2000 Vol. 15, No. 1

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Display Method:
The United Modeling Theory for both of Mean Flow and Coherent Flow of Incompressible Turbulence
Gao Ge, Yan Yong
2000, 15(1): 1-11.
Abstract PDF(711KB) icon2012 icon482
Abstract:
A unilateral statistical average scheme is used to derive a new set of closed equations of incompressible turbulent flows,which is capable of describing both of statistical mean flow and intermittent coherent flow without introducing any empirical treatments and coefficients.Besides the special average scheme,the concepts of symmetic drift flows,orthotropic trubulence and the chain of momentum transference are also used in the original derivation.More important,the obtained energy equation of series form suggests that the infinite terms in the equation are corresponding to infinite layers of structures of trubulence.If all the terms of the series are taken for determining the length scale,one obtains statistical mean results.On the other hand,if only parts of terms are taken,coherent flows would appear.To verify the adaptablity of the equations,three benchmark flows,i.e.free shear flow,boundary layer transition flow and separated flow,are numerically simulated on PC computers.Both of accurate results of statistical mean flows and vivid structures of coherent flows are obtained.
Computation of 3-D Unsteady Viscous Flow in Transonic Compressor Stage
Liu Qianzhi, Zhou Xinhai
2000, 15(1): 12-16.
Abstract PDF(339KB) icon1660 icon444
Abstract:
A time-marching finite difference method is presented for the numerical simulation of the three dimensional unsteady viscous flow by rotor-stator interaction in an axial transonic stage.A high-resolution scheme is adopted to capture flow shocks.The flow information of rotor and stator is exchanged by using the system of overlaid grids.In order to reduce CPU time,an implicit LU-SGS method is applied to obtain rapidly a steady state solution,from which an unsteady flow computaion can be started.A numerical example for a transonic compressor stage has been carried out.The results show a good prediction of the unsteady effects caused by rotor-stator interaction.
Numerical Study of 3-D Flow in a Diagonal Fan Impeller
Lai Huanxin, Kang Shun, Tan Chunqing, Wu Keqi
2000, 15(1): 17-21.
Abstract PDF(563KB) icon1805 icon440
Abstract:
The NUMECA software Fine/Turbo is employed to investigate the three dimensional viscous flow in a diagonal fan impeller at the operating conditions with and without blade tip clearance respectively.The limiting streamlines,secondary flow patterns and velocity distributions of the two flow fields are analyzed by comparison between their numerical and experimental results.The transportation of low energy fluid in the flow passage,"jet/wake" structure and the formation of tip leakage vortex are revealed.The results show that the non-uniform flow wake induced by secondary motion and vortex always appear in the corner region of casing wall and pressure surface;and the effects of the tip clearance are to reduce the efficiency of the impeller and to enlarge the non-uniform level of the outflow field in the impeller.
Establishment of Repeating Stage Conditions for Prediction of Axial Compressor Flow Field
Zou Zhengping, Xu Liping, Zhang Zhifang
2000, 15(1): 22-26.
Abstract PDF(322KB) icon1645 icon444
Abstract:
The generation of repeating stage flow pattern in a multistage axial compressor and a simulation model of its flow field are investigated.The results show that the aerodynamic loading is one of the important factors to set up the repeating stage conditions.The flow is quickly reaching the repeating stage conditions as the loading is high.At the same time,a repeating stage boundary conditions are established on the basis of the model.A multi-stage flow field is simulated numerically which is reached the repeating stage conditions,employing 1.5 compressor stages.The results show that this method can improve the convergence as well as save the required memory and time of computation.
Experimental Investigation on Effect of Stator Vane Angle Adjustment on Compressor Performance
Zhang Jian, Ren Minglin
2000, 15(1): 27-30.
Abstract PDF(367KB) icon2010 icon476
Abstract:
In order to improve the performance of a three-stage axial compressor,an experiment method and procedure are presented for improving its inter-stage matching by adjusting the stator vane angles of stages.The results show that the stator vane angle variation has a remarkable effect on the compressor performance.A set of optimum matching vane angles at design speed was found by the tests. The highest adiabatic efficiency is increased by 7.4% and the stability operation margin also has a notable increase.
3-D Turbulent Characteristics at Exit of Compressor Rotor Passage
Ma Hongwei, Jiang Haokang
2000, 15(1): 31-34.
Abstract PDF(253KB) icon1490 icon444
Abstract:
The three-dimensional turbulent flow field at the exit of an axial single rotor compressor has been measured in detail with single-slant hot-wire probe.In the design condition,substantial turbulent pulsations mainly exist in the tip mid-passage,wake and the corner between the suction surface and the hub,and the tip leakage vortex plays a leading role in the tip flow mixing.In the near stall condition,the flow becomes more turbulent,which shows the strong flow mixing in the tip region,turbulence intensities,especially the radial turbulence intensity,increase rapidly;the flow separations of the boundary layer on the suction surface occur at 0.25 span and 0.87 span.At the rotor exit,the radial turbulence intensity is the largest,and the axial one is the second.
2-D Axial Compressor Rotor-Stator Unsteady Flow Calculation by Using Euler Equations
Ge Ning
2000, 15(1): 35-38.
Abstract PDF(424KB) icon1678 icon438
Abstract:
The two-dimensional rotor-stator unsteady flow in an axial compressor is calculated by using Euler equations in absolute frame.The computational grids consist of a rotor grid,a stator grid and a intermediate grid which is designed for the connection of blade rows.The fore-boundary points of this intermediate grid rotate with the rotor blades and the aft-boundary points connect with the stator blades.Since the feature of the moving grid is considered in the Euler equations,so it is unnecesary to use the time-consuming interpolation method for information transmission between rotor and stator blade rows.The results of numerical calculation verify the feasibility of the presented approach for calculation of the rotor-stator unsteady flow.
Effects of Swept Leading Edge on Performance of Fans
Xing Siuqing, Shan Peng, Zhou Sheng
2000, 15(1): 39-43.
Abstract PDF(541KB) icon1543 icon389
Abstract:
According to the definition of the three-dimensional swept leading edge,a comparison was made between three different swept transonic rotors to study how different leading edges affect the position and intensity of shock waves,and consequently the performance of fans.Numerical analyses of their flow fields were done,and the results were compared with the study of Hah,C.(1998).The analyses indicate that the aerodynamic sweep can be used to control the shock structure not only at the mid-span but also near the casing by the end-wall effect,and has a different effect on the radial migration of low momentum fluid to the blade tip region.It can be concluded that the rotor leading edge shapes have a significant influence on the shock waves and the performance of fans.
An Experimental Study on Effect of Unsmoothed Blade on Cascade Exit Loss Distribution
Wen Jie, Zhao Guilin
2000, 15(1): 44-46.
Abstract PDF(215KB) icon1349 icon443
Abstract:
The cascades equipped with conventional smooth blades and three unsmoothed blades were investigaled experimentally in a low speed plane cascade wind tunnel to study the effects of unsmoothed blades on the exit loss distributions.The experiment results show that the unsmoothed blades can change the exit loss distributions and reduce the exit blade losses by 9.1%～16.5%.
Impeller Inverse Design by Neural Networks Coupled with Genetic Algorithms
Pan Huiyuan, Xi Guang, Wang Shangjin
2000, 15(1): 47-50.
Abstract PDF(427KB) icon1657 icon421
Abstract:
A study on application of neural networks to solving an inverse design of a centrifugal compressor impeller has been conducted.The feedforward neural networks were established by means of evolving and training with genetic algorithms for a real impeller inverse design,and then used to predict the blade profile when the velocity distribution on its surface is given.Numerical simulation shows that the neural networks can successfully yield the desired blade profile.
Prediction on of Stability Operating Limit in Aeroengines
Huang Zhitao, Hu Zhengfeng, Qiao Weiyang, Li wenlan
2000, 15(1): 51-54.
Abstract PDF(283KB) icon1590 icon418
Abstract:
A model for predicting aerodynamic stability of axial compressor in turbojet or turbofan engine is presented.The detailed numerical analyses for three examples for stability operating limits of 9-stage compressor,3-stage fan and 5-stage high-pressure compressor are given.It is shown that the compressor stability operating limit can be precisely predicted when control rule is n f =constant or n h =constant.It is also found that the numerical model and recognition criterion for aerodynamic stability in the axial compressor are feasible.The computed results are in good agreement with the experimental data obtained at medium and high rotating speeds.
Porous Medium Leakage Flow Model of Brush Seal
Huang Xuemin, Shi Wei, Wang Hongming
2000, 15(1): 55-58.
Abstract PDF(423KB) icon1387 icon457
Abstract:
In order to simplify the complex leakage flow in a brush and make it easy to calculate in real circular brush seal,a porous mdeium leakage flow model is established by means of characteristic analysis of the leakage flow in the brush.The numerical model is reasonable and practicable because the calculated results show a good agreement with experimental data.
Numerical Simulation of Aerodynamic Excitation in Labyrinth Seals in a Centrifugal Compressor
He Lidong, Diao Hailong, Zhang Yuguo
2000, 15(1): 59-62.
Abstract PDF(414KB) icon1690 icon453
Abstract:
The nonlinear oscillator model for the dynamic characteristics of structures in flow,has been extended to studying nonlinear dynamic characteristics of rotor/seal system.It is emphasized that the rotor dynamic characteristics are ffected by the nonlinear unsteady flow in the small clearance.The numerical simulation and experimental results in a rotor/seal system of the centrifugal compressor are in a reasonable agreement.It is shown that the simulation provides a theoretical basis for predicting and preventing the occurrence of seal aerodynamic excitation and for investigating the mechanism of the seal aerodynamic excitation accident.
Intelligent Support System for Passing Through Critical Speed of High-Speed Rotor by Changing Stiffness
Yan Xiaojun, Nie Jingxu, Sun Changren
2000, 15(1): 63-66.
Abstract PDF(278KB) icon1286 icon435
Abstract:
The SMA (Shape Memory Alloys) are applied as actuators and a series of experiments have been done for investigating their mechanical behaviors.An intelligent support system has been designed for active control of high-speed rotor vibration and tested to verify its effectiveness.The tests indicate that the application has a magnificent effect on the active vibration control.
Aeroelastic Response Analysis of Helicopter Rotor During Shipboard Operation
Kang Hao, Gao Zhen
2000, 15(1): 67-70.
Abstract PDF(290KB) icon1858 icon434
Abstract:
A method of transient aeroelastic rotor response analysis was developed and used to investigate shipboard engage/disengage sequences of the helicopter rotor.The blade was modeled as an elastic beam undergoing flap,lag torsion and axis deflections.The weight of blade and the inertia force due to the variation of rotation speed were taken into account.Blade element theory was used to calculate unsteady aerodynamic loads in linear and nonlinear regimes.The experimental data validated this analysis.The parameter effects on transient response were investigated.
Influence of Fluid Inertia Force on Sudden Unbalance and Accelerating Responses of Rotor Supported on Centralized SFD
Xia Nan, Meng Guang, Feng Xinghai
2000, 15(1): 71-74.
Abstract PDF(274KB) icon1817 icon422
Abstract:
The sudden unbalance and accelerating processes under the action of fluid inertia force have been investigated for an over-hung flexible rotor with two disks supported on centralized squeeze film damper.The effects of Reynolds number,and system parameters on sudden unbalance and accelerating responses are studied.It is found that the system parameters have large influence on the sudden unbalance transient process and transient time,while the fluid inertia force is considered.The response route of large solution or small solution depends on the starting rotating speed of the sudden unbalance.The system with fluid inertia force will have better accelerating and decelerating dynamic characteristics.
Overall Optimization on Machine-Tool Settings of Spiral Bevel Gears
Tian Xingbin, Fang Zongde
2000, 15(1): 75-77.
Abstract PDF(249KB) icon2168 icon442
Abstract:
The first and second order contact parameters of a spiral bevel gear drive are precontrolled by using the local synthesis method.Considering the contact pattern and transmission errors on toe,middle,heel contacts,the third order contact shortcomings are eliminated by optimizing the machine-tool settings.The overall control of engagement quality is realized.
An Investigation on Carbon Monoxide Emission of Testing Combustor with High Inlet Pressure and Temperature
Meng Xiangtai, Liu Gaoen
2000, 15(1): 78-80.
Abstract PDF(221KB) icon1595 icon385
Abstract:
The emission characteristics of carbon monoxide were investigated in the testing sector of a combustor with double swirlers.The test condition covered wide range of inlet pressure,inlet temperature and fuel-air ratio,including the highest pressure up to 4 MPa.The carbon monoxide emission data were obtained from the test.The test data are consistent with the results calculated from the Lefebvre's empirical model,based on available data.
Interaction Between Mixing Flow and Slot Film of a Combustor
Meng Xiangtai, Liu Gaoen
2000, 15(1): 81-84.
Abstract PDF(266KB) icon1833 icon423
Abstract:
The experimental investigation on slot film cooling effectiveness was conducted with different blowing rates of the sample gas—CO2,by using Heat-Mass Transfer Analogy method.The empiric formulas for calculating slot film cooling effectiveness were derived from the test data according to the turbulence-mixing model.The same experiment was also conducted with the mixing jet flow normal to the wall,and the disturbing action on film cooling downstream of the jet flow was determined.The results showed a great difference between the effects of different mixing flows on the film cooling.
Clustering Process Analysis and Pressure Disturbance Model for Microscale Boiling
Liu Dong, Peng Xiaofeng, Wang Buxuan
2000, 15(1): 85-88.
Abstract PDF(279KB) icon1803 icon489
Abstract:
The formation process of molecular clusters was considered in order to understand the boiling and nucleation of superheated liquid in microchannels and/or microstructure.The nucleation is inevitably accompanied with the volume increase of the clusters for the clusters to reach more stable state.This volume change causes pressure disturbance in the surrounding environment.Under microscale conditions,the pressure disturbance may play a leading role in phase change.The interaction of clusters with the pressure disturbance could cause the association and dissociation of clusters.The comparison between the propagation time of the pressure disturbance and the time of clusters growing to the critical radius in superheated liquid can determine whether the clusters are able to grow into boiling nuclei or vanish.Thus a critical microchannel size scale is obtained for "fictitious boiling" .The estimated value is in a satisfactory agreement with experimental data for water.
Application of Kohonen Network to Aeroengine Fault Diagnosis
Fan Zuomin, Bai Jie, Yan Guohua
2000, 15(1): 89-92.
Abstract PDF(410KB) icon1628 icon468
Abstract:
Kohonen Network (Self-organizing Mapping Model) is applied to aeroengine fault diagnosis.The technique of sequencing diagnostic results and extracting typical samples from sample group is presented.Some examples of application of Kohonen Network to JT9D jet engine fault diagnosis are given.It is shown that Kohonen network is simple to compile program and easy to use,can provide correct diagnostic results for the abnormal samples.Especially it can reveal the statistical characteristics of samples clearly and directly.The method of extracting typical samples from sample group is useful for riving the empirical engine fatult equation.
A New Model Reference Adaptive Control for Aeroengine
Liang Chunyan, Xie Jianying, Fan Ding
2000, 15(1): 93-95.
Abstract PDF(311KB) icon1529 icon472
Abstract:
A new model reference adaptive control method with excellent robustness is proposed for aeroengine.This method only needs to know the relative degree of the system.Its controller structure is simple and can be realized easily.Simulation results show that this controller can make system track the model reference output quite well.It has high adaptivity to the change of aeroengine model parameters and structure.
A Study on Co-Operating Between Thrust Vectoring Nozzle and Aeroengine
Ding Kaifeng, Fan Siqi
2000, 15(1): 96-98.
Abstract PDF(249KB) icon1601 icon427
Abstract:
The mathematical models of an axisymmetric thrust vectoring nozzle and an aeroengine with this nozzle are established.The co-operation between vectoring nozzle and engine is studied with the help of these models.The results show that deflection of the vectoring nozzle affects slightly the high-speed rotor co-operating line,and also affects slightly the low-speed rotor co-operating line when the deflecting angle of vectoring nozzle is small,but makes the co-operating line moves to downward when the deflecting angle is larger.The geometry size of vectoring nozzle has some influence on the low-speed rotor co-operating line.
Fault Detection of Measuring Channel in Aeroengine FADEC System
Wang Yonggen, Tian Lin, Gou Linfeng
2000, 15(1): 99-101.
Abstract PDF(211KB) icon1638 icon410
Abstract:
Fault detection of measuring channel in aeroengine Full Authority Digital Electronic Control (FADEC) system is investigated,especially aroundback detection is researched.The causes of the measuring channel faults have been revealed,meanwhile,the principle figure of the aroundback detection is also provided.The simulation of A/D transformer for the aroundabck detection simulation tests indicates that multi-aroundback detection range is larger than singe-aroundback one.When the aroundback detection processes small signals,it may cause error.The accuracy is 100% in detecting short circuit and open circuit by aroundback detection.
Research and Development of Engine CAD PC Integrated System for Aeroengine
Guo Shufen, Chen Juen, Wang Honggang
2000, 15(1): 102-104.
Abstract PDF(206KB) icon1227 icon445
Abstract:
A PC integrated design system,EngineCAD is introduced, which can be applied to development and improvement of aeroengine.This system can complete quickly,the realtime parametric design of turbojet,turbofan,turboprop and turboshaft engine and its parts.During designing the required information,data and structural graphics can be inquired interactively from Aeroengine Information Database and Structure Database.It is shown that the system can shorten the design period,reduce the development costs and improve the design quality of aeroengine greatly.
Solution of Shock with Variable Specific Heat for Calculation of Hypersonic Inlet
Qin Lisen
2000, 15(1): 105-108.
Abstract PDF(476KB) icon1438 icon489
Abstract:
The shock equations with fully variable specific heat are derived from the fundamental aerothermodynamic equations,considering different specific heats across the shock.A method for their solution is provided.From the comparison between the solutions with constant and variable specific heat,it can be concluded that the former gives:(1)higher total temperature,lower total pressure;(2)higher Mach number,temperature and total pressure recovery,but lower static pressure behind the shock;(3)higher total pressure recovery of the inlet;(4)lower caught area ratio than the latter at high Mach number.
Analysis of Fuel Pressure High-Frequency Pulsation in a Turbo Jet
Bao Wen, Yan Zhigang, Yu Daren, He Baocheng, Feng Yan, Li Linlin
2000, 15(1): 109-112.
Abstract PDF(282KB) icon1668 icon459
Abstract:
A dynamic nonlinear mathematics model of fuel system was set up for the high-frequency pulsation of fuel pressure in a turbo jet.The stability of the system was analyzed with whole-scale-subsection linearization.It was confirmed that high-frequency pulsation was caused by the instability of the system.An improvement method was proposed on the basis of the analysis of the relation between system parameters and system stability.

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