2001 Vol. 16, No. 1

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Deliberation Upon Advance of Aeroengine Development in China
LIU Da-xiang
2001, 16(1): 1-7.
Abstract PDF(1044KB) icon1810 icon455
Abstract:

Aeroengines seem to be the hearts of aircrafts.But the aeroengines in China lag behind the advanced world level and become the bottle neck in the development of our military and civil aircrafts.A lot of things account for this occurrence,that is worthy thinking out and summing up our experience and lessons.Thanks to our efforts in the latter half of the 20th century,particularly due to rapid development during the past two decades,we possess the capability and backbone of up-to-date aeroengine development.In front of new century there exist challenges and opporturities,as well as difficulties and chances of success.According to the deliberation mentioned in the paper,some proposals and measures are put forward to grasp the chances,to meet the challenges and advance the aeroengine development by leaps and bounds.
Performance Related Key Technologies and Difficulties of Engines with Thrust to Weight Ratio up to Level of 15
CHEN Da-guang, ZHANG Jin, ZHU Zhi-li
2001, 16(1): 8-12,7.
Abstract PDF(1038KB) icon2264 icon544
Abstract:
Performance-related critical technologies and difficulties in the development of engines with a thrust to weight ratio up to the level of 15 are considered.For typical flight roles,the selection of optimum cycle parameters of augmented turbofan engines based on integrated analysis is discussed.As thrust vectoring nozzle is the feature of advanced fighters,the difficulties in implementing thrust vectoring are summarized.The reduction of development cost and time consumed for development is very imporant.Numerical propulsion system simulation is one of the effective ways for engine design and development,as well as cost and time saving and must be the center of our attention.Engine condition monitoring and fault diagnosis may enhance engine operating safety and reduce direct operating cost,so that the development trend and key techniques of fault diagnosis are also surveyed.In conclusion some important tasks are presented.
Simulation of Turbulent Flow within an Enclosed Rotor-Stator Disc Cavity
JI Hong-hu, ZHANG Jing-zhou, LIANG Bo
2001, 16(1): 13-18.
Abstract PDF(355KB) icon1664 icon495
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The flow inside an enclosed rotor-stator disc cavity was studied numerically.The disc cavity was composed of a rotating disc,a stationary disc and a stationary shroud.The standard k-ε turbulence model was employed in the core region of the cavity.Two low Reynolds number turbulence models,single equation model and Launder-Sharma Low Reynolds number k-ε model,were used in the near wall region.The modification of dissipation rate decrease caused by solid body rotation was considered in the second model.The results showed that Launder-Sharma low Reynolds k-ε model could more accurately reproduce the experimental data than the single equation model.
Effect of Tabs Fixed on a Convergent-Divergent Nozzle on Infrared Radiation of Exhausting Jet
HUANG Yong, GUO Zhi-hui, WEI Fu-qing, WU Shou-sheng
2001, 16(1): 19-22.
Abstract PDF(586KB) icon1655 icon427
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The effect of tabs fixed on a convergent-divergent nozzle on the infrared radiation of the exhausting high speed (subsonic and supersonic) hot (about 640℃) jet was investigated,and the influence of tab block ratio and inclined angle on the suppression of infrared radiation was studied.The results show that tabs can cut down a good lot of hot jet core length and suppress the infrared radiation up to 57% from the hot jet.The increase in tab block ratio of 1% decreases the infrared radiation intensity of the whole hot exhausting gas by about 5 5% in average,and the increase in tab inclined angle by 1 degree can suppress the infrared radiation intensity of the whole hot exhausting gas by about 0 21% in average in the test conditions.
Experimental Investigation on Gas-Dynamic Performance of Caret Inlet under Condition of Large Attack Angles and Yaw Angles
ZHONG Yi-cheng, YU Shao-zhi, CHEN Xiao
2001, 16(1): 23-27.
Abstract PDF(298KB) icon1990 icon461
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An experimental investigation has been carried out.The influences of attack angle (α=0°～45°) and yaw angle (β=-15°～+15°) on caret inlet gas-dynamic performance were investigated experimentally.The variation of the inlet performance parameters with the attack angles,as well as total pressure contour plots of inlet/exit at typical states,have been presented,and the relationship between flow characteristics of the inlet and its exit total pressure contour plots has also been analyzed.It is shown that,in the condition of low speed incoming flow (Ma≈0 1),the inlet total pressure recovery coefficient decreases slowly with the increase of attack angle (α=0°～45°),and the total pressure distortion is nearly unchanging.As a result,caret inlet is favorable to maneuver flight at large attack angle.With zero attack angle and at same exit Mach number,the yaw angle has a great influence on position of inlet/exit higher and lower total pressure domains,i.e.the whole exit flow field rotates clock-wise as the yaw angle increases (β=-15°～+15°).However,the influence of the yaw angle becomes weaker with the increase of attack angle.
Numerical Simulation of Shock/Turbulence Boundary Layer Interaction in Two-Dimensional Nozzles
WANG Guo-qing, LIANG De-wang
2001, 16(1): 28-32.
Abstract PDF(824KB) icon1865 icon429
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Four kinds of two-equation turbulence model (k-ε and k-ω model) with compressibility modification,including the dilation-dissipation term and pressure-dilation term respectively,coupling with a full Reynolds-averaged Navier-Stokes code were used to simulate numerically the shock/turbulent boundary layer interactions,which occur in three different two-dimensional transonic nozzles with different Mach numbers in front of the shock.The computational results of both the time-averaged parameters,such as the velocity (u,the velocity along the x-coordinate) and the pressure (P,along the lower wall surface),and the pulsating parameters like the turbulent kinetic energy (k) were compared with the experimental results.The computational density contour of large separation case was compared with the experimental density contour.It is shown that when the two-equation turbulence models with compressibility modification are used to simulate the shock/turbulent boundary layer interaction,they predicate not only the distribution of the time-averaged parameters and the pulsating parameters but also the basic feature of the flow with or without separation.
Computational Research of Splitter Lip Effects on Fan/Compressor Performance
LIU Bo, WANG Qiang
2001, 16(1): 33-37.
Abstract PDF(882KB) icon1908 icon498
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A numerical method was applied to a S2,stream-surface streamline curvature approach to calculate the fan/compressor performance.The flow field around the splitter lip was found by calculating the potential flow field along the splitter surface and subsequent turbulent boundary layer analysis.The potential flow field was found by using a singularity method.A fan/compressor component was selected as an example to investigate the splitter lip effects on performance of fan/compressor system.A number of different splitter lip geometric parameters,such as the axial location,shape of splitter lip meanline and nose was considered and their effects on the fan/compressor performance were discussed.A proper selection of geometric parameters will be a great help to controll effectively the boundary layer flow on splitter lip surface.As a result,the boundary layer separation can be delayed and the choking can be improved.
Leak Fault Diagnosis of Liquid Rocket Engine Based on Data Fusion
WANG Jian-bo, YU Da-ren
2001, 16(1): 38-40.
Abstract PDF(202KB) icon2162 icon455
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In this paper we analyze the relation between fault diagnosis and data fusion,and summarize the correlative techniques of leak detection.In order to make up the shortage of information for leak fault diagnosis,we integrate multi-sensors,such as the dotted sensors and the infrared sensors,to detect the phenomena caused by the leak,and then the system based on data fusion for diagnosing the leak of LRE is established.The approach can enhance the validity and reliability of leak fault diagnosis.
Artificial Neural Network Identification of Burning Rate in Solid Fuel Ramjet
CHEN Xiao-qian, WANG Zhen-guo, TAN Jian-guo, YANG Tao, ZHANG Wei-hua
2001, 16(1): 41-43,48.
Abstract PDF(374KB) icon1740 icon466
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In order to search the dependency of the burning rate on the flying conditions of SFRJ,we identify the results of the simulated experiments by means of BP artificial neural network,and compare the results with those obtained with the help of Least Square Method.It is shown that the presented method of identification features high precision,fast experimental data handling and on-line process identification,and is superior in engineering application.Furthermore,it will greatly enhance the speed of training if some proper mathematic techniques are adopted in the application of artificial neural network to identifying similar big sample system.
Frequency Characteristics Computation of Liquid Rocket Engine Based on Distributed Parameter Models
CHEN Qi-feng, LIU Kun, ZHANG Yu-lin
2001, 16(1): 44-48.
Abstract PDF(308KB) icon2022 icon487
Abstract:
Linearized distributed parameter models are used to compute frequency responses of liquid rocket engine.One-dimensional distributed parameter models are used to describe engine pipelines.Other engine components are described in lumped parameter models.The linearized models of engine pipelines and components are transformed to frequency domains.Engine elements frequency domain models are described as transmission matrixes,which relates input and output variables of the engine elements.Engine system is divided into several modules according to the connections between engine elements.Matrix transform methods are used to obtain module transmission matrixes from element transmission matrixes.Equations of engine system are constituted from module transmission matrixes.These equations relate system variables and disturbances.It is convenient to generate different rocket engine systems and compute their frequency characteristics according to their own structure and parameters.The frequency characteristics of a staged combustion cycle LOX/LH2 liquid rocket engine have been analyzed numerically.
Integral Software System for Solid Motor Test
CHEN Guang-nan, GUO Jian, ZHANG Wei-hua, BIAN Xiao-zhang, ZHOU Ke, JIAO Ji-ge
2001, 16(1): 49-51.
Abstract PDF(206KB) icon1626 icon473
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A multifunctional software system for solid motor test is introduced,which consists of independent modules with shared data bases.This software system has functions such as calibration,experimental data acquisition,motor performance prediction,and parameter identification.The data base is used as data exchanging center between code modules,and makes whole package of different modules acting as an integrated program,and so it is convenient for function extending.This software can process automatically various tests,such as tests of real motor,standard experimental motor,thrust termination motor and igniter.The information about design parameters,results of theoretic analysis and experimental records can be managed comprehensively with the help of data base technique and will improve the efficiency for solid motor test.
Response of Propellant Droplet Subcritical Evaporation to Environmental Pressure Oscillation
LIU Wei-dong, ZHOU Jin, WANG Zhen-guo
2001, 16(1): 52-54.
Abstract PDF(504KB) icon1406 icon430
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A non-steady model of propellant droplet evaporation in inert gas has been developed.The model equations have been solved by numerical method with full implicit central scheme.The results show that,when the droplet diameter keeps unchanging,there exists a special pressure frequency,to which the droplet evaporation responds most strongly.In this case the droplet evaporation oscillation approaches to its maximum as the droplet temperature comes near the equilibrium temperature.Therefore,it is reasonable to believe that propellant evaporation could trigger unstable combustion in the rocket engine.
Effects of Platform Friction Damper on Resonant Stresses in Gas Turbine Blades
HAO Yan-ping, SHAN Ying-chun, ZHI Zi-gen
2001, 16(1): 55-58.
Abstract PDF(715KB) icon1461 icon695
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Experiments were conducted in laboratory to investigate the effects of platform friction dampers on resonant stresses in gas turbine blades.The results show that the resonant response can be attenuated greatly through the use of friction dampers for the fundamental bending mode of the blade.The decrease of the response can be as large as more than 70% by optimizing the mass of damper,which should be increased with the magnifying of excitation force level.Platform friction damper is an effective measure to reduce the blade vibration in gas turbine.
Aeromechanical Stability Analysis of the Coupled Rotor/Fuselage System
WANG Hao-wen, GAO Zheng, ZHENG Zhao-chang
2001, 16(1): 59-62.
Abstract PDF(738KB) icon1579 icon442
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The periodic time-varying equations for motion of the coupled rotor/fuselage system are formulated by building a new 24DOF coupled rigid/elastic element which includes 15 nodal deformation from the finite element discretization,3 rigid rotation of the flap,lag and pitch motion and 6 elastic deformation of the hub.Then they can analyze the elasticity of shaft and fuselage of helicopters by the finite element method.The dynamic coupling effects between the rigid motion of blades about the flap,lag and pitch hinges and moderately large elastic deflections are taken into account.After deriving linearized perturbation equations about the known equilibrium position,the stability is studied with the Floquet theory.Results show that the sectional stiffness of the shaft has a considerable effect on the stability of the coupled rotor/fuselage system.
Numerical Model for the Temperature and Stress Fields of Moving EBW in Titanium Alloy Plates
LIU Min, CHEN Shi-xuan, KANG Ji-dong, CHEN Yong
2001, 16(1): 63-66.
Abstract PDF(236KB) icon1778 icon492
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A moving resource FEM model for analyzing the temperature and stress fields of EBW in titanium plate was set up.The welding residual stress distribution rules in 6 mm thickness plane were researched for the three kinds of welding parameters by means of numerical model and stress measurement.The results show that there exists the longitude tensile residual stress in a very narrow region of weld and welding heat-affected zone.The biggest longitude tensile residual stress approaches to the yield stress of titanium alloy.The welding technology will affect the stress distribution greatly.The technology,in which the EBW is proceeded on the surface firstly and then on the back surface,will improve the residual distribution obviously.The residual stress measurements prove the above conclusions.
A Method for Flow Pattern Design of Axial Flow Turbine Stage
XIN Zhe, ZOU Zixiang
2001, 16(1): 67-70.
Abstract PDF(696KB) icon1453 icon426
Abstract:
A full mathematical model of optimal flow pattern design with engineering constraints was put forward,based on modern optimal control theory.An optimal flow pattern design was presented for optimizing meridional channel of axial flow turbine.According to integral optimization of turbine stages,a full physical model and mathematical expression were put forward for proposition of optimal flow pattern,including all performance parameters in turbine stages.This problem was further recast into a typical form control to maximize specific performance index such as work or efficiency of stage with given initial state,fixed terminal condition and constraints for part of state terminal variables.The program was also worked out according penalty function method and conjugate gradient method.The optimal distribution of C 1ur 1(r 1) was obtained according to constraint conditions and maximized objective function.
Numerical Simulation of Cascades with Different Turbulence Models
ZHU Yong-bo, ZHAO Xiao-lu, CAI Rui-xian
2001, 16(1): 71-74.
Abstract PDF(686KB) icon1620 icon464
Abstract:
The finite-volume TVD-LW N-S solvers were developed by using B-L model of high Re number k-ε model and low Re number k-ε model respectively.Some numerical examples have been calculated to demonstrate the resolving capability of the numerical method for boundary layer,separative region and shock.The advantage of B-L model is simplicity and convenience.The k-ε model has high adaptability,and can be divided to two types.One is low Re number k-ε model, for which the wall function is not used;and the other is high Re number k-ε model,for which the wall function is used.The precision of the low Re number k-ε model is better than that of high Re number k-ε model,but it requires more computer time,storage capacity,and larger grid.The k-ε model can predict boundary separation.For convectional calculation,high Re number k-ε model is more suitable as it can provide required precision with coarser grid.
Experimental Investigation of Thermal Energy Storage Container of Phase Change Materials for Space Station
XING Yu-ming, YUAN Xiu-gan, WANG Chang-he
2001, 16(1): 75-79,74.
Abstract PDF(1068KB) icon1739 icon489
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Container of Phase Change Material (PCM) is a key part of heat receiver in space solar dynamic power system.The receiving/releasing heat performance of heat reeeiver and its duration depend on reliability of PCM container design and fabrication.The structural design and fabrication technology of container and the filling of PCM were researched.The melting/Solidifying expeiments were completed.The phase change temperature and the latent heat of LiF-CaF 2 were measured.Several high-temperature alloys have been tested for compatibility with molten salt LiF-CaF 2 at 843℃.
Application of Fuzzy Self-Organizing Neural Network to Aeroengine Fault Diagnosis
JIANG Dong-xiang, WANNG Feng-yu, ZHOU Ming, NI Wei-dou
2001, 16(1): 80-82.
Abstract PDF(561KB) icon4681 icon727
Abstract:
A new diagnostic method has been developed,which applies the fuzzy self-organizing neural network to aeroengine fault diagnosis.In this method,the relationships between the fault causation and fault symptoms are established aecording to the fuzzy mathematics.Then the mapped 2-dimension pictures of the sample fault set and actual fault are obtained by a self-organizing neural network.At last,the reasonable conclusions are drown from the comparison between them.The case study of an engine has verified the practicability of this method.The proposed method features a simple structural algorithm,supervision free self-study and lateral association,etc.
A New Neural Network Adaptive Control Scheme Research
GUO Ying-qing
2001, 16(1): 83-86.
Abstract PDF(796KB) icon2024 icon481
Abstract:
A new neural network adaptive control scheme is presented and its applications to aero-engine control system are researched.In accordance with a turbojet engine,the identification problem of nonlinear dynamical system is studied by using a neural network firstly,including the pattern of identification and the type of input signal.Then a new neural network adaptive control scheme is presented,which is composed of two neural networks.One of them is used as identifier and the other as controller.Finally the aero-engine control system is designed at the design point.When the work of the aero-engine deviates from the design point,the parameters of the identifier and the controller are modified with the help of the learning and adaptive capabilitles of neural networks so that the control system always maintains fine behaviors.
Approaches on Trouble Quantitative Analysis of a Given Engine
MAO Jing-li, LI Ming
2001, 16(1): 87-92.
Abstract PDF(809KB) icon1621 icon444
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Based on the statistics of the troubles that happened in a given engine including their times,the appearances,the reasons,the characters,as well as the measure and the time for eliminating,quantitative analyses of the troubles have been made,and the variable relationships of the trouble-frequency with engine sample,engine operation time section and properties of the trouble have been found out.The monographic analysis has been focussed on the repeated failure and major failure.The reliability and maintainability index of the given engine have been evaluated.Finally,precautions during field maintenance are discussed,some suggestions are presented for its modification and production.
Semi-Physical Real Time Simulation of Digital Control System for Microturbo-Engine
SU San-mai, MA Rui, LEN Wen-bin
2001, 16(1): 93-96.
Abstract PDF(484KB) icon1793 icon440
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A microcomputer MCS-8098 digital control based on adaptive model with following speed control was built for microturbo-engine semi-physical simulation system.The system outline,computer engine model,hardware and software were discussed in detail.The results of the simulation show that the system not only completes real time control of the microturbo-engine but also provides a convenient means for FADEC system tests.

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