2003 Vol. 18, No. 1

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2003, 18(1): 1-1.
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The Calculation of Incompressible Wall Boundary Layer Using GAO-YONG Turbulence Equations
CHEN Guang-ye, GAO Ge, YIN Xing-yu
2003, 18(1): 2-7.
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Unlike widely used turbulence models,the GAO YONG equations use no empirical coefficients or wall functions.In this paper,two dimensional,stationary,and incompressible transitional/turbulent boundary layer with zero pressure gradient is numerically simulated with GAO YONG turbulence model.Employing staggered grid arrangement,an incompressible SIMPLE code with a second order QUICK scheme is used.The calculation successfully simulates the flow and predicts the fundamental properties of the boundary layer such as Cf,the log law,and the defect law,etc,which are close to the experimental data.All the results further verify the adaptability of the equations to real turbulent flow.
Numerical Investigation of Inlet with Swept Compress Ramp
ZHU Yu, LEE Chun-hian, LI Tian
2003, 18(1): 8-14.
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A numerical investigation was conducted about the shock structure at the entrance of the inlets and the effects of entrance flows on aft duct flowfields for a Caret inlet,and also the effect of the fillet circle and shielding region of oblique shocks.N S equations with the standard k-εturbulence model and near wall functions were employed to predict the flowfields.The results showed that asymmetry of oblique shock doesn't affect evidently duct flow due to the existence of strong normal shock.But the flow in the intersection of dual ramp affects evidently the flowfield of aft duct.
Numerical Simulation of Sound Wave Propagation in Subsonic and Supersonic Nozzle
LI Xiao-dong, GAO Jun-hui
2003, 18(1): 15-19.
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A computational aeroacoustics approach is applied to studying sound propagation in subsonic and supersonic nozzle.The spatial derivatives are discretized by DRP scheme,and the low dissipation and dispersion Runge Kutta scheme is used for time integration.The Giles' characteristic 1D unsteady non reflecting boundary conditions are applied to the inflow and outflow boundary regions.Numercial results agree well with analytical solutions and it reveals that the DRP scheme performed very well because of the high resolution and robust stability and is capable of calculating sound propagation.
Effects of Reynolds Number on Compressor Performance and Engine Stability
WANG Jin, LUO Guang-qi, TAO Zeng-yuan
2003, 18(1): 20-23.
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A mathematic model of Reynolds number correcting the performance of turbofan engine compressor was established with Wassell method.Based on the model in which the correction of Reynolds number to the turbo performance was taken into consideration,the effects of Reynolds number on the performance of compressors,on the co work point of engine,and on the surge margin were computed and analyzed.This correction model was proved to be valuable to evaluate the effects of Reynolds number quantificationally when assessing the engine stability.
Sixth Order Accurate Compact Scheme with Group Velocity Control and Application
GAO Hui, MA Yan-wen, FU De-xun
2003, 18(1): 24-31.
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The direct reason of nonphysical oscillations in numerical solution is the non uniform group velocity.This essay developed a modified sixth order accurate compact scheme with the method of group velocity control,and analyzed its accuracy and the behavior of numerical solution with Taylor method and Fourier method.The scheme is high order accurate with less stencil,simple,clear in physical explaining,and efficient in shock capturing.At last,some numerical experiments show the efficiency of the method.
Study of Several Key Technical Problems for Civil Aeroengine Remote Diagnosis
ZHANG Tian-hong, ZUO Hong-fu
2003, 18(1): 32-37.
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The network technology based on Internet and fault diagnosis technology of civil aeroengine are combined in this paper.It is believed that this approach can promote the maintenance and fault diagnosis methods to network environment.As a result,the capability and efficiency of the civil aeronautical maintenance system will be significantly improved.From the point of engineering application,several key technical problems are discussed.The technology status of fault diagnosis for civil aeroengine is analyzed first,and the architecture of remote fault diagnostic system for civil aeroengine is then demonstrated.An idea of improving diagnostic system network is presented that techniques of up down computer structure and Component Object Module (COM) are employed to realize remote operation,status monitoring and controlling.With COM and network database techniques,knowledge storage and inference are realized in web server.Two versatile Computer Supported Cooperate Work (CSCW) environments for remote fault diagnosis are developed,which are based on Labview/G Web Server and Datasocket technology of National Instrument (NI) respectively.
The Analysis of Flow Around a 2-D Airfoil at Low Reynolds Number
YE Jian, LIN Guo-hua, ZOU Zheng-ping, LU Li-peng
2003, 18(1): 38-45.
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Using high order finite difference scheme,a direct numerical simulation (DNS) of low Reynolds number flow around a NACA0012 airfoil was carried out.The Reynolds number based on chord is 1.0×10.4,the angles of attack are 0°,4° and 10°.The computation results indicate that the statistical traits of wake region are similar at angles of attack 0° and 4°.In the wake region distancing trailing edge 0.3 chord,ordered vortex streets exist,the extremum of vorticity and minimum of pressure are located in the center of vortices.Along the streamline,the absolute value of vorticity decreases gradually,while the minimum of pressure increase step by step.The statistical traits of wake region at angle of attack 10° are different from that at other two angles.The absorption of vorticity and formation of high pressure region are two conditions of vortices shedding.
The Analysis of Unsteady Blade Force in a Rotor/Stator Axial Compressor
ZHOU Zheng-gui, HU Jun
2003, 18(1): 46-50.
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Flow of the passage mid span section in a low speed axial compressor is simulated using two dimensional Navier Stokes equations.It is found that the calculated results are in good agreement with the experimental data.The characteristics of blade force frequency chart are investigated by using the Fourier series method.Results show that for different axial gaps between the rotor and stator,fluctuation of the unsteady blade force is mostly determined by the first rank Fourier component.Simplifying the fluctuation as sine function,it can be derived that as long as the number ratio of the disturbing to the disturbed blade row is not integer,the total unsteady blade force fluctuation from the disturbed blade row will approach to zero.
The Current Situation and Development Trend for More-Electric Gas Turbine Engines
XU Long-xiang, ZHOU Bo
2003, 18(1): 51-59.
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The current situation and development trend as well as key technologies such as high temperature magnetic bearing,high temperature displacement sensor,starter generator,and back up bearing for more electric gas turbine engines are reviewed.The information about this kind of aero engine in IHPTET Project is also introduced.Draper Laboratory,Synchrony Company,as well as NASA Lewis Research Center have been cooperating on the IHPTET Project for years to develop the high temperature magnetic bearing system,which is emphasized as the most important key technology for more electric gas turbine engines.Based on the references available,it is most possible that the high temperature magnetic bearing system developed by Synchrony Company will be used in IHPTET Project.By the end of 1997,a similar research project of AMBIT was drawn up in Europe Community.Britain,Germany,France,Austria,and Switzerland were involved in the AMBIT project.
The Estimation of Maximum Instantaneous Distortion Contour Maps
LIANG De-wang
2003, 18(1): 60-64.
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A new method for the estimation of maximum instantaneous distortion contour maps is proposed based on the Fletcher Reeves nonlinear optimum theory in this paper.In the method,the maximum instantaneous distortion values are obtained by experiments or predicted by statistical methods;The Fletcher Reeves nonlinear optimum method is used to determine the pressure distribution that makes the distortion value be equal to the given maximum instantaneous value.A comparison between the estimated and experimental maximum instantaneous distortion contour maps shows that the method described in this paper can accurately predict the range and position of high and low pressure regions,and the position and shape of large gradient of pressure region.
Pulsatile Analysis of Inlet Pressure Distortion in Turbofan Engine
CHENG Bang-qin, TAO Zeng-yuan, LI Jun
2003, 18(1): 65-69.
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The distorted flow field is generated by a distortion generator with a moveable sliding board in the experiment.Statistical analysis of pulsatile pressure is presented based on methods of amplitude domain,time domain and frequency domain.The characteristics of pulsatile pressure in inlet distorted flow field are obtained.And the relations of pulsatile pressure and steady total pressure distortion charts and maximum instantaneous pressure distortion charts are also researched.
Probe into the Mechanism of Clocking Effect in Turbomachinery
HOU An-ping, ZHOU Sheng
2003, 18(1): 70-75.
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A review of the research on clocking effect in turbomacinery in recent years is presented in the paper.As the experiments showed,the benefit acquired by clocking effect in turbine is prominent,and the benefit increases with the flow velocity in compressor.It is believed and interpreted in this paper that the difference of efficency induced by clocking effect results in the unsteady interaction.The introduction of clocking effect is meaningful that this phenomenon gives the way which leads us to use the unsteadiness of flow and urges people to consider function of the flow unsteadiness in the design of turbomachine.An engineering model to make use of clocking effect based on the present understanding of this phenomenon also has been given.
Geometric Design with Polynomial Method for Large Deflection Angle Blades of Transonic Contra-Rotating Turbine
FANG Xiang-jun, LIU Si-yong, WANG Ping, YAN Shan-ping
2003, 18(1): 76-81.
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It's very difficult to design transonic contra rotating turbine blades because of its large flow deflection angle character.The paper mainly discusses how to design contra rotating turbine large deflection angle blades with high order polynomial method.This method keeps the main dynamic performance design parameters unchanged,such as pitch,unguided turning and throat.But the aims of controlling the distribution of gas velocity in the supersonic large deflection angle cascade and restraining the shock produced and its intensity can be achieved by adjusting and optimizing the other subsidiary parameters,and controling the curvature of both pressure side and suction side and the passage convergence of cascade.The numerical experiments show that the high order polynomial analytic method can quickly,efficiently and reliably design high performance supersonic large deflection angle preliminary profiles.
Affection of Canister Surface Thermal Emittance on Heat Receiver
HOU Xin-bin, YUAN Xiu-gan
2003, 18(1): 82-86.
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Heat receiver is one of the key parts of the SDPS.It absorbs the solar flux and stores thermal energy.Since the surface temperatures of canisters are different,the reradiation in cavity will change the flux distribution on the tube outer surfaces,and the thermal emittance of the canister outer surfaces will affect heat receiver thermal performance significantly.The heat receiver cavity radiation mathematical model and the gas tube heat model were used for two values of surface thermal emittance to calculate heat loss,energy absorbed by gas,tube maximum temperature,gas exit temperature and liquid PCM fraction.The results obtained for these two values of emittance were compared and analysed between two surface thermal emittances.It is shown that higher surface thermal emittance is very important to improve the heat receiver thermal performance.
Numerical Simulation of Supercooled Water Droplets Impingement on Icing Surfaces
ZHANG Da-lin, YANG Xi, ANG Hai-song
2003, 18(1): 87-91.
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It is well known that ice accretion on aircraft component would take place when an aircraft flies in clouds at sub freezing temperature.The presence of ice accretion on unprotected aircraft airfoil can change the airfoil shape and can lead to a number of aerodynamic degradation problems.To compute the supercooled water impingement on icing surfaces,the Reynolds averaged Navier Stokes equations and k ε model are used to simulate the airflow over the surface in the present paper.A Eulerian model for air flows containing water droplet is used to compute the water droplet trajectories.The finite control volume formulation is proposed to solve the droplet problem.In order to avoid the numerical diffusion and to increase the accuracy,the MUSCAL scheme is appropriated for approximating the convection terms of governing equations.The Navier Stokes equations are solved independently from the Eulerian droplet equations.While the velocity field of airflow is achieved,the droplet flow equations can be computed.Both the airflow and droplet equations are computed on non staggered meshes.When solving Navier Stokes equations,the pressure correction algorithm SIMPLER is adopted.Results show that changes in MVD and angle of attack have greater effects on impingement limits and collection efficiencies.
The Design and Study of the Annular Combustion Chamber with Centrifugal Fuel Injection
ZENG Chuan, WANG Hong-ming, SHAN Peng
2003, 18(1): 92-96.
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For most micro turbojet layouts,the annular combustion chamber shows itself as one of the best combustion system arrangements.It can usually be shown to be the lightest,least expensive to manufacture,and most efficient combustion system arrangement in terms of utilization of the specified engine volume.In this paper,the design and study of the annular combustion chamber with centrifugal fuel injection are presented.
Investigation of the Ion-Probe Technology for Measuring the DDT Distance
HAN Qi-xiang, WANG Jia-hua, WANG Wei-lai
2003, 18(1): 97-100.
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In order to obtain the Deflagration to Detonation Transition (DDT) distance in the detonative tube,an ion probe system based on comparative electric circuit was made.This system was used to measure the flame propagation velocities along the tube,and furthermore to determine the DDT distance.As compared with high frequency pressure transducers,this system was simpler and cheaper,especially it could be used in the high temperature condition for a longer time.In this paper,the DDT distances of acetylene and oxygen mixture were measured with this system,and the results were consistent with that of high frequency pressure transducers.
The Finite Element Analysis of HLCF Life Prediction for PM FGH95 Based on Damage Mechanics
LIU Xiang-xin, ZHANG Xue-ren, YAN Xiao-jun, NIE Jing-xu
2003, 18(1): 101-108.
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In this paper,based on the theory of damage mechanics, using damage equivalent stress to calculate the damage under 3 D stress status and taking the close effect into account,a subroutine to calculate damage and predict fatigue life on ANSYS platform was developed by APDL and UPFs of ANSYS.The initiation and growth of cracks are simulated by damage developing.The effect of damage on material properties has been taken into considerations by two ways,one is the method of stiffness matrix modification,the other is the effective stress method.The comparison between fatigue test and calculation results indicates that this method is right and feasible,and high accuracy can be obtained when there are no initial defects in PM components.Concerning components with initial defects,a method to simplify the initial defects by means of initial damage was put forward,and was used to evaluate the life of a specimen with initial defects.The method developed in this paper can be used to predict the life of PM components accurately as long as its initial damage has been obtained in relation to its initial status exactly.If the distribution probability of initial damage is known,the reliability design and evaluation of PM components can be carried out by this method.
Detection and Diagnosis of the Gear Fault by the Delayed Correlation-Envelope Technique
MENG Tao, LIAO Ming-fu, LI Hui
2003, 18(1): 109-113.
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In order to reveal the defect signature of rolling element bearings or gearboxes,the vibration signals measured on them are usually demodulated by the envelope analysis,i.e.Hilbert Transform.However,the defect signature obtained by this demodulation is often masked by noise.In this paper,a new method of demodulation,Delayed Correlation Envelope analysis is established to suppress the noise.The autocorrelation functions of vibration signals measured on bearings and gearboxes are first computed,which will reduce the noise greatly,but not change the modulation signature of the signals.Then the autocorrelation functions are delayed for some time lags,which will reduce the noise further.The delayed autocorrelation is then demodulated by Hillbert Transform.The effect of time delay on the demodulation results is also discussed here.The effectiveness of this method is confirmed by both simulation and experiment.
Wear Particles Identification Based on Dempster-Shafer Evidential Reasoning
LI Yan-jun, ZUO Hong-fu, WU Zheng-feng, CHEN Guo
2003, 18(1): 114-118.
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As an important method of information fusion technology, the theory of Dempster Shafer (D S) evidential reasoning has been applied to many areas such as automation,image analysis and object identification and so on.In this paper,the method of D S evidential reasoning is introduced into wear particles identification based on statistic selection and analysis of characteristic parameters of debris,and the statistic tolerance and decision making probability of image parameters of wear particles are also given based on identification test.The program of auto identification of wear particles has been made by means of Dempster Shafer evidential reasoning,and a classifying experiment of wear particles by this method has been done.It is shown in the experiment that the identification accuracy of debris by D S evidential reasoning is very good,and the speed of classification is very fast.
Experimental Investigation of an Adaptive Squeeze Film Damper with Metal Rubber Outer-Ring
GUO Bao-ting, MA Yan-hong, ZHAO Fu-an, HONG Jie
2003, 18(1): 119-123.
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In this thesis an advanced Adaptive Squeeze Film Damper with Metal Rubber outer Ring (ASFD/MRR) is designed to improve high non linearity of oil film force in conventional Squeeze Film Damper (SFD).It has optimal effect of reducing vibration because it can automatically adjust the film clearance by elastic deformation of the metal rubber.The results of experiments indicate that ASFD/MRR could control the clearance of the film,and the characteristics of oil film force of ASFD/MRR are better than these of SFD.ASFD/MRR could markedly restrain the occurrence of the nonlinear vibration phenomenon such as bistable characteristic,lock up and non synchronous motion and ASFD/MRR can be suitable for wider range of unbalanced level.
Rotating Loss Analysis for Active Magnetic Bearing with Solid Rotating Rotor
CAO Guang-zhong, YU Lie, XIE You-bai
2003, 18(1): 124-129.
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Active magnetic bearing (AMB) is widely applied in many industrial fields.When the rotor becomes larger and larger,it is more difficult to manufacture a laminated rotor.Hence,solid rotor is utilized in the large rotor AMB system.Eddy currents are caused inside the rotor when a solid rotor rotates in a radial magnetic bearing.The eddy currents change the magnetic field of the radial magnetic bearing and,therefore,the forces on the rotor include not only the levitation force but also the tangential force.The tangential force causes magnetic damping and losses.This paper presents a magnetic field analytical model of magnetic bearing solid rotor system, and the forces and losses within a practical AMB system are calculated.It is shown that the calculation results are in good agreement with those of experimental study.
Vibration Character and Aeroelastic Stability Analysis of Real Labyrinth Gas Seals
LI Hui, LI Qi-han, YAN Li-tang
2003, 18(1): 130-133.
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Labyrinth gas seals are commonly used for aeroengines and other machines.But failures,such as sound machine coupling,vibration mode harmony and aeroelastic flutter,often occur.We analyzed the vibration character and aeroelastic stability of labyrinth gas seals which are used in a real aeroengine.According to the analysis result,we give some useful suggestions.
Active Vibration Control Using Magnetostrictive Material
LI Chao, LI Lin
2003, 18(1): 134-139.
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A method for active vibration control has been investigated in the field of high precision vibration control in this paper.Firstly,the magnetostrictive material,Terfenol D,and actuator made of it,were analyzed.Secondly,the application of adaptive filter algorithm (LMS) to active vibration control was discussed.Finally,section Ⅲ will be devoted to an introduction to one D.O.F active vibration control real time experiments,in which Terfenol D actuator and LMS algorithm were adopted.From the results of real time experiments,it can be concluded that the magnetostrictive material and adaptive filter algorithm are reasonable choice for active vibration control.
General Life Model Adapted to Both Stress Fatigue and Strain Fatigue
ZHAO Fu-xing, SHI Hai-qiu, GENG Zhong-xing
2003, 18(1): 140-145.
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A general life model adapted to both stress fatigue and strain fatigue is deduced,through analyzing the influence function of strain distribution on life.Strain fatigue and stress fatigue are related by the influence coefficient of strain distribution.This method can be applied to designing sample components for fatigue test as well as to forecasting various fatigue life of component from stress fatigue to strain fatigue.Examples of calculating various typical materials with typical stress concentration are listed in this paper.
Using WTCM to Analyze Rub-Impact Default of a Complex Rotor System
MENG Yue, LI Qi-han
2003, 18(1): 146-150.
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In dynamic characteristic analysis of rotor system,a new method Whole Transfer Coefficient Method (WTCM) is studied and proposed.In this paper,transient response is calculated for the rub impact fault of single rotor system and dual rotor system by WTCM and analyzed by FFT.The result compared with that of the experiments' indicates that using WTCM to analyze the transient response of rub impact between rotor and stator in rotating machinery is convenient and simple.
The Influence of Speed and Mass Unbalance on Dynamic Characteristics of a Gear-Rattling System
ZHANG Suo-huai, SHEN Yun-wen, DONG Hai-jun, LIU Meng-jun
2003, 18(1): 151-157.
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The rattling model of a one stage gear system was established,in which mass unbalance,speed fluctuation of driving shaft and backlash of the gear pair were considered.Its governing equations represent a mapping system.By means of numerical simulation,three rattling conditions were researched:(1) speed fluctuation exists only;(2) mass unbalance exists only;(3) both coexist.According to the calculation results,at different inspiring factors and amplitudes,there are different rattling dynamic characteristics,for example,one period,multiple period and quasi period.The rattling resulting from speed fluctuation is different from that resulting from mass unbalance.The rattling characteristics resulting from both simultaneously are different fro-m overlapped characteristics resulting from both individually.It is more reasonable that the factors of speed and mass unbalance are taken together to investigate the rattling dynamics of a gear system.
Effect of Igniter Charges on Internal Ballistic Performance for an Impulsive Microthruster
ZHANG Ping, LI Shi-peng, LIU Yu-qun
2003, 18(1): 158-160.
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The three sets of F t curves from impulsive microthrusters tests were studied,which are used for the attitude correction of kinetic missiles or hypervelocity rockets.It is found from the study that the amount of the igniter charge can be of significant effect on the F t curves and internal ballistic performances of an impulsive microthruster,due to its ratio of igniter charge to main propellant charge being obviously different from that of conventional SRM.The amount of igniter charge must be strictly controlled so that the satisfactory internal ballistic performances can be obtained.

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