2006 Vol. 21, No. 1

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Display Method:
Application of High-Order Accurate Scheme in DNS
XIAO Kai-tao, LIU Ji-ping, DUO Ying-xian, YUAN Xiang-jiang
2006, 21(1): 1-6.
Abstract PDF(614KB) icon1862 icon387
Abstract:
The influence of the different finite difference schemes on the transmission of T-S waves in flat plate boundary layers and free shear flow was studied.The results show that if 2nd order scheme is used,the T-S waves always decay in the flat plate boundary layer.Although the T-S wave grows in the free shear flow,no three dimensional structures appear.If high order scheme is used,the T-S wave grows in the plate boundary layer.The results obtained by DNS agree well with linear stability theory.In the free shear layer,not only the T-S wave grows quickly in the free shear flow,but also three dimensional waves appears evidently and three dimensional structures are excited.
Numerical Simulation of Incompressible Turbulence in Tubes Using GAO-YONG Turbulence Model
WANG Xu-lun, GAO Ge
2006, 21(1): 7-12.
Abstract PDF(344KB) icon1968 icon406
Abstract:
Two-dimensional,axisymmetric,stationary,and incompressible Hagen-Poiseuille flow was numerically simulated with GAO-YONG turbulence model using SIMPLER(Semi-Implicit Method for Pressure-Linked Equations) method and PLS(Power Law Scheme).As a result,the calculation successfully simulates the flow and predicts the fundamental properties of the boundary layer,including the natural transition process,which are close to the experimental data.It verifies the adaptability of GAO-YONG turbulence equations to real turbulent flow.
Performance Optimal Design of Aircraft Engine Based on Multi-Objective Genetic Algorithms
LI Li-jun, YIN Zeyong, QIAO Wei-yang
2006, 21(1): 13-18.
Abstract PDF(1285KB) icon2041 icon442
Abstract:
Multi-objective optimization concepts,linked with a Pareto genetic algorithm-Non-dominated Sorting Genetic Algorithm(NSGA Ⅱ),are applied to the preliminary design phase to automate the conceptual design process.Engine cycle selected for study was a mixed-stream,low-bypass turbofan.The robust analysis codes for the thermodynamic engine cycle,flowpath and weight estimation analyses were integrated to find higher quality design.The results showed that NSGA Ⅱ has better robustness and convergence than general multi-objective optimization methods,and could generate uniformly a Pareto optimal set in the design space.From this set,decision maker can choose the best overall optimum aircraft engine preliminary design.
CFD Simulation and Validation of Ducted Tail Rotor
YU Zi-wen, CAO Yi-hua
2006, 21(1): 19-24.
Abstract PDF(1696KB) icon1754 icon454
Abstract:
The flow field and performance of a helicopter ducted tail rotor in hovering and sideward flight were analyzed using CFD(Computational Fluid Dynamic) technique.At first the general governing equations of turbulent flow around ducted tail rotors were set up,and then directly solved by finite volume approach and SIMPLE(Semi-Implicit Method for Pressure-Linked Equations) approach in an axisymmetric coordinate system.The spinning fan was represented as time-averaged momentum source terms distributed along the span of the fan with functional relationship to the local flow conditions in N-S equations.The calculation method also included a stair-step representation of the shroud,staggered grid system,the k-ε turbulence model and wall function method on the shroud.The calculated results of flow field and performance correlation show good agreement with the measured data.Therefore,it is concluded that the numerical simulation technique is proved to be feasible for analyzing design issues of ducted tail rotor.
Numerical Investigations of Separation Control of a Hump Model with Steady Suction and Injection
JI Lu-cheng, LIN Feng, Marco P Schoen
2006, 21(1): 25-30.
Abstract PDF(1288KB) icon1566 icon363
Abstract:
A series of numerical parametric studies on active control of separation flow over a hump model are presented. The model is a generic model for both internal and external flow,designated by NASA for CFD validation of active separation control.The focus is on the influence of steady suction and injection when a variety of operating parameters are varied.An in-house-use CFD code is first validated against experimental data and other CFD results,followed by a series of numerical simulations.Results show that the behaviors of steady suction are significantly different from that of steady injection.At the given geometry,the suction alone cannot completely eliminate the separation bubble in the flow-field of the hump model regardless of how much suction flow rate is used,but the injection can.The detailed flow structure and mechanisms are also presented and discussed.
Numerical Investigation on Inlet/Isolator Flow Field of a Dual-Mode Scramjet
HAN Zhao-lin, WANG Qiang
2006, 21(1): 31-35.
Abstract PDF(317KB) icon1971 icon379
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Inlet and isolator are key components of the dual-mode scramjet.They should not only provide enough airflow to the engine,but also show preferable starting characteristics and supply airflow with good quality.In this paper,finite volume method and 2nd order TVD upwind scheme were exploited with S-A turbulence model to investigate the flow field in the inlet and isolator.The influence of inlet convergent angle and inlet cowl length on the performance of inlet and isolator was analyzed.The investigation indicates that isolator tend to resist higher back pressure and provide exit airflow with better quality under conditions of high mach number and low distortion.
Analysis of the Computational Method and the Helicopter Blade Characteristics with Coupled Rigid and Elastic Motions
HAN Dong, GAO Zheng, WANG Hao-wen, ZHANG Hong-qiu
2006, 21(1): 36-40.
Abstract PDF(768KB) icon1742 icon445
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In order to investigate the coupling characteristics between elastic deflections and rigid motions of the blades,the moderate deflection beam model was adopted to treat elastic deflections and two methods were adopted to treat rigid motions based on infinitesimal rotation and finite rotation.The impact problem of the blade droop stop was analyzed.Results show:(1) coupling of elastic deflections with rigid motions is distinctive;(2) computations of two methods are in good agreement with test data,when rotation angle is small;(3) when rotation angle is large,couplings increase distinctly and the differences between the results of the two computational methods increase;(4) the bending stiffness has evident effect on the coupling,and the coupling will increase with the decrease of bending stiffness;(5) in case of the blade is relatively soft,the calculated values of phase lag and amplitude augment based on infinitesimal rotation will exist.This phenomenon should be paid attention to,when blade dynamic response is calculated.
Performance Analysis for a Gas Generator Test-Run
MIAO MIAO, WANG Wen-jie
2006, 21(1): 41-44.
Abstract PDF(626KB) icon1713 icon443
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Parameters at different sections of some home made gas generator were measured with a technical nozzle to simulate the flow capacity of a power turbine.The data indicates that the performance of the gas generator can reach the design goal.During the ground test under different working conditions of the gas generator,the influences of the radial clearance and exhaust nozzle area were studied.This provides a technical support for improving performance of the gas generator and the matching of the power turbine with the whole engine.
Investigation on Pneumatic-Valve Pulse Detonation Engine with Partial Detonable Mixture Filling
LI Jian-zhong, WANG Jiahua, FAN Yu-xin, ZHANG Yi-ning, ZHANG Jing-zhou
2006, 21(1): 45-49.
Abstract PDF(1168KB) icon1635 icon442
Abstract:
Effects of partial detonable mixture filling proportion on detonation wave pressure properties of kerosene/air pneumatic-valve pulse detonation engine were investigated.A preliminary analysis of a series of wave's reciprocity was carried out.Experimental results show that with given double swirl and direct pneumaticvalve and detonation tube structure,the decrease of partial detonable mixture filling proportion causes a little decrease of the peak value of detonation waves' pressure,but impulse per unit volume of detonable mixture increases linearly.This investigation is important to the design optimization of the kerosene/air pneumatic-valve PDE,and to improve the performance of PDE.
Exploratory Experimental Investigation of Kerosene/Air Two-Phase Pulse Detonation Engine
ZHANG Qun, YAN Chuan-jun, FAN Wei, LI Qiang, LI Jiang-hong
2006, 21(1): 50-55.
Abstract PDF(399KB) icon1897 icon457
Abstract:
Using kerosene as fuel and air as oxidizer,two-phase detonation experiments were successfully conducted in two pulse detonation engine models with the diameters of 30 mm and 50 mm respectively.A variety of devices and means promoting the initiation of detonation were tested,and fully developed repetitive C-J detonation waves were obtained during the experiments.It's found that successful two-phase pulse detonations can be achieved in tubes with diameters less than cell size of mixtures.By means of heating kerosene and the tube wall,the ignition and the subsequent detonation initiation were promoted markedly.
Numerical Simulation of the Flowfield in a Scaled down Scramjet Combustor
WANG Yuan-guang, XU Xu, CAI Guo-biao
2006, 21(1): 56-60.
Abstract PDF(1352KB) icon1725 icon409
Abstract:
A new concept was raised and adopted to enlarge the scope of two-dimensional model particularly in dealing with three dimensional normal injection cases.Meanwhile,the method has a very good performance in terms of time consuming.The new idea was realized through special disposal with the continuity equations,i.e.,mass flow are added in the source term of the continuity equation.To prove the robustness of this simplified method,in accordance with the test condition published in the literature,calculation was carried out.Calculating results compared with three dimensional programs prove to be satisfactory.A model scramjet combustor tested on the free-jet scramjet test facility was demonstrated and undergone numerical calculation with the two-dimensional program adopted theabove injecting simplification.To simulate the chemical reaction process in thescramjet tunnel,a 5-specise,single step reaction model was introduced.The major aerodynamic parameters and components mass fraction distribution within the model combustor channel were presented.This makes it easy to observe and analyze the flow field.Comparisons of wall pressure between the numerical and experimental results prove the adequate accuracy of the calculation model.
Experimental Study of Heat Transfer Characteristics inside Two-Pass Variable Cross-Section Channels with Different Rib Angles
ZHANG Li-min, LIU Xiangyun, DING Shui-ting, TAO Zhi, XU Guo-qiang
2006, 21(1): 61-64.
Abstract PDF(446KB) icon1733 icon396
Abstract:
The effect of the rib-angle orientation on heat transfer distribution was experimentally studied inside twopass variable cross-section channels.The heat transfer distributions for ribbed channels were compared with channels without ribs.Ribs with rectangular crosssection were arranged symmetrically on two opposite walls.Analysis of the experimental results may lead to the following conclusions:the heat transfer effect of the channel with ribs is 50% higher than that of the channel without ribs.The 60° ribs were not necessarily the optimum option as published in the literature.Tests show that 90° ribs produce a higher heat transfer for the relative roughness height of 0.092.
Investigation of Flow Fields in a Short Confined Channel with Staggered Jet Impingement
KONG Man-zhao, LIU Hai-yong, LIU Song-ling, SHEN Tian-rong
2006, 21(1): 65-70.
Abstract PDF(1488KB) icon1695 icon439
Abstract:
Experimental and numerical simulation results were presented to describe the flow behavior in the channel with staggered jet impingement arrangement.Measurements of flow characteristics at different Reynolds numbers and different channel heights were performed using a five-hole probe.Important results are:(1) there are complicated vortices in the channel;(2) with the same channel height,Reynolds number does not play an important role to the channel flow characteristics;(3) the change of channel heights has significant effect on flow characteristics.
Effect of Helix-Alike Fin Surface Shape on Flow and Heat Transfer in the Internal Cooling Passage
QIU Qing-gang, SHEN Sheng-qiang
2006, 21(1): 71-76.
Abstract PDF(505KB) icon1602 icon486
Abstract:
3-D Navier-Stokes equations were solved with the conventional k-ε turbulence model to predict turbulent flow and heat transfer in the internal cooling passage of the gas turbine blades,in which the staggered arrays of discrete helix-alike rectangular-fins or wedged-fins with a certain angle were used along two inside opposite walls.Results were presented for Reynolds number in the range of 1×104 to 2×105,cross-section aspect ratio of 2.9,fin height to hydraulic diameter ratio of 0.336,fin height to passage height ratio of 0.5,and the inclined angle of the helixalike fin of 15°.A complicated 3-D accelerated spiral-flow which just likes the fluid flow in helical-fin tube has been formed and it has significant effects on the heat transfer.The averaged Nusselt number ratios decrease and the friction factor ratios increase with the increasing Reynolds number for all the studied cases.Also the detailed discussion of the influence of helix-alike fin surface shape on heat transfer and pressure drop was given.It is found that,the heat transfer enhancement in the internal cooling passage with helix-alike rectangular-fin is better than others,but the comprehensive enhancement performance ratio is lower than that with helix-alike wedged fins.
Investigation on Analytical Solution of One-Dimensional,Steady,Non-Equilibrium Transpiration Cooling
WANG Hai-nan, WANG Jian-hua
2006, 21(1): 77-82.
Abstract PDF(335KB) icon1902 icon365
Abstract:
To analyze the error caused by the assumption of Local Thermal Equilibrium(LTE) in the problems of transpiration cooling,and to avoid the problem involved in the reasonable presentation of the boundary conditions in solving the differential equations of the Local Thermal Non-Equilibrium(LTNE),the heat conduction of the gaseous coolant in the pores of porous media was neglected.Based on this simplification,an analytical solution of the one-dimensional LTNE model was obtained.Using the solution,the key parameters controlling the variation trend from LTNE to LTE were analyzed,and a quantitative criterion to evaluate the LTE assumption was suggested.The factors that influence the effectiveness of transpiration cooling were also discussed.
Numerical Investigation on Improvement of Film Cooling Effectiveness Using Delta-Shaped Tabs
LI Yong-kang, ZHANG Jing-zhou, YAO Yu
2006, 21(1): 83-87.
Abstract PDF(3766KB) icon1788 icon451
Abstract:
The flow fields and cooling effectiveness of the film cooling from a row of cylindrical angled holes with triangular tabs are investigated numerically in several blowing ratios,to reveal the effects of tabs on the film cooling performance.The tabs are located along the upstream edge of the holes and placed parallel to the film cooling surface covering a part of the hole.The results show that the tabs improve film effectiveness due to the penetration of the film secondary flow into the cross flow is suppressed under the action of the tabs.And the film cooling effectiveness improvement is significant in the cases of higher blowing ratio and higher tab blocking ratio.
Study of the Influence of Structural Parameters on the Vortex Tube Performance
JI Yu-bang, WU Yu-ting, DING Yu, HE Shu, JIANG Shu, MA Chong-fang
2006, 21(1): 88-93.
Abstract PDF(928KB) icon1779 icon446
Abstract:
The influence of different configurations,such as vortex tube length,separation chamber diameter and cold plate diameter on the vortex tube performance was investigated by experiment with air as medium.The main influence of length and diameter on the vortex tube performance was obtained in this paper.The result indicates that the performance can be improved by the increase of hot tube length in a certain range.The cooling effect of vortex tube with larger separation chamber diameter is better than that with smaller diameter in the condition of higher cold mass flow fraction.The less the diameter of cold plate is,the better performance will be.The best cooling effect and heating effect occur at the diameter ratio of hot section inner diameter to cold plate hole diameter being 50%.
Numerical Simulation of Gust-Cascade Interaction Noise
LI Xiao-dong, LIN Da-kai
2006, 21(1): 94-99.
Abstract PDF(634KB) icon1783 icon432
Abstract:
The gust-cascade interaction noise was numerically simulated using computational aeroacoustics by solving the two-dimensional linearized Euler equations.In order to minimize the dispersion and dissipation errors,the dispersion-relation-preserving scheme was applied to perform the spatial discretion and the optimized 4/6 low-dissipation and low-dispersion Runge-Kutta scheme was used for the time integration.Appropriate boundary conditions were prescribed or established for various boundaries.The non-reflecting boundary conditions were firstly validated by simulating gust convection in the free space.Then the interaction noise due to the gust/flat-plate cascade was simulated.The numerical results agree well with exact solutions.Finally the numerical results of the noise from the gust/cascade(with NACA-0012 airfoil) interaction are presented which demonstrates the feasibility of the numerical procedure.
Numerical and Experimental Investigations of the Flow in a Compressor with Circumferential Grooves
CHU Wu-li, LU Xin-gen, WU Yan-hui
2006, 21(1): 100-105.
Abstract PDF(1115KB) icon2083 icon382
Abstract:
Numerical and Experimental investigations were conducted to study the effect of circumferential grooves on the performance and flowfield of an axial-flow compressor rotor.A single-stage compressor rotor with no inlet guide vanes was tested under subsonic condition.Circumferential grooves as well as the original smooth wall configuration were analyzed to investigate the effects of circumferential grooves on compressor performance.The result shows that circumferential grooves are able to effectively extend the stall margin of the compressor with little influence on efficiency throughout the mass flow range tested.Steady-state Navier-Stokes analyses were performed to analyze flow structures associated with each casing treatment.The overall effects of circumferential grooves were correctly calculated with the numerical procedure.Detailed investigation of the calculated flow fields indicates that the key mechanism lay to the interaction with the tip leakage.Taking advantage of the existing pressure difference in the rotor blade row,circumferential grooves remove tip leakage flow in the high pressure zone and weaken or even destroy the structure of tip leakage vortex.At the same time the tip leakage reenters the main flow in the low pressure zones again and mixes with the main flow of the compressor,thus circumferential grooves influence the efficiency and stall margin of the compressor.
Flutter Analysis of 2-D Cascades under Gas-Solid Coupled Conditions
XIAO Jun, ZHOU Xin-hai, GU Chuan-gang, DAI Zheng-yuan, WANG Tong
2006, 21(1): 106-111.
Abstract PDF(356KB) icon1821 icon393
Abstract:
The structural dynamic equations for blades were introduced in this paper.Through numerical solving the aerodynamics-structure coupled equations,a 2-D unsteady viscous flow in cascade was investigated under gas-solid coupled conditions,and a preliminary analysis of the cascade flutter was prosecuted.The flows of different reduced frequencies were computed for two blade profiles respectively.By comparing the relative parameters changing with time in the oscillating cascades under different conditions,it indicates that the reduced frequency is an important factor in determining whether the blade flutter onsets or not.
Influence of Moving End-Wall on Tip Clearance Flow in an Axial-Flow Compressor Cascade
WU Yan-hui, CHU Wu-li, LIU Zhi-wei
2006, 21(1): 112-118.
Abstract PDF(1377KB) icon2116 icon394
Abstract:
Blocked structure three-dimensional Navier-Stokes flow solver has beendeveloped and applied to investigate the complex flow phenomena in the tip gap of axial flow compressor cascade.Numerical analysis was carried out to investigate the influence of tip clearance on the flow-field in a compressor cascade with a moving end-wall.The calculated results were compared with the available experimental data and good agreements were achieved.Secondary traverse flow velocity vector plots show the scrapping of the tip leakage vortex from the suction surface of one blade across the blade pitch to the pressure surface of the adjacent blade.
Design of a High Rotating Speed,Low Flow Rate Axial Flow Fan Used on Helicopters
GAO Hong-xia, YU Jian-zu, XIE Yong-qi
2006, 21(1): 119-124.
Abstract PDF(1061KB) icon1917 icon481
Abstract:
In the oil cooling system of a high performance helicopter,the low mass flow,high rotating speed and small size axial flow fan design is a key task.This special fan's structure was analyzed,and optimization of the relevant parameters was conducted.To obtain good aerodynamic characteristics,the radial aerodynamic balance equations were adopted to build the fan's rotating blades,which were evolved from the simplified three dimensional flow theories,the constraint conditions and the control vortex theory.The improved loss computing method was used to calculate the fan's efficiency,and to optimize design schemes.There is a good agreement between the design results and the experimental data while the design method is applied to an axial flow fan design for a helicopter.
Coupled Flow Analysis on the Excitation Effect in Annular Enlarged Cascade
XIONG Jin-song, TUO Wei, HOU An-ping, ZHOU Sheng
2006, 21(1): 125-130.
Abstract PDF(1533KB) icon1960 icon422
Abstract:
In regard to the excitation experiments,time-Accurate numerical stimulation was carried out to investigate the upstream disturbance frequency effect under different incidence in an annular cascade.Combined with experimental results,the disturbance frequency effect on loss coefficient,load factor,and work-loss ratio was discussed.The change of time-space flow structure is the principal cause of the performance improvement.
Aerodynamic Redesign of a Centrifugal Compressor Impeller
CHEN Jiang, JI Lu-cheng
2006, 21(1): 131-136.
Abstract PDF(916KB) icon1535 icon483
Abstract:
Aerodynamic redesign of an aero-engine centrifugal compressor impeller was presented.The goal is to increase efficiency by more than two percents.NUMECA Fine/Turbo was used as a numerical tunnel to ensure the design.Results show that the redesigned impeller successfully reached the goal.The experiences accumulated in this procedure are useful for similar impeller aerodynamic designs.
Effects of Tip Clearance Grids on the Simulations of Three-Dimensional Flow Fields in a Low Speed Compressor Rotor
ZHANG Hui, MA Hong-wei, JIANG Hao-kang
2006, 21(1): 137-143.
Abstract PDF(1616KB) icon2090 icon430
Abstract:
The 3-D flow fields of a low-speed axial compressor rotor with a tip clearance were calculated.Compared with experimental results,effects of the tip grid-matching and the grid quality on numerical results were investigated.The result shows the requirement of the gird-matching between the tip clearance and the rotor passage for simulations of flow details in the tip clearance,and the sensitivity of the second-order difference scheme to the grid quality.In addition,it was revealed that the pressure rise characteristics did not exactly reflect the effect of grid numbers on numerical results.
Numerical Simulation of the 3-D Unsteady Flow in the Steam Turbine Last Stage
QI Lei, ZOU Zheng-ping, LU Hong-zhi, YU Er-liang, Tian Dong-qiang, Shi Li-ming
2006, 21(1): 144-149.
Abstract PDF(2348KB) icon1629 icon402
Abstract:
The unsteady flow of the steam turbine at design state was studied by the method of numerical simulation of 3-D viscous flow,and the analyses of unsteady force on the blade surface and the mechanism of action were carried out.The result indicates that at typical design operating conditions in the last stage of the steam turbine investigated here,shock and potential field interaction from upstream blade row is an order of magnitude greater than wake interaction.The shock and potential field interaction effects cause a periodic increase in the strength of the unsteady force acting on the downstream rotor blade surface.In addition,the wake interaction of upstream blade row and the expansion wave at rotor exit also cause an unsteady force acting on the downstream rotor blade surface.
Influence of Incidence on Secondary Vortex in the Compressor Cascade
ZHANG Hua-liang, WANG Song-tao, WANG Zhong-qi
2006, 21(1): 150-155.
Abstract PDF(1244KB) icon1570 icon457
Abstract:
Through numerical simulation based on the experimental results,the topology theory and the rules of surface pattern were used to analyze the development of the secondary vortex with several different incidences in the compressor cascade.Then the topology patterns of the separation structures were presented.The result shows that the range of the suction surface separation expands and the unsteady effect of the flow field increases with the increase of the incidence.At the same time,the separation model transits from the open separation to the closed separation.And the corner vortex is not sensitive to the variation of the incidence.At last,the author proposed a new vortex model for the compressor cascades.
Visualized design of turbomachinery Using Bezier Spline
YIN Ming-xia, LIU Qun-hui, GUI Xing-min
2006, 21(1): 156-160.
Abstract PDF(1442KB) icon1309 icon437
Abstract:
The profile design is one of the key tasks in the design of turbomachinery.Visualized design of the profile was propitious to realize the local blade optimum directly and efficiently.Based on Bezier theory,here a visualized software using Open GL API as graphic development tool was developed for 2D blade profile optimization.The comparison between the numerical results of pre-design and post-design shows that the stagnation pressure loss coefficient of modified airfoil is significantly decreased.It is indicated that the software can be effectively applied to turbomachinery design.
Study of Vibration Response Analysis Method for the Dry Friction Damping Systems
QI Wen-kai, GAO De-ping
2006, 21(1): 161-167.
Abstract PDF(470KB) icon1583 icon432
Abstract:
The macro-micro slip model was used to analyze vibration response of plate blades with a dry friction damping.Compared to the experimental results,the analytical method was proved to be feasible.Non-dimensional normal force was defined,and by the use of it,the relationship between the vibration responses and non-dimensional normal force of the plate blades with a dry friction damper were obtained.The calculation results indicate that in the micro-slip stage,the friction damper can markedly reduce the responses of the vibration system,so that the introduction of micro-slip model is very important,and the non-dimensional normal force can be used as a design variable of dry friction dampers to optimize parameters of damper making the response of a vibration system to be minimum while resonance occurs.
Investigation of the Vibration Control by Frictional Constraints between Blade Shrouds-Theoretical Method
SHAN Ying-chun, ZHU Zi-gen, LIU Xian-dong
2006, 21(1): 168-173.
Abstract PDF(452KB) icon1798 icon472
Abstract:
A new approach was developed to solve the nonlinear responses of the blades with shrouds.Transforming the calculation between frequency domain and time domain was necessary.The nonlinear friction forces were calculated between complicated friction interfaces of the shrouds by tracing the trajectory of the contact point.This numerical method was combined with the harmonic balance method and the dynamic compliance method to solve the nonlinear responses of the blades.The effects of blade high order vibration modes and the high harmonic components of the blade response were taken into account.This theoretical method can be applied to design and fault diagnosis of the blades with shrouds.
Investigation of the Vibration Control by Frictional Constraints Between Blade Shrouds-Rule Analysis
SHAN Ying-chun, ZHU Zi-gen, LIU Xian-dong
2006, 21(1): 174-180.
Abstract PDF(484KB) icon1608 icon403
Abstract:
The performance of shroud damper was investigated systematically by researching the nonlinear responses of plate blades with shrouds.The influences of many contact parameters such as initial normal force,contact angle,contact stiffness and coefficient of friction were obtained.Furthermore the vibration responses of an aero-engine fan blade were investigated.The effects of shroud on the first bending mode and a higher mode of the fan blade were analyzed,and the reason of blade fracture due to fatigue was determined.The results can be used to the design and the fault diagnosis of blades with shrouds.
Determination of Lubricant Elastic Shear Modulus under Conditions of High Pressure and High Shear Rates
WANG Yan-shuang, YANG Bo-yuan, WANG Li-qin
2006, 21(1): 181-185.
Abstract PDF(1370KB) icon1607 icon392
Abstract:
Traction coefficients of the new aviation lubrication oil were measured on a self-made test rig.The formula for calculating the elastic shear modulus of rollers with lubricant under conditions of high pressure and high shear rates was presented.The expressions relating effective elastic shear modulus of rollers with lubricant to the lubricant elastic shear modulus were derived.Using the new aviation lubrication oil as an example,the effective elastic shear modulus were calculated in various operating conditions.The results show that both the elastic shear modulus and the lubricant elastic shear modulus increase with the increase of pressure,and the higher the pressure and the lower the temperature and rolling speed,the greater the effect of the tangential compliance on shear deformation will be.
A Framework of Cooperated Aero-Engine Pipe Routing Multi-Agent System
FAN Jiang, CHEN Zhi-ying, WANG Rong-qiao
2006, 21(1): 186-189.
Abstract PDF(603KB) icon1658 icon426
Abstract:
It is complex to design aeroengine pipe routing system because it depends on the cooperation of many disciplinary.We design a three layer framework including design,service and resource to support aircraft engine pipe routing.Each layer uses a agent to finish its function.Under this framework,a routing workflow is discussed.
Dimension Conversion from Hot State to Cold State of the Turbine Components
NIU Dong-sheng, CHEN Wei
2006, 21(1): 190-194.
Abstract PDF(1405KB) icon1514 icon454
Abstract:
Tip clearance of the turbine plays an important role on the aeroengine performance.Dimension conversion from hot state to cold state of the turbine components is an important content of tip clearance research.In this paper,dimension conversion method using design optimization was introduced.Based on this method,a blade was analyzed.Compared with simplified method,the result is reasonable and feasible.A turbine disc was also successfully calculated with the design optimization method.Thus,the problem of dimension conversion was solved.
Aero-Engine Adaptive Model Re-Construction under Sensor Failure
YUAN Chun-fei, YAO Hua
2006, 21(1): 195-200.
Abstract PDF(385KB) icon2129 icon458
Abstract:
The measured parameter deviations from nominal values can be used to predict the deterioration level of an aero-engine.A state variable model,which considered the deterioration factors,was developed.These deterioration factors were then treated as augmented states of the state variable model,thus they could be predicted by the Kalman filter based on sensed parameter deviations.If there was a sensor failure,the prediction results might not be appropriate.So a series of Kalman filters were designed as a diagnostic method to search the failed sensor.The adaptive model could be re-constructed once the failed sensor was found out.The immeasurable output parameters were trimmed by the predicted deteriorations.Adaptive performance of the re-constructed adaptive model were presented and compared with the model which had no sensor failures.The re-constructed adaptive model is shown to be able to well match the actual engine.
Investigation on Aircraft Engine Anti-Surge/Surge Eliminating Control System
QIN Hai-bo, SUN Jian-guo
2006, 21(1): 201-206.
Abstract PDF(782KB) icon1634 icon446
Abstract:
Anti-surge/surge-eliminating control system design is a key task to ensure engine safety and also a week link during the development of an aircraft engine.To solve this problem,the investigation and analysis of the system performances using a complex electronic regulator and on-site special testing equipment were carried out.The results show that the anti-surge criteria should be dynamically corrected according to engine high-pressure compressor speed and engine inlet air pressure,while protective measures should be taken to increase the reliability and safety of the system.
Aeroengine Gas Path Fault Diagnosis Using Rough Sets and Neural Networks
CHEN Tian, SUN Jian-guo
2006, 21(1): 207-212.
Abstract PDF(694KB) icon1743 icon424
Abstract:
Aeroengine is a very complex nonlinear object.Traditional methods for its fault diagnosis were proved time-consuming and low efficient.A new system based on rough sets and neural networks for the fault diagnosis of aeroengine gas path component faults was presented in this paper.At first,the rough set theory was used to detect qualitatively faults and to isolate the fault.It consists of three steps:performing the discretion of sensed data,establishing the decision table and generating rules.After that,feed-forward neural networks are added into the system to construct several subsystems,which take the engine sensible data pretreated by rough sets as inputs and compute damage degrees of the aeroengine fault.Finally,the noise rejection abilities of the engine fault diagnosis system were analyzed.The test results show that the system can quantitatively diagnose the faults of aeroengine gas path components precisely and efficiently,while it is robust for noise rejection.
Neural Network Identifier with Fuzzy Logic Compensation for Aero-Engine Rotating Speed Control System
QIAN Kun, XIE Shou-sheng, ZHANG Wei, HE Xiu-ran
2006, 21(1): 213-218.
Abstract PDF(880KB) icon1532 icon434
Abstract:
A new neural network algorithm with fuzzy logic compensation was proposed and applied to an aero-engine rotating speed control system.A dynamic neural network was used to identify the plant on-line.The control signal was then calculated iteratively according to the responses of a reference model and the output of identified plant.A fuzzy logic block with four very simple rules was added to the loop to improve the overall loop properties.Experimental results demonstrate that the proposed control strategy provides better disturbance rejection and transient properties than those achieved by conventional mechanical-hydraulic controller and Analogue Engine Electronic Controller(AEEC).At the same time,it can improve transient quality in control system,and meet the requirements of high performance guideline and high control accuracy in turbofan engine.
Application of Correlation Dimension and Kolmogorov Entropy in Aeroengine Fault Diagnosis
YU Bo, LI Ying-hong, ZHANG Pu
2006, 21(1): 219-224.
Abstract PDF(1675KB) icon1635 icon497
Abstract:
The algorithm for the calculation of correlation dimension and Kolmogorov entropy was introduced.According to the analysis of chaos identity and the correlation dimension and Kolmogorov entropy of some engine,a new method of fault diagnosis that integrated correlation dimension with Kolmogorov entropy was proposed.The results show that the different fault has different correlation dimension and Kolmogorov entropy because of their different kinetics mechanisms,and thus correlation dimension and Kolmogorov entropy can be used to identify the fault symptoms.

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