1995 Vol. 10, No. 2

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NUMERICAL COMPUTATION OF 3D TURBULENT FLOW IN A TRANSONIC SINGLE ROTOR COMPRESSOR
Chen Naixing, Huang Weiguang, Zhou Qian
1995, 10(2): 109-112,197.
Abstract PDF(278KB) icon1885 icon378
Abstract:
The 3D turbulent flow in a transonic single rotor is computed numerically by use of an explicit 3D turbulent time-marching Navier-Stokes solver in finite volume form with the option of applying Baldwin-Lomax turbulent model.This rotor served as the blind test case organized by the ASME Turbomachinery Committee.Its purpose was to provide a forum for a careful assessment of the ability of the various turbomachinery CFD codes available to predict the flow field in modern blading.The computational results by the authors' method were compared with the experiment and presented in the present paper.It is demonstrated that the present method can be used for checking the aerodynamical design.
EXPERIMENTAL RESEARCH ON NOISE REDUCTION OF A COUNTER ROTATING VENTILATOR
Feng Yucheng, Zhao Xiuhua
1995, 10(2): 113-116,197.
Abstract PDF(904KB) icon1852 icon490
Abstract:
A counter rotating ventilator with high efficiency has been made,but its noise level is too high.This paper analyzes the noise generation and noise frequency characteristics.A lot of noise experimental researches on noise suppression have been carried out successfully by the aid of acoustic liner or appropriate increase of the duct length.As a result,overall sound pressure level is reduced from 101dB(A) to 88dB(A).
STUDY ON AEROELASTIC STABILITY OF ROTOR BLADE IN HOVER
Zhang ChengLin, Yu Lin
1995, 10(2): 117-120,197.
Abstract PDF(345KB) icon2029 icon365
Abstract:
he aeroelastic stability of coupled flap-lag-torsion dynamics of rotor blades in hover is studied in this paper.According to Hamilton principle,nonlinear partial differential equations of motion for elastic flap bending and torsion of the blade are derived.The spatial dependence of the partial differential equations is discretized by use of the Galerkin finite element method.The effects of some structural parameters are taken into account,such as the collective pitch,precone,sweep,and so on.Finally,the aeroelastic stability of Dolphin's Rotor blades is analysed.The experiment shows that the aeroelastics stablity of the rotor blade in hover is influenced small by the blade sweep,but strongly by the collective pitch and precone.The experimental results verify the feasibility of the analysis and applicability to rotor design.
A BLADE FLUTTER PREDICTION METHOD INCLUDING SECONDARY FLOW EFFECTS
Li Kejian, Zhang Yangjun, Tao Deping
1995, 10(2): 121-123,198.
Abstract PDF(269KB) icon1879 icon427
Abstract:
In order to obtain a better understanding of the secondary flow effects on blade stall flutter,this paper presents an approximate method to analyse the effects of secondary flow on blade aeroelastical stability.The method combines conventional streamline curvature methods with the secondary flow model to obtain the stationary flow with circumferential nonuniformity,and then incorporates the non constant phase angle deforming actuator disk method.Several secondary flow effects on aeroelastical stability were analysed respectively.The results show that the effects of the secondary flow on the aeroelastical stability are different.The tip leakage vortex may have greater effect than other vortexes,that is consistent with the experimental results.
NUMERICAL ANALYSIS OF FLOW FIELD ABOUT SWEEP FORWARD BLADES OF COMPRESSORS OR FANS
Yang Lijun, Lu Yajun
1995, 10(2): 124-126,198.
Abstract PDF(259KB) icon1804 icon416
Abstract:
A numerical analysis of the flow field about sweep forward blades has been carried out.Time marching method is used to calculate the three dimensional inviscid flow field.Boundary layer parameters are calculated with integrated boundary layer equations in non orthogonal axises.The calculated results show that in axial compressors and fans with sweep forward blades the intensity of passage vortex,secondary flow and tip losses are decreased,the early separation from the blade surface is protected,the flow field in tip area is improved obviously.As a result,the aerodynamic efficiency of axial compressor or ventilator is enhanced.
HIGH RESOLUTION IMPLICIT PROCEDURES FOR CASCADE FLOW CALCULATIONS
Yao Jixian, Liu Qianzhi, Zhou Xinhai
1995, 10(2): 127-130,198.
Abstract PDF(840KB) icon1513 icon418
Abstract:

Based on the high resolution difference scheme structured from characteristic flux difference splitting,the implicit algorithm of the scheme has been developed.The implicit characteristic boundary procedures consistent with the scheme have been implemented as well.The implicit boundary procedures proposed in this paper eliminate the restrictions induced by explicit boundary treatments and,meanwhile,preserve all the important features of the scheme such as non oscillation and high resolution.The implicit solver effectively accelerates the convergence rate of the high resolution scheme.The comparison of cascade flow calculations under various inflow conditions with the corresponding experiments demonstrates the accuracy and efficiency of the proposed solver.
NEAR SOUND FIELD ANALYSIS OF A ROTATING SOURCE
Ju Hongbin, Zhong Fangyuan
1995, 10(2): 131-134,199.
Abstract PDF(304KB) icon1712 icon389
Abstract:
On the basis of moving source radiation theory,this paper discusses the sound solution of a rotating source in frequency domain.Emphasis is laid on near sound field which has three additional sources in contrast to far field.The computation reveals that the near sound field produced by these "additional sources" distributes in discrete viewing angles.Radial and axial deviations affect sound field respectively around the rotating plane and axial area,and their maximum connections have different characteristics.The analysis is proved preliminarily by a fan experiment.
NUMERICAL ANALYSIS OF FLOW AND LEAKAGE IN LABYRINTH SEAL
Huang Shoulong, Ma Yuyi
1995, 10(2): 135-138,199.
Abstract PDF(306KB) icon1715 icon486
Abstract:
The unsteady Navier stokes equations are solved to predict numerically the internal flow of single cavity labyrinth channel with depth to width ratios H/W=0 1,0 3 and 0 5.The numerical results demonstrate the oscillation of the flow structure and fluctuation of the exit leakage rate.It is shown that the seal efficiency is relevant to the amplitude of leakage fluctuation,furthermore,the sequence of H/W from 0 3,0 5 to 0 1 is also the order of both increasing seal efficiency and increasing amplitude of leakage fluctuation.Also,the complex physics,including motion and mergences of vortex,migration of separation bubble,bending and impact of jet,is discussed,and the influence of impact effects on the increasement of energy dissipation and decreasement of leakage are analysed.
METHOD FOR PREDICTING FATIGUE RELIABILITY AND LIFE OF COMPRESSOR BLADE
Le Xiaobin, Gao Deping, He Mingjian
1995, 10(2): 139-142,199.
Abstract PDF(1565KB) icon2567 icon451
Abstract:
In engineering application of fatigue problem,it is very difficult to obtain some working parts' load spectrum due to some reasons.This paper provides method for predicting the fatigue reliability and life of the part without working load spectrum.Fatigue tests are carried out on the part that has worked for some time.Basing on the test data,the surplus fatigue damage strength of the part can be calculated.With its surplus fatigue damage strength,we can determine its overall fatigue quantity in the working life.And based on the fatigue cumulative damage probabilistic model,the part's fatigue reliability and life can be predicted.An aeroengine compressor is taken for example to show how to use the surplus fatigue damage strength for predicting the blade's fatigue reliability and life.
A NEW RELIABILITY ANALYTICAL METHOD FOR BENDING FATIGUE STRENGTH OF GEARS
Peng Xiongqi, Liu Geng, Wu Liyan
1995, 10(2): 143-146,200.
Abstract PDF(1098KB) icon2216 icon475
Abstract:
Based on the three parameters reliability analysis model and the fatigue theory of gears,a new reliability analytical method for the bending fatigue strength of tooth root is proposed by use of blending stochastic finite element method.This method takes into account such random factors for the reliability of gears,as load,fatigue limit,the material parameters and radius chamfer of tool.Analyses completed with this method indicate:The radius chamfer of tool has unignorable effect on the reliability of gears' bending fatigue strength;In the linear elastic problems,the Young's modulus has no effect on the structure reliability;The Poisson ratio has a little leverage on the gears' reliability;But the gears' reliability reduces with the increase of variation coefficients of the above mentioned random factors;So the gear's reliablity will increase as the skewnesses of fatigue limit and the radius chamfer of tool rise.But the skewness of load has an inverse influence.This paper also considers the modified coefficient's (no random factor) effect on the gears' reliability.
MEASUREMENT AND EXPRESSION OF MAIN CHARACTERISTICS OF NiTi SHAPE MEMORY ALLOY WIRES
Du Yanliang, Nie Jingxu
1995, 10(2): 147-150,200.
Abstract PDF(285KB) icon1436 icon355
Abstract:
Experiments and analyses of the main characteristics of NiTi alloy wires were completed to research their ability in active detection and control of cracks growth as the special requirements of the intelligent material structures.The expressions of the main characteristics as recovery force and other parameters are deduced on the basis of measurements.The research results show that the NiTi alloys wires are very good functional materials for manufacturing the intelligent structures capable of actively detecting and controlling the growth of cracks and vibration.
OPTIMIZATION FOR REDUCING VIBRATION OF ENGINE PIPELINE
Li Lin
1995, 10(2): 151-154,200.
Abstract PDF(284KB) icon1891 icon464
Abstract:
The paper deals with structural optimization for reducing vibration of engine pipeline.The method can give the best postion,stiffness and damping of clips to be attached on condition that pipe system's structure has been given.Based on the finit element analysis of original structure,the analytical process is limited between the locations where are to be attached clips,excited points and dangerous points.It is not necessary to make again a finit element analysis for the improved system.An exemple for reducing the vibration of an engine pipeline is presented.
NUMERICAL STUDY ON BIFURCATION PHENOMENON IN A COMBUSTOR WITH A NON SLOT CONICAL SWIRLER
Chen Liru, Jiao Shujian
1995, 10(2): 155-158,201.
Abstract PDF(270KB) icon1688 icon430
Abstract:
The numerical simulations of bifurcation phenomena in a combustor with a non slot conical swirler and in a diffuser fixed before the non slot conical swirler have been carried out.The results of the simulations show that there are two different kinds of vortex emerged before the conical swirler,that may be one of the feed back factors controlling bifurcation phenomenon,and the characteristics of the turbulent flow in the combustion zone must be changed abruptly as the bifurcation phenomenon occurs.These conclusions may reveal the causation of bifurcation phenomenon in this combustor from the viewpoint of aerodynamics.The calculated results are consistent with the experimental data.
STUDY ON COOLING PARAMETERS OF A NEW SEMI TRANSPIRATION COOLING SCHEME
Li Wei, Tang Ming, Li Changlin, Yan Chuanjun
1995, 10(2): 159-162,201.
Abstract PDF(275KB) icon1407 icon438
Abstract:
The mat wall cooling is a new semi transpiration cooling scheme.A heat transfer model of the mat wall cooling is established and a numerical iteration method is employed to calculate its cooling parameters (i.e.thermal effectiveness and wall temperature ratio) in the porosity range from 0 0204 to 0 0625.It is shown that the cooling parameters are affected mainly by the porosity and coolant flow number,and the boundary conditions have insignificant effect.The calculated results are consistent with the existed experimental data.This fact indicates that the presented heat transfer model is principally adequate,but must be further improved for more accurate prediction.
MODEL BASED FAULT DIAGNOSIS ALGORITHM FOR LIQUID PROPULSION SYSTEM
Cui Dingjun, Liu Guoqiu, Zhang Zhenpeng
1995, 10(2): 163-166,201.
Abstract PDF(291KB) icon1965 icon425
Abstract:
A quasi dynamical mathematical method of fault simulation and a diagnosis algorithm based on Grey Relational Analysis are given for a liquid rocket engine (LRE) system with series double turbine pump feed structure.By use of this algorithm,numerical simulations of various typical fault modes have been carried out for a certain system determined by adjustment calculation,the fault mode database for this system was obtained in advance,a group of parameters collected from the engine tests were diagnosed in real time by use of the above database and model to determine the health conditions of the engine.In consequence it is possible to take measures in good time to enhance the safety and reliability of the engine.
A MULTIGRID SCHEME FOR CALCULATING THREE DIMENSIONAL FLOWS THROUGH COMPRESSOR BLADE ROW
Ning Wei, Zhou Xinhai
1995, 10(2): 167-169,202.
Abstract PDF(239KB) icon1522 icon354
Abstract:
Based on the MacCormack explicit difference Scheme,a multigrid scheme has been developed to solve the three dimensional Euler equations expressed by weak conservation law in cylindrical coordinate system.The distribution and interpolation formulas of corrections for the presented multigrid scheme have been derived.The present Euler solver was used to calculate the flows of two sets of transonic compressor rotor blade rows,and proven to be a valid and useful design tool.The computed results indicate that this scheme is enable to accelerate the computation convergence greatly,and the method is accurate and reliable.
DESIGN AND EXPERIMENT OF CENTRIFUGAL COMPRESSOR 3-D IMPELLERS FOR HEAVY GASES
Wang Shangjin, Xi Guang, Liu Sixue, Yuan Yan, Wang Siyi
1995, 10(2): 170-172,202.
Abstract PDF(791KB) icon1631 icon411
Abstract:
An inverse problem method based on s 2 flow surface theory of 3 D flow field has been developed to design centrifugal compressor impellers for heavy gases and some techniques to improve the performance of high pressure ratio impellers have been presented too.Two impellers with Mach number M u 2 =1 26,1.06 and relative width b 2/D 2=0 054,0 036 respectively have been designed by use of this method.Experiments of the impellers have been performed in a closed loop test rig with Freon gases (R11) to verify the design method.The dynamic pressures distribution from shroud to hub at the exits of impellers and the losses of vaneless diffusers and volutes have been measured and analyzed under different work points.Their good performance obtained from tests shows the design method and techniques presented in this paper is feasible and favourable.
A MODEL FOR ESTIMATING TIP CLEARANCES IN GAS TURBINE ENGINE TRANSIENTS
Zhu Zhili, Liao Kuo
1995, 10(2): 173-174,202.
Abstract PDF(1329KB) icon1562 icon364
Abstract:
During the gas turbine engine transient,the clearances of the compressor and turbine blade tips differ from those in stable operation because the heat change between gas and components causes the different radial movements of the rotor and case.In order to simulate the real thermodynamics process in the gas turbine engine transient as possible,a model for estimating the variations of the tip clearance and efficiency with time is given.In this model,the typical stage chosen from a multi stage turbomachinery will be decomposed into three components (case,blade and disc),the instantaneous heat growth of each component is calculated individually by means of the different heat transfer model,and the instantaneous centrifugal growths of blade and disc are also estimated,therefore the instantaneous tip clearance are obtained by summing the heat and centrifugal growths of all components.The shifts in efficiency resulted from the change of tip clearance will be predicted by semi empirical formula,with the aid of the tip clearance model of the varations of the tip clearance,efficiency and thrust with transient time have been estimated.The results prove the effectiveness and accuracy of the model.
EFFECT OF CURVING OF HEAVY DUTY BLADES ON WALL FLOW
Han Wanjin, Lü Hongwei, Lu Wencai, Wang Zhongqi
1995, 10(2): 175-178,203.
Abstract PDF(533KB) icon1740 icon412
Abstract:
Static pressures on endwalls and blade surfaces and growth of the losses along flow direction were measured,and the flow visualizations of the endwall and blade suction surface with ink traces were also made.The experimental results show that the positive curving of the blade increases the streamwise adverse pressure gradient in the cascade inlet and makcs isobars on the front part of the blade suction surface into opposed C shape,thereby the saddle point separation near the blade leading edges and convergence of separation lines on the suction surface to the cascade middle are intensified.The negative curving of the blade reduces the adverse pressure gradient in the cascade inlet and makes isobars perpendicular to the endwall on the front part of the blade suction sarface.As a result not only the separation flow near saddle point weakens,but also the separation flow on the suction surface turns into free vortex laminal separation so as to aviod interception of the upper and lower separation lines.In consequence,the secondary vortex losses are decreased greatly.
CHARACTERISTICS OF INTERNAL FLOW PERFORMANCE OF AN STF FAN PROPULSION SYSTEM
Shan Peng, Ma Jihua
1995, 10(2): 179-182,203.
Abstract PDF(839KB) icon1786 icon479
Abstract:
The total characteristics of a Supersonic Through Flow (STF) fan propulsion system of unconventional configuration have been studied.Therefrom some conclusions are obtained as:1.The system's bypass ratio must be actively controlled by adjusting both core and bypass engine's through flow areas.2.A general propulsion system with a bypass ratio variable cycle is able to hold a higher fan compression ratio or a stronger fan power in supersonic flight,when it is coupled with a variable core nozzle critical section area.3.For this new concept propulsion system,the specific thrust per unit of the total air mass flow does not vary with altitude up to the stratosphere.Some calculational results are presented briefly to support the above mentioned conclusions.
EVALUATION OF SAFETY LIVES OF AEROENGINE PARTS
Kong Ruilian, Wang Yanyong
1995, 10(2): 183-186,203.
Abstract PDF(292KB) icon1605 icon388
Abstract:
The safety lives of parts in an aeroengine are determined by use of the confidence limits of three parameter Weibull distribution.The safety lives obtained by the point estimation of three parameter Weibull distribution have been compared with those of two parameter Weibll distribution.It is shown that this method is convenient in engineering application.
RELIABILITY ANALYSIS OF LOW CYCLE FATIGUE LIFE FOR A DISC
Lu Wenlin, Zhang Dingzhen
1995, 10(2): 187-189,204.
Abstract PDF(261KB) icon1536 icon350
Abstract:
When a failure model with low cycle fatigue is identified,the failure function for reliability analysis reduced as follows:As cumulative damage of varying amplitude cycles is calculated with Miner's law,the total damage is considered to be a random value varying from 0 3 to 3,and follows logarithmic normal distribution.Furthermore,damage of low cycle loads of each amplitude is evaluated according to the formula of flow cycle fatigue life prediction proposed by R.W.Landgraf.Then,the failure function for reliability analysis is derived from the above formulas by transforming strain expression into stress expression.If a stress at certain point of a disk is influenced by a disturbance of some random variables,the stochastic finite element method is employed to find the variance of the stress distribution.When stresses in a disk are in elasto plastic condition,nonlinear SFEM is required to obtain the variance of the stresses.Finally,a numerical example for a disk with equal thickness is presented and is verified by the Monte Carlo simulation.
OPTIMIZATION OF TURBINE BLADE FIR TREE ROOTS
Cheng Kaijun, Ma Mei
1995, 10(2): 190-192,204.
Abstract PDF(704KB) icon2397 icon386
Abstract:
An optimization system for fir tree root is developed for design layout of the fir tree joint area in gas turbine so as to decrease the weight of aero engine and shorten the design cycle.This system is suitable to design the 2￣5 pairs of teeth used in modern aero engines.After the optimization the smallest weight subject to the static strength constraints has been attained,the FEM is used to check the distribution of stresses,particularly the concentration stress,and the results are shown on the screen for making decision.
COMMENT ON THE PROBLEM OF TURBULENCE
Zhao Songnian
1995, 10(2): 193-196,204.
Abstract PDF(326KB) icon1723 icon365
Abstract:
This paper points out that Navier Stokes equation is an essential equation for studying turbulent flows,it governs the motion of fluid flows.Reynolds equation represents coexistence of random and determinative phenomena in the turbulent flows.But,Burgers KdV equation has no relation to mechanism of turbulence,so we can't regard it as a "new equation" for researching turbulent flows.

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