2009 Vol. 24, No. 7

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Display Method:
Heat shield position on infrared characteristics of a vectored nozzle
LIU You-hong, LIU Yu
2009, 24(7): 1437-1442.
Abstract PDF(902KB) icon1653 icon475
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The inner and outer flow field,temperature field and gas concentration field models including the heat shield in the after burning room of a vectored nozzle were established and computed.The effect of the heat shield position on the inner wall,i.e.the heat shield and the nozzle wall,temperature distribution and the corresponding infrared characteristics was studied.The results show that the transonic flow field solution governed by the Navier-Stokes equations based on the density solver is successful.The wall temperature firstly decreases and then increases when the heat shield length(or position) covering the converging nozzle increases.There is an optimized heat shield position that makes the wall temperature reach the minimum value.Finally the infrared radiant intensity emited out of the nozzle outlet section was calculated using autor's proposed discrete net-radiation method.
Design of vapourization type combustion heater with high temperature and pressure
LI Ming, WU Er-ping, TANG Ming
2009, 24(7): 1443-1448.
Abstract PDF(1086KB) icon1469 icon460
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A vapourization type heater fueled by kerosene with high temperature and pressure was designed for the certain thermal wind tunnel platform.According to performance requirements of the heater,the main components were designed,the air flow distribution and flowage parameters were calculated by the methods of flow resistance and one dimension flow.The experimental results show that the designed heater meets the demand for structural project,main components and overall performance and is valuable for engineering application.
Numerical simulation of mixing flow of air and water droplet in the test duct of icing research tunnel
KE Peng, YANG Chun-xin, WU Jiang-hao, ZHANG Shu-guang
2009, 24(7): 1449-1456.
Abstract PDF(1276KB) icon1584 icon501
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Numerical simulation was conducted for the flow and heat transfer process of the mixing flow in the test duct of the icing wind tunnel,where the temperature of air was low but that of the sprayed water was high to keep the nozzles from freezing.A simplified model based on Lagrangian method was built and solved,whilst the model of droplet size distribution,the phase transmission model of water freezing and solidification,the heat and mass transfer between air and water/ice droplets were considered.The variation of temperature,humidity and velocity of air and the temperature,radius and velocity of droplet during the flow process was obtained under different conditions.Furthermore,the patterns about how initial parameters affect the finial flow were achieved.This model and conclusion were validated by comparison with current literatures.
Pressure distribution and stress calculation of glaze ice on iced airfoil
XIAO Chun-hua, GUI Ye-wei, YI Xian, DU Yan-xia
2009, 24(7): 1457-1463.
Abstract PDF(1389KB) icon1453 icon499
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Under different air velocity and attack angle conditions,the variation of pressure distribution along glaze ice on airfoil was analyzed.The effect of pressure distribution on mechanics characteristics of glaze ice on airfoil was investigated.And variation of max shear stress of interface between glaze ice and airfoil was investigated.Combined with experimental curve of shear strength vs.temperature on interface,the contribution of max shear stress to ice shed was analyzed.The results show that max shear stress accounts for about 5.48% of shear strength.Thus contribution of aerodynamics to ice shed is nonsignificant.If heat deicer is turned on,temperature will climb and shear strength between the ice and airfoil will fall continuously.Max shear stress can exceed 10% of shear strength above-2℃ where the ice may be fractured and ice shed will be accelerated consequently.
Large-eddy simulation of particle dispersion and velocity similarity in a two-phase round turbulent jet
WANG Bing, ZHANG Hui-qiang, WANG Xi-lin
2009, 24(7): 1464-1469.
Abstract PDF(1953KB) icon1702 icon420
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A high-Reynolds two-phase round turbulent jet was numerically simulated by means of large eddy simulation for gas-phase and particle trajectory model for particle-phase.The dispersion behavior of particles with median Stokes number in large scale structures was studied.Two-phase statistical velocities were compared with each other.It's shown that particle dispersion is dominated both by large eddy structures and particle inertia,resulting in a high particle concentration distribution in the edge of vortex structures or interlaced regions of vortexes(called as particle preferential distribution).The decaying rate of two-phase velocity in the axial direction is different,and the particle-phase velocity decays slower than that of gas-phase.In the near field,two-phase velocities differ from each other significantly.In the far field,two-phase mean velocities are similar,and particle velocity decays radially slower.
Measurements of the flow fields in a model annular combustor using particle image velocimetry
DANG Xin-xian, ZHAO Jian-xing, ZHANG Xin, XU Rong, YAN Ying-wen, LIU Yong
2009, 24(7): 1470-1475.
Abstract PDF(1520KB) icon1673 icon469
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The cold and combustion flow fields were measured by particle imaging velocimetry(PIV) in a model annular combustor with the dual-stage swirler.Influences of different inlet temperatures on generations of re-circulation zone and distributions of gas velocities were investigated experimentally in the non-reacting and reacting flow fields.Experimental data shows the lengths of re-circulation zone of combustion flows are shorter than that of cold flows,and reacting fluctuating velocities are larger than non-reacting fluctuating velocities.In addition,the length of re-circulation zone decreases slightly with the increase of the inlet temperature in the non-reacting and reacting flow fields.
Performance comparison between the ramp injectors with different structures in supersonic combustion
WU Hai-yan, ZHOU Jin, WANG Hong-bo, SUN Ming-bo, ZHANG Shun-ping
2009, 24(7): 1476-1481.
Abstract PDF(1093KB) icon1571 icon413
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The compression and expansion ramps were designed to study the mixing performance of the different structured ramp injectors.The experiments of flame transfer,schlieren photograph and oil flow were conducted for the ramp injectors.The calculation fluid dynamics was used to simulate the pressure distribution,the interaction of shock and the forming of stream eddies following the ramps injection.The simulation results are coincident with the experiments.Finally,the differences between this experiment and the previous reports were analyzed.It's concluded that the expansion ramp of the two injectors has better performance of self-ignition and flame holding than the compression one.
Impact of mainstream on the vortex flow of cavity in trapped vortex combustor
LI Rui-ming, LIU Yu-ying, LIU He-xia, YANG Mao-lin
2009, 24(7): 1482-1487.
Abstract PDF(1272KB) icon1546 icon450
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Particle image velocimetry(PIV) was used to experimentally study the cold flow field of a model rectangular trapped vortex combustor(TVC) in this paper.The influence of mainstream velocity and mainstream structure(with or without flame stabilizer) on the behavior of vortex in the cavity was analyzed.It shows that the dimension and shape of vortex,location of vortex center are not sensitive to mainstream velocity.But the swirling strength and circulation mass flow rate in cavity increase with mainstream velocity.The vortex center is located in the center of cavity without stabilizer.The vortex center moves backward at the symmetry section,but moves forward at the stabilizer section.The result can provide references for TVC design and performance optimization.
Investigation on film cooling heat transfer for double row dust-pan shaped holes
GUO Tao, ZHU Hui-ren, XU Du-chun
2009, 24(7): 1488-1492.
Abstract PDF(809KB) icon1981 icon410
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Film cooling heat transfer for injection from single row and double row dust-pan shaped holes has been investigated experimentally.Distributions of heat transfer coefficients at downstream holes were measured.The effects on average heat transfer coefficient ratio by distribution of heat transfer coefficients,blowing ratio,Reynolds number of jet flow and distance between rows were analyzed.The Reynolds numbers of jet flow were between 5 000 and 15 000,the blowing ratios from 0.5 to 2.0,and the distances between rows were 5D,10D and 15D.The results indicate that the heat transfer downstream the double row film cooling holes is enhanced and the distributions are more uniform as compared with the case of the flow injection from single row holes.The heat transfer coefficient ratio increases firstly and then decreases with the increase of blowing ratio;the lowest value is at the blowing ratio of 1.0.The heat transfer enhancement increases and then decreases with the increase of the distance between rows,and is highest when the distance between rows is 10D.
Effect of covering shelter on infrared radiation characteristics of helicopter infrared radiation suppressor
WANG Tong-hui, WANG Xian-wei, ZHANG Jing-zhou, SHAN Yong
2009, 24(7): 1493-1499.
Abstract PDF(1008KB) icon1906 icon444
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Based on numerical calculation of computational fluid dynamics/infrared(CFD/IR),the effects of the covering shelter fixed onto the curved mixing duct on the infrared radiation characteristics of the helicopter infrared radiation suppressor were revealed.The results show that: the infrared radiation intensity of the IR suppressor with covering shelter could be reduced more than 90% in the horizontal plane or the bottom of the vertical plane,if compared with that without covering shelter.With the increase of the slot distance between the mixing duct and the covering shelter,the surface temperature of the covering shelter is decreased monotonously.For three slot distances(5,10 mm and 35 mm) in the present study,the infrared radiation suppressing effect seems more advantageous when the slot distance is 10 mm.
Heat transfer enhancement within an internal passage by combinations of ribs and suction holes
SU Fu-bin, ZHU Hui-ren, GUO Tao, XU Du-chun
2009, 24(7): 1500-1506.
Abstract PDF(2177KB) icon1787 icon464
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The experimental investigations of heat transfer characteristics of internal passage with rib and suction hole have been conducted.The transient thermochromic liquid crystal technique was used to measure the heat transfer coefficients in the case that Reynolds number(based on average mainstream velocity and hydraulic diameter of the internal passage) changed from 20 000 to 80 000 and suction ratios(Br) changed from 0.30 to 0.60.The results show that heat transfer is firstly enhanced near suction holes.Also,the heat transfer coefficients of upstream ribs are larger than those downstream.Secondly,heat transfer distribution of the wall is not significantly affected by changes in suction ratios and Reynolds number.Thirdly,within the range of parameters,changes in suction ratios do not significantly affect the magnitudes of average heat transfer coefficients and heat transfer enhancement.However,the value of average heat transfer coefficients increases as Reynolds number increases,but the enhancement factor distributions are found to be a weak function of the Reynolds number.
Experimental study on thermal-vibration test of thermal insulating component for cruise missile
WU Da-fang, ZHAO Shou-gen, YAN Zhen-qian, ZHAO Xing
2009, 24(7): 1507-1511.
Abstract PDF(609KB) icon1696 icon439
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As the need of thermal-vibration composite test for the high-speed vehicle,a thermal-vibration experimental simulation system was established.This experiment system included the vibration experiment system and the thermal experiment system.In the test process,the thermal experiment system simulated the heating process of high-speed cruise by the air,at the same time the vibration experiment system provided the flight vibration environment to the high-speed cruise.The results of the experiment show that this composite environment experiment system can provide a reliable basis for the safety flight of cruise missile under high-speed,high-temperature and vibration conditions.
Research on pedestal looseness fault of multi-disc over-hung rotor system
MA Hui, SUN Wei, REN Zhao-hui, WEN Bang-chun
2009, 24(7): 1512-1517.
Abstract PDF(1057KB) icon1488 icon435
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In view of pedestal looseness fault often occurred in the engineering,a finite element model with looseness fault was established and dynamic characteristics of one-support looseness and two-support looseness were studied.The results show that the system motion experiences period-one,period-two,period-six and period-four with the decrease of looseness stiffness in two looseness cases.However,the rotor trajectory is different,since one-support looseness,rotor trajectory is an 8 shape curve with large difference in up and down layers,then becomes two nested 8 shape curves,finally becomes a spiral shape curve.For two-support looseness,rotor trajectory is approximately triangle,then two adjoining 8 shape curves,and finally becomes a spiral curve.The results will provide theoretical references for fault diagnosis,dynamic design,and safe operation of rotor-bearing system.
Experimental research on metal rubber shock isolation system
YAN Hui, JIANG Hong-yuan, LIU Wen-Jian, HAO De-gang
2009, 24(7): 1518-1522.
Abstract PDF(1329KB) icon1768 icon463
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The damping performance of metal rubber(MR) anti-shock isolator depends on the dry friction and elastic deformation that dissipates vibrating energy.An MR isolator was investigated to satisfy the need of shock isolation system of some aircrafts by the shock experiments.The results show that the maximal accelerator response and the shock isolation coefficient increase with the shock duration,while the shock isolation coefficient is affected by shock load.It is concluded that under smaller shock load,the shock isolation coefficient of MR isolator decreases with the increase of external load,however,when the load exceeds a certain value,the shock isolation coefficient increases with external load.
Dynamical response analysis on blades arisen by aerodynamic forces through sequential method
ZHANG Da-yi, MA Yan-hong, HONG Jie, CHEN Lu-lu
2009, 24(7): 1523-1529.
Abstract PDF(1529KB) icon1561 icon415
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The coupling of mathematical equations was substituted by coupling of physical process,and the basic governing equations of fluid domain,solid domain and fluid-solid interface were deduced respectively for flow-blade interaction system.Furthermore,the numerical method was given through bidirectional sequential method,and the corresponding physical process of blade vibration from unsteady to steady state was described.Finally,certain engineering sample was discussed to verify the method,and the dynamical responses of certain secondary stator used in a missile engine were obtained.Thus the characteristics of flow field and stress distribution on stator were gained,and the advantages of sequential method on solving fluid-solid interaction(FSI) problems were pointed.
Estimation of the unbalance magnitude of rotor system based on model
LI Chang-you, XU Min-qiang, GUO Song, WANY Yue-wu, WANY Ri-xin, GAO Jing-bo
2009, 24(7): 1530-1536.
Abstract PDF(945KB) icon1499 icon428
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The approach based on model was employed to estimate the unbalance magnitude of rotor system in this paper.The original vibration signal of rotor system must be recorded,then,the differences between online detected unbalance responses and original signals were computed.The equivalent loads on each node were calculated through dynamics equation of rotor system with the differences.The magnitude,location and phase of the unbalance were acquired according to the equivalent load.The vibration responses of the need nodes were estimated according to the response of the finite nodes by the modal expansion technique.The denoise approach based on gauss wavelet was proposed due to the existence of a lot of noise.The results show that the proposed approach in this paper is able to estimate the unbalance magnitude accurately.
Slip model for the plastic behavior of Ni base single crystal based on dual-phase microstructure cell
CAO Juan, WANG Yan-rong, SHI Duo-qi
2009, 24(7): 1537-1543.
Abstract PDF(851KB) icon1969 icon437
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A dislocation slip model based on the periodic dual-phase microstructure cell of Ni base single crystal was established,in which the analytic stress model was set up at different regions of microstructure cell and dislocation slip model was combined with the mechanisms of dislocation filling the matrix channel,climbing along the precipitation,shearing cell and slipping backward when unloading to simulate the tension,creep and cycle behavior of SC16 at 1 123 K and DD3 at 1 033 K.The results show that the several mechanisms govern the different aspects of the deformation respectively and that the simulation results match well with the tests.
Determination of rotation center in industrial computed tomography system
LI Bao-lei, FU Jian, WEI Dong-bo, LI Jun-jiang
2009, 24(7): 1544-1548.
Abstract PDF(680KB) icon1744 icon530
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The determination of the COR(center of the rotation) of the rotating table is a key step to set up an industrial computed tomography system.The error of the COR can lead to artifacts in CT(computed tomography) image.The current popular methods about COR determination were described and their disadvantages were presented.Based on the analysis,one novel method was put forward.The proposed algorithm was based on the redundancy character of sinogram,and the COR was located by calculating the position at which the sum of the sinogram data was divided equally.As compared with the current methods,the proposed algorithm need not any phantom and geometry parameter,and is hardly affected by random noise.The feasibility of the method is validated by the experiment data.
Research on low cycle-multiaxial fatigue-creep life prediction at high temperature for turbine blade
PENG Li-qiang, WANG Jian
2009, 24(7): 1549-1555.
Abstract PDF(2244KB) icon1656 icon508
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SHANG Deguang multiaxial fatigue damage model was used to amend Manson-Coffin equation of multiaxial fatigue prediction and SWT(Smith-Waston-Topper) formula,based on working condition of turbine rotor blade in aviation engine.A new method of fatigue life prediction of turbine blade was presented,which was adapted for non-proportional loading of turbine blade fatigue damage at high temperature.A case of turbine blade was calculated for fatigue life and the total damage of 1000 hours flying,in well agreement with the fact of blade fatigue damage.So the model of multiaxial fatigue prediction is rational and feasible.
Numerical investigation on gas flow in Laval micronozzle
LIU Zhao-miao, ZHANG Tan
2009, 24(7): 1556-1563.
Abstract PDF(1374KB) icon1629 icon494
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Characteristics of gas flow in a 2-D Laval micro-nozzle with 37 μm throat-width were studied through numerical simulation based on continuum theory in this paper.Influences of pressure ratio on the configuration of the flow field were investigated in detail.The formation mechanism and requirement of supersonic annular phenomenon,whose essence is "Mach disk" formed in micro-nozzle under over-dilation condition,were analyzed in micro-scale by shock wave theory.While the exit pressure remained unchanged,the possible existent range of supersonic annular phenomenon was judged,and the influence of pressure ratio and shock wave on total pressure drop in the micro-nozzle was discussed.
Conceptual design of Mach number 3.5 air-breathing propulsion system
CHEN Min, TANG Hai-long, LIU Da-xiang, JIN Jie
2009, 24(7): 1564-1569.
Abstract PDF(1008KB) icon1678 icon406
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Two sets of propulsion concept were analyzed based the existent low bypass ratio augmented turbofan engine with mixed exhaust nozzle,in order to meet the mission requirements on the low Mach propulsion system(Ma≤3.5) in the hypersonic transportation.The result shows: as for the turbofan(TF) concept,by means of optimizing the control law of the base turbofan engine,total pressure difference between the two streams at the mixed zone was effectively reduced,contributing to flow organization at the afterburner inlet and flame stability.Also,the optimized control law contributes to lower specific fuel consumption.As for the turbofan/ramjet combined cycle engine concept with over-under configuration compared with the TF concept,independent inlet and nozzle were both required for the two engine models due to the aerodynamic mismatch during mode transition,which would increase the structure complexity,weight and technology risk.
Computed study on power recovery of turbocharged two stroke spark ignition engine at altitude
LIU Bo, DENG Kang-yao
2009, 24(7): 1570-1576.
Abstract PDF(2016KB) icon1722 icon467
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The power recovery ability of a turbocharged two stroke spark ignition(SI) engine at altitude was studied experimentally at ground and simulated at altitude.A new exhaust system was applied for the purposes of achieving good scavenging performance.Through proper design of the exhaust pipe's length and cross section area variation,scavenging performance was improved,but always deteriorated on turbocharged engine because of back pressure rising in the exhaust pipes.Turbocharged two stroke spark ignition(SI) engine is better than corresponding original engine at altitude both in terms of output and economics.So,it is suitable to work at high altitude.
Aerodynamic noise analysis and control for mini-van car side view mirror
WANG Yi-ping, GU Zheng-qi, YANG Xue, LI Wei-ping, YUAN Zhi-qun
2009, 24(7): 1577-1583.
Abstract PDF(1141KB) icon1816 icon417
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The transient exterior flow field of a mini-van was computed by large eddy simulation(LES),and then the noise characteristic was predicted using FW-H acoustic model based on Lighthil-Curle acoustic analogy theory.The local shape of the mirror was modified to reduce the aerodynamic noise.Finally a real vehicle road test was implemented,with the test velocities from 60 km/h to 120 km/h.The result shows that the vehicle noise has been noticeably reduced,or even down to 1.2 dB,by modifying the mirror shape.
Numerical simulation of fluid-structure interaction in conical parachute's opening process
WU Zhuo, CAO Yi-hua, SONG Qian-fu
2009, 24(7): 1584-1593.
Abstract PDF(1854KB) icon1579 icon398
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According to a multi-node model,this paper has constructed dynamics equations of conical parachute system to simulate distortion process of the flexible canopy in the opening process.By combination of dynamics equations code and computational fluid dynamics(CFD) software,the fluid-structure interaction study of the parachute was carried out,and the change of its shape and flow flied,inflation time,the rate of decline,the distant of decline,and other relevant data were achieved in agreement with foreign research results.
Analysis of drags trait in three-dimensional sidewall hypersonic inlet
WEI Yong-bin, ZHANG Kun-yuan
2009, 24(7): 1594-1600.
Abstract PDF(941KB) icon1662 icon440
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The internal drag trait of three-dimensional sidewall hypersonic inlet(before the throat) has been investigated by numerical simulation,streamline tracing and constant dynamic pressure of incoming flow(variation of Ma=4.65～6.65).The results show that: 1) Pressure drag and total drag on the internal walls decrease when the Ma increases,but the friction drag on the internal walls increases when the Ma increases and the ratio of friction drag is less than 20%.2) Thrust efficiency and thrust and drag ratio increase with the increase of Ma.Thrust efficiency increases by 13.8% and thrust and drag ratio increase by 2.73.3) Additive drag decreases when the Ma increases and the additive drag actually becomes "additive thrust" at high Mach number.
Wind tunnel experiment of sidewall compression inlet with adjustable attack angle
GUO Bin, ZHANG Kun-yuan
2009, 24(7): 1601-1605.
Abstract PDF(715KB) icon1554 icon439
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This paper conducted a wind tunnel experiment at Ma=3.85,during which a continual blowing process was finished at the sidewall compression inlet with designed Ma=6 and starting Ma=2.5,when attack angle changed from 0° to 8°,and again to 0°.Experimental results show that,in the case of Ma=3.85,attack angle=0°,the inlet starts smoothly,and the pressure distribution is consistent with numerical simulation to a large degree.In the dynamic process of attack angle changing from 0° to 8°,when it increases to 5.7°,the inlet fails to start.In the dynamic process of attack angle changing from 8° to 0°,when it decreases to 5.4°,the inlet succeeds in startup.What's more,with the increase of attack angle,the flow coefficient decreases when the inlet starts,and it decreases sharply when the inlet doesn't start.When the attack angle changes from 0° to 4°,and again to 0°,the inlet starts in the entire process.
Effect of circumferential forward-skewed blade on aeroacoustic performance of axial fan
LI Yang
2009, 24(7): 1606-1609.
Abstract PDF(1412KB) icon1565 icon485
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Low pressure axial fan with forward-skewed rotor blade was studied.The relationship between sound pressure level and flow rate and 1/3 octave spectrum at design condition was obtained through aerodynamic noise experiment.The effects of blade forward skew angle on aerodynamic noise were analyzed.The distributions of wake width at outlet of rotors were obtained from simulation.The effects of blade forward skew angle on wake width were also analyzed.The results show that,with the increase of blade forward skew angle,the wake width declines and then increases,leading to similar relationship curves between aerodynamic noise measurement data and flow rate.The lowest aerodynamic noise occurs at forward skew angle between 6° and 8°.The difference of aerodynamic noise among the rotors occurs mainly at frequency zone between 300 Hz and 4 000 Hz.
Research on flow instability of transonic compressor rotor and boundary suction effect at low Reynolds number
XIA Qin-bin, WANG Ru-gen, ZHOU Min
2009, 24(7): 1610-1615.
Abstract PDF(1320KB) icon2098 icon456
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The flow instability of NASA Rotor 37 transonic compressor rotor at low Reynolds number was investigated by numerical simulation.The result shows that the boundary layer radial vortex becomes an important factor for causing compressor flow instability.It's found that the compressor stability range is obviously enlarged by suction on the blade suction surface at different blade heights and axial chords.The influence of suction mass on the characteristic of the compressor was also compared.
Three-dimensional numerical research on stall inception in axial compressor
TU Bao-feng, HU Jun, ZHAO Yong
2009, 24(7): 1616-1621.
Abstract PDF(1994KB) icon1593 icon549
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A 3-D dynamic stall inception analysis method was developed based on the 3-D unsteady Euler equations and the 3-D actuator-disk model.The stall inception of the first stage of a high compressor was studied using this method.The compressors were designed using 3-D method,showing that the characteristics of the rotor are different in the radial direction,so three different static-to-total pressure ratios of rotor were studied in this paper,and the effects on the stall inception were investigated.The results show that this method can compute the 3-D stall inception of the axial compressor,the 3-D space configuration of stall cell,and also the effects of 3-D characteristic of rotor on the stability.This method is also able to detect the dangerous section of the compressor which is helpful to study the stability in multi-stage compressors.
Numerical method for fluid-structure interaction in turbomachinery bladings
ZHANG Xiao-wei, WANG Yan-rong, ZHANG Xiao, PEI Wei
2009, 24(7): 1622-1626.
Abstract PDF(592KB) icon1898 icon509
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A numerical simulation method for fluid-structure interaction(FSI) in turbomachinery bladings was presented to predict the aeroelastic stability of blades.The vibrational displacements of computational structural dynamics(CSD) nodes have been interpolated to computational fluid dynamics(CFD)grids at the blade surface using a data transfer method.In CFD analysis,the grid coordinates of the moveable region have been updated by multi-layer moving grid technique,and the finite volume method has been applied to calculate the Reynolds-averaged Navier-Stokes(RANS) equations closed by k-ε turbulent model.For NASA Rotor 67,the total work done by the unsteady aerodynamic force in one oscillating period and the corresponding aerodynamic modal damping ratios of the first four modes of blade vibration at the design speed have been predicted numerically,and the aeroelastic stability of blades has been analyzed preliminarily.The study shows that the developed FSI procedure is feasible to predict the aeroelastic stability of blades.
Improvement and validation of a planar cascade inverse design method
ZHANG Pei, CHU Wu-li, WU Yan-hui, ZHANG Hao-guang, LU Jia-ling
2009, 24(7): 1627-1632.
Abstract PDF(1021KB) icon1484 icon395
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With the hypothesis that one fluid element moves along a curved average streamline in cascade passage due to the pressure force acting on the element,a feasible planar cascade inverse design method was introduced;the design parameters for yielding desired cascade geometry mainly include: inlet/outlet flow angles,section radius,prescribed profile loading and thickness distribution along axial chord.To supplement and improve original design method,a new theory was put forward,in which the density distribution along axial chord could be calculated,and the algorithm with leading/trailing circles was modified with obvious improvement of cascade aerodynamic performance.To validate the improved cascade design method,the Aachen turbine cascade from Germany was re-designed in this paper.
Experimental investigation of a solid/arc slot asymmetrical combined casing treatment
QIAN Yu-ping, LIU Jian-yong, LI Qiu-shi, LU Ya-jun
2009, 24(7): 1633-1638.
Abstract PDF(1776KB) icon1463 icon431
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This thesis experimentally investigated the solid/arc slot combined casing treatment on the transonic compressor test facility.Unlike traditional casing treatments,not only the stall margin of the compressor could be enlarged greatly by using the solid/arc slot combined casing treatment,the adiabatic efficiency could also be increased nearly 1%.The main reason for this phenomenon is that the combined casing treatment increases the flow mass of the tip region,prevents the flow separation,suspends the rotating stall;with the use of the asymmetrical combination in circumferential direction,the loss in the treatment slots is reduced,the income of the combined casing treatment is more than the loss,and the adiabatic efficiency is improved.
Design of forecasting model for aero-engine lubrication debris support vector machines based on immune-particle swarm optimization algorithm
LI Ben-wei, ZHANG Yun, SUN Tao
2009, 24(7): 1639-1643.
Abstract PDF(1429KB) icon1617 icon428
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An immune particle swarm optimization algorithm(immune-PSO) based on clonal selection was proposed.In the method,the strategy of antibody clone,mutation and limit was introduced into PSO algorithm to avoid trapping in local minimum.To resolve the problem that the choice of parameters influences the forecast precision of support vector machine(SVM) forecasting model,the immune-PSO algorithm was used to design the aero-engine lubrication debris forecasting model based on SVM with self-adaptive optimized parameters.The simulation results show that the forecasting model optimized by immune-PSO algorithm can achieve automatic optimization of parameters,and increase forecasting accuracy than the conventional cross-validation algorithm.
Aero-engine fault diagnosis based on consistent-approximative denoted space
CHENG Si-yi, SUO Zhong-ying, WU Hua, ZHANG Guan-rong, ZHONG Qiu
2009, 24(7): 1644-1648.
Abstract PDF(1656KB) icon1721 icon408
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The acquisition of decisions based on maximal distribution is one of important aids in aero-engine fault diagnosis,and consistent-approximative denoted space(CADS) offers a tool to uniformly process them;and,aero-engine fault is a typical problem of small samples set.Aimed at decision-making information system of a certain aero-engine fault,the paper firstly sought its CADS based on maximal distribution,then introduced the method of rule fusion to obtain all decision rules under different conditions,and the history faults were recognized accordingly with a higher rate of identification.The result shows the effect of this method and the applicability of the decision-rules received from rule fusion.
Research on performance fault fusion diagnosis of aero-engine component
LU Feng, HUANG Jin-quan, CHEN Yu
2009, 24(7): 1649-1653.
Abstract PDF(404KB) icon1704 icon468
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A method of engine component fault diagnosis based on fuzzy decision fusion was proposed to improve the accuracy of component fault diagnosis,and reduce the probability of false alarming and missing detection.By using Kalman filter algorithm and least square support vector machine(LSSVM),the sensor outputs were both sent to two different modules —— self-tuning model and data-based diagnostic module —— to estimate the health parameters.Fuzzy algorithm was operated to adjust the weights of two modules,and then the fault fusion decision was made by D-S(Dempster-Shafer) theory.Simulation on a turbofan engine shows that,as compared to these two modules,this method has better accuracy of fault diagnosis.
Numerical simulation of multi-phase combustion flow in solid rocket motors with metalized propellant
SHAFQAT Wahab, XIE Kan, LIU Yu
2009, 24(7): 1654-1660.
Abstract PDF(697KB) icon1533 icon426
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Multi-phase flowfield simulation has been performed on solid rocket motor and effect of multi-phases on the performance prediction of the solid rocket motor(SRM) is investigation.During the combustion of aluminized propellant,the aluminum particles in the propellant melt and formliquid aluminum at the burning propellant surface.So the flow within the rocket motor is multi phase or two phase because it contains droplets and smoke particles of Al2O3.Flowsi mulations have been performed on a large scale motor,to observe the effect of the flowfield onthe chamber and nozzle as well.Uniform particles diameters and Rosin-Rammler diameter distribution method that is based on the assumption that an exponential relationship exists betweenthe droplet diameter,dand mass fraction of droplets with diameter greater thandhave been used for the si mulation of different distribution of Al2O3 droplets present in SRM.Particles sizes in the range of 1-100μm are used,as being the most common droplets.In this approachthe complete range of particle sizes is dividedinto a set of discrete size ranges,eachto be defined by single streamthat is part of the group.Roe scheme-flux differencing splitting based on approxi mate Riemann problem has been used to si mulate the effects of the multi-phase flowfeild.This is second order upwind scheme in which flux differencing splitting method is employed.To cater for the turbulence effect,Spalart-All maras model has been used.The results obtained show the great sensitivity of this diameters distribution and particles concentrations to the SRMflowdynamics,primarily at the motor chamber and nozzle exit.The results are shown with various sizes of the particles concentrations and geometrical configurations including models for SRM and nozzle.The analysis also provides effect of multi-phase on performance prediction of solid rocket motor.
Cold test of pulse thruster with high combustion chamber pressure
LIANG Shu-qiang, LIU Yu, QIN Li-zi, LIN Zhen
2009, 24(7): 1661-1665.
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Abstract:
In order to verify the design and analyze the characteristics of pulse thruster with high combustion chamber pressure,the cold test was carried out.Using O-ring as a dynamic seal of the moving injector,the channels enabled the propellants to flow from manifold cavities to extrusion cavities,and few propellants were recirculated.The sealing result of O-rings was tested,and the friction force was measured.According to test results,the sealing result is good,and the friction force accords with the design requirement.In the cold test,the thruster can work at pulsating state,and the moving injector can increase the pressure of propellants in extrusion cavities.
Design and dynamic investigation on driving equipment of micro flapping flight
ZHANG Xi-jin, FANG Zong-de, YANG Xiao-hui
2009, 24(7): 1666-1671.
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Abstract:
By combining piezoelectric ceramics actuator with flexible joint four-bar mechanism,the paper designed a compact driving equipment for micro flapping flight,and optimized its structural parameters by means of the particle swarm optimization.Using the Lagrange equation,the paper also gave a dynamic model of the driving equipment,and investigated its dynamic characteristics through simulation.The investigation result shows that,with sine wave driving voltage,the driving equipment of micro flapping flight will achieve stable flapping motion.In addition,high efficient flapping will be obtained only using standard sine wave driving voltage in a certain frequency range,and flapping amplitude can be changed through controlling driving voltage amplitude.The research lays a foundation for the motion control of micro flapping flight.
Digital simulation of spiral bevel gears' real tooth surfaces based on non-uniform rational B-spline
ZHANG Jun-hui, FANG Zong-de, WANG Cheng
2009, 24(7): 1672-1676.
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Abstract:
Based on the test of the real aviation spiral bevel gears,a new method was presented instead of the traditional rolling test.First,the real coordinate of a pair of spiral bevel gears was obtained with reference to the Gleason's measure criterion of spiral bevel gears,by using three coordinates test machine;then the digital gear faces were fitted by NURBS(non-uniform rational B-spline);finally,the tooth contact analysis was simulated according to the space engagement theory,and compared with the real rolling test experiment.The result demonstrates the accuracy and feasibility of the proposed method.

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