1998 Vol. 13, No. 3

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A MODEL OF INTERACTION BETWEEN SHOCK WAVE AND LEAKAGE VORTEX ON TRANSONIC FAN
Yang Zhi, Ma Jihua, ao Deping
1998, 13(3): 225-229.
Abstract PDF(389KB) icon1679 icon473
Abstract:
A strong interaction between shock wave and leakage vortex,induced by an intensive inter-impact of rotating motion on abrupt anti-pressure gradient,makes their formations and strengths varied.The vortex breakdown deteriorates the stability and efficiency of compressor and fan.So a model of interaction between shock wave and leakage vortex is formulated.The solution of vortex core movement equations shows that the small initiative vortex core velocity and enhanced initiative vortex core pressure will induce the vortex instability.The high Mach number and circulation gradient outside the vortex core will result in breakdown of the vortex.The analysis of the factors leading to vortex breakdown serves as a foundation for its controlling.
A 3D EULER NUMERICAL RESEARCH METHOD WITH REGARD TO ROTOR/STATOR INTERACTION OF AXIAL TURBOMACHINERY
Ji Lucheng, Meng Qingguo, Zhou Sheng
1998, 13(3): 231-234.
Abstract PDF(337KB) icon1812 icon484
Abstract:
Based on steady Euler solver developed by the author,a new time accurate Euler solver is modified to study Rotor/Stator interaction problems.The inviscid flow field of a highly loaded transonic fan stage is simulated by this time accurate method.The results indicate that rotor inlet flow fields are not affected by the downstream stator at choke condition,but the shock in the rotor will oscillate periodically.Moreover the stator will operate at highly varying incident angle.The method can be easily extended to viscous unsteady flow research in axial turbomachines.
THREE-DIMENSIONAL BLADING AND ITS INFLUENCE ON BLADE AERODYNAMIC LOADING
Zou Zhengping, Zhao Lingde, Chen Maozhang, Xu Liping
1998, 13(3): 235-241,343.
Abstract PDF(856KB) icon2150 icon574
Abstract:
The effects of turbomachinery blade bow and sweep on aerodyna mic loading distribution of the blade are investigated.A general definition of sweep angle is given in the case of turbomachinery.By means of linearized small perturbation theory,the effects of each factor are analyzed respectively,then a numerical simulation for three-dimensional viscous flow is used to verify and elaborate the analytical results.It is shown that the blade bow,twist and leading edge sweep are effective in adjusting the loading distribution on the blade surface.It is possible to make rational and effective use of the three dimensional blading to adjust the loading distributions both spanwise and chordwise,it thus provides a set of means for blading optimization.
MEASURING TECHNIQUE OF THREE-DIMENSIONAL PERIODIC UNSTEADY FLOWFIELD IN TURBOMACHINERY
Guo Enmin, Li Zhigang, Lu Yajun, Zhou Sheng
1998, 13(3): 242-245,343.
Abstract PDF(288KB) icon1666 icon381
Abstract:
Measuring technique of three-dimensional periodic unsteady flowfield in turbomachinery,including velocity and pressure fields has been developed.A more effective empirical correlation is proposed to express the sensitivity of single slant hot-wire anemometer output to flow velocity,sensor yaw angle and pitch angle.An improved single slant hot-wire three-dimensional unsteady velocity measuring technique is provided,by which the three-dimensional velocity can be measured with very high accuracy and efficiency within a wide range of the flow angle and velocity.Based on measured three-dimensional velocity field and two-dimensional pressure field,measured by pressure transducer fixed on the casing of turbomachinery,a simple experimental-numerical method has been developed to measure the three-dimensional pressure field.With the help of two-dimensional traverse mechanism,high speed data acquisition system and phase-locked sampling and ensemble averaging technique,the three-dimensional periodic unsteady flowfields at the exit of an axial fan have been successfully measured,and its structure has been revealed.
A MULTIGRID COMPUTATION OF INCOMPRESSIBLE FLOW IN COMPLEX GEOMETRIES
Hou Lingyun, Yan Chuanjun
1998, 13(3): 246-249,344.
Abstract PDF(350KB) icon1490 icon502
Abstract:
A procedure using a Full Approximate Scheme (FAS) multigrid is developed in SIMPLEC algorithm with a layout of staggered grid in generalized curvilinear coordinates.This method is applied to three flow problems as test tasks.The comparison between the iteration performance of the Multi-Grid (MG) and Single-Grid (SG) methods in different grid sizes,Reynolds number and geometries demonstrates that the multigrid method improves convergence rate,reduces CPU time,and overcomes the deficiency of single-grid SIMPLEC algorithm in generalized curvilinear coordinates.
EFFECTS OF GEOMETRIC AND AERODYNAMIC PARAMETERS ON INTERACTION OF WAVES AND VORTEX ON PERFORATED PLATE
Tang Lingyun, Wang Tongqing, Sun Xiaofeng
1998, 13(3): 250-254,344.
Abstract PDF(726KB) icon1960 icon404
Abstract:
An experimental investigation has been carried out on a kind of perforated liner with a bias flow through the apertures,according to Howe’s vortex sound theory.The attention was focused on the effects of the aperture size,the cavity depth and the perforated plate thickness on the impedance of the liner.The algorithm of the reactance is modified for the liner with thick perforated plate,based on the analysis of experimental results.The perforated liners with sucking and blowing bias flow are compared and the same conclusions are drawn out.
AN EXPERIMENTAL INVESTIGATION ON ARC SKEWED SLOT CASING TREATMENT
Zhang Yong, Lu Yajun
1998, 13(3): 255-259,344.
Abstract PDF(334KB) icon1653 icon448
Abstract:
Different geometrical designs of arc skewed slot casing treatments have been investigated experimentally to research their influences on stall margin and operating efficiency.A study on the mechanism of the casing treatment was carried out on the basis of three dimension flow field measurement.The comparison of different casing treatments revealed that the best configuration of an arc skewed slot casing treatment improved the stall margin by 27%,and the peak efficiency by 1%.Compared with an axial skewed slot casing treatment,the arc skewed one not only made an improvement in stall margin,but also ended the history that the casing treatment had to pay a loss of efficiency in order to improve stall margin.
CONTROL OF BLADE TIP CLEARANCE WITH SHAPE MEMORY ALLOYS
Zhang Xueren, Nie Jingxu, Zhang Chiming
1998, 13(3): 260-263,345.
Abstract PDF(270KB) icon1709 icon461
Abstract:
An adaptive sealing ring is developed to control the blade tip clearance of compressors with the help of shape memory alloys.Such a ring can change the blade tip clearance in adaption to the working conditions of engine. Its control mechanism is described.The structural design of the adaptive sealing ring is completed.The deformation of the adaptive ring is calculated and analyzed according to the constitutive relation of shape memory alloys.
NUCLEATE BOILING OF BINARY MIXTURE AT HIGH HEAT FLUX UNDER MICROGRAVITY
Chai Lihe, Peng Xiaofeng
1998, 13(3): 264-267,345.
Abstract PDF(295KB) icon1256 icon395
Abstract:
An analytical model for nucleate pool boiling heat transfer of binary mixtures in high-flux regime is formulated according to Helmholtz instability theory of vapor-liquid interface.The nucleate pool boiling for binary mixtures at high heat flux under microgravity is also characterized by the existence of a liquid layer known as macrolayer between the heater surface and the vapor mass.The dual bubble layer structure can maintain up to CHF condition due to less buoyancy.The expressions for fraction of bubble contact area on the heater surface and initial macrolayer thickness are derived in term of the thermophysical properties or/and the heat flux.A CHF model based on hydrodynamics is provided.The predicted results are compared with experimental data and theoretical analysis.Some important conclusions are drawn as follows:The fraction of bubble contact area on the heater surface is independent of the input heat flux,but much greater than that at terrestrial conditions;Initial macrolayer thickness is much greater than that at terrestrial conditions due to less velocities of vapor phase and liquid phase;The CHF values for binary mixtures under microgravity are about 60～80% of those at terrestrial conditions,but are much greater than those of single components under microgravity.
CALCULATION OF HEAT CONVECTION IN COMPLEX 3D GEOMETRIES
Zhu Songlin, Zhu Fangyuan
1998, 13(3): 268-272,346.
Abstract PDF(383KB) icon1551 icon411
Abstract:
A simulation method is presented for heat convection in 3D complex geometries.For a non-orthogonal coordinate formulation of the governing equations with cartesian velocity components,pressure and temperature,a finite volume method is utilized for discretization,SIMPLER algorithm is applied to pressure-velocity coupling,and the cell-face velocity interpolation method is employed for overcoming the pressure oscillations associated with the nonstaggered grid system.A visualization computing software is deve loped and applied to prediction of the heat convection in the cooling passage of low heat rejection engine.
DROPWISE CONDENSATION AS A TYPICAL FRACTAL GROWTH PROCESS
Yang Chunxin, Wang Ligang, Yuan Xiugan, Ma Chongfang
1998, 13(3): 273-274,346.
Abstract PDF(393KB) icon1644 icon405
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The dropwise condensation is a typical fractal growth process, according to the experimental data and conclusions published in last 30 years.The drop size distribution in dropwise condensation is deduced,based on the random fractal model.The fractal dimension index in the size distribution is determined with renormalization method.The analytical results are in good agreement with experimental data.
A STUDY ON AVERAGED HEAT TRANSFER CHARACTERISTICS OF A ROTATING CAVITY WITH PRESWIRLING INFLOW
Ding Shuiting, Tao zhi, Xu Guoqiang, Yuan Yixiang, Qiu Xuguang
1998, 13(3): 278-281,346.
Abstract PDF(911KB) icon1907 icon470
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A turbine cooling configuration of an aeroengine was simplified to a rotating cavity with a tangential preswirling fringe guide vane and a radial outlet.The influences of rotating Reynold number,cooling air Reynold number and Grashoff number on the averaged heat transfer characteristics were experimentally investigated.The experiment indicated that the flow pattern in the rotating cavity is mainly controlled by Rossby number.The averaged heat transfer coefficient on the main disk increases with the increase of cooling air Reynold number and Grashoff number,the increase of rotating Reynold number decreases the heat transfer coefficient at some regions of the Rossby number and causes it to increase at others.Two experimental correlations for different regions of Rossby number,are established for the averaged heat transfer coefficient on the main surface.
A STUDY ON AVERAGED HEAT TRANSFER CHARACTERISTICS OF A ROTATING CAVITY WITH AXIAL FRINGE INFLOW
Ding Shuiting, Tao zhi, Xu Guoqiang, Yuan Yixiang, Qiu Xuguang
1998, 13(3): 282-285,347.
Abstract PDF(294KB) icon1859 icon475
Abstract:
A turbine cooling configuration of an aero-engine was simplified to a rotating cavity with an axial fringe inlet and a radial outlet.The influences of rotating Reynold number,cooling air Reynold number and Grashoff number on the averaged heat transfer characteristics were experimentally investigated.The experiment indicated that the averaged heat transfer coefficient on the main disk increases with the increase of cooling air Reynold number and Grashoff number,and decreases with the increase of rotating Reynold number.An experimental correlation of the averaged heat transfer coefficient on the main surface is formulated.
NUMERICAL SIMULATION OF FILM COOLING IN ROTATING BLADE TIP
Yang Huitao, Cao Yuzhang
1998, 13(3): 286-289,347.
Abstract PDF(634KB) icon1606 icon479
Abstract:
Numerical simulation of film-cooling in two types of blade tip in rotating case is completed by SIMPLE method.Turbulent eddy viscosity is determined by k-ε two equation model,while the wall function is considered in boundary layer.The simulation shows that centrifugal and Coriolis forces affect the flow and centrifugal force also brings about buoyancy,which is different from the usual viewpoint that the rotation has no effect on heat transfer and film cooling in blade tip.The result also indicates that the cooling effectiveness of the rotating blade is better than that of non-rotating one in the range considered.
ANALYSIS OF EDGE CONTACT FOR HYPOID GEAR AND SPIRAL BEVEL GEARS
Gao Jianping, Fang Zongde, Yang Hongbin
1998, 13(3): 290-293,348.
Abstract PDF(782KB) icon1766 icon463
Abstract:
The simulation of gear meshing is performed by TCT programs in the light of the assumption that gear tooth surfaces are in contact at every instant.But the edge contact may occur due to misalignment,deflection of teeth and unsuitable machine-tool settings.So the vibration and noise of gear drives are inevitable.A new simulation method of the edge contact for hypoid gear and spiral bevel gears is provided.The contact patterns and transmission errors for the aligned and misaligned gear drives are obtained in an example of spiral bevel gears.Although the proposed method deals with the hypoid gear and spiral bevel gears,the basic idea is suitable for spur and helical gears.
KINETIC CHARACTERISTICS OF TRANSMISSION TEST EQUIPMENT FOR SPIRAL BEVEL GEARS
Zhao Ming, Yang Haiyan, Ren Pingzhen, Xu Lingzhi, Yang Bingyu
1998, 13(3): 294-297,348.
Abstract PDF(280KB) icon1706 icon377
Abstract:
The transtfer matrix method of the lateral/torsional coupling is applied to calculation of kinetic characteristics of transmission test equipment for spiral bevel gears.The relationships of the kinetic characteristics for the test rotor are investigated in the engagement of the spiral bevel gears.The forces on the bearing and gear-box vibration are analyzed,all callculated results are consistent with the test data.
A STUDY ON LUBRICATION OF SPIRAL BEVEL GEARS IN AEROENGINE
Wei Wenshan, Lin Jishu, Ding Jinyuan, Xia Yanqiou, Yang Wentong
1998, 13(3): 298-301,348.
Abstract PDF(641KB) icon1845 icon373
Abstract:
The vector method of the gear engagement theory is used to describe the manufacturing and meshing process of the spiral bevel gears in the aeroengine.The geometry and kinematic parameters of each contact point are considered,including the position,the curvature and the speed of each contact point on the tooth surface.The load on tooth in each contact position is determined with the help of Loaded Tooth Contact Analysis (LT CA) and the thickness of oil film on each contact position is obtained as theoretical foundation for judging the lubrication state.Meanwhile,300 hours test of the gears has been made and the topographical feature of the tooth surface by means of scanning electron microscope is investigated.The results of calculation and experiment show that the gears are under boundary lubrication and partial elasto-hydrodynamic lubrication.
COMPUTATION OF VISCOELASTICAL DAMPING STRUCTURE ATTACHED TO GEARS
Sun Tao, Shao Changjian, Shen Yunwen
1998, 13(3): 302-305,349.
Abstract PDF(339KB) icon1856 icon411
Abstract:
A computational method is developed to solve engineering problems for the viscoelastical damping structure attached to gears,and a simple model is setup by combining 20-node element technique according to the modal strain energy theory.Thus,a practical and simple approach for engineering application is provided to predict loss factors and optimal location of damping layer in the structure without the difficulty of solving complex eigenvalues.As an example,the loss factors and optimal damping location have been calculated for a real gear.The results are in a good agreement with its experimental data.
A STUDY ON VIBRATION DEPRESSION OF GEAR SYSTEM BY MODIFICATION REANALYSIS OF STRUCTURAL DYNAMICS
Shao Changjian, Sun Tao, Shen Yunwen, Zhang Xianmin
1998, 13(3): 306-310,349.
Abstract PDF(336KB) icon1673 icon388
Abstract:
The complex Mode Theorem and Matrix Perturbation Method are applied to execution of the modal sensitivity analysis and the Fourier Series Method for calculation of the vibration responses.The dynamic characteristics of a complicated aerogear system,so-called star gear system,are elaborated thoroughly.The damping enhancement and modifications of other structural parameters for the vibration depression of the system are also considered in order to find the most efficient measures to minimize the vibration responses of the whole gear system.As a result,an accurate and efficient procedure for the dynamic analysis and redesign of viscously damped linear vibration system is developed,and some practically useful conclusions are drawn out.
AN EXPERIMENTAL RESEARCH OF PULSE-GEL PROPELLANT ROCKET MOTOR
Li Yuesen, Wang Desheng, Li Qihai
1998, 13(3): 311-315,350.
Abstract PDF(365KB) icon1975 icon468
Abstract:
Gel propellant rocket motor has been developed as a new advanced technique in rocket propulsion field since the late eighties.To a great extent,it overcomes respective disadvantages of liquid and solid rocket motors,and especially has flexible and simple controllability of the rocket energy.A kind of rheological composite propellant without curing agent is used as initial formulation of gel propellant,the extrusion adaptability and frictional security of gel propellant have been studied in an experimental motor,and the relations and effective factors of its viscosity and extrudsion adaptability have been discussed and double-pulse combustion pressure-time curves have been obtained from its static firing test successfully.Thereby,the security and usability of the gel propellant and the feasibility and flexibility of pulse gel propellant rocket motor for thrust control and multiple-start have been preliminarily verified.
AN IN-FLIGHT ADAPTIVE MODEL OF TURBOFAN
Li Songlin, Sun Jianguo, Huang Jinquan, Li Jianming
1998, 13(3): 316-319,350.
Abstract PDF(720KB) icon1805 icon469
Abstract:
A real time adaptive model for turbofan engine is developed,which uses Kalman Filter concept to estimate unmeasured output variables and characterizes the effects of off-nominal engine behavior as biases on the measurable output variables.An adaptive engine model is formulated and its block diagram is set up with this method.The estimates of the output variables obtained from the presented model are compared with nonlinear simulation results of the engine for testifying its adaptability to the off-nominal behavior of the engine with deteriorated performance.
A NEW FAULT DIAGNOSIS METHOD BASED ON NEURAL NETWORKS AND EXPERT SYSTEM
Liu Zhansheng, Wu Xin hua, Zhang Xinjiang
1998, 13(3): 320-323,350.
Abstract PDF(724KB) icon1731 icon431
Abstract:
In order to diagnose the faults in trubomachinery,a new type of diagnosis system based on Expert System(ES)and Neural Network(NN) is proposed.The NN diagnosis system is used to remember directly and associate faults happened before.The NN diagnosis system gives a set of candidate faults.The back reasoning mechanism of the expert system is applied to verifying these candidate faults.This diagnosis method is proved to be reliable and superior to the traditional ones.
APPLICATION OF BPN TO QUANTITATIVE DIAGNOSIS OF GAS PATH COMPONENT FAULTS IN TURBOFAN
Sun Bin, Zhang Jin, Zhang Shaoji
1998, 13(3): 324-327,351.
Abstract PDF(895KB) icon1866 icon406
Abstract:
The possibility of using BPN to quantitative diagnosis of turbofan engine gas path component faults is investigated.By organizing the fault samples quantitatively,the construction of BPN is built and applied to the fault diagnosis of a low bypass ratio turbofan engine.The diagnostic results show that BPN can not only isolate the gas path component faults,but also identify the severity of component performance deterioration.It is proved that the BPN is adaptive to random errors in measure system and different engine operation regimes for a control plan.But the construction of BPN must be rebuilt under the condition of different engine control plans.Because it has a little ability of self-organization,it is diffcult for BPN to isolate the engine faults quantitatively when several faults occur at the same time.
DYNAMIC SIMULATION OF AVIATION HIGH-SPEED ROLLER BEARINGS WITH SURFACE ROUGHNESS EFFECT
Chen Guoding, Li Jianhua, Zhang Chenglie
1998, 13(3): 328-330,351.
Abstract PDF(254KB) icon1674 icon486
Abstract:
A new dynamic analysis method for high-speed roller bearings is put forward by coupling dynamic theory of high-speed roller bearing with Partial Elasto-Hydrodynamic Lubrication (PEHL) theory.With taking the surface roughness effects of bearing components into consideration,the dynamic characteristics of high-speed roller bearings are analysed in detail.The results indicate that the surface roughness and surface roughness texture of bearing component exert a considerable influence on the dynamic cha racteristics of the high-speed roller bearings.The improvement of the surface manufacturing quality of the bearing components can suppress the dynamic instability of bearing components in operation.Our experimental work verifies not only our analysis,but also the conclusion made by Averbach that high-speed roller bearings operate in mixture lubrication state.
RESIDUAL VIBRATION FATIGUE LIFE OF COMPRESSOR BLADE DAMAGED BY FOREIGN OBJECT
Kang Jidong, Chen Shixuan, Xu Zhihuai
1998, 13(3): 331-333,352.
Abstract PDF(750KB) icon2007 icon447
Abstract:
The residual vibration fatigue life of TC4 plate blade subjected to Foreign Object Damaged (FOD) is investigated by means of eddy current excited vibration fatigue tests.The results show that the extent of FOD depends on both impact energy E and geometric scale S.There exists a critical damage for a given blades.Repairing of the damaged parts and lowering of the vibration stress in the blade are effective measures to improve the resistance of the blade to FOD.Moreover,the comparison of the titanium and steel blades indicates that the excssive fatigue strength of the steel blade is more than that of the titanium one,because the designed stress is usually based on the tension strength of the blades.
SIMILARITY TRANSFORMATION OF FIGHTER ENGINE DESIGN LOADING SECTIONS
Yi Jun, Zhao Fuxing
1998, 13(3): 334-336,352.
Abstract PDF(240KB) icon1640 icon358
Abstract:
This paper deals with a similarity-transformation method for obtaining engine design loading section.The principal method of flight dynamics is used and the thrust of the engine serves as the key of the transformation.The loading sections of other similar engines can be obtained from transforming the measured section of a prototype engine with success.This method has been applied in engineering practice.
NUMERICAL SIMULATION OF COMBUSTION PROCESS IN A LIQUID H2/O2 ROCKET ENGINE
Liu Weidong, Wang Zhenguo, Zhou Jin
1998, 13(3): 337-338,352.
Abstract PDF(643KB) icon2098 icon383
Abstract:
Numerical simulation is employed in calculation of the combustion processes in the rocket engine which uses liquid hydrogen and oxygen as propellants.A random spray model is used to describe the initial conditions of oxygen droplets.The evaporation rate of the oxygen droplets at high pressure is calculated by ZKS model.The Arrehnius model is adopted to compute the chemical reaction rates.PISO algorithm extended by the authors is used to calculate the spray combustion flow.The convection terms of the governing equations are discretized by a second-order upwind scheme.
AN EQUIVALENT MECHANIC MODEL OF DOUBLE EXTENDIBLE NOZZLE
Yan Deyuan, Zhang Yanyu, Zhang Jingsheng, Zhang Xiaohong
1998, 13(3): 339-341,352.
Abstract PDF(322KB) icon1704 icon429
Abstract:
In order to simplify the kinematics of double extendible nozzle and make it easy to calculate,its equivalent mechanic model is established with equivalent forces and masses by means of loading and kinematic analyses of its actuators and extendible cone.Then the kinematics of the complex mechanism is turned into that of equivalent components and its mechanic characteristics can be simulated and calculated.

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