2002 Vol. 17, No. 5

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Time-Frequency Analysis of Correlation Coefficient Stationary Process
FU Hui min, LIU Cheng rui, MA Xiao bing
2002, 17(5): 505-512.
Abstract PDF(1092KB) icon1585 icon508
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The correlation coefficient stationary process in which the mean and variance vary with time is familiar in engineering,and the traditional correlation function stationary process is just a special case of that.The method of time frequency analysis and AR(p),MA(q) and ARMA(p, q) models of the correlation coefficient stationary process are presented in this paper.Its mean function, variance function and correlation coefficient function can be gained by the method in time domain.Thus the spectrum density of the correlation coefficient stationary process can be obtained by Fourier transform,short time Fourier transform or wavelet transform.The formulas for calculating the response of a linear system are derived when the input is a correlation coefficient stationary signal.In addition, the concepts of trend component spectrum density and random component spectrum density in random processes are also presented herein.The method has been used in the performance tests of aircraft and satellite successfully.It shows that a great number of specimens and time have been saved.
Aerodynamic Design of Tilt Rotor/Propeller Blade
LUO Dong ming, ANG Hai song
2002, 17(5): 513-517.
Abstract PDF(916KB) icon1943 icon488
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Considering the operational characters of tilt rotor/propeller,a design method for tilt rotor/propeller is presented.This approach,based upon axial flow blade element theory and genetic algorithms,can define the rotor/propeller blade design variables to converge on a best compromise that meets the desired hover/cruise performance requirements.The design results show that an improvement of hover performace without causing a decrease of cruise efficiency can be obtained by the method.
Effect of Grazing-Bias Flow Interaction on Acoustic Impedance of Perforated Plates
ZHANG Hou wu, LI Yun min, JING Xiao dong, SUN Xiao feng
2002, 17(5): 518-523.
Abstract PDF(971KB) icon2094 icon508
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The effect of grazing bias flow interaction on the orifice acoustic impedance has been experimentally investigated.It is shown that the acoustic resistance of an orifice increases slowly with the increase of bias flow speed because of grazing flow effect,but the acoustic resistance is dominated by the bias flow effect when bias flow speed is comparatively high.In addition,there is some difference between grazing inflow and grazing outflow interactions.Finally, an attempt is made to correlate the experimental data in terms of the effective discharge coefficient.
Numerical Computation and Examination of a Two-Dimensional Mixer-Ejector System
ZHANG Jing zhou, SHAN Yong
2002, 17(5): 524-527.
Abstract PDF(705KB) icon1903 icon482
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Numerical computation of 2 D flow fields inside a mixer ejector was conducted using one dimensional ejector pumping relationship and full Navier Stokes equations.Firstly,the ideal pumping coefficient was determined based on the one dimensional ejector pumping relationship.Then the coefficients in the one dimensional ejector pumping relationship were corrected according to the velocity distribution and wall friction resulting from the calculation of Navier Stokes equations.The final pumping coefficient can be obtained by repeating the above process until the residual is satisfied.From the comparison between the computation results and experimental data,it is concluded that the present method is reasonable in predicting the mixer ejector pumping capacity.
Experimental Study of RCS for a Helicopter Inlet
HAN Dong, GUO Rong wei, TAN Hui jun, YI Hai yun, ZHOU Bei bei
2002, 17(5): 528-532.
Abstract PDF(328KB) icon1683 icon464
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An experimental study of the radar cross section in a helicopter inlet syncretized with engine cabin was completed in different polarization ways,terminals,attack angles and azimuth. Meanwhile,the RCS characteristics were also analyzed at various states.The results indicate that RCS of this inlet is lower in vertical polarization way than that in horizontal polarization way,and higher in plate terminal than in blade terminal.The radar cross section at nearly sideslip is larger than that at front flight and nearly backward flying.In the experiments of different attack angles (-10°,-5°,0°,5°,10°),the RCS at 10° is relatively low,and at -5° is relatively high.
Aeroengine Fault Diagnosis Based on Self-Organizing Topology Maps
ZHU Jia yuan, DENG Zhen ting, ZHANG Heng xi, QU Yu an
2002, 17(5): 533-537.
Abstract PDF(736KB) icon1655 icon425
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This paper proposes a visualized aeroengine fault diagnosis system mode based on self organizing topology map which combines vector quantization,fast clustering,information fuse and topology preservation,estimation of topographic error and quantization error is also given.And then this method is applied to aeroengine gas path fault diagnosis.The results show that this diagnosis mode is effective and rational.Furthermore,the paper has set up component visualized gray plane in which characteristics of fault vector,correlation of measured parameters and tendency of components can be observed easily,and also we can analyze inherence of faults by this approach.
Investigation on the Maximum Single Stage Loading Level of the Super- or Tran-Sonic Axial Flow Fans and Compressors
ZHU Guo dong, LI Pei jun, SHAN Peng
2002, 17(5): 538-541.
Abstract PDF(184KB) icon1586 icon456
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The quest for higher stage pressure ratio has been promoted by engine researchers.But in the multi stage fan and compressors,the rise in total and static pressures of a single stage axial flow compressor is constrained by many factors.The maximum stage loading level has a limitation.Using a simplified stage model,this paper investigates this level of a super or tran sonic single stage axial flow compressor under the conditions of the widest rotor stator matching and the stage matching.The paper concludes that the stage pressure ratio must be less than 37 when considering only the theoretical loading mechanism.Meanwhile it gives several graphs to exhibit the influencing strength of each constraint.
Research on the Axial Position of Treated Casing in Multistage Axial-Flow Compressors
WU Yan hui, ZHU Jun qiang, LIU Zhi wei
2002, 17(5): 542-548.
Abstract PDF(981KB) icon2329 icon450
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A new method for determining the axial position of treated casing in multistage axial flow compressors is set up in this paper.Firstly,the stalling pressure rise capability of axial flow compressor stages is predicted,and the stage in which stall occurs first could be located theoretically and be verified experimentally.Secondly,the stage stall appearing first is taken as the axial position of treated casing.The idea is verified in a systematic way with the help of four kinds of different casing treatment in a subsonic two stage axial flow compressor.Experimental results indicate that the treated casing placed on the first stalling stage could improve the stall margin better.The method presented in the paper could be used as the guide in the casing treatment design for determining the axial position of the treated casing.
Three-Dimensional Numerical Simulation of Whole-Ring Rotor/Stator Interaction in a Single-Stage Compressor
JIANG Kang tao, XU Gang, ZHANG Hong wu, HUANG Wei guang, CHEN Jing yi
2002, 17(5): 549-555.
Abstract PDF(1068KB) icon1437 icon466
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This paper presents three dimensional unsteady numerical simulation of whole ring rotor/stator interaction in a single stage transonic axial compressor by using the commercial CFD software FLUENT.The different flow fields of both elongated axial gap and normal axial gap between rotor and stator are calculated and compared.The numerical results acquire clear flow pictures of rotor/stator interaction,and show the periodic oscillations and lag phenomena of outlet mass flow rate in three successive stator passages.The paper supports that the mature commercial software can be employed to study complex physical phenomena in turbomachinery.
Numerical Simulation of Trailing Edge Vortex Shedding in a 2-D Compressor Cascade
ZHANG Wen long, YUAN Wei, ZHANG Jian, ZHOU Sheng
2002, 17(5): 556-560.
Abstract PDF(718KB) icon1654 icon454
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Although vortex shedding is a self excited unsteady flow phenomenon in turbomachinery blading with a blunt trailing edge,and the trailing edge of a compressor is not blunt,the phenomenon of vortex shedding is still thought to occur in a compressor blade row because of the viscosity and pressure gradient.The flow in the boundary layer is strongly affected by the adverse pressure gradients that tend to make the flow to separate,so there are a lot of vortices in the blade region.A numerical study has been carried out to simulate trailing edge vortex shedding of some kind of compressor cascade.A series of flow simulation are performed,and the structure of flow field and the mechanism of unsteady flow are investigated preliminarily.The numerical results indicated that the flow is strong unsteady flow,though the boundary conditions are steady.When incidence is big,the trailing edge vortex shedding is like Karman vortex shedding.The frequency of vortex shedding and the position of separation are affected by the incidence and Mach number.
Research of the Unsteady-Fluid Characteristic Parameter in an Annular Cascade
WEN Xue, LI Zhi ping, ZHOU Hai, GE Jing dong
2002, 17(5): 561-566.
Abstract PDF(827KB) icon1752 icon405
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In the annular cascade test,we aim to observe the fluid field behind the annulus blades,focusing on the velocity field and the vortex shedding frequency in particular,and to investigate the effect of fluid incidence and flux on them.In comparison with the cascade with high positive incidene,the high negative incidence cascade has wider separating section,stronger vortex,and slower wake delay,but weaker vortex intensity.As the incidence approaches the designed value,it can be seen obviously that the separation diminishes and dissipates as the vortices quickly blend with the main flow. Additionally,there is a characteristic frequency valued at 723 Hz in the diverse cases.
An Investigation on the Fluid Characteristics of Trapped-Vortex Combustor
HE Xiao min, WANG Jia hua
2002, 17(5): 567-571.
Abstract PDF(319KB) icon1812 icon490
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In 1995,a new,compact and efficient method to stabilize flame,referred to as Trapped Vortex concept,was introduced firstly by K.-Y.Hsu,a professor of Dayton University.For obtaining good performance characteristics in a trapped vortex combustor,the fluid dynamics should be studied in depth.On the basis of former research work,a numerical investigation and experimental research work were performed for understanding the relationship of trapped vortex characteristics and pressure loss varying with the diameter afterbody (Da) and the length of centerbody (H) under cold environments when the diameter of forebody and the inlet annular velocity are fixed at Df=70 mm and Ma=03 respectively.The results show that within the range of Da/Df=05～08,each value of Da/Df corresponds to a specific optimal H/D (02～20),when a stable vortex is trapped in the cavity.The characteristics of this trapped vortex,mainly the vortex core and vortex area,meet the requirements for the injection of fuel and primary air introduction.In addition,a minimum pressure drop is achieved across the combustor.
Experimental Investigation of Heat Transfer between Co-Rotating Disks
HE Ya jun, XU Guo qiang, TAO Zhi, DING Shui ting, CAI Wei hua
2002, 17(5): 572-576.
Abstract PDF(316KB) icon1551 icon471
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Two real turbine disks are simplified to become a co rotating plan disk system.The effects of the coolant flow rate,rotational speed and the interval between the two discs on the performance of fluid flow and the heat transfer were investigated experimentally.Conclusions are drawn as follows:(1) the inlet Reynolds number could always have significant effects on average Nusselt number.(2) the rotational Reynolds number has little effect on averaged Nusselt number of the two disks.(3) the interval of two disks also has effect on averaged Nusselt number of the two disks.
Turbine Blade Surface Heat Transfer and Film Cooling Measurements in a Turbine Cascade with Injection on Surface
XIANG An ding, Luo Xiao qiang, ZHU Hui ren, XU Du chun, LIU Song ling
2002, 17(5): 577-581.
Abstract PDF(698KB) icon1949 icon497
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Detailed heat transfer measurements were conducted on the turbine blade surface of a large scale low speed turbine cascade with injection on the surface of turbine blade.Local film cooling effectiveness and heat transfer coefficient with coolant injection were determined at different blowing ratios.In conjunction with the previous measurements of the flow field,the behaviours of turbine blade surface film cooling and heat transfer were studied.The results show that turbine blade surface film cooling and heat transfer are different greatly in different hole array position.The coverage of the coolant on the surface is mainly determined by blowing ratio for same geometry.It was also observed that coolant injection made the overall averaged heat transfer increase remarkably with blowing ratio and then made the thermal loads on the surface decrease effectively.
Numerical Simulation of Infrared Radiation Characteristics for Aeroengine High-Speed Exhaust System
JIN Jie, ZHU Gu jun, XU Nan rong, ZHANG Xiao ying
2002, 17(5): 582-585.
Abstract PDF(584KB) icon1821 icon482
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The numerical simulation of infrared radiation from cavitation,plume and cavitation plume composition of aeroengine high speed exhaust system has been conducted.This is achieved through solving the radiation transfer equation (RTE) of dissipation emission medium by means of closure domain theory and Goody band model on the basis of 3 D flowfield calculation of aeroengine exhaust system.The results of computation have been compared with that of practical engine ground test.The investigation results indicated that the relative tolerance of infrared radition is less than 30% and the infrared radition distribution of computation is roughly consistent with that of engine test.The computation methods and code referred could be applied to estimating the infrared radition of practical aeroengine exhaust system.
Numerical Investigation of Fluid Flow and Heat Transfer Characteristics within a Rotating Cavity with a High Positioned Axial Inlet and a Radial Outlet
SUN Ji ning, TAO Zhi, DING Shui ting, XU Guo qiang
2002, 17(5): 586-590.
Abstract PDF(816KB) icon1833 icon454
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Numerical simulation was performed to study the turbulent flow and heat transfer within a rotating cavity with a high positioned axial inlet and a radial outlet.Analysis was carried out for the variation of the averaged Nu number on the heated disk surface vs.Reωand Re.
Vibration Control Method and Damper Design of Labyrinth Gas Seals
LI Hui, LI Qi han, YAN Li tang
2002, 17(5): 591-596.
Abstract PDF(829KB) icon1775 icon490
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The vibration control theory of the dry friction damper used in the labyrinth gas seals is studied in the paper,and for the effect of the damper loop and damper tube is also investigated by means of the aeroelastic stability analysis method for the labyrinth gas seals.Based on the analysis result,we give the damper design process used for engine.According to the analysis,dry friction damper can raise the aeroelastic stability of the labyrinth gas seals.
Research on the Response of a Rub-Rotor System Supported on Squeeze Film Dampers
ZHANG Tao, MENG Guang
2002, 17(5): 597-604.
Abstract PDF(474KB) icon2129 icon480
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The nonlinear character of a rub rotor system with SFD is analyzed in this paper.It was found that with an increase in the rotating speed,the amplitude of the system response increases in the end.In such a process,the max amplitude of the system response several kinds of changes.Sometimes it increases,sometimes it decreases,and sometimes it keeps constant.It also was found that there is close relationship between the period solution bifurcation and the max amplitude of the system.At the bifurcation point,the max amplitude of the system varies intensely.SFD has an obvious absorber effect of the system.But when the parameter of SFD exceeds a certain value,the variation of this parameter hasn’t any obvious infection on the absorber effect of the system.And the friction coefficient of the rub has a good effect on the absorber effect of the system too.A large friction coefficient can make the system to work more steadily.But sometimes,a smaller friction coefficient can play a positive role for the absorber to.An imbalance coefficient influences the max amplitude of the system greatly.The higher the coefficient is,the larger the max ampiltude of the system.It also was found that keeping the system under period solution state can make the max amplitude decreasing.
Finite Element Method Analysis of Rotating Shell Buckling
CAO Hang, ZHU Zi gen
2002, 17(5): 605-609.
Abstract PDF(684KB) icon1680 icon459
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Due to the effect of centrifugal force the buckling critical pressure of rotating shells is higher than that of non rotating shells.The linear buckling finite element equations of rotating shells are established in this paper.The finite element program MSC/NASTRAN is used to analyse the rotating shells linear buckling and the solution sequence is modified by DMAP (Direct Matrix Abstraction Program) to take into account the effect of centrifugal force.Nonlinear buckling and post buckling behaviors of rotating shells are analysed by geometric nonlinear finite element method,and the effect of centrifugal force is considered by different load step.The initial geometrical imperfection also is discussed in this paper.
Mathematical Modeling of a Maneuvering Asymmetric Rigidity Rotor with Initial Bending
LIN Fu sheng, MENG Guang
2002, 17(5): 610-614.
Abstract PDF(694KB) icon1706 icon490
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A mathematical model of an unbalanced rotor system located in aircraft with asymmetric rigidity and initial bending is given in this paper.The model for the maneuvering rotor can be used to study the dynamic characteristics of a rotor running with constant rotating speed,constant acceleration or deceleration,to investigate the influence of the velocity and acceleration of aircraft on the rotor dynamics,to analyze the amplitue response of a rotor and to diagnose the fault of a maneuvering rotor.
Application of Chaboche Thermal Viscoplastic Model
ZHANG Ke shi, Brocks Wolfgang
2002, 17(5): 615-622.
Abstract PDF(1020KB) icon2020 icon583
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In the present paper,the research on the parameter determination of Chaboche thermal viscoplastic constitutive model has been carried out and a method is proposed.By using this method a set of parameters for the material TiAl has been determined.Furthermore the finite element analyses by using the UMAT coded by Arzt and Brocks et al associated with above parameters for uniaxial tension at different rates, uniaxial creep under different stress levels and creep procedure of a CT specimen under a ladder type load have been performed.
Strength Analysis for Multiple Double-Lapped Joints in CFRP Laminates
CUI Hai tao, WEN Wei dong
2002, 17(5): 623-634.
Abstract PDF(645KB) icon2013 icon486
Abstract:
Double lapped bolted joints are the main structure in design of composite laminates.The effect of the distance between holes is taken into consideration,strength of multiple double lapped joints of T300/KH304 CFRP is analyzed by three dimensional finite element model.Based on the result of stress analysis,Yamada Sun criterion is used to predict the ultimate strength of the joints.Experimental results show that bearing failure is the main failure type,together with the net tension and shear out types,the curve of displacement load approximate a straight line,and Yamada Sun criterion is suitable for prediction of the ultimate strength.Compared with the predictions,a good agreement between experimental and numerical predictions is obtained.
Investigation of Fault Mechanism for Spinal Bevel Gear Sets of an Aeroengine
SHI Ya jie, HONG Jie
2002, 17(5): 635-640.
Abstract PDF(779KB) icon1620 icon399
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The spinal bevel gear is one of the key components in the accessory gear transmission system of aeroengine.By means of computing the modal properties,critical rotating speed,and stress levels,this paper investigated the fault mechanism of spinal bevel gears in various aspects of the vibration,strength,manufacture and material etc.The results indicate that the main reason of the failure is due to fatigue damage caused by the meshing forces between the gear teeth.
Research on Structural Dynamic Characteristics of Brush Seals
LIU Zhan sheng, YE Jian huai
2002, 17(5): 641-644.
Abstract PDF(350KB) icon1621 icon458
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In order to formulate a simple and exact expression for studying rotor bearing sealing system,the structural dynamic characteristics of brush seals were analyzed.On the basis of the elastic theory,this paper establishes the nonlinear dynamic equations describing the actions between the ring seal and the rotor,in which nonlinear friction between the ring seal and the rotor was considered.Then an approximate expression of the nonlinear supporting stiffness was derived,which provides the mathematical model and method for the study of nonlinear dynamics of rotor bearing sealing system.Finally the correctness of the expression was proved by using numerical simulation.
A Research of SRM Firing Tests under a Kind of Typical Vibration
LI Feng xiang, LI Yue sen, ZHOU Wei min
2002, 17(5): 645-649.
Abstract PDF(292KB) icon1739 icon451
Abstract:
An experimental investigation has been performed and presented in the papaer to clarify the effects of low frequency vibration on the rocket moter performance which occurred a number of times during the active flight period of a missile.Firing tests of a small size motor mounted on a vibration stand simulating low frequency vibration in flight have been conducted.Some problems such as grain structural integrity,motor internal ballistic propereties and insulation erosion have been studied.The preliminary results show that low frequency vibration in flight does not destroy grain structural integrity and does not remarkably affect main motor performances,but burning rate of propellant and ablation rate of insulation in vibration direction are influenced to some extent.The research results can provid some basis for relevant engineering design.
A Method for Analysing Sensitivity of Fault
LI Jia wen, ZHANG Zhen peng
2002, 17(5): 650-654.
Abstract PDF(287KB) icon1539 icon432
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This paper discusses the sensitivity of fault in fault diagnosis when structural elimination method is applied.Fault diagnosis in the structural elimination is based on mathematical model and measured parameters.Because the measured parameters vary with the different faults,it is necessary to make deeper analysis when employing (0,1) fault matrix to reduce the possibility of making wrong diagnosis.The analytical method mentioned above which uses the sensitivity matrix is proposed in this paper.The method of calculating sensitivity matrix and an example that uses the matrix are also presented.The sensitivity matrix as well as the sensitivity degree of parameters for fault is compared with (0,1) fault matrix.The best test parameters can be chosen and the parameter’s combination can be eliminated according to different relationships of fault when the fault diagnosis system is designed by using the sensitivity matrix.Therefore,the reliability of the result of fault diagnosis will be improved.
Recent Development and Prospects for the Distributed Simulation of Gas Turbine
LIU Yong wen, ZHANG Hui sheng, WENG Shi lie
2002, 17(5): 655-664.
Abstract PDF(653KB) icon1723 icon436
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Due to the complexity of gas turbines and the increasing requirements (including economic,safety and environmental protection) being imposed upon,the pressure to decrease the design and development costs,time and risks of gas turbine is accordingly increasing.With in depth study of various physical phenomena,precise models of different parts and different disciplines have been developed.However,it is not an easy job to integrate these models into a system model.One particular difficulty comes from the fact that different hardware/software platforms and different programming models are used.In order to make these models interact,distributed simulation environment and unified programming model must be used.The programming models used in general distributed systems can be classified into message passing,control flow,data flow,blackboard/shared space, mobile object/agent.In this article,these programming models are generally described and their applications in gas turbine distributed simulation are also reviewed.However,one serious drawback of the programming models been used is that they lack direct support for distributed simulation,so the needed features have to be added usually at the will of the developers, without taking into consideration of standardization.The US Department of Defense has set down a distributed interactive simulation standard High Level Architecture,whose main purpose is to facilitate the reusability and interoperability of simulation.The HLA should also be adopted as the standard for gas turbine distributed simulation to facilitate the multi site,muliti part,and multi discipline integrated simulation of gas turbine.Some advice on further development of gas turbine simulation is also given to domestic researchers.

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