2007 Vol. 22, No. 2

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Methods for test and factor analysis of determinate simulation results
FU Hui-min, WU Wen-juan
2007, 22(2): 169-174.
Abstract PDF(344KB) icon1663 icon457
Abstract:
A test method for determinate simulation results,in which random factors are not taken into account,is presented.It can analyze the error between simulation and experiment results,distinguish between system error caused by simulation incorrectness and accident error caused by the scatter of experiment results,and determine whether simulation results are right or not.A method for multiple factors analysis of determinate simulation results is also presented,which can analyze every influencing factor of simulation results and determine which factors have been simulated correctly and which have not.In this way,the method can guide the programming of simulation software.
Integral estimate method for interval censored data
FU Hui-min, AO Liang
2007, 22(2): 175-179.
Abstract PDF(294KB) icon1766 icon466
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A new method of integral estimate for interval censored data is presented in this paper.The integral distribution parameter estimators and their covariance are derived,the confidence limits of percentiles and percentages for the interval censored data from normal distribution,Weibull distribution or other location-scale distribution are also obtained.This method takes test data in different states as an integer,makes an statistical inference,and extends traditional regression analysis that is only suitable for complete data to interval censored data.
Analysis method of droplets parameters based on rotating multicylinder in an icing wind tunnel
ZHU Chun-ling, LI Yu-qin, ZHANG Quan
2007, 22(2): 180-186.
Abstract PDF(478KB) icon1810 icon451
Abstract:
An analysis method based on the droplets parameters calculated by the rotating multicylinder in an icing wind tunnel is presented.The impingement characteristic of the droplets on the two-dimension cylinder was calculated and the rime ice accumulation on the two-dimension rotating cylinder was numerically simulated. According to the influence to the icing accumulation of the rotating multicylinder and the mathematical approach methods,the software that uses the results derived from the rotating multicylinder measurements to analyze and calculate the droplets parameters in the icing wind tunnel was programmed.Eventually,the analytical result was validated by the overseas experimental data.The results indicate that the method in this paper is correct and the fast measurement of the droplets parameters in an icing wind tunnel can be achieved.
Combined features of the inner impingement and outer film cooling holes of a vane
DING Shui-ting, CUI Liang, SUN Ji-ning, TAO Zhi, XU Guo-qiang, LI Qiu-shi
2007, 22(2): 187-192.
Abstract PDF(626KB) icon1560 icon428
Abstract:
Numerical simulation has been used to investigate a cooling configuration of a guide turbine vane.This vane has outer sparse film cooling holes and inner impingement holes.In this paper,we mainly studied how different positions and diameters of the film cooling holes influenced the cooling efficiency on the pressure and suction sides of the vane;and discussed the cooling efficiency and uniformity of temperature distribution on the pressure and suction sides of the vane.The computational results show that,within the parameters used in this simulation,the increase in the film cooling hole diameters obviously improves the cooling efficiency on the pressure side of the vane,but the effect is more complicated on the suction side.Considering the cooling efficiency and the uniformity of temperature distribution on the pressure and suction sides of the vane,the position of the film cooling holes located on the front side of the chamber results in the best cooling efficiency.
Experimental investigation of flow resistance and heat transfer characteristics of typical lamilloy models
TAO Zhi, WEI Hao-jie, DING Shui-ting, DENG Hong-wu, XU Guo qiang, LIN Yu-zhen
2007, 22(2): 193-198.
Abstract PDF(462KB) icon1725 icon422
Abstract:
Experimental investigation of flow resistance and heat transfer characteristics has been carried out on a typical lamilloy model whose ratio of inlet hole,pin-fin,and outlet hole is 1:4:1.The results show that for a lamilloy model,the heat transfer coefficient of the internal surface of outlet board is the highest,followed by the pin-fin's surface,and that of the internal surface of inlet board is the lowest.The comparisons show that at the same mass flow,the flow resistance increases,the heat transfer coefficient of the outlet board decreases,and the heat transfer coefficient of the intlet board changes little by enlarging the inlet hole.Comparisons also show that the flow resistance and the heat transfer coefficient of the inlet board increase,but the heat transfer coefficient of the outlet board has little change by reducing the outlet hole or increasing the obliquity of the outlet hole.
An experimental study of the effects of air flow through Helmholzt cavity on heat transfer within a smooth round tube
DING Shui-ting, GAO Xiang-yu, DENG Hong-wu, XU Guo-qiang, TAO Zhi, ZHOU Zheng-ping
2007, 22(2): 199-204.
Abstract PDF(771KB) icon1518 icon411
Abstract:
When the air flows through the Helmholzt oscillation cavity,it will be pulsing.The inlet and outlet diameters of Helmholzt cavity remain const,but the length of cavity is changed so that,the Reynolds number at the inlet changes from 22 000 to 82 000.The experimental investigation was conducted under equiflux conditions.Comparison was made between the heat transfer coefficient of steady air flow and unsteady air flow.The results show that: The pulse air flow can increase the heat transfer,but the enhancement of heat transfer takes place mainly at the distance of 10 times of the diameter along the axial direction of the round tube.The ratio of enhancement lies between 1.1 to 1.9.This ratio decreaser significantly as the distance becomes longer.Beyond the distance of 10 times of the diameter,the ratio of enhancement fluctuates slightly as the Reynolds number increases.The experimeotal investigation also shows that the heat conduction coefficient is influenced by the length of the Helmholzt cavity.
Experimental investigation of heat transfer and flow resistance in a crossed-rib channel
DING Shui-ting, QIN Ling, DENG Hong-wu, TAO Zhi, XU Guo-qiang, LIN Yu-zhen
2007, 22(2): 205-209.
Abstract PDF(481KB) icon1881 icon475
Abstract:
The investigation of heat transfer and flow resistance in a crossed-rib channel located in turbine blade was conducted experimentally.Experimental results show that the Nusselt Number in the rectangular channel and the variable channel is 4～6 times and 7 times higher than that in a smooth channel,while flow resistance coefficient was enlarged by about 400 and 600 times.The total thermal performance in the variable channel is about 1.2 times higher than that in the rectangular channel.
Study of overall cooling effectiveness of discrete holes with different angles to concave wall
ZHAO Meng-meng, ZHANG Chi, LIN Yu-zhen, LIU
2007, 22(2): 210-215.
Abstract PDF(1008KB) icon1885 icon448
Abstract:
Overall cooling effectiveness of curved walls with discrete angled holes has been studied in the paper through approximate simulation employing experimental concave walls with a constant curvature,which were applied intensively in the curved duct for turboshaft engine reverse-flow combustor.An experiment by heat transfer method for the overall cooling effectiveness was performed and the effect of blowing ratio on the overall spanwise averaged cooling effectiveness was obtained.The experimental result shows an improved overall cooling performance for the curved wall and the insignificant difference between the discrete holes with 30° inclined angle and normal to the concave wall at high blowing ratio.The flow in the curved duct has influence on the overall cooling effectiveness significantly.
Experimental investigation of a double-decker jet impingement/film structure's cooling coefficient
LIU Zhen-xiong, MAO Jun-kui, GUO Wen, JIANG Hefu
2007, 22(2): 216-221.
Abstract PDF(340KB) icon1931 icon473
Abstract:
Experiments were conducted out to investigate cooling coefficient of a lamellar double-decker jet impingement/film structure.Blowing rate M,the ratio of the jet impingement distance to the diameter of the jet hole H/d,and the ratio of the distance between the jet hole and film hole to the diameter of the jet hole P/d were changed to study the rules of local cooling coefficient varying with these parameters.All the results show that higher cooling coefficient was achieved under larger blowing rate conditions.And there exists a proper range of H/d and P/d,which can result in a maximum cooling coefficient.It is verified that when H/d=0.5 and P/d=4,the maximum cooling coefficient can be achieved.
A numerical investigation of the minimum coolant injection rate for transpiration cooling
SHI Jun-xiang, WANG Jian-hua
2007, 22(2): 222-227.
Abstract PDF(348KB) icon1865 icon421
Abstract:
An advanced design of transpiration cooling system is not only to ensure thermal protection of propulsion system from ablation,but it also should utilize the full temperature potential of porous matrix.A numerical investigation of transient processes of transpiration cooling and the control parameters of the lowest limit of the coolant mass flow rate is conducted with the help of a compressible, unsteady and local non-thermal equilibrium model.The numerical investigation presents that it is important to study transient cooling process,because the porous matrix could be ablated before the cooling process reaches a steady state,though the steady temperature may be lower than the melting point.A higher initial temperature and a larger characteristic size of the porous matrix will result in an increase in the minimum coolant injection rate to prevent ablation of the porous matrix.From the view point of cooling effect,a higher porosity corresponds to a larger coolant mass flow rate.Contrarily,a higher thermal conductivity of the porous matrix corresponds to a lower demand for the minimum coolant flow rate.
Investigation of several delay times in operation process of multi-cycle pulse detonation engine
ZHANG Yi-Ning, WANG Jia-Hua, LIU Hong, ZHANG Jing-zhou
2007, 22(2): 228-232.
Abstract PDF(651KB) icon1708 icon426
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In order to promote the operating coordination of a two-phase pulse detonation engine(PDE),the delay time of detonation and operating performance of the solenoid valve were experimentally studied by using ion-sensors and pressure transducers of high-frequency response.The detonation tube is of 58mm inner diameter and 1 270 mm long.Liquid gasoline/air mixture is filled for the engine multi-cycle operations.According to the research,the mixture ignition delay is 3～4.5 ms,the aero-valve closing delay is 4.9～6.4 ms,and the solenoid electric valve on/off delay time is 2.4 ms and 3.4 ms respectively.The transition time from deflagration-to-detonation is about 3.0～3.8 ms.The solenoid electric valve cannot operate orderly when the engine operating frequency is higher than 20 Hz.These data obtained are helpful to coordinate PDE operation process.
Experimental research on infrared suppressor integrating the exhaust system with the tail part of a helicopter
TANG Zheng-fu, ZHANG Jing-zhou, WANG Xian-wei, LIU Qiang
2007, 22(2): 233-237.
Abstract PDF(772KB) icon1797 icon465
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Utilizing a ground test model,an experimental diagnostic study on the infrared suppressor integrating the exhaust system with the tail part of a helicopter has been performed to investigate the effects of ambient air pumping-mixing and rotor downwash on reducing the exhaust system temperature and diminishing the target infrared signature.The result shows that the gas temperature can be reduced by 50% at least by lobed nozzle which injects ambient air to mix with the hot gas;and rotor downwash flow that cools the tail part of the model will cause a decrease of total infrared radiation between 3-5 μm and 8-14 μm equivalent to about 39% and 33%.In addition,simply enlarging the lobed nozzle is not propitious to the enhancing of the entrained flux,while it will reduce the injection coefficient.
Helicopoter coupled rotor/fuselage air resonance dynamic stability in forward flight
XUE Hai-feng, XIANG Jin-wu, ZHANG Xiao-gu
2007, 22(2): 238-244.
Abstract PDF(414KB) icon1865 icon442
Abstract:
It is more difficult to investigate the helicopter dynamic stability in forward flight than in hover.Air resonance dynamic stability in forward flight is examined in the paper.The eigenvalues,eigenvectors and mutual excitation of different degrees of freedom of representative instance are calculated and analyzed.The effect of parameters on air resonance dynamic stability was studied through the analysis of mutual excitation of different degrees of freedom.
Analysis of flow loss induced by inlet total pressure distortion in a small fan
SUN Peng, FENG Guo-tai
2007, 22(2): 245-250.
Abstract PDF(823KB) icon2135 icon417
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Numerical simulation of the unsteady flow field in a small fan using time-accurate three-dimensional Navier-Stokes solver was carried out.The numerical simulation focused on a small fan with inlet square wave total pressure distortion.The pattern and causation of flow loss caused by the pressure distortion in rotor and stator were analyzed.It is found that the influence of distortion is different at different radial positions.In the hub area,transportation-loss and mixing-loss are the main loss patterns.Distortion not only complicates them but also strengthens them.Especially in stator,inlet total pressure distortion induces large-scale vortex,which causes backflow and increases the loss.Finally,the details of flow loss both distorted and non-distorted flow fields are described and analyzed.
Application of agglomeration multigrid method in calculation of rotor forward flight flow
XU He-yong, YE Zheng-yin, WANG Gang, SHI Ai-ming
2007, 22(2): 251-256.
Abstract PDF(1688KB) icon1708 icon468
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An agglomeration multigrid method was applied to numerical calculation of rotor forward flight flow based upon the unstructured dynamic overset grids.Two overlapping subareas could be generated speedily from original global unstructured mesh,while the original hole fringe and donor elements could be established without using a background grid.And,the hole fringe needn't update during dynamic oversetting,and the new donor elements could be searched quickly by using a new technique without background grid.The agglomeration multigrids were generated separately in each subarea,and a three-level V cycle method was used to solve the unsteady Euler equations by dual time stepping.The flow field parameters were coupled in the overlapping area.Finally,the rotor forward flight flow was calculated.The results show that,the agglomeration multigrid method can facilitate the convergence of rotor forward flight flow effectively.
Nozzle afterbody design of hypersonic flight vehicle
XU Hua-song, GU Liang-xian
2007, 22(2): 257-260.
Abstract PDF(876KB) icon1857 icon433
Abstract:
A model based on numerical solution of Navier-Stokes equations was established for hypersonic flight vehicle nozzle afterbody optimization design.The internal portion and the upper wall of nozzle were designed,and the optimized configuration was obtained.The result was compared to the norm configuration that Edwards claimed.The results show that the performance of nozzle afterbody was improved.
An extensible propulsion simulation platform Part I-foundations of engineering model
CAO Zhi-song, YU Long-jiang, PIAO Ying
2007, 22(2): 261-267.
Abstract PDF(435KB) icon1785 icon439
Abstract:
EPSP(extensible propulsion simulation platform) was developed as a Java-based object-oriented platform for propulsion system simulation.The architecture represents the hierarchal structure of the engine,its components and substructures using recursive composition.This paper presents the design of a common engineering model framework for use in EPSP.This technique provides an access to build models with increasingly complex elements out of simpler ones.The foundations of the platform's engineering model were described.To test the platform,we can easily construct a component based engineering model,and the "pluggability" of the architecture is shown.The example proves the validity and feasibility of the modeling of the platform.
An extensible propulsion simulation platform:Part Ⅱ-extensible framework
CAO Zhi-song, YU Long-jiang, PIAO Ying
2007, 22(2): 268-273.
Abstract PDF(558KB) icon1916 icon457
Abstract:
EPSP(Extensible Propulsion Simulation Platform)was developed as a Java-based object-oriented platform for propulsion system simulation.EPSP provides a flexible environment for defining,modifying and simulating the component-based propulsion models.EPSP has a friendly GUI for easily modifying parameters of the components.EPSP enables users to customize and extend the framework to add new functions or adapt simulation behavior as required.The visual assembly framework and the connection services framework were introduced,and the design pattern of the computation framework was studied.An example of transient simulation of a twin-spool turbofan engine was provided.It shows that EPSP is effective in extendable and flexible simulation computation for propulsion system.
A rapid prototype control system for micro turbine engine
ZHANG Tian-hong, WANG Ji-ye
2007, 22(2): 274-279.
Abstract PDF(747KB) icon2024 icon435
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To meet the requirements of micro turbine engine(MTE) control,this paper proposed a kind of rapid prototype control system based on the industrial control computer,which can provide integral interface for actuators and sensors of the MTE control system and Windows-based real-time control software development environment.The technology of rapid prototype can significantly improve the development efficiency of embedded control systems.This rapid prototype control system can not only control MTE,but also log the experimental results in real-time with friendly man-machine interface,which is very important for MTE control study.The effectiveness of this rapid prototype control system was validated by a series of test bed experiments.
Study of rotor speed sensors fault accommodation and test run of turbo-shaft engine
HUANG Kai-ming, YIN Ze-yong
2007, 22(2): 280-284.
Abstract PDF(400KB) icon1633 icon454
Abstract:
Fault-tolerant control scheme for rotor speed sensor of a turbo-shaft engine and full authority digital engine control(FADEC) was studied.And,the fault-tolerant rule of a turbo-shaft engine was determined.A "fault simulator" was used to carry out fault-tolerant test under a test rig.The results show that,fault accommodation and verification method are easy to implement,and fault-tolerant control can maintain efficiently the power output of engines.The test run provides useful experience for matching of multiple engine installation,and also lays a basis for other types of aero-engines.
Aerodynamic design optimization of cascade airfoils based on multiobjective genetic algorithm
JIN Dong-hai, GUI Xing-min
2007, 22(2): 285-290.
Abstract PDF(856KB) icon2140 icon459
Abstract:
A multiobjective genetic algorithm(GA) has been developed by introducing Pareto ranking and fitness-sharing techniques.Performance of the cascade airfoils was evaluated based on the two dimensional Navier-Stokes equations.To demonstrate the feasibility of the algorithm,a multiobjective design optimization of cascade airfoils was performed for minimizing the total pressure loss coefficient and maximizing the high pressure ratio at the same time.The optimization results show that the present method is effective and efficient in multiobjective aerodynamic design optimization.
Integrated inverse problem optimization method of through-flow design/airfoil design/CFD simulation for centrifugal compressors
WANG Qi, SHAN Peng
2007, 22(2): 291-297.
Abstract PDF(821KB) icon1885 icon459
Abstract:
An integrated inverse problem optimization method for through-flow design/airfoil design/CFD simulation of centrifugal compressors has been developed in this paper.Using the scheme of "DOE(design of experiments)+RSM(response surface model)+Approximate optimization",the relevant four-component-code system establishes an integrated parameterized optimization workbench for centrifugal compressors.A centrifugal compressor used in a micro-turbojet with a thrust of 100 N is optimized.And this fast optimization method is proved to be very effective.
CFD study on casing treatment in a transonic compressor
CHEN Hai-xin, HUANG Xu-dong, FU Song
2007, 22(2): 298-304.
Abstract PDF(1742KB) icon1803 icon407
Abstract:
This paper introduces an in-house developed 3D N-S solver specialized for the flow field study in compressors.Based on a typical sample calculated for the validation of the code,a 3D simulation of the flow in a transonic compressor with tip gap and casing treatment is performed.The numerical study focuses on the casing treatment with circumferential grooves.The comparison of the influences on the compressor performance of variant groove configurations is carried out.
Application of genetic algorithm to multi-stage compressor aerodynamic optimization design
TUO Wei, XIONG Jin-song, HOU An-ping, ZHOU Sheng
2007, 22(2): 305-309.
Abstract PDF(1220KB) icon2145 icon414
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A multi-objective aerodynamic optimization method is developed using genetic algorithm and duct-flow code that employs streamline curvature approach.Velocity circulations at the trailing edges of each blade-row are optimized for overall maximization of total pressure ratio and isentropic efficiency.The test indicates that the optimization algorithms can auto-search for optimal result globally and efficiently.A five-stage high pressure compressor is redesigned by using this method and the performance is enhanced greatly.
Research on kinetic kill vehicle's guidance method in boost phase
GUO Qing, YANG Ming, WANG Zi-cai
2007, 22(2): 310-315.
Abstract PDF(1697KB) icon1505 icon419
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A guidance method used in boost phase for intercepting the high-speed target in outer space was presented.After constructing the model of motion of the target and the kinetic kill vehicle(KKV),constraints of interception were analyzed and the computing method of orbit transfer was also derived.Then orbit transfer was optimized to get valid launching areas satisfying the constraints.Moreover,KKV's required velocity increase at firing time was selected as the specific performance index to optimize the computed launch parameters.Simulation results show that this method can implement efficiently KKV's guidance during the boost phase.
Hydrogen/oxygen hot-firing tests of altitude compensating nozzles
WANG Yi-bai, QIN Li-zi, LIU Yu, LIAO Yun-fei, WANG Chang-hui
2007, 22(2): 316-322.
Abstract PDF(835KB) icon1678 icon396
Abstract:
By employing the gaseous oxygen as oxidizer and gaseous hydrogen as fuel,hot-firing tests were performed for aerospike nozzle and dual-bell nozzle test engines with altitude compensating features.The gaseous hydrogen/oxygen experimental system,the test nozzles' configuration,design parameters and assembly graphics were described.Made of the ablation-resistant tungsten-copper alloy,the test components of nozzles have successfully passed several short-period hot-firing tests.The measured parameter curves,test photographs and results are obtained,thus obtaining the performance data of aerospike nozzle and dual-bell nozzle under different altitudes,both of which have good altitude compensation characteristic as compared with the conventional bell nozzle.For example,the thrust coefficient efficiency of aerospike nozzle is 92%-95% and dual-bell nozzle is 96%-98% at low altitude,and about 95% at high altitude.
Numerical simulation of the priming process of satellite propulsion system
XUE Ke, ZHANG Li-hui, SU Long-fei, PAN Hai-lin
2007, 22(2): 323-326.
Abstract PDF(1319KB) icon1878 icon423
Abstract:
An analytical model is developed using the water hammer and one-dimensional fluid transient theory.Based on the finite difference method of characteristics,the hydrokinetics models and model for the head of fluid are established.The average friction model and the frequency-dependent dynamic friction model are adopted to simulate the frictional resistance in the transient fluid equations.During the simulation of the priming process,the variation of sonic speed affected by the gas dissolved in the liquid is taken into account.The comparison with the experimental results shows: numerical models give reasonable descriptions for water hammer and flow oscillation,and could provide guidance for transient analysis of priming process in pipelines of other propulsion system.
Stress analysis and fatigue life estimation of four kinds of super-alloy welded joints
LUO Gang, FAN Yin-he, LIANG You-jiang
2007, 22(2): 327-331.
Abstract PDF(885KB) icon2051 icon485
Abstract:
In accordance with the welded structures on the mount-box of jet engine case,the finate element model(FEM) models of four kinds of welded joints including normal butt welding,dislocation butt welding,non-isopachous butt welding and new material butt welding are established.Stress analysis of these butt welding's is carried out by means of the finite element analysis software ANSYS,and the stress-concentration-coefficient of the four welded joints is obtained.The stress fatigue tests are implemented on the four kinds of butt welding pieces.The experimental results are analyzed and compared using the method of group comparison,and the fatigue life for the four kinds of butt welding is predicted.The result of the scanning electron microscope(SEM) fracture analysis indicated that the defection in the stress-concentrated area is the dominant factor to affect the fatigue life of the weld-joint.
Design of the control mechanism for the multistage axial compressor variable vane
HE Fei, CHEN Guo-zhi, WEN Quan, SHI Lin
2007, 22(2): 332-336.
Abstract PDF(330KB) icon1507 icon465
Abstract:
The motion of the variable vane assembly of turbo-shaft engine is complicated.The kinetic equation of variable vane assembly was deduced using the method of homogeneous coordinates analysis and Matlab software.The dimensions of variable vane assembly components were optimized.This newly developed method was applied to the design of an engine's variable vane assembly.The calculated results were compared with the simulation result of CATIA.It shows the accuracy of control satisfies the design requirement.

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