2002 Vol. 17, No. 1

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Development of Fan/Compressor Techniques and Suggestions on Further Researches
CHEN Mao zhang
2002, 17(1): 1-15.
Abstract PDF(1692KB) icon4609 icon702
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Fan/compressor is one of the key components of turbo jet engines.As higher performance is demanded by the engines with higher thrust/weight ratio,some new techniques appeared and were needed to be further studied.The development trend of fan/compressor is described.The main measures for improving performance,such as high blade speed,low aspect ratio,high through flow inlet stage,swept blade,splittered vane rotor,are discussed.Unsteady flow in fan/compressor not only affects its gasdynamic performance,but also reliability,since high cycle fatigue,stall and flutter will cause serious machine damage.CFD provides possibility of fast development of our fan/compressor techniques.Further researches are proposed in this paper.
Development of Controlled Diffusion Airfoils for Multistage Compressor Application Part 2 Test and Numerical Simulation of Controlled Diffusion Airfoils
WANG Hui she, ZHONG Jing jun, WANG Zhong qi
2002, 17(1): 16-22.
Abstract PDF(1647KB) icon1963 icon480
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A series of Controlled Diffusion Airfoils (CDA) has been developed for multistage compressor application.These airfoils are designed analytically to be shock free at transonic Mach numbers and to avoid the separation of the suction surface boundary layer for a range of inlet conditions necessary for stable compressor operation.From the results in the cascade testing,it has been demonstrated that CDA has higher critical Mach number,higher incidence range,and higher loading capability than standard series airfoils designed for equivalent aerodynamic requirements.By using these airfoils in single and multistage rig testing,the high efficiency,the high loading capability and good stage matching can be obtained,the costs can be reduced and the surge margin can be improved.The CDA profile shapes tend to have thicker leading and trailing edges than the conventional standard series profiles,which lead to the improvement of compressor durability.
An Inverse Method for 3-D Aerodynamic Design of Fans and Pumps
CHEN Nai xing, XU Yan ji, HUANG Wei guang, John J J Chen, CHEN Xiao dong
2002, 17(1): 23-28.
Abstract PDF(967KB) icon1578 icon441
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The method for 3 D design of fans or pumps in the present paper is presented which is based on the solutions of a quasi 3D inverse method and a 3D N S solver.At beginning the flow rate,the pressure ratio and the geometry of meridian pattern were given. The span height distributions of inlet and exit pitch wise averaged flow angles (or blade circulation) of the blade channel were obtained by the preliminary calculations.They are served to be the target parameters of the present calculation.Successively using a quasi 3D inverse method and a N S solver,a 3 D blade configuration can be obtained.As an example,an axial single rotor fan is shown.
Multipassage Unsteady Simulation of Flow and Temperature Fields in a Turbine Stage
DONG Su yan, LIU Song ling, ZHU Hui ren
2002, 17(1): 29-34.
Abstract PDF(836KB) icon1587 icon452
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A two dimensional Navier Stokes equation was solved to predict the unsteady,multipassage flow and temperature fields with hot streak in turbine inlet.Comparing with the results of single passage's simulation,the present multipassage simulation leads to more precise results,especially for temperature fields.Time averaged temperature distributions on rotor surface will greatly change with the hot streak/airfoil ratio,and the temperature distribution changes more on the pressure surface than that on the suction surface of the rotor.
Investigation on Two-Flow Mixing Enhancement by Small Tabs at Atmospheric Pressure
CHEN Fang, WU Shou sheng, WEI Fu qing, HUANG Yong
2002, 17(1): 35-39.
Abstract PDF(301KB) icon1728 icon457
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A variety of exhaust mixers with small tabs in comparison with a conventional annular exhaust mixer were tested at atmospheric pressure to study the effects of tab structure parameters-number and fix angles on the aerodynamic characteristics of the exhaust mixer system.The results showed that:Small tabs could enhance two flow mixing,distort downstream flowfield,increase entrainment,and improve system mixing uniformity,but the pressure loss coefficient of the system would increase a bit.Several tabs well distributed and alternately tilted inward and outward around the nozzle exit were more effective on the two flow mixing enhancement.
Preliminary Experimental Investigation on the Divergent Wall Cooling of Two Dimensional C-D Nozzles at High Speed and Hot Jet Conditions
Eriqitai, WANG Zhi jie, WU Shou sheng
2002, 17(1): 40-44.
Abstract PDF(608KB) icon1682 icon402
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At high speed and hot exhaust flow conditions,a preliminary experimental investigation on the divergent wall cooling of Two Dimensional C D Nozzle had been conducted.There were three film cooling schemes used,namely,slot,discrete hole and wiggle strip.In the experiment,the infrared radiation and axial distribution of wall temperature and near wall flow pressure were measured with and without film cooling.The results showed:The cooling had significant influence on the near wall flow pressure,and the influence was different with cooling schemes.The infrared radiation and wall temperature were obviously decreased by cooling.There were better benefits through cooling by slot and wiggle strip film cooling.
Aerodynamic Performance of Lobed Mixers at Different Velocity Ratios
LU Yu xia, WU Shou sheng, WEI Fu qing, HUANG Yong
2002, 17(1): 43-57.
Abstract PDF(401KB) icon1638 icon430
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The exit flow fields of a circular convergent nozzle with three lobed mixers were measured at atmospheric pressure and two flow conditions,to study the impact of velocity ratio on the mixing performance.An annular mixer was also tested for comparison.The results show that the curves of pressure uniformity with the velocity ratio have "convex" shapes.Their peak values appear at velocity ratio 1 under cold conditions,and at velocity ratio 0 68 under hot conditions.The two velocity ratio values are directly proportional to the square root of temperature ratio under cold and hot conditions.Contrary,the curves of pressure loss coefficient with the velocity ratio have "concave" shapes.The velocity ratio values at the valley points of the curves are dependent on the configuration of the mixers,and are both less than those at the peak points of the pressure uniformity curves under cold and hot conditions.The temperature uniformity decreases with the increase of velocity ratio in the test range.The correlation is linear when the velocity ratioslie 0 2～0 7,and then it changes smoothly as the velocity ratio is greater than 0 7.
Experimental Study on the Acoustic Property of Bonding Honeycomb Nacell Models in Compressor Inlet
LI Chun lin, WANG Tong qing, LAI Shi hong, QIAO Hai tao
2002, 17(1): 45-48.
Abstract PDF(283KB) icon1722 icon441
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Using nacell to reduce airplane noise is an important method.The paper presents an experimental acoustic investigation in a high speed compressor rig,of which the measurement method has been improved based on the research work finished previously.In the experiment an anechoic termination and an inlet sound absorbing nacell model made from bonding honeycombs are used.The results were discussed,and some conclusions about the effects of liners on the acoustic field and its sound absorbing capability were obtained.
An Algorithm for Euler Equations Using Adaptive Unstructured Grid Based on Riemann Problem Solution
CHANG Li na, YIN He, YAN Chuan jun
2002, 17(1): 49-52.
Abstract PDF(733KB) icon1636 icon449
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An algorithm to solve two dimensional Euler equations on adaptive unstructured grids is presented.It uses the analytical solution of Riemann problem to calculate the numerical conservative fluxes.With the velocity tangent to the face being treated as a passively advected quantity, the flux is obtained by solving Riemann problem for the projected equations along the normal to that face.Within the framework of adaptive mesh refinement,the algorithm obtains high resolution.Convergence to steady state is accelerated by multigrid method.Cases are run for subsonic and supersonic internal flows.The results show that the algorithm is robust and accurate,even in the presence of nonlinear discontinuities.
Numerical Experiment of the Unsteady Flow in a Centrifugal Compressor Stage Model Due to Impeller/Diffuser Interaction
LIU Li jun, XU Zhong, ZHANG Wei
2002, 17(1): 58-64.
Abstract PDF(1036KB) icon2038 icon432
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Using the technique of collocated grid scheme and sliding mesh,coupled with standard k ε turbulence model,the computation of the unsteady flow in a centrifugal compressor stage model due to impeller/diffuser interaction is performed by a pressure based algorithm under the general curvilinear coordinate system.The computation results show that,the impeller/diffuser interaction has unsteady effect on the whole flow field of the stage.The unsteady component of the velocity is marked in the gap between the impeller and diffuser,while vanishes quickly in the blade channels of the impeller and diffuser.However,the pressure unsteadiness due to the impeller/diffuser interaction remains obviously throughout the blade channels.The results simulate the impingement of the flow from the impeller on the diffuser blades adjacent downstream,and,the transportation of the vortex series at the diffuser inlet and its interaction with the diffuser blades,which may result in noise.
A Study of Object-Oriented Detailed Nonlinear Real-Time Performance Simulation for a Mixed-Flow Two-Spool Turbofan Engine with Afterburner
CONG Jing mei, TANG Hai long, ZHANG Jing
2002, 17(1): 65-68.
Abstract PDF(720KB) icon2076 icon494
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This report discusses the study of detailed nonlinear real time performance simulation for a two spool turbofan engine with afterburner.On the basis of the extensible,flexible,and reliable VC++ language,we can easily build a real time simulation program for a mixed flow two spool turbofan engine with afterburner on a PⅡ450 computer.The engine performance and engine component operation can be simulated accurately.The average time is 0 542 ms for a flow path calculation.It takes the model less than 25 ms to calculate an operating point.This is a general method and it can be used in modeling of other types of engines.The real time simulation model of an existing engine has been used successfully in IFFPC (Integrated Fire/Flight/Propulsion Control) research.
The Research of Gas Path Trouble Diagnosing for a Given Turbo-Shaft Engine in the Stable Condition
MAO Jing li, LI Ming, LIN Jian
2002, 17(1): 67-74.
Abstract PDF(902KB) icon1566 icon479
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This paper presents the research results of trouble diagnosing methods for a given turbo shaft engine.According to the monitoring functional requirements,applying gas path parameter analysis principle,the measured parameters which reflect the performance degradation of monitoring components are determined.A diagnostic model was established,with which methods of diagnosiing six faults by using six and four measured parameters were explored.
The Investigation of the Simulating Model for Transient Performance of the Turbofan Engine
CHEN Hong mei, ZHU Zhi li
2002, 17(1): 75-79.
Abstract PDF(279KB) icon1548 icon441
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A mathematical model is developed for simulating transient performance of the turbofan engine,in which the transient heat transfer between the components and airflow,tip clearance and components efficiency changes caused by heat transfer are analyzed.The calculated result shows that there are significant influences of heat transfer on the engine's transient performance,and the component efficiency loss caused by tip clearance changes can not be ignored.The simulation accuracy can be improved by above model for the turbofan engine transient performance.
An Experimental Research on Identification of the First Stall Stage of a Certain Engine
JIANG Tao, LI Ying hong, LI Jun
2002, 17(1): 80-82.
Abstract PDF(483KB) icon1728 icon468
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Aiming at surge problem of a certain engine,this paper tries to find out the starting stage resulting in rotating stall/surge in an experimental way.A data processing program based on Matlab language is developed.A criterion based on stall theories is proposed to identify the first stall stage of the compressor.During data processing,spectrum theories and time domain methods are employed.The results of experiment show that the engine stalls first at the 3rd compressor stage,and stalls simultaneously at different height of blades.The followed experiments proved the verity of the judgement.
An Investigation on a New Technique for Designing Supersonic Blade Airfoil of Axial Flow Compressor
XIAO Min, LIU Bo, CHENG Yong hui
2002, 17(1): 83-86.
Abstract PDF(208KB) icon1813 icon427
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This paper presents a new technique for designing the superso nic blade airfoil of axial flow compressor,whose meanline consists of multi circular and leading arc is elliptic.This new method makes the design flexible to control the curvature distribution of meanline,effective to control the diffusion factor of designed blade,and it enhances flow to resist separation.The ellipse arc may depress the acceleration of supersonic flow in inlet area,decrease the strength of inlet shock wave.The ideal curvature in front part of designed blade may reasonably form shock position,so the shock loss is reduced greatly.Two kinds of airfoil are modified by means of this new method.Flow fields of cascade are calculated by the finite volume TDM method.The results show this new technique is an excellent application to engineering.
New Method for Damage Tolerance Analysis of Turbine Disk and its Application
LU Shan, HUANG Qi qing
2002, 17(1): 87-92.
Abstract PDF(361KB) icon1680 icon411
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A new method for damage tolerance analysis of three dimensional component under temperature and centrifugal loads is proposed in this paper.First,stress intensity factors of three dimensional cracks on a pin hole of a turbine disk under temperature and centrifugal loads can be analyzed by use of the new type of dual boundary element method.Then incremental Euler forward analysis can be made to determine the shape of crack and crack growth life of the turbine disk step by step, with the help of Paris's formula of crack growth,until the maximum effective range of SIF of the 3 D crack reaches.Next,a second order estimation of crack growth life can be obtained by the trapezoid formula integration through the curve of crack length versus effective range of SIF.By virtue of the new type of dual boundary element method,influences of pin loads,temperature fields and shapes of cracks on stress intensity factors are analyzed.The crack growth life of a turbine disk is obtained using the method given in this paper afterwards.Approximation of an engineering method used before to calculate stress intensity factors of a crack near pin hole of a turbine disk is discussed too.Examples given in the paper demonstrate the high efficiency and easily modeling of three dimensional analysis of crack growth under complex loads by the present method.
Testing and Prediction of Thermal-Mechanical Fatigue Crack Growth Rates in Ni3Al Superalloy
HE Yu huai, LIU Shao lun, ZHAO Xi hong
2002, 17(1): 93-96.
Abstract PDF(335KB) icon1924 icon402
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In this paper,the experimental study and the analysis about the behavior of thermal mechanical fatigue (TMF) crack growth were conducted in Ni 3Al superalloy,with thermal cycle of 450℃ to 990℃.The effects of phase angle,load hold,temperature and frequency on thermal mechanical fatigue crack growth rate in Ni 3Al superalloy,respectively,were studied.A predictable model about thermal mechanical crack growth rate in Ni 3Al superalloy is proposed.The key results drawn from this study are as follows:Increasing temperature and decreasing frequency accelerate crack growth rate;The crack growth rate of in phase thermal mechanical fatigue is much larger than that of out phase thermal mechanical fatigue and both of them are between the crack growth rates of 450℃ isothermal and 990℃ isothermal tests;Load hold also accelerates crack growth.A linear summation model is proposed about thermal mechanical fatigue crack rate in Ni3Al superalloy based on these experimental results.This model is composed of cycle dependent component and time dependent component.And two proof tests were conducted to verify this model.The results predicted by this linear summation model agree well with experimental data.
Coupled Bending and Torsional Vibrations Due to Rotor-to-Stator Contacts
DENG Xiao wen, LIAO Ming fu, Robert Liebich, Robert Gasch
2002, 17(1): 97-104.
Abstract PDF(1000KB) icon1701 icon499
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A new Rotor to Stator contact model is well developed,which consists of a rotor with two discs mounted on a massless shaft and a stator.This model is used to describe the bending/torsion coupled vibrations of a rotor and an elastic stator due to the contact.The model is suitable to simulate full annular rubs,partial rubs and also the heavily destructive dry friction whip when the rotor rolls on the stator's inner surface.The numerical calculations show a variety of rotor orbit figures due to the different types of contacts and reveal the significant influences of all system parameters on the rotor behaviour.The rotor stator contact problem can be detected by monitoring the torsional vibration signals.
The Vibration Performance of the Double-Disk Cantilever Rotor in Flight Mission
XU Min, LIAO Ming fu, LIU Qi zhou
2002, 17(1): 105-109.
Abstract PDF(678KB) icon1877 icon512
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Previous researches on the vibration performance of the double disk cantilever rotor (DDCR) haven't considered the flight mission's influence.But sometimes the performance of DDCR in flight is quite different from the ground test,especially for those fighter planes with great maneuver.In order to study the flight mission's influence,we set up the motion differential equations for two kinds of flight mission,horizontal hover and vertical dive hike.Rugger Kutta method is used to solve the equations.The initial conditions are all set zero.The effects of the flight mission on the vibration performance of DDCR are calculated and analyzed.In general,the flight mission will add centrifugal force and gyroscopic moment on the rotor,which will make the rotor vibrate transiently and will deflect the orbit of the axial center from the axis.The amplitude of the transient vibration is nearly 50% higher than that of stable state in this example.Meanwhile,the shaft will deform evidently.So,the influence of the flight mission on the rotor should not be neglected.
Dynamic Analysis of Bladed Disc Systems with Vibrational Dampers
MA Xiao qiu, WANG Qin meng, ZHANG Jin, CHENG Tao
2002, 17(1): 110-114.
Abstract PDF(902KB) icon1746 icon461
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The theories of the vibrational dampers in turbomachineries are studied and the dynamic response characteristics of bladed disc systems with dry friction damper devices are investigated both by theoretical analysis and numerical approach.The HBM (harmonic balance method) is used to linearize the nonlinear dynamic behaviors of the systems effectively.The nonlinear behaviors are caused by the discontinuity of the displacement that occurs between two contact interfaces.The equivalent linearized damping and stiffness of the systems are obtained.Numerical approach of dynamic response characteristics is adopted.The calculation and analysis of dynamic response characteristics of aeroengine examples are executed by applying ANSYS finite element software.The rotor discs with shrouded blades and with lacing rod blades are selected as the engineering cases.The concepts of optimal normal pressure and critical damping characteristics between contact interfaces of dry friction damper are derived from a set of response amplitude versus frequency curves under different friction damping values.The conclusions of this dissertation can be applied to the optimal design of dry friction dampers for the future turbomachineries.
Numerical Simulation of the Coupled Radiation and Convection Heat Transfer of a High Temperature Developing Tube Flow
XIA Xin lin, LIU Shun long, MA Guo song
2002, 17(1): 115-121.
Abstract PDF(390KB) icon1925 icon462
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The coupled radiation and convection heat transfer of a high temperature participating medium in a tube is investigated by numerical simulation.The medium with constant properties is gray and flows in a developing laminar status.The conservation equations governing the convection heat transfer are discretized by the control volume method (CVM) and solved by the SIMPLEC algorithm.The radiation transfer in medium is solved by the discrete ordinate method (DOM) and its contribution to the coupled heat transfer is dealt with as the source term in the energy equation.With different optical thickness of the medium and different tube wall temperatures,the numerical results of the temperature distribution in medium,the local radiation and convection heat fluxes at wall as well as the corresponding local Nusselt numbers are presented and discussed.The reliability of the numerical results is validated by comparing with the previous investigation and by analyzing the influence of discrete grid number.The results and analysis show that the thermal radiation of high temperature medium plays an important role in the coupled heat transfer of a developing laminar flow in the tube.It has a significant effect on the temperature distribution and influences the convection heat transfer.In addition,the tube wall temperature also influences the actions of radiation and convection in the coupled heat transfer.
Experimental Investigation on Heat Transfer Characteristic of Porous Lamellar tablet
DONG Wei, HAN Shu jun, CAO Yu zhang
2002, 17(1): 122-126.
Abstract PDF(291KB) icon1777 icon461
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The experiment has taken a typical structure model as experimental tablet to test the heat transfer characteristic of the porous lamellar tablet.Research on the changing regulation of the cooling effectiveness of the porous lamellar tablet with the blowing ratio of the hot and cooling flow has been done.Furthermore,careful research on the cooling effectiveness of internal layer along the axis downstream has been performed.The mathematics fit formula of the partial Nu x and the cooling effectiveness E with respect to partial Rex and the blowing ratio M of the hot and cooling flow has been given.
The Mathematics Foundation and Application of Fuzzy Fault Graph
SONG Zhi ping, LI Ying hong, LIU Jian xun
2002, 17(1): 127-131.
Abstract PDF(775KB) icon1200 icon459
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To describe and analyze the uncertain fault relation,fuzzy fault graph was presented.Its mathematics foundation,named fuzzy Mid Set and some other relevant conceptions,were defined and analyzed.So the structure and property of fuzzy fault graph became definite.Then the method of fault diagnosis based on fuzzy fault graph was also put forward.When the method was used in a factual system analysis,the fuzzy fault diagnosis was realized preferably.The fuzzy fault graph can be used in describing the fault relationship of complicated system effectively and realizing the fuzzy fault analysis preferably.
Application of N4SID in Aero-Engine
MA Yan, LI Zhi-shun, ZENG Qing fu
2002, 17(1): 132-134.
Abstract PDF(306KB) icon1870 icon460
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It is important to establish system dynamic model for many fields,especially in the fields of adaptive control and failure monitor of advanced aero engine.Many identification methods were used for this problem,including AR,OE,and so on.Numerical algorithm for subspace state space system identification (N4SID) is proposed in recent years and applied to communications.It is based on state space model.N4SID is described in this paper.Though areo engine is a complex non linear system,at "little bias" state,the model is linear time invariable system.In this paper,N4SID is applied to identifying aero thermal model of a certain double spool turbojet aero engine at "little bias" state.Moreover,the result shows us that this algorithm is feasible.
An Innovative Partition Model of Liquid Rocket Engine Combustion Chambers
LIU Kun, ZHANG Yu lin
2002, 17(1): 135-139.
Abstract PDF(758KB) icon2002 icon460
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An innovative partition model of liquid rocket engine combustion chambers is developed in this paper,which divides combustion chambers into two regions.One region is named as combustion region in which propellant changes into combustion gas instantaneously after constant time lag,and the combustion gas instantaneously and uniformly mixes with the staying gas of the region.The other is flow region,in connection with nozzle being treated as ideal gas pipe and being modeled by employing the finite element state variable model of one dimensional ideal gas flow.An example using the model to calculate the start up process of a liquid rocket engine is given,and the calculated results show that the model describes the thrusters' transients well.The model is expressed in the form of state variable equations,therefore it has simple expressions and can be solved easily.It is suitable for the simulation and control of liquid rocket engines.
Optimal Tooth Surface Correction of Spiral Bevel Gears and Computerized Simulation
FANG Zong de, YANG Hong bin, DENG Xiao zong
2002, 17(1): 140-144.
Abstract PDF(741KB) icon1634 icon425
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Due to unavoidable manufacturing errors and heat treatment distortions,the bearing pattern and kinematical behavior of actual spiral bevel gear drives are usually different from the analytical results of the original design obtained by Tooth Contact Analysis (TCA) technique.In this paper,an identification approach to determining the machine setting corrections by using Least Square Method is presented.A numerical example by means of computerized simulation shows the agreement of TCA results between corrected tooth surface and the original design,including the bearing pattern and kinematical behavior.

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