2004 Vol. 19, No. 4

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Effects of Rotating Inlet Distortion on a 5-Stage HP-Compressor Stability
LI Chuan-peng, HU Jun
2004, 19(4): 433-437.
Abstract PDF(288KB) icon2092 icon477
Abstract:
The inlet flow rotating distortion effects in a five-stage HP compressor have been investigated experimentally。For co-rotating distortions,the results exhibited significant loss in stability margin and there were two peaks in surge margin degradation corresponding to two distortion rotating frequencies;For counter rotational distortions,the tests showed minimal loss of stability margin,especially in some cases.The range of stable operations was even enlarged.
Low-Re Number Effects on the Performance of Some Fans and the Modified Design
GU Ming-hao, GUI Xing-ming
2004, 19(4): 438-443.
Abstract PDF(314KB) icon1761 icon476
Abstract:
Under the conditions of high-altitude and low-Ma,the low-Re number affects the performance of the fan/compressor greatly.In order to analyse the effect of low-Reynolds number on the performance of some fans,Wassell semi-empirical method and 3D numerical simulation method have been employed to study the aerodynamic performance and flow field structure of the fan.For the sake of denting the influence of low-Reynolds number,the stator aerofoil was redesigned and the effect of the modified design was evaluated.
Modeling Turbofan Engine Startup Based on Component Matching Principles
WANG Zhan-xue, QIAO Wei-yang, LI Wen-lan
2004, 19(4): 444-448.
Abstract PDF(763KB) icon1865 icon487
Abstract:
Because general simplified component-level engine start models were based on sub-idle steady-state operating line relationships,these models are not capable of simulating startup well for different engine starting operations.In this paper,a new one dimensional mathematical model based on component matching principles has been developed for simulating engine startup.A small turbofan engine starting operation as an example was simulated by using this model.According to modeling results,we find that the model developed in this paper captured a small pressure overshoot prior to stabilizing and combustor blowout in initial accelerating phase.
LDV Measurements of Turbulent Flow Field in a Centrifugal Impeller at Off-Design Flow
LIU Zheng-xian, WANG Yong, CAO Shu-zhen, GU Chuan-gang, MIAO Yong-miao
2004, 19(4): 449-454.
Abstract PDF(684KB) icon1889 icon415
Abstract:
An experimental investigation of the shrouded centrifugal backswept impeller flow field has been conducted at off-design flow using Laser Doppler Velocimeter (LDV) and shaft encoder.Measurements of the three-dimensional velocity field at flow rates greater and smaller than design value were acquired.The measurements describe both the throughflow and secondary velocity field along several main planes through the passage.The velocity vector profile clearly documents the different positions,intensity and development of the separation flow when changing the inlet flow rates.The secondary velocity vector plots show that the migration of the secondary vortex across the main flow was influenced by flow rates which made the centrifugal and Coriolis force changing.
Qusi-3D LDV Measurements of Unsteady Flow Field in a Rim Sealing of a Turbine Stage
MA Hong-wei, Dieter E Bohn, Achim Decker, Bernd Rudzinski
2004, 19(4): 455-458.
Abstract PDF(586KB) icon1860 icon418
Abstract:
Experimental flow data are urgently necessary to study interaction between the sealing flow and main flow in a turbine stage as well as the unsteady flow phenomena of hot ingestion in a disk cavity.However,there are many difficulties in measurements such as light path arrangements due to the narrow space in a rim sealing.Having worked out a lot of technique problems, this paper reports quasi-3D LDV measurements of unsteady flow field in a rim sealing of a turbine stage.The measurements were taken in two steps.First,radial and tangential velocities as well as turbulence intensities were measured using two-dimensional LDV probes put on the casing,then the measurements were repeated by one LDV probe put in the hub.Axial velocity of the flow was calculated from the two sets of data. With the help of a phase-locked technique,the periodically unsteady flow field in both a rim sealing and a disk cavity can be disclosed at different rotor-stator relative positions.This paper presents some typical results of the unsteady flow field.
Design Method of Two-Dimensional Hypersonic Forebody/Inlet of Mixed Compression
LI Ming, SONG Wen-yan, HE Wei
2004, 19(4): 459-465.
Abstract PDF(379KB) icon1841 icon469
Abstract:
It is possible to define a fixed geometry hydrocarbon fuel dual-mode scramjet operating in a large Mach number range (between Ma=3 to 8).The efficient design of an inlet is crucial to the successful operations of the scramjet.The goal in the design of any hypersonic inlet is to define a minimum weight geometry that provides an efficient compression process,generates low drag,produces nearly uniform flow entering the combustor,and provides these characteristics over a wide range of flight and scramjet operating conditions.A two-dimensional hypersonic forebody/inlet of mixed external and internal compression with plane lip and wedged lip is designed in this paper by using constant shock angle method and constant shock intensity method.The design point of the designed forebody/inlet is determined to be Ma=6,H=25 km.The effects of temperature and shock/boundary-layer interaction are considered in the design.The design and off-design performance and flow field of several types of designed forebody/inlet are calculated and compared.The comparison results indicate,at lower flight speed,the starting performance and total pressure recovery coefficient of forebody/inlet with wedge lip are better than that with plane lip.At high flight speed,the forebody/inlet with plane lip shows higher pressure ratio and lower cowl drag,but the forebody/inlet with wedge lip exhibits high total pressure recovery coefficient and high cowl drag.Moreover,the performance of inlet designed by constant shock angle method or constant shock intensity method is similar.The presented method is applicable to the preliminary scheme choice of hypersonic forebody/inlet.
Investigation of Supersonic Inlet Mathematical Model with Attack Angle
SHI Rui-jun, LU Xian-feng, FAN Si-qi
2004, 19(4): 466-471.
Abstract PDF(329KB) icon3224 icon455
Abstract:
At different attack angles,Mach numbers and ramp angles,the numerical calculations of inner and external flow field are performed for an adjustable mixed compression inlet.The full flow field characteristics of a supersonic inlet are illustrated at design conditions;The influence of attack angle on flow field of the inlet is investigated;B-spline theory is used to model the inlet with attack angle.On basis of the modeling results,the effects of Mach number,attack angle and ramp angle on the inlet performance are analyzed.
Numerical Study and optimization of a Single Stage Compressor/Pylon Interaction
ZHANG Yong-xin, CHEN Mao-zhang, JIANG Hao-kang, ZHANG Hui
2004, 19(4): 472-477.
Abstract PDF(411KB) icon1625 icon522
Abstract:
Numerical simulations were carried out to investigate interaction between a single stage compressor and pylons.Analysis of results shows that the pylons cause large disturbance on flowfield in compressor,and that the disturbance imposes significant effects on the flow field of rotor,which brings the blades of rotor under large unsteady surface pressure.Flow near the pylon leading edges was drawn out,which almost completely shielded the influence of pylons on rotor.
Experimental Investigation of Parameter Measurements in An Axial-Flow Multistage Compressor
XING Xiao-long, REN Ming-lin, GU Yang, YIN Hong-shun, HUANG Ming-jing
2004, 19(4): 478-483.
Abstract PDF(377KB) icon1863 icon464
Abstract:
This paper details the experimental methods and results using the airfoil sensors to measure total pressure and total temperature distributions behind the rotors in a multistage axial-flow compressor.The experimental results demonstrate the experimental method is feasible,and the flow field data measured behind the rotor are believable.The airfoil sensors can decrease the influence of a plugged probe in the flow field behind the rotor.This paper investigates a new measuring method for studying matching in stages of multistage compressor.
Turbomachinery Profile Design by an Improved Inverse Method Based on Optimization Technique
CAO Zhi-peng, JIN Jun, LIU Bo, LIU Jing-xin, WANG Yan-gang
2004, 19(4): 484-489.
Abstract PDF(776KB) icon1686 icon474
Abstract:
It is very important for gas turbine engineers to have better blade design method, especially for axial flow turbomachinery with high pressure ratio,and increased mass flow rate.The design method proposed in this paper is,in principle,based on the potential-stream function inverse method.By investigating the influence of prescribed velocity coefficient distribution on blade surface,it is found that the non-physical solution usually obtained by general inverse method could be effectively avoided by adjusting the local velocity coefficient distribution.The object functions were set up for leading edge closing and trailing edge closing problems respectively for numerical optimization.The optimized blade profiles with satisfactory performance and reasonable geometric shape can be obtained by this improved optimization method.Three examples of profile design give good results in terms of design precision and wider application aeras in turbine and compressor blade profile designs,could be developed.That,in turn,strongly suports the proposed optimization design procedures to have potential application in engineering.
Study of Stall in the Compressor Based on the Time-Freqency and Wavelet
LU Jian-wei, LI Jun
2004, 19(4): 490-494.
Abstract PDF(249KB) icon1834 icon480
Abstract:
By means of the pressure signals of a certain research engine which has an eight axial stage compressor.A method of time-frequency analysis is presented in the paper.Information on the stall inception and development,which has some correlations with the onset-frequency and stall-frequency can be obtained during the engine operations.Therefore,the two main frequencies at the stall inception can be observed in the time-frequency plots.In order to identify the signal of the onset of stall accurately,this paper introduces the technique of the wavelet analysis,and provides an example of the 1st-6th compressor stage signals which are decomposed by Daubechies wavelets.The result indicates that different frequencies show different stall inception prior to the stage stall,and proves the singularity of the signal of stall.The stage of the first stall is ascertained by this method in the paper.
Continuum Structural Topology Optimization Using Simulated Annealing Genetic Algorithm
WANG Zhong-hua, WEN Wei-dong
2004, 19(4): 495-498.
Abstract PDF(641KB) icon1677 icon475
Abstract:
In continuum structural topology optimization,Genetic Algorithm (GA) was served as optimization method,binary chromosome of GA was employed to represent a topology structure,and finite element method was used to obtain the displacement,stress and strain of each node,which was included in constraint conditions.In order to improve the efficiency and to make the optimization results better,the simulated annealing technique was embedded with genetic algorithm.The method could adjust the function during optimization.A cantilever plate,as an example,was optimized to show the efficiency of the method.
Design and Dynamic Characteristics Study of Micro Actuator of Flapping-Wing MAV
HOU Yu, FANG Zong-de, LIU Lan, FU Wei-ping, WU Li-yan
2004, 19(4): 499-505.
Abstract PDF(882KB) icon1655 icon448
Abstract:
Flapping-wing Micro Air Vehicles (FMAV) are new conceptual air vehicles.They surpass the research fields of traditional airplane design and aerodynamics in relation to application technologies,and initiate the applications of MEMS technologies to aviation fields.The design,fabrication and dynamic characteristics of micro flapping actuator are the keys of FMAV designing.This paper studies a micro flapping mechanism based upon insect thorax and actuated by electrostatic force.Because there are strong nonlinear couplings between the two physical domains,electrical and mechanical,the dynamic characteristics of this system are very complicated.In this paper,the stable properties of equilibrium points are analyzed,the nonlinear dynamic characteristics of the system without damping and with damping are studied in the phase space,and the effects of original conditions and damping on the pull-in voltage are discussed.In addition,dynamic responses of the system to different voltage signals are analyzed.The results are helpful to the design,fabrication and application of the micro flapping actuator.
Method of High Speed Dynamic Balance to Balance a Slender Flexible Rotor
DENG Wang-qun, LI Shang-fu, GAO De-ping, LIAO Xue-jun
2004, 19(4): 506-511.
Abstract PDF(881KB) icon1826 icon524
Abstract:
A new technology method of high speed dynamic balance to balance a slender flexible rotor is presented by using auxiliary tool of balance-balance collars in this paper.A set of precise balance collars are designed and processed according to design criteria and their strength calibration is completed by using finite element method.The experiments of checking and verifying balance collars are accomplished through two simulating shafts.The results of experiments show that the balance behavior of the collars is good and they have little influence on critical speed and vibration characteristics of each simulating shaft.Based on this,high speed dynamic balance of power turbine rotor of turbine shaft engine is satisfactorily conducted by using these balance collars and the effect is very ideal.
Experimental Investigation of Flow Characteristics of Synthetic Jet and It's Preliminary Application to Combustion
ZHAO hong, YANG Zhi-guo, LOU Hui-juan
2004, 19(4): 512-519.
Abstract PDF(885KB) icon1718 icon431
Abstract:
The velocity distributions of synthetic jet were measured with Hot-wire anemometer.Experimental result shows that two distinct regions exist in the flow-field created by the actuator.Close to the slot-exit,the mean centerline velocity accelerates downstream to a maximum at distance of approximately 10～15 slot-width,when signal frequency is 980 Hz and amplitude is 40 V.At streamwise distance larger than approximately 10～15 slot-width,the flow pattern changes as conventional jet.Velocity profile across the synthetic jet appears like the profile in conventional jet,but velocity gradient is much large.At the exit of combustor,excitation using synthetic jet can improve the distribution of temperature and decrease contents of NOx.Synthetic jet is effective for active flow control purpose.
Experimental Investigation of Cooling Effectiveness of Laminate Porous Plates
QUAN Dong-liang, LIU Song-Ling, LI Jiang-hai, XU Du-chun, YOU Shao-kun
2004, 19(4): 520-524.
Abstract PDF(1617KB) icon1592 icon491
Abstract:
Four typical configurations of laminate plates for ultra-high temperature turbine blade were made and tested in a large scale low speed close-looped wind tunnel.The internal flow resistance and the cooling effectiveness were obtained.The experimental results showed that very high cooling effectiveness can be achieved by using laminate plates and the ratio of the hole area to the plate area plays the most important role in determination of the cooling effectiveness and the internal flow resistances,the higher the ratio,the smaller the resistance and the higher cooling effectiveness.The research results are of reference value for the application of the laminate plates to aero-engine turbine blade.
Neural Network Model for Solving Multi-Variable Inverse Heat Conduction Problem
WANG Xiu-chun, ZHI Hui-qiang, MAO Yi-zhi, YANG Zeng-jun, HAN Peng
2004, 19(4): 525-529.
Abstract PDF(287KB) icon1319 icon429
Abstract:
Neural network was applied to solving multi-variable inverse heat conduction problem,and a valid numerical model was presented.The processing method of the inputting data and outputting data and the determining method of the number of inner layers were discussed.By the numerical simulation,the change of the training error and the testing error accompanying the variation of the number of inner layers is developed.The results indicate that the method is practicable and has high precision.In addition,in order to create a neural network which has high level of generalization,test sets for trial and error must be used to monitor the training process.The extension of the method in this paper to other inverse heat conduction problem is straightforward.
Optimum Design of Plate-Fin Heat Exchanger with Genetic Algorithm
ZHANG Li-na, YANG Chun-xin, WANG An-liang
2004, 19(4): 530-535.
Abstract PDF(183KB) icon2187 icon509
Abstract:
A method of optimum design for a plate-fin heat exchanger based on genetic algorithm (GA) is put forward in this paper.Not only the structure of a heat exchanger can be optimized with this method,but also the optimal type selection of fins can be obtained in the case of many types of fins are given.For different requirements of design,weight or effectiveness of a heat exchanger can be taken as an object function respectively by GA.A database of fins has been set up for selecting the optimal type of fins easily,which includes the geometric parameters, heat transfer factors and friction factors of fins.These parameters can be directly applied to computer programs.Compared with the conventional optimization results,it is showed that the weight and the volume of heat exchanger optimized in this paper are both reduced.The optimizing software and the database of fins are universal and can be used for general optimum design of heat exchangers.
Theoretical and Experimental Research on Microwave Plasma Thruster With Coaxial Resonant Cavity
TANG Jin-lan, HE Hong-qing, MAO Gen-wang, YANG Juan, HAN Xian-wei, HUANG Xiao-di
2004, 19(4): 536-540.
Abstract PDF(398KB) icon1601 icon439
Abstract:
The system construction and resonance mode of 100 W power Microwave Plasma Thruster (MPT) With Coaxial Resonant Cavity are introduced.The Resonant Cavity is an important part in the MPT system in which the microwave energy is absorbed by the working gas.In this paper,the numerical simulation of the coupling between microwave energy and plasma flow under the resonant state was analyzed using a coupled Maxwell,Saha and Navier-Stokes solver and the performance of prototype was calculated.All results show that the system principles of 100 W MPT are feasible and the performance of prototype is good.
Numerical Simulation of the Dynamic Process for Pressure Regulator
ZHANG Xue-mei, ZHANG Li--hui, JIN Guang-ming, WEI Yan-xiang
2004, 19(4): 541-545.
Abstract PDF(591KB) icon1754 icon487
Abstract:
Based on the dynamic adjustment of regulator in pressuring and working processes of engine,a dynamic mathematical model of converse and unloading regulator that was usually applied in Liquid Rocket Engine was built.The numerical simulation adopted four-step Runge-Kutta method.The dynamic characteristics of regulator were analyzed in starting boosting pressure.Calculated exit prssure transients of the reduces are in good agreement with those measured in the experimental diagnostics for various inlet pressures.The results show that the analytical model is correct and the simulation method is in accordance with the precision reguirements.The study and its conclusions are useful for the design of congener regulators and the system analyses.
Dynamic Characteristics Study of Spacecraft Propulsion System Engine
ZHANG Li-hui, LI Jia-wen, ZHANG Xue-mei, JIN Guang-ming, WEI Yan-xiang
2004, 19(4): 546-549.
Abstract PDF(246KB) icon2711 icon460
Abstract:
Based on the transient theory of one dimensional fluid,finite difference scheme of characteristic line method is employed.The general simulation software for dynamic process of spacecraft propulsion system engine is formulated.The dynamic characteristic of an engine system are studied.The results show that the model preferabl describes system transient properties and water hammer phenomenon.The simulation software can conveniently analyze other propulsion systems and provide guidance for the design and optimization of engine systems.
Method of Computing Temperature Field in Regeneratively-Cooled Thrust Chamber
LI Jun-wei, LIU Yu
2004, 19(4): 550-556.
Abstract PDF(1019KB) icon1991 icon467
Abstract:
To quickly and accurately obtain temperature distribution in regeneratively-cooled thrust chamber,a method of computing temperature field in thrust chamber was developed.Firstly,one dimensional cooling model of axi-symmetric thrust chamber was formulated and empirical formulas were used.Temperature of gas wall along thrust chamber axis was obtained.Secondly,two dimensional conductive model of cooling jacket was set up and numerical simulation was carried out using one dimensional results.Temperature field in cooling jacket was computed.Then using this method,influence of gas wall material,gas wall thickness and flow rate of coolant on regenerative cooling of thrust chamber was investigaed.The results were satisfactory.In terms of computing time and accuracy of results,this method could provide a reference for optimization design and performance estimation.
Design of Concentrator for Solar Thermal Propulsion
ZHANG Chun-liang, ZHANG Zhen-peng, WEI Zhi-ming
2004, 19(4): 557-561.
Abstract PDF(781KB) icon1720 icon427
Abstract:
Based on engineering practice,performance of commonly used concentrators is compared.As a results,a new method for designing a kind of solar concentrator which is applicable to the Solar Thermal Propulsion (STP) is studied and presented,as well as its performance is analyzed.The correlation formula and key technique which can be employed as guidance for designing space solar systems also are demonstrated.
Recent Development and Prospects of System-Level Modeling of Aircraft Engine
CAO Yuan, JIN Xian-long, MENG Guang
2004, 19(4): 562-571.
Abstract PDF(1461KB) icon1584 icon494
Abstract:
It is time-consuming and expensive to design and develop a new aircraft engine.Computational simulation is a promising means for alleviating cost,much work about it has been done and many achievements have been acquired.In the past,limited computer resources forced component representations to be based on relatively simple equations and empirical data obtained from components and system testings.As the aerospace industry enters the 21st century,there is increasing pressure to reduce the time,cost and risk of aircraft engine development.Now the traditional method for numerical simulation of the gas turbine engine is not suitable.As a result,the common simulation model for aircraft engine becomes important and some research teams are developing these models and some models have been used in aircraft industry.On the other hand,with the in-depth study in various domains relating to the engine,precise models of different parts and different disciplines have been developed.But it is a hard work to integrate these advanced multidisciplinary and multifidelity analysis methods.Thanks to the big progress in computer science and other domains,to construct flexible simulation softwares and integrate different precise models of engine into one system has become possible and realistical.In order to make clear the development direction of the simulation of aircraft engine,the recent development and results have been summarized and the prospects have been studied in this paper.At last some advice on further development of gas turbine simulation is also given for domestic researchers.
A Simulation of the Anti-Surging Regulator Performance for the Aero-Engine Using AMESim
REN Xin-yu, GUO Ying-qing, YAO Hua-ting
2004, 19(4): 572-576.
Abstract PDF(556KB) icon1752 icon456
Abstract:
Abnormal phenomena of detonation and fuel-rich were observed when the anti-surging regulator was employed to reduce the fuel during the grand test of an aero-engine.In order to solve this problem,a dynamic simulation of the anti-surging process was conducted using the AMESim software.The simulation has showed that the AMESim software can deal with such hydro-mechanic dynamic process.The dramatic change of the fuel pressure,which results in unstable burning,causes these abnormals,but tyey can be alleviated if the diameters of the main throttle and the auxiliary throttle are properly changed.
A Volterra Progression Model of Nonlinearity Dynamic Respondence of Aero Engine
SONG Zhi-ping, CHENG Li, WEI Rei-xuan
2004, 19(4): 577-580.
Abstract PDF(323KB) icon1953 icon415
Abstract:
Modeling of nonlinearity dynamic respondence of the aero engine was studied.The dynamic process of the aero engine was described by using the Volterra progression model.And identification arithmetic of the Volterra progression model for aero engines was proposed.It was applied to a certain turbofan engine by imitating the dynamic respondence.The Volterra progression model can describe the dynamic process from low to high rotating speed of aeroengine.

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