1999 Vol. 14, No. 1

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CONNECTION BETWEEN LOSS COEFFICIENT AND BLOCK COEFFICIENT USED IN TRANSONIC FAN DESIGN
Xing Xiuqing, Zhou Sheng, Zhang Jian
1999, 14(1): 1-6.
Abstract PDF(1044KB) icon1545 icon385
Abstract:
Loss coefficient and block coefficient are interrelated in fact and the relation between them represents the relation between loss and separation.An engineering model is established to connect them,based on an analysis of many fan designs.The model determines the block coefficient from the loss coefficient,because the block coefficient derived from test loss coefficient is more believable than that from experience.At the same time,a computation test of a transonic fan is given as an example to verify the feasibility of the model.A conclusion has been drawn from the computation results that this model can estimate exactly the block coefficient and flow direction at the trail edge of rotor so as to improve the situation of the stator.It also explains why the rotor efficiency is superior to the stage efficiency.
MULTIOBJECTIVE OPTIMIZATION DESIGN FOR TRANSONIC TURBINE CASCADES
Tong Tong, Feng Zhenping
1999, 14(1): 7-10.
Abstract PDF(533KB) icon1655 icon359
Abstract:
This paper presents a multiobjective optimization design method for transonic cascades with mixed variables and constraints.On the basis of the computation method of two-dimensional Euler equations coupled with boundary equations for transonic viscous flow,the cascade aerodynamic losses and work potential are considered as the two objective functions,and a united objective function is formulated using dimensionless minimum-deviation method,by which the two-objective optimization problem is divided into two single-objective optimization problems.Then,the efficient optimal solution is obtained with the optimization algorithm of flexible tolerance method.
PREDICTION OF INTERNAL FLOW FIELD IN A HIGH SPEED IMPELLER WITH VISCOUS BODY FORCE TECHNIQUE
Yang Ce, Suo Yisheng, Jiang Zikang, Zhu Wei, Lao Dazhong
1999, 14(1): 11-14.
Abstract PDF(1368KB) icon1877 icon347
Abstract:
It is very important of understanding the internal flow field in high speed centrifugal compressor in order to design an impeller with higher efficiency and high pressure ratio.In this paper,a three-dimensional viscous code has been developed to solve simplified Reynolds-averaged Navier-Stokes equations .The viscosity is simulated with viscous body force method.The governing equations are spatially discretized in the cell-vertex finite volume scheme on a simple H mesh and temporally integrated by an explicit two-step Runge-Kutta scheme.The turbulence closure is made by using Baldwin-Lomax model.This code is demonstrated for predicting the internal flow field of a high speed impeller.Some laser measure data are also illustrated to testify the calculated results.
A MODIFIED MODEL OF SUPERSONIC/TRANSONIC FAN AERODYNAMIC DESIGN SYSTEM
Zhao Yongjun, Xing Xiuqing, Zhou Sheng
1999, 14(1): 15-18.
Abstract PDF(495KB) icon1658 icon369
Abstract:
The two-dimensional aerodynamic design and the three-dimensional flowfield analysis,which are two of the three main parts of supersonic/transonic fan aerodynamic design system,do not match in flow model.Therefore,a triangular model of aerodynamic design system is put forward to improve the design system.As a part of its implementation a quantitative indicator is provided which uses the inner flow deviation angle and its deviation to evaluate quantitatively the designed flowfield and to guide the next design iteration.The possibility of developing the indicator into a criteria is also discussed.
NUMERICAL SIMULATION OF BOUNDARY LAYER ON BLADE SURFACE UNDER DIFFERENT INLET FLOW CONDITIONS
Liu Bo, Wang Yangang
1999, 14(1): 19-22.
Abstract PDF(279KB) icon1766 icon348
Abstract:
The boundary layer flow pattern on the blade surface of a two dimensional cascade is simulated numerically to investigate the transition process from laminar to turbulent flow and the length scale of transition region under different inlet Mach number and incidence.The influence mechanism of some inlet flow conditions on the transition is also elaborated.The results indicate that the inlet Mach number and incidence have significant effects on the starting and ending positions of the viscous flow transition.Under an enhanced inlet Mach number,the starting position of the transition moves forward so that the transition region becomes small.As the inlet incidence decreases,the transition region becomes smaller.
TIME-MARCHING METHOD FOR THROUGH-FLOW COMPUTATION OF TURBOMACHINERY
Ji Lucheng, Meng Qingguo, Zhou Sheng
1999, 14(1): 23-26.
Abstract PDF(205KB) icon1680 icon372
Abstract:
The philosophy of time-marching method is firstly applied to through-flow computation.The governing equation is solved with four step Runge-Kutta scheme.In result,the difficulty in the transonic highly-loaded turbomachinery designing,is surmounted.As an example,an axial supersonic inflow shock rotor is designed,with a fine grid,a strong shock is found in flow path.It is indicated that the time-marching method is suitable for through-flow calculation,especially for turbomachinery,whose flow velocity axial component is transonic.
AN EXPERIMENTAL INVESTIGATION ON INTERACTIONS AMONG VORTICES AND VORTEX WITH BOUNDERY LAYER
Zhong Yicheng, Chen Xiao
1999, 14(1): 27-30.
Abstract PDF(495KB) icon1652 icon344
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An experimental investigation on the interactions among vortices and the vortex with boundery layer was performed with a boundery pressure probe and a small-size five-hole pressure probe,which can both be placed at any point in the flow field by an accurate small-displacement coordinate apparatus.The vortices were generated by doubled half delta ramp submerged Vortex Generators (VG).The counter-rotating vortices interaction increased the down-washed and up-washed velocity,and the distance of the interaction may reach 50 h (the height of the VGs) or more.The interaction between two ajacent co-rotating vortices was counteractive,and due to their mirror-image interaction the crossflow underneath the vortex core was larger than that above it,so that stronger second flow near the wall was generated.The strength of co-vortices decreased so rapidly downstream that the vortices began to break out and disappear at distance from 20th to 30th,however the second flow velocities near the wall were still large even at distance from 30th to 40th.The effect of the vortices on the boundary layer improved the velocity distribution in boundary layer i.e.,the velocity profile near the wall became fuller both in up-washed and downd-washed field,so the shape factors in both fields became small.The boundary layer leads to intense exhaustion of the vortex due to its strong interference.As a result,the strength of the vortex in thick boundery layer became smaller than that in thin boundery layer,and the radius of vortex core became larger,and the effective distance of the vertex lessened.
A NEW PROGRESS IN AERODYNAMIC DESIGN OF DRAFT FAN
Li Qiushi, Lu Yajun, Feng Yucheng, Yu Qing
1999, 14(1): 31-34.
Abstract PDF(277KB) icon1713 icon350
Abstract:
A new aerodynamic design system developed by authors for draft fan with enhanced efficiency,suppressed noise,enlarged flux and high load.The new design system features:A twist regulation for vortex control is employed in designing to lessen the secondary flow loss in the blade tip and hub;The feasibility and high efficiency of this procedure has been verified by the tests of the prototype fan;A new computer-aided 3D blading is used to optimize the blade;Numerical inverse checking is adopted to enhance accuracy in designing and cut down the period of the designing and production.This design system can make the optimized blade with 'forward inclination ', 'inclining sweep ','bending sweep ',to minimize the various secondary flow losses,to expand the steady working range of the fan,and to suppress the aerodynamic noise source.
INFLUENCE OF GEOMETRIC VARIATION ON PFERORMANCE OF VGE
Zhu Zhili, Li Dong
1999, 14(1): 35-38.
Abstract PDF(1586KB) icon1739 icon366
Abstract:
A model based on the characteristic maps of the variable geometric components is applied to performance estimation of Variable Geometry turborfan Engine (VGE).The influences of readjusting the geometric parameters,such as the variable guide vanes of fan and compressor,and variable turbine throat areas,on the installed and uninstalled performance have been researched for a VGE with high thrust-weight ratio.The results show that a significant influence on the engine performance is exerted by shifting the fan variable vanes,but a less influence by adjusting the other three parameters under the calculation conditions selected.But if the four parameters could be readjusted coordinatively,the components will be controlled with high efficiency to ensure the high performance of VGE.
A NEW INVERSE DESIGN METHOD OF DIFFUSER BLADES PROFILE
Fan Huiyuan, Wang Shangjin, Xi Guang
1999, 14(1): 39-43.
Abstract PDF(560KB) icon1543 icon383
Abstract:
A genetic algorithm combined with a neural network technique is proposed to search for turbomachinery diffuser blade profile under the condition of a given velocity distribution on its surface.Such a new inverse method works through minimizing the error between surface velocity distribution of candidate blades and the target velocity distribution.For ease in employing genetic algorithm,the blade profiles searched are parameterized with Bezier spline curves.The flow analysis of the candidate blades is carried out by BP neural networks which have been trained with a set of samples.The proposed approach is demonstrated through the application to a diffuser with two-dimensional height-and thickness-constant blades.The simulations show that the new method is not only feasible,but also reliable and effective.
RESEARCH ON OPTIMIZATION OF CYCLE PARAMETERS FOR ATF PROPULSION
Wang Rugen
1999, 14(1): 44-46.
Abstract PDF(225KB) icon1677 icon359
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The cycle parameters of ATF propulsion with or without supersonic cruise missions have been optimized respectively and compared.And the effects of supersonic cruise range,engine life cycle cost and engine part efficiencies on the optimization of the engine cycle parameters have been researched.The results show that a turbofan engine with a small bypass ratio must be installed,and a suitable turbine entry temperature is obtained by optimization with life cycle cost.The enhancement of the engine part efficiencies has influence on the optimization of the cycle and the aircraft markedly raises the aircraft performance.The afterburner temperature must be taken very high due to the limit of the engine maximum diameter.
FORMULATION OF A TRAINER ENGINE ACCELERATED TEST SPECTRUM
Song Yingdong, Gao Deping, Lin Hongzhen, Cheng Weihua
1999, 14(1): 47-50.
Abstract PDF(410KB) icon1502 icon402
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Two composite rise and fall mission profiles and two composite maneuver flight mission profiles are obtained from the initial design missions of a trainer engine.These composite missions are accelerated according to life analysis of engine main components under the condition of equivalent damage.The accelerated mission test spectra include two rise and fall profiles,a maneuver profile and a high cycle fatigue test spectrum.
REGULATION BEHAVIOR ANALYSIS OF AUTO-EVEN-LOAD CONNECTING COMPONENT
Du yanliang, Zhao Weigang, Liu Xiandong, Zhu Xinqun, Ma Liming, Hao Huazen, Zhang Zuping
1999, 14(1): 51-54.
Abstract PDF(265KB) icon1286 icon350
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According to the deformation or fracture caused by uneven loads on the structural connection,the smart structure with sensible and regulative functions has been proposed to be used in bolt groups.The smart structure is constituted with the auto-even-load connecting component made of the shape memory alloy material.The mechanical behavior of the auto-even-load component in the bolt groups is analyszed.Its auto-even-load and the regulative principle to prevent the fracture are also studied.
INTEGRAL STRESS ANALYSIS TECHNIQUES AND SOFTWARE DESIGN FOR A COMPOSITE ROTOR
Zhou Chuanyue, Sheng Huiyu, Lin Xiangdong, Li Ming
1999, 14(1): 55-59.
Abstract PDF(378KB) icon1820 icon384
Abstract:
A mathematical and mechanical model for analyzing the integral stress of a composite rotor is presented,which takes into account such factors as mating relations of the various components of the rotor,rotating centrifugal forces and thermal expansion,etc.A general-purpose software (REC) for the analysis of the rotor integral stress has been designed,which can be employed not only for a complicated rotor incorporating both radial and axial pretightenning,but also for a rotor with any arbitrary axisymmetrical structures.With the help of the software it is possible to ascertain automatically whether the mating surface among the various components loosens,and to determine a rational radial interference and axial pretightenning.The analysis of numerical examples and practical engineering applications indicates that the provided method is correct,the software design rational and the calculation precision and the speed quite high.
RESEARCH ON COUPLED LATERAL TORSIONAL VIBRATION OF ROTOR-GEAR COUPLING SYSTEM
Li Ming, Zhang Yong, Jiang Pei, Lin Yulie
1999, 14(1): 60-64.
Abstract PDF(657KB) icon1391 icon393
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Based on the meshing condition of the gears,the constraint equation describing relations between the displacements in the centers and torsional angular displacements of the mating gears is derived.The coupled lateral and torsional vibration model of a rotor system with a gear coupling is developed with Lagrange's Equation and the constraint equation in rotating reference frames.The system of two Jeffcott rotors connected by a gear coupling has been analyzed numerically and the results show that the transient response frequency of aligned rotors approximately equals to the uncoupled model in lateral vibration,but the even-integer multiples of lateral vibration and the odd-integer multiples of torsional vibration are found out by the coupled model for the misaligned rotors.
STABILITY OF RUBBING MOTIONS OF SYMMETRIC RIGID ROTOR IN HIGH SPEED ROTATING MACHINERY
Ji Jinchen, Yu Lie
1999, 14(1): 65-68.
Abstract PDF(293KB) icon2096 icon451
Abstract:
The cylindrical and conical rubbing motions of a symmetric rigid rotor in high speed rotating machinery are investigated.When both journal bearings of the rotor are simultaneously under starvaton lubrication condition,both ends of the rotor contact locally with the bearings so that the cylindrical rubbing motions occur.The stability margin of the cylindrical rubbing motions is determined,and the relationships of instability with the radial clearance,the bearing/rotor friction coefficients,and the angle of incidence during successive rubs are obtained.When one of the journal bearings is under starvation lubrication condition,the conical rubbing motion of the rotor occurs.The analysis shows that in this case the stability of rotor depends on its physical parameters,the transcritical bifurcation is analyzed.Then the first order approximation formula of whirling angular speed is given,which provides theoretical analysis for diagnosis of rotor systems.
SIMULATION OF DOPPLER ON-LINE MONITORING TECHNIQUE FOR BLADE CRACK FAULT
Yang Haiyan, Liu Zhouqi
1999, 14(1): 69-73.
Abstract PDF(300KB) icon1524 icon422
Abstract:
An on-line monitoring technique for blade crack fault is set up according to the mechanism of an acoustic doppler on-line monitoring technique,which is based on cracked blade's resonant phenomenon in turbine machinery.But the resonant phenominon can not be captured easily,because the fatigue crack expands very quickly due to the high frequency vibration of turbine blade.So that a new monitoring method based on the unsymmetry in vibration response of the cracked blade is developed,which utilizes the achivements in analyzing the vibration of the cracked blade.The program for calculating vibration response wave form of the rotating blade from acoustic doppler signals is worked out.Simulation research indicates that this new method can monitor the crack fault more effectively.
PREDICTION FOR NONLINEAR PERIODIC SOLUTIONS OF UNBALANCED ROTOR BEARING SYSTEM
Liu Heng, Yu Lie, Xie Youbai, Yao Fusheng
1999, 14(1): 74-78.
Abstract PDF(665KB) icon1512 icon358
Abstract:
A new prediction method for periodic solutions of unbalanced bearing rotor system is provided,which uses the steady state and transient state information of the periodic solutions to solve Jacobi matrix.Then this method can predict and trace the periodic solution of the system.At the same time,the Floquet multiplier of the periodic solution can be obtained from Jacobi matrix to judge its nonlinear stability.Because the steady state and transient state information of the periodic solution can be observed in practice,the method would be used widely.A rigid unbalanced bearing rotor system is taken as an example,the T periodic solution of this system is predicted and traced.
AERODYNAMIC CHARACTERISTICS OF HEAD IN SECTOR ANNULAR COMBUSTOR
Zhao Jianxing, Hu Jin, Ding Wanshan, Lai Shouchang, Deng Shuwen, Deng Wu
1999, 14(1): 79-82.
Abstract PDF(271KB) icon1628 icon434
Abstract:
The aerodynamic characteristics of sudden expansion region between the prediffuser exit and the head of the flametube in relation to its geometric parameters are investigated with the purpose of the annular combustor optimization.The mass flow ratio,total pressure loss of outer and inner annulus,and whole combustor are measured with different total pressure probes and flowmeters,respectively.Flow velocity profiles in the asymmetric sudden expansion region are measured by Laser Doppler anemometry.Experemental results of flow field total pressure loss and flow ratio for two types of combustor and seven configuration sectors show that two eddies occur in the sudden expansion regions;the prediffuser geometric parameters,such as deflection angle;relative sudden gap L/h and inlet Mach number,have an effect on the airflow patterns,drag coefficient and mass flow ratio.
AN ENGINEERING EVALUATION SYSTEM OF TURBINE DISC COOLING CONFIGURATION
Ding Shuiding, Tao Zhi, Xu Guoqiang, Qiu Xuguang
1999, 14(1): 83-86.
Abstract PDF(287KB) icon1487 icon341
Abstract:
An engineering evaluation system is proposed to appraise the fluid flow and heat transfer in a turbine cooling configuration of an aero-engine.The system includes resistance evaluation,heat transfer evaluation and temperature distribution evaluation.The former determines the whole system flow friction loss,the later two determine the relative cooling effect and the level of thermostress.The relationships of rotating Reynolds number,cooling air Reynolds number,Grashoff number with the three evaluations have been investigated experimentally.The engineering evaluation system serves as a tool to optimize turbine cooling configuration system.
A STUDY ON CONVECTIVE HEAT TRANSFER IN HOLES OF INCLINED MULTIHOLE WALL FILM COOLING
Lin Yuzhen, Song Bo, Li Bin, Liu Gaoen
1999, 14(1): 87-90.
Abstract PDF(493KB) icon1646 icon346
Abstract:
The local and the overall convective heat transfers inside the small holes have been investigated experimentally for the inclined multihole wall film cooling,according to the similarity theory.The results demonstrate that the convective heat transfer intensifies very greatly in the region inside the hole entrance.The results also reveal that the Renolds number of the hole has strong influence on the convective heat transfer.The higher the Renolds number,the more intensive the convective heat transfer inside the hole.
AN INVESTIGATION ON FILM COOLING EFFECTIVENESS OF INCLINED-MUTIHOLE WALLS WITH DIFFERENT PATTERNS
Song Bo, Lin Yuzhen, Liu Gaoen, Wang Huafang
1999, 14(1): 91-94.
Abstract PDF(278KB) icon1928 icon375
Abstract:
An experimental investigation on the film cooling effectiveness of the inclined-multihole walls with different patterns(In-line,Staggered,In-line+compound angle,Staggered+compound angle) was conducted by using the method of heat-mass transfer analogy.The holes were inclined with 30° to the wall surfaces and the compound angle was 45° to the mainstream.The multihole patterns were arranged with streamwise row-to-row spacings of eight hole diameters and spanwise hole pitch-to-diameter ratio of four.The superior mutihole pattern was found out from the experiments.
INVESTIGATION ON HEAT TRANSFER IN PIN FIN ARRAY
Dong Suyan, Liu Songling, Su Hongzhen
1999, 14(1): 95-99.
Abstract PDF(647KB) icon1616 icon408
Abstract:
Detailed heat transfer measurements were performed by using 178 thermocouples in the channel with pin fin array.Local heat transfer coefficients and local heat transfer enhancement coefficients were obtained for the total eight Reynolds numbers ranging from 2000 to 100000 on the endwall of the channel.The endwall boundary conditions for the heat transfer investigation are heating bottom endwall and heating symmetrically on bottom and top endwalls.The mechanism of heat transfer enhancement with pin fin array has been elaborated.
VIBRATION FATIGUE CHARACTERISTIC OF COMPRESSOR BLADES
Kang Jidong, Xu Zhihuai, Chen Shixuan
1999, 14(1): 100-101.
Abstract PDF(332KB) icon2104 icon489
Abstract:
Investigation on the vibration fatigue characteristic of the third compressor blades made of steel 1Cr11Ni2W2MoV is presented.A new electro-magnetic eddy-current exciting system has been used to the tests for vibration fatigue strength measuring by up-and-down method.The results show that:(1)The vibration fatigue failure modes of the blades vary with the service duration.The failure location of the new blades is at the maximum stress point on the back of the blade,while with the increasing of the service duration,the failure location changes to the leading & trailing edge of the blades.(2)The vibration fatigue strength decreases with the increase of the service duration that is verified by the up-down method tests on blades in different service durations of 0 h,200 h,and 400 h,respectively.(3)Maintenance of the blades is an effective measure for increasing of the fatigue strength.The comparison tests on the in-maintenance and maintained blades of 400 h service duration show that maintenance of the blades has positive effects on the fatigue strength but the failure location is still at the leading & trailing edge.

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