1996 Vol. 11, No. 4

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A NEW APPROACH TO DETERMINING ROTOR DYNAMIC RESPONSE
Liao Mingfu, Alex Sievi, Hartmut Walter
1996, 11(4): 337-340.
Abstract PDF(267KB) icon1562 icon419
Abstract:
In order to determine the dynamic response of a complex rotor system to imbalance,a new approach is developed,based on the state equation and transition matrix of motion of a rotor.By means of this method,the exact solution of rotor vibration response can be directly obtained without any information about its modes in advance.Furthermore,as the transition matrix can be transformed into a transfer matrix,so this approach can be combined with transfer-matrix method,and the dynamic response of a complex rotor system to imbalance can be easily computed.A numerical example shows,that this approach is an effective and short-cut method.
A COMPUTATIONAL MODEL FOR LIFE CONSUMPTION AND LIFE MONITORING OF AEROENGINE
He Jinglan, Hong Jie, Li Qihan
1996, 11(4): 341-344.
Abstract PDF(585KB) icon1986 icon400
Abstract:
A mathematical model is set up for life consumption of the high temperture parts in aero-engine.Low Cycle Fatigue, Thermal Fatigue,Creep,and any combination of them are considered in the model.Engine life usage must be determined for each flight mode by its mission analysis.A military engine flight mode can be divided into three types of cycle:zero-maximum RPM-zero,cruise-intermediate-cruise,idle-maximum-idle.The relative life consumption and remaining life of the high temperature parts of an engine for every flight can be obtained by the Miner's Rule summation.As an example,the life consumption of the high pressure turbine disk of a given engine is calculated by the model.Based on the mathematical model and its computational program in C language,the real-time life monitoring of high temperature parts in an aeroengine can be conducted.
AEROENGINE LIFE MONITORING AND REAL-TIME DATA PROCESSING
He Jinglan, Hong Jie, Li Qihan
1996, 11(4): 345-348,434.
Abstract PDF(344KB) icon1520 icon364
Abstract:
Aeroengine load and life monitoring technology play very important role in monitoring and assessing operating conditions,life consumption and remaining life of aeroengine.Aeroengine load can improve the safety and reliablity of an engine in high performance operation,and reduce its direct operation cost.The on-board life monitoring system requires the real-time analysis method of flight data processing and life consumption evaluation.Three point method,shortest sail-route method and rain-flow method are used to conduct real-time data condensing processing,including peak valley values inspection,uneffective magnitude value detecting and LCF counting for each flight.The information obtained by the on-board life monitoring system is very useful for life track on the data base of the engine parts.
AEROENGINE LIFE MONITORING AND REAL-TIME DATA PROCESSING
Yang Zhiguo, Ying Zeyong
1996, 11(4): 350-351,434.
Abstract PDF(248KB) icon1208 icon420
Abstract:
Aeroengine load and life monitoring technology play very important role in monitoring and assessing operating conditions,life consumption and remaining life of aeroengine.Aeroengine load can improve the safety and reliablity of an engine in high performance operation,and reduce its direct operation cost.The on-board life monitoring system requires the real-time analysis method of flight data processing and life consumption evaluation.Three point method,shortest sail-route method and rain-flow method are used to conduct real-time data condensing processing,including peak valley values inspection,uneffective magnitude value detecting and LCF counting for each flight.The information obtained by the on-board life monitoring system is very useful for life track on the data base of the engine parts.
A STRUCTURE LIFE EVALUATION MODEL AND ITS APPLICATION TO DYNAMIC COMPONENTS OF AIRCRAFT POWERPLANT
Xiong Junjiang, Huang Xinyu, Gao Zhengtong, Gan Weimin, Sun Rulin, Sun Shuling
1996, 11(4): 352-354,434-435.
Abstract PDF(571KB) icon1660 icon427
Abstract:
The life of a structure is evaluated with its safe-life design,and its safety is ensured with the damage tolerant design,so the safe-life design and the damage tolerant design are combined and a structure life evaluation model is developed. The formulas to determine the service life and the inspection periods of a structure with the high reliability are presented.Then the model is applied to evaluating the inspection periods for aircraft powerplant dynamic components, and an example is given.
DETERMINATION OF AXIAL PRELOADS OF ROTORS WITH CURVIC COUPLINGS
Yin Zeyong, Hu Baian, Wu Jianguo, Xu Youliang, Zhen Qixuan
1996, 11(4): 355-357,435.
Abstract PDF(549KB) icon1880 icon528
Abstract:
Rotors with curvic couplings,which are separately prestressed from the front part and the rear part,are often applied to modern turboprop and turboshaft engines.It is very important but difficult to determine the values of preloads for a rotor.The prerequisite of the axial relaxed/pressed forces caused by variety of rotor loads in operation is available,the criteria to determine the axial preloads of rotors are proposed in this paper,which takes into account synthetically the factors,such as tightness margin,strength margin,assembling relationship and etc.Hence the optimiztion model of the axial preloads is established,and the corresponding solution is presented.The computer program is developed according to the presented criteria and method.Finally,an example is given.
AN OPTIMUM METHOD OF JOURNAL BEARING STABILITY
Liu Rongqiang, Wu Xinhua, Xia Songbo, Liu Zhangsheng
1996, 11(4): 358-360,435.
Abstract PDF(248KB) icon1818 icon455
Abstract:
The expression of journal instantaneous whirl energy is formulated,based on solution for shaft center whirl orbit of a short bearing under the nonlinear oil film force.An optimization model of journal bearing parameters with optimum stability is established with the aim of minimizing time integration of whirl energy.The model has been solved with the optimal control method.In the last,a numerical example illustrates the determination of the optimal parameters of a given bearing.
A NEW APPROACH TO COMBINED FATIGUE EXPERIMENT OF TURBINE DISK MORTISES AT ELEVATED TEMPERATURE
Wang Rongqiao, Nie Jingxu
1996, 11(4): 361-363,435-436.
Abstract PDF(306KB) icon1562 icon392
Abstract:
Crack and fracture fault emerged in the mortises of a given aeroengine second-stage turbine disk for a long time and seriously endangered the aircraft's regular flight.The fractography analysis indicated that the faults were caused by combined fatigue at elevated temperature.So we were engaged in this experiment to study and research a new failure criterion of the disk.A real disk was used as experimental component,we worked out a new failure experimental approach,including key technique to ensure the noninterference between the low cycle loading and high cycle loading,the high frequency induction local heating (550℃ constant temperature),the control of high cycle vibration frequency and amplitude, and crack real-time detection.Experimental load spectrum and temperature field emulated the reality,and the experiment completely reproduced the practical flight fault. The present experimental approach can be applied to the combined fatigue analysis of any components.
A STUDY OF A DUAL-PULSE MOTOR TECHNIQUE
Zhu Guangchen, Hu Kexian, Wang Chunli, Cai Xiangfen, Zhang Yucheng, Fang Shuzhou
1996, 11(4): 364-368,436.
Abstract PDF(662KB) icon1724 icon597
Abstract:
A new type of dual-pulse solid rocket motor concept with an intermediate nozzle is presented and a test motor with changeable structural parameters was designed.Several firings of the motor with changing the structural parameters were conducted and the corresponding experimental data were obtained.A two-dimensional unsteady mathematical model was constructed for analyzing the multithroat flowfields,and numerical calculation with this model was completed.The results were compared with the test data.
NUMERICAL SIMULATION OF 3-D FLOW IN A TRANSONIC COMPRESSOR STAGE
Liu Qianzhi, Ning Wei, Yao Jixian, Zhou Xinhai
1996, 11(4): 369-372,436.
Abstract PDF(297KB) icon1698 icon365
Abstract:
An implicit Navier-Stokes solver is presented for numerical simulation of three-dimensional steady compressible turbulent flow in a transonic compressor stage.The LU-SGS(Low-Upper Symmetric-Gauss-Seidel)implicit time-marching scheme developed by Jameson and Yoon is used to improve the computational efficiency.In order to obtain distinct shock system and valid boundary layer characteristics,one kind of high resolution schemes,the third order accurate NND (Non-oscillatory,Non-free-parameter,Dissipative)scheme is incorporated in this solver.The governing equations,the numerical scheme,the grid system and the boundary treatment method are considered in this paper.The Baldwin-Lomax Algebra model is utilized to compute the turbulent viscosity.The viscous flow in a single stage transonic compressor is calculated by this solver.The calculation was performed by coupling the rotor and stator flow fields at each time step through an overlapped grid.The computed results were compared with experiment data.
A CAD SYSTEM OF SOLID ROCKET MOTOR NOZZLE
Xu Xu, Yang Li, Zhang Zhenpeng
1996, 11(4): 373-376,437.
Abstract PDF(276KB) icon1758 icon499
Abstract:
A Computer-Aided Design (CAD) system for solid rocket motor nozzle based on microcomputer is described.The developed software can accomplish a series of structure designs and performance calculations by way of man-machine interaction.At last,a number of data files,charts and engineering drawings will be outputted for further use.This software has been put into use and is proved to be with high efficiency and convenience.
A RESEARCH ON CORRELATION OF ENGINE PERFORMANCE PARAMETERS TO INPUTS
Yu Yanglin, Sun Jianguo, Lan Chunxian
1996, 11(4): 377-380,437.
Abstract PDF(271KB) icon1770 icon443
Abstract:
A correlation analysis algorithm has been researched to find out correlation among model updates,engine inputs and its component performance.This work is required for development of an on-board real-time engine model which is based on component tracking filters,and also is significant for modern control algorithm and analytical redundancy technique to be applied to engine control.The results of numerical simulation show that the correlation analysis not only can reduce calculation work,but also enable the model developed track and match engine very well,even under the condition that the number of sensors is limited.
AN OPTIMIZATION DESIGN APPROACH OF STATOR CONTOUR CURVES FOR DOUBLE-ACTING VANE PUMP
Ye Zhifeng, Sun Jianguo
1996, 11(4): 381-384,437.
Abstract PDF(276KB) icon1888 icon445
Abstract:
Optimal control theory is applied to design of contour curves of stator transition zone for a double-acting vane pump.In order to improve characteristics of the pump,a performance index function is proposed in consideration of service life,vibration and noise.An optimal contour curve is obtained from calculation by using Pontryagin's Minimum Principle.The calculated results show that the novel contour curve can effectively decrease the shock and noise in comparison with that designed by polynomial method.It makes a vane pump run at enhanced speed and pressure.Significant improvements are also made in other aspects.Some parameters in the performance index can be adjusted to satisfy special requirements of double-acting vane pump of high performance.
EXPERIMENTAL INVESTIGATION ON PERFORMANCE OF A LARGE S-SHAPED DIFFUSER WITH "CARET" INLET
Zhong Yicheng, Yu Shaozhi, Chen Xiao
1996, 11(4): 385-388,438.
Abstract PDF(278KB) icon1904 icon528
Abstract:
A "caret" inlet was designed for Mach number 2.0 according to theory of waverider.The experimental investigation on flow characteristics of a large S-shaped diffuser with such an inlet has been carried out.The flow characteristics of the inlet and the S-shaped diffuser have been analysed by means of flow visulization on the walls,measurements of total pressure recovery distribution and velocity vector plots in the sections concerned.The performance of this large S-shaped diffuser was compared with that of the same diffuser but with conventional inlet.It is shown that,under takeoff condition and at the same Ma2 of the diffusers,the total pressure recovery of the former is a little higher but the circumferential total pressure distortion index △ σo and DC60 of the former are larger than that of the latter.
A CVFEM FOR 2-D CONVECTION-DIFFUSION EQUATION
Wang Xu, Yan Chuanjun
1996, 11(4): 389-392,438.
Abstract PDF(277KB) icon2005 icon461
Abstract:
The formulation of a control-volume-based on finite-element method (CVFEM) for two-dimensional convection-diffusion equaitons is presented.It has a main advantage in capability of the obtained discretization equation to be solved with point-by-point and conjugate gradient iteration method,so that it is more suitable to complex geometrical fields and can save much more computer memory.Some numerical examples proved that the accuracy to any high Peclet number is quite encouraging.
A HIGH-ORDER ANISOTROPIC K-ε MODEL AND ITS NUMERICAL INVESTIGATION IN TWO DIMENSIONAL TURBULENT FLOW FIELDS
Liu Zhengxian, Song Baojun, Gu Chuangang, Miao Yongmiao, Su Moming
1996, 11(4): 393-396,438-439.
Abstract PDF(367KB) icon1758 icon462
Abstract:
A new anisotropic K-ε model(MAKE) is deduced and simplified based on the basis of anisotropic K-ε model.It has been applied to numerical analysis of two dimensional turbulent flows.Its main feature is the presence of the first and third order functions of velocity gradient in the Reynolds shear stress formula,so as to be applicable for strong anisotropism of turbulent flow fields.The new coefficients of the MAKE model are analyzed and selected.The straight two dimensional turbulent flows are numerically studied by using MAKE standard K-ε model (SKE) and anisotropic K-ε model (AKE).The numerical results obtained from the three models are compared with previous experimental data.It is shown that the main flow velocity field is predicated by MAKE as well as the other two models,but MAKE is more accurate than SKE to prediction of the Reynolds normal stress.
A STUDY ON FLOWRATE CHARACTERISTICS OF GAS-LIQUID COAXIAL ATOMIZERS IN HYDROGEN/OXYGEN ROCKET ENGINE
Zhou Jin, Hu Xiaoping, Huang Yuhui, Wang Zhenguo
1996, 11(4): 397-400,439.
Abstract PDF(318KB) icon1679 icon363
Abstract:
An experimental and theoretical study on the flowrate characteristics of gas-liquid coaxial atomizers in hydrogen/oxygen rocket engine are presented in this papaer.The dependence of the gas and liquid flowrates of atomizers with different recess ratio on the injection pressure drops was determined by the tests with air and water.The effect of the interaction between gas and liquid flows within atomizer on the flowrate characteristics was investigated experimentally.The results show that the interaction between gas and liquid flows has a certain effect on the flowrate characteristics,and the effect is greater for the atomizers with larger recess ratio.A simplified theoretical model is developed to calculate the flowrates of gas-liquid coaxial atomizers.The comparison between the theoretical and experimental results shows a reasonable agreement.
TRANSITION SIMULATION USING GLM-EM BASED CLOSED EQUATIONS OF TURBULENCE
Gao Ge, Y.Yong
1996, 11(4): 401-405,439.
Abstract PDF(390KB) icon1735 icon333
Abstract:
The half-wave Generalized Lagrangian Mean (GLM) method is applied to deriving the closed equations of incompressible turbulent flow.The set of equations does not contain any correlation terms and empirical coefficients.The eddy-viscosity is determined by the Stokes drift velocity,its length scale and divergence.Without using the wall function and any empirical treatments,the transition process of a plan boundary layer has been successfully simulated by the equations.All the transition details,such as the change of the mean parameters,the transformation of the velocity profiles from laminar to turbulent,the evolution of the thickness of the boundary layer,the length of transition zone,and the curve of friction coefficients,are well consistent with experimental results.
IMPROVEMENT OF PRESSURE FIELD IN S-SHAPED DIFFUSER AT HIGH INCIDENCE BY VARIABLE LIP
Weng Peifen, Guo Rongwei
1996, 11(4): 406-408,440.
Abstract PDF(244KB) icon1738 icon431
Abstract:
The effects of a variable lip on pressure field in an S-shaped air intake at high angle of attack have been investigated experimentally.The measurements of wall and exit static pressures were made at the range of incidence from 0° to 80° of lip angle from 0° to 50°.With increasing angle of the variable lip,two effects exist:(1)the incidence seems to reduced,(2)a door with the same effect as auxiliary air intake door (AAID) occurs behind this lip because of its rotation,which allows air flow with a high kinetic energy into the diffuser.The results show that the pressure promotion is obtained in this kind of intake with the help of the variable lip technique.
REGULARIZATION PROCESSING OF INPUT DATA IN INVERSE HEAT TRANSFER PROBLEM AND ITS INFLUENCE ON THE SOLUTION
Zhou Jingwei, Cheng Shangmo, Li Wenjun, Li Xijing
1996, 11(4): 409-411,440.
Abstract PDF(278KB) icon1419 icon338
Abstract:
The major difficulty of the inverse problem lies in the fact that its solution does not depend continuously on the data and therefore is ill-posed.Based on Tikhonov's regularization method,a numerical procedure is provided for processing the input data in the inverse heat transfer problem,so that a uniform approximation is obtained both for the data function and its derivative.The effectiveness of the methods illustrated through simulated experiments using inexact data.The results demonstrate that the accuracy and stability of the inverse problem solution are significantly improved.The influence of the time step and the regularization parameter is also investigated.In addition,it is also shown that such a regularizing smooth procedure is obviously superior to the ordinary least square approximate method.
A STUDY ON HORIZONTAL EJECTION CHARACTERISTICS OF EFFERVESCENT ATOMIZERS
Fan Quanlin, Guo Zhihui, Liang Xueping, Xu Hang, Gu Shanjian
1996, 11(4): 412-416,440-441.
Abstract PDF(365KB) icon1785 icon512
Abstract:
The atomizing and flow field characteristics of a novel type of injector have been investigated.Essentially,the injector is a plain-orifice atomizer with injecting air or gas into the liquid upstream of the final discharge orifice.Measurements of mean drop size and drop-size distribution and velocity characteristics of the spray are obtained with the aid of Particle Dynamic Analyzer (PDA).The liquid employed is water and all tests are carried out at normal atmospheric pressure and temperature.The injecting pressures of water range from 1.5×105 to 5.5×105Pa,and air/liquid mass ratios from 0 to 0 12.Investigations are focused on the influence of gas-ejecting methods and the convergent angles on atomization performance of horizontally ejecting effervescent atomizer.The results show that atomization quality changes obviously at horizontally and downwards injecting of the atomizer.Different two-phase flow patterns lead to various atomization effects.
EFFECTS OF MECHANICAL HETEROGENEITY ON FATIGUE CRACK GROWTH IN WELDED JOINTS
Li Xiaoyan, Xu Tang, Gao Deping, Fan Yinhe, Zhu Hongguan, Tian Xitang
1996, 11(4): 417-419,441.
Abstract PDF(224KB) icon1692 icon426
Abstract:
Welded joints were simplified as sandwiched crack bodies of CCP type.By means of experiments and elastic-plastic finite element method,the law of fatigue crack propagation in the simplified models both with and without mechanical heterogeneity was researched.It is found that,fatigue crack growth not only depends on material properties of crack tip region,but also on material properties adjacent to the crack tip seriously.The shape of plastic zone and distribution of stress and strain in heterogeneous cracked body magnificently differ from these of homogeneous one.It can be considered that the essential effect of mechanical heterogeneity on the fatigue crack growth life is its effect on crack closure.
SOFTWARE PACKAGE SRMICAD FOR DESIGNING SRM IGNITER
Zhang Weihua, Li Qinnian, Hou Zhongxi, Shi Lihua, Guo Jian
1996, 11(4): 420-425,441-442.
Abstract PDF(493KB) icon1745 icon378
Abstract:
The design methods of four kind of commonly used igniters of Solid Roctet Motor (SRM) are considered in this paper.C Language is used to complete software programming.A software package has been worked out for designing the igniters of SRM,which uses Chinese interface,window input and drawing show.The software package can predict mass flux time curve and pressure time curve of the igniter,transient pressure time curve in main motor pressure set-up process and pressure time curve for the SRM with the given free volume.Therefore the package SRMICAD will serve as an important tool for design and theortical analysis of various solid rocket motor igniters.
AN OPTICAL FIBER FLAME MONITOR
Xue Xiusheng, Deng Yong
1996, 11(4): 426-428,442.
Abstract PDF(228KB) icon1906 icon372
Abstract:
A new fast monitor technique for flames in an environment of high temperature and infrared radiation.The first set of optical fiber monitors for afterburning igniter flame has been successfully applied to engineering measurements and shot a trouble in aeroengine afterburner measurement.
FAULT DETECTION,IDENTIFICATION AND ACCOMMODATION OF AEROENGINE SENSORS
Zhang Jing, Wang Dingqiang
1996, 11(4): 429-432,442.
Abstract PDF(622KB) icon1872 icon371
Abstract:
The fault detection filter is adapted to designing detectable matrix and diagnostics logic.The concept of fault gain is used to incorporate the accommodation logic.An algorithm is proposed,which is able to detect,identify,accommodate the faults of the sensors.The results of simulation proved the availability of the algorithm.

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