2004 Vol. 19, No. 5

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Identification of Non-Liner Vibration Characteristics of Cracked Rotor Using Harmonic Wavelet Analysis and Fractal Theory
LI Shun-ming, GAO De-ping
2004, 19(5): 581-586.
Abstract PDF(798KB) icon2295 icon428
Abstract:
The investigation of harmonic wavelet analysis revealed good characteristics in vibration signal analysis on partial frequency domain.Harmonic wavelet analysis was applied to the non-linear vibration signal analysis in the low frequency segment of a cracked rotor.The results of theoretical calculation and experiment show that for a cracked rotor,it is possible to obtain the non-linear character spectrum of non-integral multiple period bifurcations with the help of harmonic wavelet analysis on partial frequency domain.Comparison was made between the calculated and experimental results.It was found that the actual vibration signal of a cracked rotor is more complex than that of calculated.The multi-fractal can be used as an index of whether crack exists in a rotor.The singularity spectrum method obtained from Harmonic wavelet transformation can be regarded as a new identification method and it is put forward for non-liner character spectrums of non-integral multiple period bifurcation identification.Using this new method, the vibration signal of an actual cracked rotor was analyzed.The result is satisfactory.
Reliability Sensitivity Design of Engine Connecting Rod
ZHANG Yi-min, WANG Long-shan
2004, 19(5): 587-592.
Abstract PDF(801KB) icon1511 icon520
Abstract:
Based on the reliability design theory and sensitivity analysis method,the reliability sensitivity of engine connecting rod is extensively discussed and a numerical method for reliability sensitivity design is presented.The variation rules of reliability sensitivity were obtained and the effects of design parameters on reliability of connecting rod were studied.The method presented in this paper provides the theoretical basis for reliability design of connecting rod.
Path Planning in Pipe System Based on Coevolution
FAN Jiang, MA Mei, YANG Xiao-guang
2004, 19(5): 593-597.
Abstract PDF(635KB) icon1599 icon405
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In the process of aero-engine pipe laying design,it is import to solve the problem of interference among pipes.Genetic Algorithms (GAs) were used to put forward a multi-pipe path planning method based on coevolution concept.Between any two pipes in the pipe system,the cooperative function was used to measure the fitness of pipes.A validation of the 2D path planning using this method is presented.
Stresses Analysis of Turbine Disk Based on B-P Constitutive Equations
CHEN Yong, SONG Ying-dong, GAO De-ping, FAN Xu-ji
2004, 19(5): 598-603.
Abstract PDF(343KB) icon1819 icon366
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Based on the Bodner-Partom visco-elastic-plastic constitutive theory,after developing a self-adaptive time integration method for the constitutive equation,a user defined subroutine was developed and implemented into the general purpose non-linear finite element software ANSYS.The software takes material deformation,cyclic and variable loading condition into account.Compared to the published results, it shows that the calculated results are satisfactory,and the accuracy and efficiency are acceptable.Further,stress analysis of a turbine disc based on B-P constitutive equations was carried out. The calculated results show that the coded subroutine can be applied to the nonlinear structure analysis of aero-engine hot sections.
Nonlinear Dynamic Behaviors of an Imbalance Rotor on Multi-Lobe Bearings
SHEN Guang-yan, XIAO Zhong-hui, ZHENG Tie-sheng, ZHANG Wen
2004, 19(5): 604-609.
Abstract PDF(785KB) icon1752 icon440
Abstract:
Based on the free boundary theory and the variational method,a fast and accurate model for the calculation of the fluid-film forces under the Renolds boundary condition is presented.The model has been applied to the nonlinear dynamic behavior analysis of an imbalanced rigid rotor with two three-lobe bearing supports.Numerical simulation shows that the imbalanced rotor undergoes a bifurcation from synchronous motion to double period motion and at last loses its stability as chaotic motion. This paper also studied the influences of the rotor mass and the mass eccentricity. It is found that the threshold speed at which the rotor will lose stability decreases with the increase of rotor mass.The eccentricity influences the motion of the rotor seriously.The rotor threshold speed increases rapidly with the increase of mass eccentricity.Study of the elliptical bearing shows that the threshold speed of rotor supported by three-lobe bearings is higher than that of the elliptical bearings.
Analysis of Integrated Centrifugal Impeller Blade Vibration Reliability
JIN Xiang-ming, GAO De-ping, CAI Xian-xin, WU Li-qiang
2004, 19(5): 610-613.
Abstract PDF(637KB) icon1613 icon455
Abstract:
The characteristic of the integrated impeller blade structure and its failure mode is presented.A method for integrated impeller blade resonance reliability analysis based on forced vibration magnifying factor model combined with sensitivity analysis of natural frequency is proposed.Fatal resonance and forced vibration can be avoided by controlling the magnifying factor of forced vibration,and by controlling the natural frequency which is affected by the thickness of the integrated impeller blade.Finally,an example is presented.Compared with succedent test result,it shows that the method presented here is effective.
A Study on the Maximal Turbine Disk Strain Cycle with Residue Stress
YANG Xing-yu, ZHAO Fu-xing, GENG Zhong-xing
2004, 19(5): 614-618.
Abstract PDF(282KB) icon1941 icon441
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In order to avoid the difficulty and expensive measurement of transient temperature field,a method for maximal stress and strain cycle calculation using residue stress is proposed.This method was used to analyze a high pressure turbine disk with the displacement of stress release as geometrical boundary condition.The residue stress and the maximal stress and strain cycle of the critical points adjacent to central hole and radial pin hole are obtained and the life of low cycle fatigue is predicted.The result shows that using the residue stress we can calculate accurately the maximal stress-strain cycle,which is the main factor influencing component life.
The Vibration Performance of Metal-Rubber Material
XU Jian-dong, GUO Bao-ting, ZHU Zi-gen, LI Qi-han
2004, 19(5): 619-622.
Abstract PDF(241KB) icon1955 icon465
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Experiments were performed to study the effect of varies excitation level relative density and material properties on the vibration characteristics of Metal Rubber (MR).Some general disciplinarians of characteristics of MR were found.Based on non-rigidity and non-damping,the method of describing vibration performance of MR was presented,steady response was calculated,and the results were contrast to testing results.The results show that the large the vibration intensity,the better the damping effet will be.
A Method for Calculating Axial Preloadof Turbo-Shaft Engine Combined Compressor Rotor
GUO Fei-yue, DENG Wang-qun, CHEN Xiao-ming
2004, 19(5): 623-629.
Abstract PDF(618KB) icon2105 icon418
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The mathematic model of 3D cycle symmetry finite element was established using PATRAN software.MSC/MARC software was used to perform the analysis of axial preload.Axial preloads have been determined for the central tension rod and small tension rod of a turbo-shaft engine combined compressor.The calculated results were verified by the related experiment.Finally,an effective way is proposed for axial preload calculation of similar rotor.
On the Spatial Difference Schemes of Direct Simulation of Aeroacoustics
YANG Ai-ling, XIE Cui-li, CHEN Kang-min
2004, 19(5): 630-635.
Abstract PDF(945KB) icon2064 icon407
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Direct numerical simulation of aero-acoustics needs excellent numerical characteristics of spatial difference schemes such as dispersion relation and dissipation.The idea of compact finite difference scheme and Dispersion Relation Preserving (DRP) scheme is discussed first.Then,the dispersion characteristics and the dissipation characteristics of the two schemes are analyzed.The results show that either the solvable range of number of waves or the dissipation characteristics of the scheme combined with four-stage four-order Runge-Kutta method,the solvable range of the 6th-order compact scheme is larger than that of DRP scheme.However,the computational workload of the 6th-order compact scheme is far beyond DRP scheme.
A Preliminary Analysis of Developing Series of Engines Based on an Existing Core Engine
TANG Hai-long, ZHU Zhi-li, LUO An-yang, ZENG Yuan-jiang
2004, 19(5): 636-639.
Abstract PDF(596KB) icon2201 icon442
Abstract:
A series of engines can be derived based on an existing core engine.Components matching constraints will restrict design cycle parameter selection.A performance simulation model was established for quantitative analysis.As an example,the development of a high bypass ratio turbofan engine was used to demonstrate how the constraints restrict design cycle parameters.Preliminary analysis shows the relationship between cycle parameters and engine performance.
Characteristic of Flow Resistance and Heat Transferin a Turnover Variable Cross-Section Channel with Different Rib Pitches
LIU Xiang-yun, DING Shui-ting, TAO Zhi, XU Guo-qiang
2004, 19(5): 640-644.
Abstract PDF(344KB) icon1924 icon471
Abstract:
Experimental investigation of a turnover variable cross sectional area channel with transverse ribs of different pitch has been carried.Specimen used is the mid-span section of an actual aero-engine turbine blade.It is aimed at studying the flow resistance and heat transfer characteristics of the channel with different rib pitch to rib height ratios.The inlet Reynolds Number is ranged from 7 000 to 6 000.Experimental results show that with the increase of inlet Reynolds Number,the flow resistance coefficient decreases.The effect of rib pitch to rib height ratio on the averaged flow resistance coefficient and the averaged Nusselt numbers reveals a multiple peak distribution.
Experimental Investigation of Heat Transferin Turn-Over Variable Cross-Section Channels with Interleaving Ribs
WEI Zhe, DENG Hong-wu, TAO Zhi, DING Shui-ting, XU Guo-qiang
2004, 19(5): 645-649.
Abstract PDF(371KB) icon1695 icon406
Abstract:
Measurements has been carried out on a 180° turnover variable cross-section channel with 60° interleaving ribs.The design of the channel inner configuration was referred to an actual aero-engine turbine blade.Heat transfer characteristics were investigated at three different inlet widths to heights ratio channels. The influence of non-dimensional parameters on heat transfer of the surfaces with ribs was analyzed.The results show that at high Renolds number,the channels with large width to height ratio have better average heat transfer effect,but at low Reynolds number,the effect does not vary much with width to height ratio.Heat transfer coefficient distribution in the whole channel is basically the same for all the cases studied.
Research of Combustion Efficiency of Combustors Using Hybrid Airblast Atomizer under Low Pressure
LIU Wei, LIN Yu-zhen, LIU Gao-en, WANG Hua-fang
2004, 19(5): 650-655.
Abstract PDF(807KB) icon1878 icon498
Abstract:
Preliminary investigation of combustion efficiency under low pressure was carried out.This study is aimed at investigating the enhancement of combustion efficiency using the hybrid multistage swirling cup.The hybrid multistage swirling cup was made up of a pilot simplex nozzle combined with airblast atomizer.A single nozzle combustor was fabricated for combustion efficiency test.Combustor inlet velocity and overall fuel/air ratio were simulated under low pressure condition.The gas sampling was used for the combustion efficiency measurement.The results show that the hybrid multistage swirling cup can improve combustion and enhance combustion efficiency with combustor inlet pressures ranged from 0.07 MPa to 0.11 MPa.
Assessment Analysis of Pulse Detonation Engine Performance in Flight Regime
QIU Hua, YAN Chuan-jun, FAN Wei, HUANG Xi-qiao, ZHANG Qun, ZHENG Long-xi, XIONG Cha
2004, 19(5): 656-659.
Abstract PDF(650KB) icon1806 icon459
Abstract:
A theoretical performance analysis model of air-breathing pulse detonation engine is established in the flight regimes.It is based on single-cycle pulse detonation engine analysis model.The influence of the flight regime change on performance of pulse detonation engine was studied.The results show that the average thrust is decreased with the increase of flight altitude at given Mach number, and the influence of Mach number on thrust depends on the propulsive characteristics of inlet and detonation chamber.The effect of detonation frequency and combustor diameter is also considered in the model which is useful to the design and analysis of pulse detonation engine.
Investigation of the Effects of Inlet Type on Pulse Detonation Engine Resistance Characteristics
ZHENG Dian-feng, WANG Jia-hua, ZHANG Hui-qiang, LIN Wen-yi
2004, 19(5): 660-665.
Abstract PDF(304KB) icon2089 icon461
Abstract:
The resistance characteristics were investigated for various inlet types in opening or closing mode to simulate the periodic working of Pulse Detonation Engine (PDE).The result shows that PDE resistance is in proportion to the square of flying velocity.For the inlet opening mode,the influences of different inlet types on the flow rate of detonation tube were studied.Consequently,during selecting and designing the inlet,effects of PDE inlet type on both resistance of PDE and flow rate in detonation tube can be considered.PDE resistance was also investigated when aerovalve and spoiler were installed.It is helpful to recognize how different part of PDE effects on and contributes to resistance.These results are also important to aerovalve and spoiler design.
The Influence of Endwall Wing Fence Length on Secondary Flow in Compressor Cascade
LIU Yan-ming, ZHONG Jing-jun, LI Hai-bin, WANG Song-tao
2004, 19(5): 666-670.
Abstract PDF(306KB) icon1782 icon426
Abstract:
The numerical simulation has been carried out to investigate the influence of the endwall wing fence with different length on the secondary flow in compressor cascade.The results show that the boundary layer fences can reduce the strong cross-flow in cascade near the endwall.The additional energy loss of long-fence is larger than that of short-fence.A counter-rotating streamwise vortex was found over the fence and the strength is closely related to the strength of the crossflow.The numerical results show that the influence on secondary flow is most effective when the fences are located in the foreside of the passage with a length of 75 percent axial chord.
Investigation of Rotor Dynamic Stability and Mutual Excitation of Different Degrees of Freedoms in Forward Flight
XUE Hai-feng, XIANG Jin-wu, ZHANG Xiao-gu
2004, 19(5): 671-677.
Abstract PDF(354KB) icon1798 icon448
Abstract:
It is more difficult to investigate the helicopter dynamic stability in forward flight than in hover.The rotor structure model,aerodynamic model and equations of motion were established.The treatment of equations with periodic coefficients and the influence of related parameters on rotor dynamic stability were investigated.The degree of freedom of the dynamic inflow was introduced into the dynamic stability analysis in forward flight.Starting with the analysis of mutual excitation of different degrees of freedom,the physical nature and influence factors on rotor dynamic instability are revealed.
Stability Analysis of Axial-Flow Compressor Post-Stall Transients Based on Parameter B
CHEN Ce, LI Jun
2004, 19(5): 678-683.
Abstract PDF(402KB) icon1425 icon499
Abstract:
Based on 2-order Greitzer model of axial flow compressor,a nonlinear analysis of the stall to surge process has been carried out.According to the variation of parameter B,the process was divided into four successive phases, and the compressor system equation was locally linearized.The trend of the system change near the critical point of parameter B was observed and the critical point could be determined accurately.Under the condition that parameter B exceeds its critical value,theorems of Lyapunov stability and local invariable set were introduced to global stability analysis to make up the shortage of local linearization methodology.Compared with numerical simulation,the fact was proved that the compressor system produces stable limit cycle of surge and the system locus converges in finite domain.
A Novel Aero-Engine Identification Model Based on Support Vector Machines
WEI Xun-kai, LI Ying-hong, WANG Jian-ying, ZHANG Pu, LU Jian-ming
2004, 19(5): 684-688.
Abstract PDF(935KB) icon1828 icon452
Abstract:
Because of the strong non-linearity and time-varying properties,and the existence of local minima,overlearning of conventional neural networks, a novel aero-engine identification model is introduced.The model is based on modern statistical learning theory,and Structure Risk Minimization (SRM) principle.It has very good generalization ability.By solving a quadratic convex programming problem, a global optimum can be automatically found.The identification model was established based on support vector regression machines using the real flight recorded data as learning samples.The results show that this method reveals high precision,good robustness and fault-tolerant ability. It provides a general way for aero-engine model identification.
The Research of Gas Turbine Performance Modeling Based on Theory of Similarity
DING Yi, HUANG Xiang-hua, ZHANG Tian-hong
2004, 19(5): 689-694.
Abstract PDF(769KB) icon1834 icon468
Abstract:
A new method based on theory of similarity aimed at establishing the gas turbine performance model in case of lacking of component characteristics is presented.Speed similarity and flow similarity are used to modify the component characteristics of a reference gas turbine.Because the object gas turbine is not precisely similar to the reference gas turbine,a series of correction steps to enhance the model accuracy were investigated.The model so obtained was verified by applying to the matter-in-loop simulation experiments of a gas turbine control system.The results show that the model has good real time,convergent and dynamic response property,which satisfies the requirements of matter-in-loop simulation.
H∞ Control Applied in Integrated Flight and Propulsion Control Systems
WANG Xi, LIN Yong-lin, WU Yong-kang
2004, 19(5): 695-702.
Abstract PDF(988KB) icon1754 icon432
Abstract:
This paper deals with the application of advanced multivariable control technologies to integrated flight and propulsion control systems.Focusing on the coupled flight and propulsion subsystems,the integrated flight and propulsion model was established.The approach which translates the multivariable feedback control problem of integrated flight and propulsion system with multiplicative output perturbation and tracking error performance uncertainty into mixed weighted sensitivity function shaping problem was analyzed.The methodology of selecting weighted sensitivity function based on the Integral of Time multiplied by Absolute Error (ITAE) rule is presented and applied to the design of the integrated flight and propulsion control system model.The optimum control system so obtained is verified by simulation.
Thermodynamic Model of Turbo-Shaft Engine Starting Process
HUANG Kai-ming, ZHOU Jian-bo, LIU Jie, HUANG Jing-quan, CHENG Ben-lin
2004, 19(5): 703-707.
Abstract PDF(697KB) icon2096 icon420
Abstract:
The thermodynamic real-time mathematic model of aero-engine starting process was established.It is based on component characteristics and it is part of the full-state thermodynamic mathematic model.The influence on starting process caused by temperature rise was studied with the component characteristics change at low part power condition,the boundary condition and the atmospheric condition constraints taking into account.The simulation results are presented,and they prove that the mathematic model can simulate the engine starting process satisfactorily.
Application of Electronic Synthesized Resistor to Matter-in-Loop Simulation Experimentations of Aero-Engine Control Systems
ZHANG Tianh-hong, DING Yi, MOU Lu-yong
2004, 19(5): 708-712.
Abstract PDF(366KB) icon1729 icon464
Abstract:
A kind of synthesized resistor is proposed to emulate thermal resistors in an interface simulator.Several key problems of synthesis are discussed in detail,such as the precision improvement of synthesized resister,the voltage scope expansion of resistor's application circuits,the synthesis circuits adaptation for positive or negative voltage,the multi-channel synthesis circuits development on one board,and the nonlinear characteristic curve fitting.The calibration experiments show that,the steady state accuracy of this synthesized resistor is better than 0.02 Ω,and under the control of programming,it has good dynamic resistance simulation capability,therefore,it is very suitable for matter-in-loop simulation experimentation of aero-engine control system.
Experimental Investigation on Secondary Combustion in Unchoked Ducted Rocket
XIA Zhi-xun, HU Jian-xin, WANG Zhi-ji, GUO Jian, ZHANG Wei, JIANG Chun-lin
2004, 19(5): 713-717.
Abstract PDF(344KB) icon1740 icon474
Abstract:
Some experimental investigations have been done on a direct-connect test bed.The experimental investigation is aimed at exploring factors that affect unchoked ducted rocket combustor efficiency.Aluminum/magnesium-loaded fuel-rich HTPB (Hydroxyl Terminated Polybutadiene) propellant was used.The effect of factors, such as air/fuel ratio,dome height,angle of gas injector on performance of the combustor and the engine was examined.In a definite range of air-fuel ratio,with the increase of air-fuel ratio,combustion efficiency increases.After air-fuel ratio reaches some definite point,further increase of air-fuel ratio,a decrease trend of combustion efficiency is observed.Decreasing the dome height increases combustion efficiency.The impinging jet injection device improves combustion efficiency.If the fuel streams impinge with the airstreams directly at the exit of air-inlet,it makes negative effect on combustion efficiency.
Research on Fault Diagnoses Expert System of Space Propulsion System
ZHANG Chun-liang, ZHANG Zhen-peng, YANG Er-fu, ZHANG Jia -feng
2004, 19(5): 718-723.
Abstract PDF(332KB) icon1711 icon422
Abstract:
Based on artificial intelligence,the combined red-line algorithm is adopted to pick up fault symptoms.The fault diagnostic expert system for space propulsion system was established.The existing experimental data and off-line data display prove that this expert system is effective in real-time fault diagnosis, post flight fault analysis and healthy monitoring, and it can be used in solving engineering problems.
Base Aerodynamic Behavior and Its Effects on Performance of Aerospike Nozzle
WANG Chang-hui, LIU Yu, LIAO Yun-fei
2004, 19(5): 724-729.
Abstract PDF(335KB) icon1540 icon451
Abstract:
Base pressure of a two-cell tile-shaped aerospike nozzle was measured under conditions of 10°,20°,30°,40° cell inclination and 0.0%,0.4%,1.0%,1.4%,2.0%,3.0% base bleed ratio.It was found that in the base region there exists open wake,close wake or open to close transition condition under different ambient pressure.Base aerodynamic behavior does not change with variations of cell inclination or base bleed ratio.Experimental performance change with altitude of two-cell linear aerospike nozzle truncated at 80%,40%,30% and 20% of the full plug length was obtained.The performance of the experimental aerospike nozzle and the pressure distribution along the plug were also computed.The predicted performance show good agreement with measured data.Based on experiments and numerical simulation,the effects of plug truncation and base aerodynamic behaviour on the performance of the aerospike nozzle are investigated.
Quasi-Hertzian Method Based on Numerical Meshing Points Analysis of Spiral Bevel Gears
LIU Guang-lei, FANG Zong-de
2004, 19(5): 730-734.
Abstract PDF(816KB) icon1883 icon457
Abstract:
With the knowledge of tooth surface meshing grids,the influence of tooth surface elasticity on meshing points was analyzed.First a set of numerical methods for meshing points calculation was developed.Then the elastic deformation of the spiral bevel gears was calculated using Hertzian theory and the change of meshing point due to micro angle shift brought about by the elastic deformation was determined.The micro angle induced by the tooth surface elastic deformation causes the change of meshing points. Quasi-Hertzian analysis is defined as the process of tooth meshing analysis.The results show that the micro rotational angle induced by the tooth surface elastic deformation has definite effect on meshing points.
The Tooth-Cutting Design and Analysisfor Non-Zero Modified Spiral Bevel Gear
ZHANG Jin-liang, FANG Zong-de, DENG Xiao-zhong
2004, 19(5): 735-740.
Abstract PDF(779KB) icon2024 icon432
Abstract:
Based on the local synthesis method,the tooth cutting of non-zero modified spiral bevel gear was researched.By proper selection of the spiral bevel gear modification coefficients,the load bearing capacity can be raised and the structures of the tooth surface can be improved.Based on the local synthesis method, the meshing behavior is optimized with the help of controllability of the second order contact parameters.Comparison between the non-zero modified spiral bevel gear and the gear based on Gleason formula,tooth root thickness is added up,the maximal tension stress,compressed stress and contact stress of non-zero modified spiral bevel gear are markedly reduced.

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