1995 Vol. 10, No. 3

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PRELIMINARY SEARCH FOR NEW FLOW-TYPES IN TURBOMACHINERY
Liu Jingmei, Zhou Sheng
1995, 10(3): 205-209,307.
Abstract PDF(1044KB) icon1613 icon403
Abstract:
As viewed from flow-types,the developing process of aircraft aerodynsmics is compared with that of turbomachine gasdynamics.For the branch of turbomachine′s gasdynamics,it is found that the steady body-fitted flow-type is still the searching object.However,the entire body-fitted flow-type is impossible.It means that the unexpected separations in turbomachinery can not be eliminated.And our comparison has shown that,as for the development of flow-types,the branch of turbomachine′s gasdynamics lags considerably behind the branch of aircraft aerodynamicsSome of the suggestions,with regard to the possible ways of introducing new ideas of flow-types from aircraft aerodynamics into turbomachine gasdynamics,are presented in this paper.
AEROACOUSTIC SOLUTION OF TURBOMACHINERY IN FREQUENCY DOMAIN
Ju Hongbin, Zhong Fangyuan
1995, 10(3): 210-212,307.
Abstract PDF(251KB) icon1725 icon405
Abstract:
According to the sound radiation solution of rotating source in frequency domain,formulae of noise sources in turbomachine have been derived.Then the detailed aeroacoustic solutions of the sound field in the turbomachine,the blades of which are thin and bent slight in the mid-chord alignment were obtained.The result is suitable for near sound field analysis.Moreover the influence of geometric parameters and operation conditions are explicitly expressed in the frequency domain solutions.
EFFECT OF SMALL RADIAL DISTORTION OF INLET FLOW ON STALL FLUTTER IN AXIAL FLOW COMPRESSOR
Feng Yucheng, Zhao Xiuhua, Hu Zongan, Ji Tu, Wang Yunwei
1995, 10(3): 213-216,307.
Abstract PDF(309KB) icon1987 icon400
Abstract:
The effect of small radial stagnation pressure distortion of inlet flow on the stall flutter has been investigated experimentally.The results of experiments show that the small radial distortion of the inlet flow at blade tip can eliminate the stall flutter.This phenomenon is verified by computation with three dimensional actuator disk method.The computed results conform with the experimental data.
NUMERICAL SIMULATION OF INTERNAL FLOW IN 2-D NOZZLES WITH THRUST VECTORING
Yong Honwei, Chun-Hian Lee
1995, 10(3): 217-220,308.
Abstract PDF(286KB) icon1671 icon462
Abstract:
Numerical simulation of internal flow with thrust vectoring in two-dimensional convergent nozzles is described,which utilizes multigrid technique in conjunction with MacCormack’s explicit scheme.In computations,the Reynolds averaged Navier-Stokes equations are adopted for the five grids with K-ε turbulence model;and on the other hand,Euler equations are solved on the coarse grids.Numerical results provide good resolution to the flow fields,and the computed pressure distributions are found in good agreement with the experimental data.The influences of geometric parameters upon the flow quality and thrust coefficient are also analyzed.It is demonstrated that the multigrid technique adopted here is reliable and suitable for parametric study.
COMPUTATION OF 2-D TRANSONIC AND SUPERSONIC FLOW FIELDS USING TVD SCHEME AND FOUR-STAGE RUNGE-KUTTA TECHNIQUE
Wang Shangjin, Ni Mingjiu, Xi Guang
1995, 10(3): 221-224,308.
Abstract PDF(288KB) icon1641 icon448
Abstract:
Harten′s TVD scheme is extented to 2-D general curvilinear coordinates by local rotation matrix translation.A new fully explicit solving method based on Four-Stage Runge-Kutta technique is developed to predict 2-D supersonic and transonic flow field.Comparison between computation and experiment is presented for both supersonic and transonic flow.The numerical results show that this scheme is not only convenient to solve the supersonic flow,but also capable of predicting the transonic flow.
INVESTIGATION ON FLOW RESISTANCE AND HEAT TRANSFER IN COOLING PASSAGES OF GAS TURBINE BLADE
Gu Weizao, Tu Jianping, Liu Wenyen, Wang Zhifang, Zhao Dongmei, Sheng Rongchang, Liu Xiaofeng, Ling Jinru
1995, 10(3): 225-228,308.
Abstract PDF(1063KB) icon1897 icon453
Abstract:
An enlarged test blade of gas turbine has been investigated experimentally for flow resistance and heat transfer in its cooling passages.Air entered the radial cooling channel inside the leading part of the blade and contrary flowed downward into the passage between two plates while the air flow reached to the top.The bulk of the air stream flowed through five holes on the plate into the chordwise wedged passage with three pin-fin rows and exhausted to the atmosphere.The experimental results of the pressure distribution,the flow resistance under heating and without heating,and the distribution of the local heat transfer coefficient in the cooling passages of a gas turbine blade are presented.Therefrom an emperic formula is obtained.
AN INVESTIGATION ON LOCAL HEAT TRANSFER PERFORMANCE FOR RIM HEATED ROTATING DISK WITH CENTRAL AIR INFLOW
Xu Guoqiang, Ding Shuiting, Qiu Xuguang, Cao yuzhang
1995, 10(3): 229-232,309.
Abstract PDF(357KB) icon1783 icon464
Abstract:
An actual Gas-Turbine disk was simplified to a rim heated rotating disk with central air inflow.The effects of rotational Reynolds number, Re ,Mass flow coefficient C w ,gap ratio G and shrouded clearance ratio G s upon local heat transfer were experimentally studied.The disk diameter was 360mm and the maximum rotational speed was 3600 r/min.It was found that the distribution of the local heat flux on the disk surface was U-Shaped.The heat transfer could be enhanced by increasing mass flow coefficient and rotational Reynolds number.The effects of gap ratio and shrouded clearance ratio were small.
A METHOD FOR CALCULATION OF CONTACT HEAT RESISTANCE BETWEEN TWO CONTACTING SURFACES
Gu Weilan
1995, 10(3): 233-236,309.
Abstract PDF(282KB) icon1911 icon542
Abstract:
A method is provided for calculation of contact heat resistance between two contacting surfaces.The contact heat conductance was derived for a single contact spot of a simplified disk contact model.The distribution function of contact spots can be solved by using the method of counting functionals.As a result,an empiric formula of the contact heat resistance with the fluctuations of extruding stress is derived.
A PSEUDOTHERMAL LOAD ANALYTICAL METHOD FOR CONTROLLING CRACK GROWTH IN AN INTELLIGENT COMPOSITE COMPONENT
Du Yanliang, Nie Jingxu
1995, 10(3): 237-240,309.
Abstract PDF(337KB) icon1514 icon483
Abstract:
A new method to analyze the stress fields of the intelligent composite components,namely the pseudothermal load method,is proposed for active control of crack growth according to their structural characteristics.This method has been applied to computing and analyzing several intelligent composite components.The results are in good agreement with experimental data.So this is the theoretical basis for research and application of the intelligent composite material with the aim of the crack growth active control.
DEFORMATION AND STRESS ANALYSIS OF RUBBER O-RING
Ren Quanbin, Chen Ruxun, Yang Weiguo
1995, 10(3): 241-244,310.
Abstract PDF(858KB) icon2063 icon390
Abstract:
A model of multilateral frictional contact problem of two objects with far different stiffness was established.In addition,a stress relax model of rubber-like material was developed according to the poly-dimension stress creep theory.On the basis of the above models,the deformation and contact stress of the rubber O-ring was calculated by using a finite element method approaching large strain in ref..Some useful conclusions can serve as trustworthy principles for rubber O-ring design.
APPLICATION OF ULTRASONIC FATIGUE TESTING TECHNIQUE
Ni Jingang
1995, 10(3): 245-248,310.
Abstract PDF(1480KB) icon1656 icon462
Abstract:
This paper deals with the application of ultrasonic fatigue testing technique to the study of fatigue life and fatigue crack growth behavior of metals and alloys under vibrational excitation at high frequency (20kHz).The mechanical damage and fracture mechanism of materials were investigated in the case of ultrasonic fatigue cycles.This testing technique has remarkable advantages in time-saving,economy and noiselessness and capability for investigating mechanical damage models of aeroengine and rocket structures in real service.
DYNAMIC PROCESS MODELLING IN ROCKET ENGINE WITH NEURAL NETWORKS
Cui Dingjun, Yang Erfu, Zhang Zhengpeng, Liu Guoqiu
1995, 10(3): 249-252,310.
Abstract PDF(284KB) icon1615 icon464
Abstract:
According to principles of neural networks and BP algorithm,the relationship between the neural networks and nonlinear modelling is anlyzed.A general idea and a basic method for modelling with neural networks are put forward on the basis of the study of dynamic process in liquid rocket engine was formulated.Then a new modelling approach to researching the parameters of the engine was formulated.An example given in this paper shows that the application of the neural networks to the investigation of the dynamic process in the liquid rocket engine is a great success.
A MULTISTAGE FINITE ELEMENT METHOD FOR TRANSONIC FLOW CALCULATION IN TURBOMACHINERY
Zhu Gang, Shen Mengyu, Liu Qiusheng, Wang Baoguo
1995, 10(3): 253-255,311.
Abstract PDF(468KB) icon1738 icon389
Abstract:
In the light of the idea of Multistage Finite Element Method,The anisotropic tensor force finite element and the Taylor-Galerkin finite element method have been combined properly into a new method which called anisotropic multistage finite element method.This method is superior in convergence speed and stability and suitable to transonic flow calculations.We applied this method to analyzing the transonic flow in a two dimensional cascade and compared with its experimental data.It is shown that this method is a powerful tool for the transonic flow calculation.
ANALYSIS OF FATIGUE CRACK GROWTH IN GLALL
Zhang Xueren, Nie Jingxu
1995, 10(3): 256-258,311.
Abstract PDF(250KB) icon1752 icon449
Abstract:
A finite element analysis is applied to the fatigue crack growth properties in glass aluminum hybrid laminates (GLALL).The stress and strain fields of GLALL with different crack length are obtained from the computation,in which the cracks are assumed to expand only in Al layers.The relationship of the effective stress intensity factors on the crack tips to the crack length is derived by the energy method.It is found that the bridging effect of the glass fibers with high strength on the cracks in Al layers decreases obviously the effective stress intensity factors thus the growth rate of the fatigue cracks is cut down to a great extent .The computation results agree well with the experimental data.
STRUCTURAL RELIABILITY ANALYSIS OF AN AEROENGINE WITH COMPLEX UNCERTAINTY
Wang Zhenying, Lu Wenlin, Fan Xing
1995, 10(3): 259-262,311.
Abstract PDF(735KB) icon1777 icon491
Abstract:
Random meterial properties,geometrical shapes,forces and displacement boundary condition of an aeroengine are directly introduced into functional variational formulations and a unified random variational principle and the probabilistic finite element method with the small parameter perturbation method are provided.Based on second-order perturbation technique,the formulations for the random stresses and the reliability of the aeroengine′s structures are derived.According to analysis the characteristics of these random parameters,the simple methods for analyzing the aeroengine structural reliabilty are obtained.At last,the reliability of a rotating disk of the aeroengine is analyzed with a simple numerical example.
RELIABILITY DESIGN OF TURBINE PART VIBRATION
Shi Jinyuan, Lin Zhenkun, Gong Hansheng
1995, 10(3): 263-266,312.
Abstract PDF(286KB) icon1802 icon503
Abstract:
This paper presents a reliability design method of turbine part vibration,based on conventional vibration design method for turbine parts.The method considers excitation force frequencies,natural frequencies and vibration responses of turbine parts as random variables according to actual conditions.The reliability for the vibration design of parts is estimated by means of probabilistic design.Methods for determining the distribution parameters of design magnitudes are given together with reliabilty calculation models for distancing from resonance and limiting vibration response.Reliability design methods of rotors and bearings as well as blades are elucidated with some practical examples.
A STRESS INFLUENCING MATRIX METHOD FOR CALCULATING BENDING ROOT STRESSES OF HELICAL GEARS
Zhao Ning, Fang Zongde, Sun Xuemei
1995, 10(3): 267-269,312.
Abstract PDF(241KB) icon1861 icon394
Abstract:
A method of the stress influencing matrix is proposed for calculating bending stress courses on teeth root of the helical gears.The stress influencing matrix of mesh nodes on the surface of the gear teeth and on nodes of its contact lines is established by using 2-D interpolation and then is multiplied by the load distributing matrix on the nodes.Therefore,the bending stress courses on the gear teeth root are obtained.By means of generating the flexibility matrix on the gear teeth root the finite element calculation of this method is only needed once to obtain the distributing conditions of loads on the working surface of the gear teeth and distributing conditions of the bending stresses on root surface of the gear teeth for whole meshing period.The calculated results are compared with the experimental data.It is proved that the method of the stress influencing matrix is as accurate as the finite element method,but can save computer memory and calculating time to a great extent.
DERIVATION OF MISSION DUTY CYCLES FOR A TRAINER ENGINE
Song Yingdong, Shang Weijun
1995, 10(3): 270-271,312.
Abstract PDF(248KB) icon1542 icon444
Abstract:
The main objective of this study is to establish a method for deriving engine mission duty cycles.Seven typical training profiles of a trainer engine are recorded.The flight mission mix is obtained from statistics of the trainer engine operations on fields.Based on the typical flight mission profiles and the mission mix,the mission duty cycles of the trainer engine are derived which can be used as a design load requirements for a new trainer engine.This study showes that due to short average flight time,a great difference exists between the mission duty cycles of the trainer engine and the design requirements of Engine Structural Integrity Standard (MIL-STD-1783).
A FINITE ELEMENT METHOD FOR COMPUTING DYNAMIC COEFFICIENT OF HYDRODYNAMIC JOURNAL BEARINGS
Wang Dongwei, Zhu Jun
1995, 10(3): 272-274,313.
Abstract PDF(256KB) icon2002 icon399
Abstract:
A finite element method is presented for computing the oil film dynamic coefficients of hydrodynamic journal bearings.Once the integral equations of the four functions.
AN INVESTIGATION ON VIBRATION MONITORING TECHNIQUE FOR A TURBOSHAFT ENGINE
Li Xifa
1995, 10(3): 275-276,313.
Abstract PDF(187KB) icon1506 icon500
Abstract:
The Vibration characteristics of the turboshaft engine on ground and in flight are considered.According to the distribution of the vibration frequency spectrum,a method is presented to display and record vibration velocity value of the turboshaft engine on ground or in flight.A vibration monitor made of INTEL 51 series 8031 single chip microcomputer has eight channels.Six channels are employed to record vibration signals and the other two channels to measure engine rotating speeds.The system operation performance has been proved by a large amount of measurements on fields and airbrone measrements.
A STUDY ON MOTION BEHAVIOURS OF PARTICLES THROUGH TURBINE CASCADE
Yi Jinghai, Shi Feng, Xu Zhong
1995, 10(3): 277-279,313.
Abstract PDF(241KB) icon1820 icon511
Abstract:
A high speed camera is used to photograph the motion process of particles through turbine cascade.The effects of particle size and initial position on the particle trajectories and velocities are analyzed.The particle trajectories and velocities are also computed with the Lagrangian method under conditions of flow with and without boundary layer.Comparison between computational and experimental results shows that it is necessary to consider the effect of the boundary layer for the smaller particles,but it is unnecessary for the larger particles when the Lagrangian method is used to compute the motion behaviours of particles.
RELATIONSHIP BETWEEN BLADE FLUTTER AND LEAKAGE VORTEX OF COMPRESSOR ROTOR
Li Kejian, Zhang Yangjun, Tao Deping
1995, 10(3): 280-282,314.
Abstract PDF(229KB) icon2017 icon529
Abstract:
By using the Tip Vortex Method (TVM) and the Center Tip Vortex Method (CTVM) with the deforming disk method of flutter prediction respectively,the relationship between the tip leakage vortex and the blade aeroelastical stability has been studied.The results show that the tip leakage flow vortex has a great effect on the blade aeroelastical stability and large tip leakage vorticity may restrain blade flutter.The calculational results are consistent with the experimental data.
OPTIMIZATION OF GEOMETRICAL PARAMETERS FOR A SUBSONIC AXIAL FLOW COMPRESSOR STAGE
Chen Lingen, Sun Fengrui, Peng Yiheng
1995, 10(3): 283-285,314.
Abstract PDF(252KB) icon1631 icon390
Abstract:
Design of a subsonic axial flow compressor stage has been formulated as a nonlinear multiobjective mathematical programing problem in which minimizing the aerodynamic losses and the weight of the stage,and maximizing the compressor stage stall margin are selected as the objectives.Aerodynamical and mechanical constraints are considered in the problem formulation.A model for estimating the performance of the compressor stage is also presented.Three objective functions,eight design variables and fourty-six constraint conditions are involved in the optimization.A numerical optimization is given for a subsonic axial compressor stage with maximum efficiency,minimum weight,maximum stall margin,in which weighted optimum relationship between efficiency,weight and stall margin has been obtained.
NUMERICAL SIMULATION FOR MIXING FIELD OF TWO INCOMING STREAMS IN A DCR
Ma Jihua, Zhang Fan, Wu Bin
1995, 10(3): 286-288,314.
Abstract PDF(253KB) icon1721 icon399
Abstract:
The flux vector splitting method is adopted to solve the 2-D Euler equations and a numerical simulation is conducted for the division-flow inlet of Dual Combustor Ramjet (DCR) as well as the cold-mixing flow field of both flows from a dump combustor and from a supersonic inlet.The computational results provide a clear shock construction of the whole flow field and physical pictures of the two mixing high-speed streams in the supersonic combustor.The numerical results of the research can be available for reference to the ignition and combustion of the DCR.
AN EXPERIMENTAL INVESTIGATION ON TURBULENT CHARACTERISTICS IN COUNTERROTATING AIRFLOW FIELD
Huang Xuemin, Wang Hongming, Zou Zhengping
1995, 10(3): 289-291,315.
Abstract PDF(247KB) icon1817 icon500
Abstract:
Fluctuating velocity,turbulence intensity and the fluctuating frequency of turbulent airflow within a counterrorating airflow field were investigated experimentally with hot-wire anemometers.It is showed that turbulence intensity and fluctuating velocity are very large in the boundary layer region,where counterrotating airflow mixes violently;after mixing,the turbulence intensity of swirling airflow decreases and distributes uniformly in radial direction;various eddy scales exist in airflow field,the fluctuating frequency band is very wide without main frequency.
AN EXPERIMENTAL INVESTIGATION ON EFFECTS OF BACKGROUND ON TARGET INFRARED RADIATION MEASUREMENTS
Wei Fuqing
1995, 10(3): 292-294,315.
Abstract PDF(237KB) icon2097 icon372
Abstract:
The effects of background on target infrared radiation measurements were investigated experimentally by means of background treatment and under different meteorological conditions.Some suggestions are offerred for eliminating the effects of the background and improving the infrared radiation measurement of the target,as well as for recording meteorological conditions to correct the infrared radiation measurements.
THERMAL CAVITY-PLUME COMBINATION RADIATION
Xu Nanrong, Zhu Gujun
1995, 10(3): 295-298,315.
Abstract PDF(278KB) icon1944 icon435
Abstract:
The problem of thermal cavity (afterburning cylinder of a jet engine) and plume combination radiation is considered.The radiative transfer differential equation was derived.The solution of the differential equation was then obtained under the radiative boundary conditions.The detailed solution of radiative transfer equation was elaborated for a thermal cavity,filled with high temperature gas and surrounded with multiple walls of different temperatures.The detailed spectral radiant intensity expression was also given for the back hemisphere.Then a spectral radiation intensity expression was also derived for the thermal cavity-plume combination radiation.Finally a numerical example was given.Its results show that the spatial distribution of the thermal cavity-plume combination radiation has a pear shape just like that of measurements.The spectral distribution is also consistent with measurements.
STUDY ON SATURATED WATER VAPOR PRESSURE EQUATIONS FOR CALCULATION OF AIRCRAFT AIR-CONDITIONING SYSTEMS
Fang Xiande
1995, 10(3): 299-300,316.
Abstract PDF(190KB) icon1969 icon474
Abstract:

There are notable errors in saturated water vapor pressure equations used in the calculation of aircraft air-conditioning systems.With the aid of regression technique,a new water vapor pressure equation is derived from recent saturation pressure data of pure water and ice.Compared with the equations used at presnt,the new equation remains simple in form,but its accuracy is enhanced so magnificently as to give satisfactory results for aircraft air-conditioning engineering in possible saturation temperature range.
LQG/LTR DESIGN METHODOLOGY FOR A MULTIVARIABLE AEROENGINE CONTROLLER
Huang Wanwei, Zhang Jiazhen
1995, 10(3): 301-303,316.
Abstract PDF(240KB) icon1814 icon457
Abstract:
This paper researches the design methodology for multivariable robust controller of aero-engine.A small-divergence state space model for a given jet aero-engine has been established with the difference method.The Linear Quadratic Gaussian with Loop Transfer Recovery (LQG/LTR) method has been used to design a BIBO robust controller for the engine.The functions of the controller such as command following,decoupling and disturbance rejection have been considered.It is demonstrated that the LQG/LTR controller has excellent robustness for the uncertainty of the plant model.
APPLICATION OF KALMAN FILTERING FOR AN AEROENGINE PARAMETER ESTIMATION
Liu Xiaoyong, Fan Siqi
1995, 10(3): 304-306,316.
Abstract PDF(233KB) icon1938 icon485
Abstract:
The Kalman filtering method for an aeroengine parameter estimation has been investigated by using flight data.The research purpose is to solve the Kalman filtering divergence problem in the aeroengine parameter estimation.The main content is the integrated Kalman filtering method of the adaptive processing,the compensation in flight condition and the aeroengine modification.Finally,the results of the parameter estimation are presented.

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