2002 Vol. 17, No. 4

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Three Dimensional Aerodynamic Investigation of a Turbine Nozzle Guide Vane with Combination Design of Tip Endwall Contouring and Positive Leaned Airfoil
SHI Jing, ZHOU Yong, ZHOU Si-ping, LI Wei, LUO Jian-qiao, LU Cong-ming
2002, 17(4): 385-391.
Abstract PDF(381KB) icon1609 icon470
Abstract:
The combination design of tip endwall contouring and positive leaned vane in low aspect ratio turbine nozzle can not only reduce secondary losses on both endwalls,but also match the requirements for using plain blade body when impingement cooling is in use.The paper describes the mechanical mechanism and the flow field character that how the combination design redues the secondary losses.A quality factor which allows qualitative evaluation of the effect of blade design on secondary losses is selected and verified.Based on a lot of 3D computations,the paper investigates in detail the effect of some main characteristic parameters on 3D flowfield,such as leaned angles,the start place of tip endwall contraction and the curvatures of the contours,etc.The design method, steps and the evaluation criteria of flowfield quality have been given.The combination design method has significance for the successful design of a low aspect ratio high temperature turbine nozzle.
Study of Flow Structures within Turbine Cascade with Large Tip Clearance
HUANG Hong-yan, YANG Qing-hai, HAN Wan-jin, WANG Zhong-qi
2002, 17(4): 392-398.
Abstract PDF(451KB) icon1888 icon481
Abstract:
Flow visualizations on wall surface and numerical simulations within turbine cascade with large tip clearance were carried out.Based on the experiential results and with the aid of numerical simulations,detailed flow structures within a typical turbine cascade were discussed.The detailed information of the flow fields near the wall surface,in the tip clearance,and especially,around the trailing edge was shown in the present study.In the up-half-span region,the flow became very complex due to the existence of the tip clearance.There are interactions among those vortices such as leakage vortex, up passage vortex,shed vortices on the pressure and suction sides,and trailing edge vortices.In the low-half-span,the flow fields near the region formed by the trailing edge and the endwall were also very complex.There are 3 saddle points company with 6 separation lines and 2 nodal points represent the trailing edge vortices on the wall surface near those region.At the end of this paper,vortical structures of the turbine cascade were developed.
Numerical Study of Interaction between Clearance Flow and Passage Secondary Flow in Turbomachinery
JIA Xi-cheng, WANG Zheng-ming
2002, 17(4): 399-403.
Abstract PDF(383KB) icon1948 icon534
Abstract:
In this paper,the interaction between tip leakage flow and passage secondary flow in a compressor stator was investigated by numerical method.The calculations are based on the 3D Navier-Stokes equations expressed with nonorthogonal curvilinear coordinates and corresponding nonorthogonal velocity components, and the explicit time marching algorithm and Baldwin-Lomax turbulence model are adopted.An efficient integral H-grid is employed to solve the grid singularity in the tip region.The details of generation and development of passage vortex,leakage vortex and tip separation vortex were predicted.The computed results show,because the direction of the leakage flow is opposite to that of the passage secondary flow,proper leakage flow can weaken the intensity of passage vortex and improve the flow in tip region.
Contra-Rotating Turbine Test Rig with Transonic-Supersonic Profiles
LIU Si-yong, WANG Ping, LU Cong-ming, YAN Shan-ping, FANG Xiang-jun
2002, 17(4): 404-406.
Abstract PDF(406KB) icon1907 icon456
Abstract:
The test rig consists of intake and exhaust collectors,axial tester (two rotors),two speed reducers,two eddy-current brakes, heater and lubricating system.The high pressure and low pressure rotors can rotate either in the same or opposite directions.Research about aerodynamics of turbine with or without guide vanes are conducted.The interstage flow field is analyzed by means of noncontact measuring and visualization device,such as PIV laser velocimeter.
Experimental Evaluation of High Temperature Low Cycle Fatigue/Creep Life of Turbine Blade
WANG Yan-rong, SONG Zhao-hong, HOU Gui-cang
2002, 17(4): 407-411.
Abstract PDF(817KB) icon1900 icon488
Abstract:
The high temperature low cycle fatigue life of the 2nd stage turbine blade in an aircraft engine in service has been evaluated by use of the experimental method,in which the effect of creep has been considered.In order to shorten the test period,according to the principle of damage-equivalence,the equivalent accelerated test loading-spectrum has been determined.The test has been implemented on a test-bed in which eddy current inducted heating and hydraulic pressure driven force are applied.The test results have been analyzed statistically by use of logarithmic normal distribution and Weibull distribution,and the safe in-service life of the blade with the confidence level of 95% and the reliability of 99.87% has been determined.
Information Entropy Method for Engine Reliability First Approximate Confidence Limits
SUN You-chao, ZUO Hong-fu, SHI Jun
2002, 17(4): 412-415.
Abstract PDF(253KB) icon1711 icon456
Abstract:
According to the equivalence theorem of information quantity provided by the practical test of the parts or subsystems and the equivalence test of the system the test data of the parts or subsystems are converted into the equivalence test data of the system.Furthermore,the computation model of the practical test information of the parts or subsystems and the system equivalence conversion model are formulated and presented.In the light of the basic principle of unit reliability assessment,the general models of entropy method synthesis are established for system reliability first approximate confidence limits.These models include system reliability s-Classical non-randomization optimization first approximate limits (lower,upper and two-side limits),and system reliability s-Bayes first approximate limits (lower and upper limits).An example is given and the assessment results are satisfactory in comparison with the traditional methods.
The Investigation of the Stiffness Characteristics and the Stress-Strain Relation of Metal Rubber
CHEN Yan-qiu, GUO Bao-ting, ZHU Zi-gen
2002, 17(4): 416-420.
Abstract PDF(720KB) icon2155 icon546
Abstract:
Metal rubber is a kind of non-linear and nonelastic material that has excellent damping performance.It can especially be compatibly used in aviation,space flight and atrocious environment.Some experimental studies of stiffness performance of thinner MR material have been carried out in this paper.The factors that affect the performance of MR and their affecting rules have been summed up on the basis of plentiful tests.There is important and practical value for perfecting the MR.The investigation results provided credible evidence for the application and theoretical research of MR damper or material.The strain-stress relation of MR is established and the coefficients of the equation are given based on the test data.The result of the theoretic calculation is consistent with the experimental data.
Piping System Design of Aero-Engine Using Genetic Algorithms
CHEN Yan-Qiu, Zhu Zi-gen
2002, 17(4): 421-425.
Abstract PDF(691KB) icon2284 icon529
Abstract:
In this paper,a universal and effective optimal program for piping system of aero-engine is presented.Based on the finite element method,the genetic algorithm (GA) is selected for optimization according to the structure and vibration characteristics of the piping system.And this program is carried out on the FEM software NASTRAN.A full size pipe is designed using frequency and amplitude adjustment as the optimization objective functions.The calculation result and analysis show that this design method can acquire optimization solutions effectively.These solutions are testified to satisfy the stress distribution of the engineering requirements.A proposal is made that a damper of metal rubber should be fixed on the pipe to avoid greater vibration which emerges during the operation of aero engine.
Investigantion on the Tangential Stiffness of Friction Damper
HAO Yan-ping, ZHU Zi-gen
2002, 17(4): 426-431.
Abstract PDF(771KB) icon1957 icon486
Abstract:
Friction damper is an effective way to reduce the response of structure and it has been widely used to alleviate the resonant stress of blades.The friction damper is often modeled as a hysteretic spring.The stiffness of spring is just the damper's tangential stiffness.So it is very important to know the stiffness value of a real damper.In this paper,a new method to evaluate the stiffness of damper is proposed,by which the tangential stiffness of damper can be identified.The constitution of stiffness is studied systematically based on the experimental data.It is found that the value of tangential stiffness depends on both normal load and excitation.There is a fixed relationship among these three factors.
The Analysis of 2D Temperature and Thermal Stress of TBC-Coated Turbine Vane
YANG Xiao-guang, GENG Rui
2002, 17(4): 432-436.
Abstract PDF(305KB) icon1738 icon501
Abstract:
The paper used the FEM to carry out the analysis of 2D temperature distribution and thermal stress of a TBC-coated turbine vane under design condition.The thermal barrier coatings include the plasma sprayed and electrical beam physical vapor deposition (EB-PVD) coatings.The constitutive equation is the advanced viscoplastic constitutive theory (Walker type).The typical "column type" structure of EB-PVD TBC can be dealt with and was implemented into the user-defined subroutine of MARC FEM software.The different cooling effects were analyzed according to different TBC types and different thickness of the TBC.The effects of stress distribution and direction on the bonding strength were discussed.The results are beneficial to build the strength design and evaluation methods for hot-section components with TBC.
Nonlinear Time Series Analysis of the Rub-Impacting Rotor Vibration Response
REN Hui, PEI Cheng-ming, HE Er-min, LIU Qi-zhou, ZHANG Zhi-yu
2002, 17(4): 437-441.
Abstract PDF(305KB) icon1603 icon429
Abstract:
Rub-impact of rotor system is a typical failure for an engine.The vibration response of a rub-impacting rotor system exhibits some nonlinear characteristics.How to diagnose the fault of the rub-impact rotor with the new theories of the modern signal analysis has become a noticeable research project.In this paper,the researches of the fault diagnosis of rub-impact rotor are carried out by the theory of nonlinear time series analysis considering the nonlinear dynamical characteristics of the rub-impacting rotor.Based on the theory of phase space reconstruction,the estimations of the embedding delay and dimension are deduced,and the reconstruction of the time series of the rub-impacting rotor system is completed.Then the correlation dimensions of the different time series are estimated.The performances of the diagnosing methods are studied and evaluated by means of the simulation data and the testing data of the rub-impacting rotor.It is found that the correlation dimension values can describe the extent that the behavior of the system approaches to chaos.The different correlation dimension values show the system to be in quasi-periodic vibration,chaotic vibration with quasi-periodic or obvious chaotic vibration.When rub-impact of the rotor system is serious,the correlation dimension increases.The computation of the testing data also prove this.
Classification and Identification of the Rotor Rub-Impacting Chaotic Signals with Noise
REN hui, GU Jia-Liu, HE Er-min, ZHANG Zhi-yu
2002, 17(4): 442-446.
Abstract PDF(675KB) icon1479 icon509
Abstract:
In this paper,we will try to identify the chaotic signals of the rub-impacting rotor system using learning vector quantization (LVQ) which is based on competitive learning and clustering analysis.The theory analysis and results of the computation are given.We have mainly studied the situations of the different classification when the response signals are in the different ratio of signal to noise.Our research shows that the LVQ neural network not only can identify rub-impacting chaotic signals but also work well for the signals with noise.So the network supplies a direct method for classifying such nonlinear signals of the rub-impacting rotor system and a possibility of practical application for a real rotor system.
Theoretical and Numerical Methods for Solving Friction Force of Circular Motion in Contact Plane
SHAN Ying-chun, ZHU Zi-gen
2002, 17(4): 447-450.
Abstract PDF(247KB) icon1523 icon561
Abstract:
In this paper,a theoretical method is proposed to calculate friction force when friction interfaces are constrained to circular motion in a plane.Using this method we can,get the solution of friction force in theory and analyze its features.The comparison of the analytical solution with the numerical one shows that the numerical method is valid.Additionally,the source of errors is analysed in order to provide basis for further application of this method to calculating the friction force when friction interfaces are constrained to complex two-dimensional motions.
Numerical Simulation of Turbine Stage with Cooling Gas Injection
CHEN Hai-xin, SHEN Meng-yu
2002, 17(4): 451-457.
Abstract PDF(389KB) icon1604 icon426
Abstract:
In order to numerically simulate the viscous flow field in turbine stage with cooling gas injection,Jameson's Finite Volume Methods are employed to solve Reynolds averaged Navier-Stokes Equations on H-H type structural grid generated with elliptical method.For the simplicity and robustness of the software,Baldwin-Lomax algebraic model is chosen for turbulence closure.According to the so called One-Dimension Isentropic Flow model,the mass,momentum,and energy flux injected through film cooling holes or slots to flow field are computed and then coupled to the boundary conditions to reveal the effects of cooling gas.Using of Mixing Plane model makes the simulation of stator-rotor interaction be realized with acceptable computer resource costs.A typical configuration-C3x cascade with film cooling,which has experimental data,is computed to validate the present methods.Results of both flow field parameters and heat transfer parameters are in good agreement with experimental data.To illustrate the present methods' capability of handling configurations with engineering complexity,simulation results of two realistic turbine stages,a transonic one and a subsonic one, both with complex layout of cooling holes and slots,are presented.
Thermodynamic Optimization of Convective Heat Transfer Through Cross-Flow over Single Tube
CAI Wei-hua, XU Guo-qiang, TAO Zhi, DING Shui-ting
2002, 17(4): 458-463.
Abstract PDF(320KB) icon1454 icon436
Abstract:
The first and second laws of thermodynamics,combined with the method of weighted mean value of outside fluid temperature,have been utilized to optimize the convective heat transfer of one tube cross-flow heat exchanger.The spatial distributions of the field of fluid temperature inside and outside the tube,irreversibility,and entropy generation rate profiles are presented.It is shown that the entropy genaration rate may be minimized through proper selection of some parameters of the system.
An Analysis of the Effectiveness of One Pass Cross-Flow Finned Tube Bundle Heat Exchangers
CAI Wei-hua, XU Guo-qiang, TAO Zhi, DING Shui-ting
2002, 17(4): 464-468.
Abstract PDF(292KB) icon1681 icon518
Abstract:
Using the method of weighted mean value of outside fluid temperature along with the Laplace transformation and recursive procedure,an analysis of the heat transfer and temperature fields of one pass finned tube bundle cross-flow heat exchanger has been carried out.The spatial distributions of the fluid temperature fields inside and outside the tubes are presented.It is shown that for such flow arrangement,the relation for heat exchanger effectiveness has a simple explicit form.
Three-Dimensional Thermohydrodynamic Analysis of Circular Journal Bearing
FU Yan-li, MA Xi-zhi, ZHU Jun
2002, 17(4): 469-474.
Abstract PDF(332KB) icon1743 icon472
Abstract:
The simultaneous solution of the generalized Reynolds equation,three-dimensional energy equation,three-dimensional heat transfer equation and force equilibrium equation were presented and the changes of the lubricant viscosity and density with the temperature and pressure were taken into account.Consequently,the three-dimensional temperature field was obtained with the heat flux continuity condition imposed at the interface between the oil film and the bush.The result show that the maximum temperature did not appear at the interface between the film and bush and the point of the maximum temperature was different along the film thickness direction at different circumferential locations.The differences of the bearing performances were validated between the three-dimensional temperature model and the two-dimensional temperature model.A Newton-Raphson approach was used in solving the generalized Reynolds equation and the force balance equations,simultaneously.For the energy equation and the heat transfer equation,the finite difference method was carried out with the help of a sweeping scheme.The approaches we used were found to be fast converged and saved computing time greatly.
Study on Cooling Effectiveness of Various Film Coolings
ZHANG Xiao-ying, WANG Xian-wei
2002, 17(4): 475-479.
Abstract PDF(290KB) icon1617 icon556
Abstract:
The cooling effectiveness of following film cooling types for expansion regulating parts of high performance aeroengine nozzle has been calculated and compared:slot film cooling,full coverage film cooling,and compound slot and full coverage film cooling.The method to calculate the film cooling effectiveness for multi-row of holes and for compound slot and full coverage is developed on the basis of film cooling effectiveness for single row of holes film and for slot.The temperature distribution when taking into account the effect of high temperature gas radiation and film cooling is calculated,the result provides beneficial references to selecting film cooling type for nozzle of high performance aeroengine nozzle.
An Improved Variable Memory Length Identification Algorithm
LI Jian, XIE Shou-sheng
2002, 17(4): 480-482.
Abstract PDF(290KB) icon1576 icon465
Abstract:
Based on multiresolution analysis method,an improved variable memory length wavelet transform multiresolution analysis method is proposed.The method decomposes data into different frequency segments,then for different frequency segments different memory lengths are used for identification.An aero-turbine starter is taken as a numerical example,and the simulation results show the method is effective to improve identification precision.
Discussion on Key Technical Problems in Developing Numerical Simulation Test-Bed for Aeroengine
FENG Guo-tai, HUANG Jia-hua, WANG Shong-tao, XU Jing-lei
2002, 17(4): 483-488.
Abstract PDF(340KB) icon1747 icon457
Abstract:
In this paper some key technical problems about developing numerical simulation test-bed for aeroengine are discussed,including:aim and elementary object,three-dimensional multi-field coupling model as well as its validation and parallel arithmetic,integrate software package,generic framework of simulation test-bed and simulation environment, and all these should be prepared before numerical simulation test-bed could be established.
Application of Contra-Rotating Turbine without Guide Vanes to High Thrust Loading Aeroengine
LIU Si-yong, WANG Ping, FANG Xiang-jun, YAN Shan-ping
2002, 17(4): 495-499.
Abstract PDF(690KB) icon1863 icon608
Abstract:
To meet the needs for developing contemporary new fighter,it is imperative to develop fan turbo-engine with thrust loading exceeding ten.Adopting contra-rotating turbine characterized by transonic-supersonic profiles,large load,low blade density,without guide vanes and high deflection angle is an important measure.It would greatly reduce the weight of engine and raise the thrust loading.This paper reviews its primary advantages and new requirements for aerodynamics design and computing.A contra-rotating turbine test rig has been constructed in cooperation with 608 Research Institute of China Aviation Industry.
Dynamic Characteristic Study of Staged Combustion Cycle Rocket Engine
HUANG Min-chao, LIU Kun, ZHANG Yu-lin, WANG Nan
2002, 17(4): 500-504.
Abstract PDF(326KB) icon1813 icon574
Abstract:
The dynamic process in the staged combustion cycle liquid rocket engine was simulated through the module codified.Owing to the mathematical model form mulated that took account of the inertia,viscosity and compressibility of the liquid flow at the same time,this method could generally express the distributed characteristic of the dynamic process in the supplying system.What is more,in order to obtain higher precision in simulation calculation,we also made use of the experimental results to adjust parameter values of some important characteristics.Finally based on the simulated data,the fluctuations of the engine working parameters were discussed in this paper.And with the analysis results we provide some comparisons and basis for designing the staged combustion liquid rocket engine in the future.

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