigue of TBC was formulated for two types of TBC:plasma sprayed and electrical beam physical vapor deposition coatings.Main work includes to set up the life prediction model of thermal fatigue of TBC,to develop a method for obtaining the parameters of the life model,and to give a method or procedure for obtaining stress/strain at the life critical location.The research has given a whole procedure for predicting the thermal fatigue life of TBC.And based on the results of thermal fatigue experiments,the procedure or method was evaluated and verified.
A Research of Fatigue Damage Evolution of TC4 Alloy Welded Joint
GUO Hai-ding, WU Hua-zhi, LIU Guan-ri, GAO De-ping
2003, 18(2): 206-210.
Abstract PDF(376KB) icon1746 icon485
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In this paper,the damage evolution law of low cycle fatigue (LCF) of welded blisk is studied,to which the damage mechanics theory is applied.The LCF damage evolution model is built on the basis of strap in variable thermodynamics,the LCF damage characteristics and the coupled strain equivalence principle with damage.The damage of welded specimens is measured in the strain controlled LCF experiment of titanium alloy (TC4) which is often used in aero engine and the damage evolution model is verified.The parameters in this model have definite physical meaning and are easy to be measured.The research results are of reference value for the life predication of the welded blisk of aero engine.
Artificial Neural Networks-Based Creep Reliability Analysis Method of Turbine Disk
LI Quan-tong, JING Xiao-ning, L Wen-lin
2003, 18(2): 211-215.
Abstract PDF(281KB) icon1943 icon438
Abstract:
The basic variables are sampled by Monte Carlo method. Instead of complicate finite element analysis,a Neural Network,which was well trained by the results of ADINA program,is used to calculate the displacement at the rim of turbine disc.As a result,this paper shows how to use Neural Network method to calculate the creep reliability of an aero engine turbine disc.
Structure Design Optimization Based on BP-Neural Networks and Genetic Algorithms
GUO Hai-ding, LU Zhi-feng
2003, 18(2): 216-220.
Abstract PDF(766KB) icon4679 icon665
Abstract:
Owing to the increasing demand for raising the thrust weight ratio of modern aero engine,it is very important to optimize the structures of the components.Traditional optimization methods of structure design are time consuming and hard to be put into practice.So,in this paper,a new method of structure design optimization is induced to which both BP neural networks and genetic algorithms (in short:BPN GA) are applied.A program which contains 9 variables is designed for the structure optimization of a disk model with the BPN GA method,which proves that it has better calculating rate and precision than those with traditional optimization methods.
A Study of Local Rich Fueling Design for Widening Combustor Lean Ignition and Blowout Limits
LI Ji-bao, LIU Da-xiang
2003, 18(2): 221-224.
Abstract PDF(234KB) icon1866 icon430
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A compromise between lean blowout characteristics and overall performances in the gas turbine combustor primary zone design is introduced.A uniform and a local rich fueling designs of dome have been made,and tests for comparing the influence of the two designs on combustor lean ignition and blowout limits have also been carried out in an experimental annular combustor.Ignition and blowout regulations of the local rich fueling design have been analyzed and summarized.The results show that the local rich fueling design can widen the combustor lean ignition and blowout limits apparently.
Analysis of Boiling Nucleation in Capillary Tubes
TIAN Yong, PENG Xiao-feng
2003, 18(2): 225-229.
Abstract PDF(303KB) icon1626 icon415
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Theoretical and experimental investigation was conducted to explore microscale boiling nucleation characteristics.By using a statistical mechanics approach,the effect of spatial scale on the bubble nucleation in capillary tubes was analyzed and the superheat temperature of liquid heated in capillary tubes was theoretically derived as a function of spatial scale.The boiling phenomena were observed and the nucleation temperatures were measured for four kinds of fluids (water,methanol,ethanol,and carbon tetrachloride) boiled on a platinum wire confined in capillary tubes.The comparisons indicate reasonable coincidence between theoretical findings and experimental observations.
Coupled Method of Flow-Heat Transfer to Calculate Temperature Field of Multi-Hole Wall
ZHU Hui-ren, BAI Luo-lin, ZHANG Li, LIU Song-ling
2003, 18(2): 230-234.
Abstract PDF(760KB) icon1563 icon420
Abstract:
A code was developed by using the basic principles of aerodynamics,heat transfer,thermodynamics and numerical heat transfer taking into account the compound relationship among pressure difference,mass flow,temperature difference and heat flux,including the influence of heat convection between cooling air and inner surface of film cooling holes.Using this code we can calculate the two dimensional temperature field of burner inner liner with annular slots and multi film cooling hole by giving the air/gas parameters at the inlet and outlet of the combustion chamber.
Effect of Rib Turbulator Orientation on the Discharge Coefficient of Suction Hole in the Internal Passage
QIU Yun, ZHU Hui-ren, NI Meng, LIU Song-ling
2003, 18(2): 235-238.
Abstract PDF(707KB) icon2936 icon524
Abstract:
Measurement of suction holes' discharge coefficients Cd in an internal passage with rib turbulators and suction holes are presented.The internal passage is a rectangular channel with two opposite ribbed walls,the aspect ratio is 0.5,and the rib turbulators are arranged in a staggered way on the two wider walls.The cylindrical suction holes are 45° inclined and perpendicularly oriented,they are placed on one ribbed wall.Tests were run by varying rib tubulators' angles as 45°,60°,90° and 120°,with Reynolds numbers Re changing from 40000 to 80000 and suction ratios (SR) changing from 0.30 to 0.60.Influences of rib tuburlators angles,Reynolds number and suction ratio on Cdare studied. Results indicate:(1) Cdincreases a little along the internal passage;(2) increasing rib turbulator's angle leads to higher Cd,and the maximum Cdis obtained when the rib angle is 120°;(3) varying suction ratio contributes no remarkable effect on changing discharge coefficients;(4) Reynolds number also has no obvious influence on discharge coefficients.
Investigation of Liquid Thermal Driving in Small-Size Circular Enclosures
MAO Jun-kui, CHANG Hai-ping
2003, 18(2): 239-243.
Abstract PDF(295KB) icon1853 icon449
Abstract:
With the development of technology,the integration of electric equipment is increasing greatly,and the new and high effective cooling methods are paid more and more attention.Experiments and 3D numerical simulations have been performed to investigate a new cooling method,which employs the thermal driving of fluid in small size circular enclosures to enhance heat transfer rate.A clear view of the fluid flow was kinescoped in the experiments and numerical simulations were applied to investigating the details of flow and heat transfer in the enclosure.The simulation result agrees well with that of the experiment.All results show that this new cooling scheme will have a good future if applied to the high efficient electronic cooling equipment.
The Simultaneous Measurement of Pressure in Rotating System
ZHANG Dong, DING Shui-ting, TAO Zhi, XU Guo-qiang, NING Lei
2003, 18(2): 244-247.
Abstract PDF(266KB) icon1754 icon529
Abstract:
Pressure transducers for pressure measurement of rotating disk surface have to rotate with the disk and this may give rise to the difficulty that measuring error may be unavoidable due to the membrane deformation caused by the centrifugal force.A real time local calibration,thus,has to be introduced for an accurate pressure measurement.A device was installed onto the test rig to generate a standard pressure source under rotating frame and this standard pressure was used for real time calibration.
Experimental Research on Tile-Shaped Aerospike Nozzles
MA Bin, LIU Yu, DAI Wu-ye
2003, 18(2): 248-252.
Abstract PDF(349KB) icon1853 icon525
Abstract:
To understand the performance of aerospike nozzles and to design aerospike nozzle with higher efficientcy,the experimental research on two tile shaped aerospike nozzles has been conducted.The gaseous oxygen and alcohol were used as propellants in the experimental study.The engines researched here include a four unit tile shaped aerospike nozzle and a fourteen unit tile shaped aerospike nozzle.The experimental setup and the geometry of the two tile shaped aerospike nozzles are presented.The typical experimental curves are showed.The altitude characteristic and the effect of base bleed on aerospike nozzles are analyzed too.The experimental results indicate that the tile shaped aerospike nozzle has good altitude compensation ability,and that the proper base bleed can promote the nozzle performance.
Fault Diagnosis for Space Propulsion System Using the Bond Graph Method
ZHANG Chun-liang, ZHANG Zhen-pengZHANG Ben-bin, ZHANG Ben-bin, CAO Yong-peng
2003, 18(2): 253-257.
Abstract PDF(344KB) icon1878 icon471
Abstract:
This paper introduces basic theory of the bond graph,and by using the theory,fault diagnosis for space propulsion system is studied.The analysis shows that the wethod has following advantages in fault diagnosis of space propulsion system:simple modeling,intuitive model,easy fault locating.It is a new way to diagnose liquid rocket engine.
Numerical Study of Particle Trajectories in a Nozzle with a Tail Pipe
DAN Lin-peng, ZHANG Zhen-peng, ZHAO Yong-zhong, ZHANG Tong-biao, LI Jia-yu
2003, 18(2): 258-263.
Abstract PDF(936KB) icon2115 icon459
Abstract:
Two phase flow field in a nozzle with a tail pipe is studied by using the trajectory model to define particle trajectories of different sizes under both fully elastic bounce and fully non elastic bounce.Both particles of different sizes and particles under fully elastic bounce or fully non elastic bounce are traced to find out the properties of particles flowing.Some of rules of particles flowing in a nozzle with a tail pipe have been obtained.
Strength Analysis of SRM Flexible Joint under Tensile Load
LIU Yong-qiong, YOU Jun-feng
2003, 18(2): 264-268.
Abstract PDF(390KB) icon1767 icon489
Abstract:
The solid rocket motor (SRM) flexible joint is the main part of the flexible bearing nozzle that allows nozzle to deflect in any given direction for motor thrust vector control.It consists of elastomer rings,reinforcement rings,front and rear flanges which are concentric spherical sections bonded.The finite element method is used to analyze the strength of flexible joint under tensile load.The stress field of flexible joint under 05 MPa distributing tensile load is acquired.Because the maximal tensile stress and layer shear stress at the interface between elastomers and reinforcement rings are 234 MPa and 028 MPa respectively,thus the strength of bonded interface can satisfy the design need.
Turbulent Flow of Power Law Fluid under the Influence of Its Material Parameters and Pump Impeller Blade Geometry
ZENG Zhuo-Xiong, LIU Wen-hong, YU Chun-jin, KANG Li-qiang
2003, 18(2): 269-273.
Abstract PDF(418KB) icon1809 icon473
Abstract:
The character of pseudothermal temperature equation is expounded;numerical computation of two phase flow of power law fluid in different kind of pump impeller blade and under the influence of its material parameters (viscosity and flow exponent) has been performed.Pseudothermal temperature on tension side is higher than that on suction side,and pseudothermal temperature near wall is higher than that in interior.Pseudothermal temperature can be used to describe abrasion level.Form the point of view of diminishing the abrasion,we can find blade pump impeller with double arc shape is better than that with single arc shape,pump impeller with small outlet angle is better than that with big outlet angle.The conclusions lay foundation for efficient design and improving the property of pump impeller.
Numerical Simulation of Sound Generation and Radiation from a 2-D Parallel Shear Layer Based on the Full Euler Equations
LI Xiao-dong, GAO Jun-hui
2003, 18(2): 274-278.
Abstract PDF(942KB) icon1883 icon474
Abstract:
The generation and radiation of acoustic waves from a 2 D shear layer is numerically simulated by an aeroacoustic approach based on the 2 D full Euler equations.The dispersion relation-preserving (DRP) finite difference scheme is employed for space discretization and the low dissipation and low dispersion Runge Kutta (LDDRK) scheme is utilized for time integration.Numerical results show that the full Euler solutions agree well with the analytical solutions as well as the solutions by the linearized Euler equations if the amplitude of sound source is not too large.However,there is great discrepancy between the linear Euler and full Euler solutions if the strength of sound source is strong enough (140 dB).This means that the nonlinear effects can not be neglected whereas the linearized equations do not work.
Experimental Studies of a Caret Inlet at Supersonic Speed
ZHU Yu, LEE Chun-hian, LI Tian
2003, 18(2): 279-282.
Abstract PDF(315KB) icon2001 icon420
Abstract:
A Caret inlet was studied by testing.Basic aerodynamic characteristics of the inlet at supersonic speed are presented.The total pressure recovery rapidly drops from Mach 1.6 to 2.0.No inlet/engine match point at Mach 2.0 without bypass was found due to the fact that the surge margin happened to be too narrow.Steady circumferential distortion declines from surge to critical state,nevertheless,dynamic turbulence intensity increases rapidly.Flow separations are visible in duct from critical to supercritical states,these separations stem from the intersection of two ramps and low outboard.
Parallel Numerical Study of the Unsteady Flow in 3-Dimensional Linear Cascade
ZHANG Zhi-bin, LI Xin-liang, SHEN Meng-yu
2003, 18(2): 283-288.
Abstract PDF(810KB) icon1493 icon432
Abstract:
Dynamic separation is directly connected with the issue of the safety and economy in compressor operation.Therefore,the study of separated flow is of great significance in the investigation of flow field in turbomachinery.In this report a genernal program code for numerical simulation of 3 Dimensional linear compressor cascade is developed.In this code,high accuracy difference schemes and B L turbulence model are used.For testing the code,numerical simulations of the 3 Dimensional flow field in compressor cascade for various attack angles are performed and compared with experimental results.The numerical results agree well with the corresponding experimental results,thus the code is verified.The spectrum of pressure fluctuation at the attack angle of 10 degree agrees with those from experiment qualitatively,it shows that this code can be used to simulate the dynamic sparational flow.The code is deserialized and optimized for PC Cluster,actual computations show that the code has very high parallel efficiency.
A Non-Iterative Method of Aero-Engine Modeling Using Complementary Variables
YANG Gang, SUN Jian-guo, HUANG Xiang-hua, SU Wei-sheng
2003, 18(2): 289-294.
Abstract PDF(674KB) icon1833 icon465
Abstract:
In aero engine modeling,Newton iteration method is often used to solve the non linear equations of engine model.But due to the strong non linearity of the equations,this algorithm often fails to converge at some points of the full envelope.In order to solve this problem,this article proposes a method to avoid iteration.Several variables and equations of volume dynamics in aero engine are introduced as complementary variables and equations,and as a result,the whole set of equations becomes closed form and can be solved without iteration.This method has been successfully applied to a turbofan engine and the simulation results show the feasibility and effectiveness of the proposed method.
Fight and Train State Control Technique of a Jet Engine
LI Xi-fa, GAN Xiao-hua, LIU Yan-mei
2003, 18(2): 295-298.
Abstract PDF(317KB) icon1225 icon413
Abstract:
The fight and train state control method as well as the control device for the engine in airport using is briefly introduced.The control device is made of INTEL 8051 series single chip microcomputer which has eight analogy and seven I/O channels.It has self check and fault diagnoses ability.Through flight test and application in aircraft,it has been proved that the control device is simple to install and works reliablly.
An Extensive Review of Elasto-Dynamics of Planetary Gear Trains
YANG Jian-ming, ZHANG Ce, LIN Zhong-qin, Chen Guan-long, LAI Xin-min
2003, 18(2): 299-304.
Abstract PDF(934KB) icon1757 icon477
Abstract:
Planetary gear trains are widely used in industry due to their unique advantages,such as compact volume and high load capability etc,over other kinds of transmissions.In the past years,several mathematical models for the elasto dynamics have been developed for different purposes.In this paper,the models used in elasto dynamics of planetary trains are discussed and a classification of the models is made.The algorithms frequently utilized to search for the response of the system are also outlined.Some aspects relating to dynamics of planetary gear trains,such as vibration mode shape,load sharing and vibration control are discussed.Finally some important problems deserving more efforts to study in the future are pointed out.

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