2011 Vol. 26, No. 1

  Previous Issue | Next Issue 
Display Method:
Three-dimensional DSMC calculation and heat transfer analysis of four capsules for hypersonic rarefied conditions
WANG Bao-guo, LI Yao-hua, QIAN Geng
2011, 26(1): 1-20.
Abstract PDF(3377KB) icon2060 icon31
Abstract:
Hypersonic rarefied flow field of four vehicles (Apollo, Orion, Mars Pathfinder and Mars Microprobe) in the atmosphere of Earth and Mars was calculated using the DSMC(direct simulation Monte Carlo) source code compiled by us. Detailed aerodynamic coefficients and thermodynamic coefficients of these vehicles under 42 conditions (with the altitude from 250km to 90km, attack angle from 45° to -45°, Knudsen number from 111.0 to 0.0057, velocity from 7.6km/s to 9.6km/s for the Earth atmosphere; with the altitude from 141.8km to 80.28km, attack angle from 45° to 0°, Knudsen number from 100.0 to 0.0546, velocity from 7.47km/s to 6.908km/s for the Mars a tmosphere) were presented and compared with flight data announced by other countries and calculation results published by NASA (National Aeronautics and Space Administration) Langley Research Center. The results are satisfactory. Three-dimensionless parameters were used to describe the characteristics of thermodynamic non-equilibrium, chemical non-equilibrium and wall heat flux of these four typical vehicles respectively. These results are quite useful for thermal protection design of spacecrafts.
Experimental investigation on effects of swirl number on aerodynamic characteristics of combustor
DANG Xin-xian, ZHAO Jian-xing, XU Rong, YAN Yin-wen, LIU Yong
2011, 26(1): 21-27.
Abstract PDF(1258KB) icon2212 icon34
Abstract:
To investigate the influence of different swirl numbers on flow structure and aerodynamic characteristics of the model annular combustor with double axial swirler,the isothermal and spray combusting flow fields of the model annular combustor with double axial swirler were measured by a particle image velocimetry (PIV) system.Effects of different swirl numbers on the formation of recirculation zone,profiles of ensemble-averaged velocities ( , ),fluctuating velocities (urms,vrms)and Reynolds shear stress u'v' in the combustors were investigated experimentally.Results of the PIV show that influences of different swirl numbers on isothermal and reacting flow fields are considerable.The length of central recirculation zone of reacting flows is shorter than that of non-reacting flows.However,the recirculation velocity,fluctuating velocity and Reynolds shear stress of reacting flows are higher than those of non-reacting flows.The changes of length and recirculation velocity for the central recirculation zone decrease with increase in swirl number under reacting flows.
Experimental study on self-excited oscillations in premixed combustor
ZHANG Hao, HUANG Zheng, ZHU Min
2011, 26(1): 28-34.
Abstract PDF(1224KB) icon1759 icon19
Abstract:
Combustion instabilities were studied experimentally by coupling unsteady heat release and pressure perturbations.In this paper,the experimental studies were conducted to analyze the dynamic processes of self-excited combustion oscillations through dynamic pressure and phase-locked chemiluminescence measurements.The effects of air mass flow,equivalence ratio and boundary conditions on combustion system were examined.This shows that the amplitudes of oscillation will enlarge with the increasing system load,leading to more unstable combustion.Moreover,the higher modes of oscillation frequency may occur when the combustion operation is closer to lean limits.
Performance studies of annular pulse detonation engine ejectors
QIN Ya-xin, YU Jun-li, GAO Ge
2011, 26(1): 35-41.
Abstract PDF(1247KB) icon1992 icon21
Abstract:
The distributions of detonation parameters in detonation chamber were gained by analytical numeration,and then multiple-cycle numerical simulations were carried out after detonation wave broke up to shock wave.The analysis on the mechanism of unsteady ejection shows that the process of unsteady ejection can be divided to four stages,and the ejection performance of annular pulse detonation duct is stronger than round pulse detonation duct.Different structures and parameters could induce different time-averaged thrust augmentations.The better shape of the ejector inlet,interior surface,ejector length-to-diameter ratio and axial placement were obtained through analysis,offering references to augment the performance of pulse detonation engine.
Simulation of fluid-solid coupled heat transfer of cylinder of a small two-stroke air-cooled aero-engine
TANG Zi-jie, DING Shui-ting, DU Fa-rong
2011, 26(1): 42-47.
Abstract PDF(1082KB) icon1958 icon22
Abstract:
Based on a small two-stroke air-cooled aero-engine,the heat transfer of cylinder for air-cooled engine was simulated according to the theory of the fluid-solid coupled heat transfer,in combination with characteristics of heat transfer and discipline of combustion.In this theory,the heat conduction between the cylinder and cylinder liner was considered as internal condition of the system,which can make the simulation simple and convenient;as compared with the experiment result;this shows that coupled analysis is reliable about the heat transfer of the cylinder.Considering the whole working condition of the aerial vehicle,the heat transfer of the cylinder within the working altitude was simulated, thus establishing a basis for further study of the cylinder heat transfer.
Analysis of components infrared radiation of afterburning turbofan engine under non-afterburning condition
HUANG Wei, JI Hong-hu
2011, 26(1): 48-53.
Abstract PDF(1123KB) icon1722 icon17
Abstract:
The effective infrared radiation intensity (self-radiation intensity and reflected radiation intensity),gas radiation intensity and total radiation intensity of afterburning turbofan engine under non-afterburning condition were calculated and analyzed using reverse Monte-Carlo method.The distributions of them were discussed and analyzed.The results show that,under the conditions given hereto,the cone is the strongest infrared radiation source,which contributes more than 65% to the maximum infrared radiation intensity;the turbine blade and radial flame holder are the second ones when the detective angle is less then 20°;the divergent part of nozzle plays an important role to the spatial distribution of infrared radiation towards the aft-hemisphere,especially in the region with detective angle bigger than 20°;the reflected radiation intensity of cone,turbine blade and radial are less than 10% of the self-radiation intensity.
Research of electrodynamics in electro-impulse de-icing (EIDI) system
LI Guang-chao, HE Jiang, LIN Gui-ping
2011, 26(1): 54-59.
Abstract PDF(965KB) icon1786 icon17
Abstract:
The current status of the research on electrodynamics in electro-impulse de-icing (EIDI) system was summarized in this paper;several common calculation models were analyzed.By taking Bernhart-Schrag model,for example,the theoretical basis of electrodynamics model,the establishment of equivalent model and the solution of state equation were expatiated;the correctness of the model was also analyzed.For the simplified system of EIDI composed of circular flat coil and metal flat plate,Bernhart-Schrag model can help to predict the regular variation pattern of current in the coil and the pulse effect under the skin.
Influences of pores distribution on thermal radiation properties of ceramic materials
LI Dong-hui, XIA Xin-lin
2011, 26(1): 60-64.
Abstract PDF(1054KB) icon1541 icon18
Abstract:
A rigid Mie solution on scattering by a spherical particle immersed in an absorbing medium was introduced. By combining with independent scattering discipline for polydisperse particles, a theoretical method was presented for calculating thermal radiation properties of ceramics with pores in modified Gamma distribution. Influences of pores distribution and mean diameter on thermal radiation properties of a specific Yt stablized zirconium (YSZ) were analyzed. Results show that pores distribution and mean diameter have significant influences on thermal radiation properties of the ceramic. Extinction coefficient, scattering albedo and asymmetry factor decreases with pores distribution approaching mono dispersion and increases with pores distribution approaching poly dispersion. An optimal mean diameter of pores exists for extinction coefficient in short wavelength while the coefficient decreases with pores mean diameter in long wavelength. Both scattering albedo and asymmetry factor increase with pores mean diameter.
Numerical investigation on heat transfer mechanism of impingement jet with cross-flow
ZHANG Chuan-jie, SUN Ji-ning, TAN Ping
2011, 26(1): 65-71.
Abstract PDF(1260KB) icon1692 icon15
Abstract:
Numeration analysis was made to simulate the influence induced by upstream jet on downstream jets in impingement chamber.The results shows that,(1) As the cross-flow increases,the heat transfer efficiency on the impinged surface changes in a very complicated way.(2) Cross-flow influences the heat transfer of the impinged surface mainly in two aspects:as the cross-flow Reynolds number increases,the strength of stretched vortex pair downstream of the jet firstly increases and then decreases,resulting in the same influence on the heat transfer of the target surface;the deviation of the impinging jet induced by cross-flow makes the high heat transfer zone move backward. (3) As cross-flow increases,the heat transfer efficiency induced by impingement and cross-flow changes,making the heat transfer on the target surface more complicated.
Numerical study on the mixing characteristics of chevron mixers for the afterburner
WANG Ya-meng, ZHANG Jing-zhou, GAO Jia-chun, SHAN Yong, LIU Tao
2011, 26(1): 72-77.
Abstract PDF(1101KB) icon1965 icon21
Abstract:
Three-dimensional computational fluid dynamics (CFD) computations were conducted to analyze the mixing characteristics of three types of chevron mixers and the confluent mixer used in the afterburner.The research results obtained in the present conditions show that:(1) an array of stream-wise vorticity could be induced by chevron mixers,and the stream-wise vorticity scale and intensity are affected seriously by the chevrons arrangement and inclined angle;(2) the chevron mixer with chevrons tilted alternately inward and outward demonstrates the best performance with higher thermal mixing efficiency and lower extra pressure loss,the total pressure recovery coefficient decreases 0.2% compared to confluent mixer,and the mixing flow temperature increases about 150K in front of flameholder by enhancing the mixing process between core flow and bypass flow.
Coupled heat transfer simulations of an air-cooled turbine with single cooling channel
WANG Qiang, GUO Zhao-yuan, ZHOU Chi, FENG Guo-tai
2011, 26(1): 78-84.
Abstract PDF(1148KB) icon1741 icon15
Abstract:
The developed coupled solver HIT-3D was applied to the coupled heat transfer simulations of an air-cooled turbine with single cooling channel.Different turbulence and transition models were utilized.The numerical results validated the ability of the developed solver in the engineering simulation.Then a method combining the coupled heat transfer and engineering design techniques was developed to reduce the computational loads of simulations of turbines with complex cooling systems.With the same test case mentioned above,such method was validated,and the influences of rough inner wall on the blade thermal load were investigated.The results show that the transition model predicts lower vane thermal load than the full turbulence models at the transition zones on the vane surface,and that the developed method can greatly reduce the computational load during the turbine design.
Experimental investigation on stator-rotor interaction flow with trailing edge blowing stator
WU Ya-dong, TIAN Jie, ZHU Xiao-cheng, DU Zhao-hui
2011, 26(1): 85-91.
Abstract PDF(1446KB) icon1749 icon15
Abstract:
The mixed flow field and noise characteristic of the stator wake interaction with rotor with/without injection through a slit along the stators rear end was investigated using noise measurement equipments and particle image velocimetry.In the velocity fields,the spreading characteristics of the wakes across the rotor row were gained.The interaction flow field between pure wake and rotor was compared with the flow field between weak wake,momentumless wake,jet and rotors.The results show that the momentumless wakes make the inlet flow of the rotor more uniform,and improve the inlet flow angle of the rotor.By comparing aerodynamic and aeroacoustic performance,the trailing edge blowing up to momentumless wake can reduce BPF(blade-passing-frequency) noise,and has little effect to the aerodynamic performance.
Mechanism of influences of axial positions of axial skewed slot casing treatment on a compressor performance
ZHANG Hao-guang, CHU Wu-li, WU Yan-hui
2011, 26(1): 92-98.
Abstract PDF(1298KB) icon2004 icon14
Abstract:
Two investigations were performed for an axial-flow compressor rotor to explore the effects of axial positions of axial skewed slot casing treatment on the rotor performance.The steady operating range of compressor rotor was extended and the compressor efficiency was reduced with all casing treatments in the experimental and numerical investigations.The ability to improve the rotor steady operating range was the best when the axial position of casing treatment was unchanged.The ability was depressed obviously by moving the axial position of casing treatment backwards.The degree of damage on compressor isentropic efficiency was decreased when the axial position of casing treatment was moved forwards or backwards.The detailed analyses of the flow-filed in compressor with casing treatment indicate that,the development of tip leakage vortex could not been restrained by moving the axial position of casing treatment backwards,and the pumping ability of slot was reduced likewise,thus weakening the effect of extending the steady operating range of compressor;the work of blade forcing on air in the blade tip was not only increased,but also the flow loss caused by tip leakage flow and secondary flow were reduced when the axial position of casing treatment was moved forwards or backwards,making the rotor isentropic efficiency increase if compared the slot with axial position unchanged.
Method for reducing tip clearance leakage of turbine
CAO Chuan-jun, HUANG Guo-ping, XIA Chen
2011, 26(1): 99-107.
Abstract PDF(1297KB) icon2194 icon16
Abstract:
A kind of method for reducing tip clearance leakage of turbine was presented using backward vortex generators (BVGs) in this paper.In order to reduce tip leakage flow,the gas is guided to flow into BVGs from pressure side of blade and flow out of blade tip with high speed in the inverse-direction of leakage flow,based on the pressure difference between pressure surface and blade tip.Numerical simulations of typical turbine cascade in millimeter scale with/without BVGs were performed and the influences of BVGs on mass of leakage flow and circumferential load were analyzed.The results show that mass of leakage flow decreases by 3.3% and circumferential load increases by 6.2% in typical entrance condition.Moreover,the smaller entrance Mach number means the better effect of reducing mass of leakage flow;the larger entrance Mach number means more obvious improvement of circumferential load.When entrance Mach number increases,the improvement of turbine efficiency grows.
Intensity analysis of blades in axial compressor with inlet distortion
ZHANG Ming-ming, HOU An-ping, HE Xiao-fan, LI Shao-bin, LIANG Chao
2011, 26(1): 108-114.
Abstract PDF(1215KB) icon1613 icon21
Abstract:
A method of examining inlet distortion for intensity of compressor blades was described.A CFD (computational fluid dynamics) modeling of entire compressor flowpath was conducted to analyze the pressure fluctuation on the rotor blades due to inlet total-pressure distortion.A finite element model of the blade was then used to analyze the modal frequencies and stress,providing information on the fatigue failure potential and sensitivity to the imposed distortion.Results show that circumferential total-pressure distortion not only causes the decrease of efficiency and stall margin of compressor,but also leads to nonuniformity of aerodynamic force of blades at different circumferential positions,producing an important influence on the blade intensity.
Experimental research on boundary layer behaviors of ultra-high-lift low-pressure turbine profile based on surface-mounted hot-film
LI Wei, ZHU Jun-qiang, LI Gang, XU Yan-ji
2011, 26(1): 115-121.
Abstract PDF(1094KB) icon2022 icon21
Abstract:
A hot-film experimental investigation on steady boundary layer separation behaviors of the suction surface of an ultra-high-lift low-pressure turbine profile was described,which was compared with loading distribution.The experimental results indicate that the surface-mounted hot-film is a reliable indicator of the position of separation bubble and transition for the ultra-high-lift low-pressure turbine blade.In the event of lower Reynolds numbers,the size of separation bubble and transitional regime increases under declining Reynolds numbers.
Numerical method of transonic axial compressor performance prediction
HU Jiang-feng, ZHU Xiao-cheng, DU Zhao-hui
2011, 26(1): 122-127.
Abstract PDF(1055KB) icon1826 icon19
Abstract:
The deviation and loss models were developed by taking into account different influential factors using two-dimensional streamline curvature mathematic method at off-design conditions.The internal flow field of NASA(National Aeronautics and Space Administration) Stage 37 was calculated,and then the characteristic curves of design and off-design points were obtained.Through comparison between simulation and experimental values,the results show that the predicted characteristics and parameters distribution of compressor are in good agreement with the experimental values.This method can predict the performance and span-wise aerodynamic parameters of transonic axial compressor with better accuracy and can be used for compressor design and optimization.
Investigation on distributed viscous body force modeling and its application
LIU Chao, NING Fang-fei
2011, 26(1): 128-135.
Abstract PDF(1945KB) icon1766 icon16
Abstract:
The modeling method of viscous terms of Navier-Stokes equations using distributed viscous body forces was investigated.Then a fast calculation code for the three-dimensional(3-D)unsteady flow in turbomachine was developed,by solving 3-D unsteady Euler equations with the distributed viscous body force model.The code was used to simulate the unsteady flow in a two-stage compressor under circumferential total pressure inlet distortion,and the results were compared with Reynolds averaged Navier-Stokes(RANS) results.This demonstrates that,in the simulation of the unsteady flow in the multi-stage compressor under inlet distortion,the results obtained by the distributed viscous body force model agree well with the RANS results,with substantially less computational cost.
Investigation on aerodynamic characteristics of flexible wing with different flexibilities
LI Zhan-ke, XU Ding-guo, NIU Wen
2011, 26(1): 136-140.
Abstract PDF(1046KB) icon1599 icon15
Abstract:
In order to study aerodynamic characteristics and wind-resistance performance of the flexible wing with different flexibilities,nine flexible wing micro air vehicles (MAV) with different flexibilities were produced,and wind tunnel test was performed in special micro air vehicle wind tunnel of Northwestern Polytechnical University (NPU).The influence of wind velocity and angle of attack on aerodynamic characteristics was investigated and the aerodynamic characteristics of a good flexibility of the flexible wing MAV were optimized.The results of experiment can guide us in conceptual design and aerodynamic design of flexible wing MAV.
Flow field characteristics of a two-dimensional integrated asymmetry-expansion nozzle
XIE Wen-zhong, GUO Rong-wei
2011, 26(1): 141-147.
Abstract PDF(1221KB) icon1754 icon15
Abstract:
The flow field characteristics of a two-dimensional uninhabited combat air vehicle (UCAV) aft-body integrated asymmetry-expansion nozzle in ground condition were simulated using a numerical approach which has been validated by NASA (National Aeronautics and Space Administration) experimental data.This study was conducted at NPR (nozzle pressure ratios) from 2.0 to 5.5.Results indicate:(1) In spite of nonuniform expansion at different transverse slices of the UAV (unmanned aerial vehicle) aft-body integrated nozzle,the maximum propulsive performance strongly lies on area ratio of upper shorter ramp end location to the throat. (2) The mixture of internal jet and external cold air can be enhanced by secondary flow and vortex,which are induced by the nonuniform expansion at different transverse slices of the UAV aft-body integrated nozzle. (3) As the NPR increases within this study,the propulsive performance of the nozzle varies a little.
Numerical simulation of unsteady propeller slipstream
XU He-yong, YE Zheng-yin
2011, 26(1): 148-153.
Abstract PDF(1346KB) icon1934 icon33
Abstract:
Numerical simulation of three-dimensional unsteady Euler equations was conducted to investigate the unsteady propeller slipstream based on the unstructured dynamic overset grids.The rotational movement of the propeller was simulated by establishing a rotational subzone,and the airframe was contained in the stationary subzone.The method of overset grids was suitable to simulation of relative movement between the propeller and airframe.The control equations were solved by using the dual-time method and standard explicit four-stage Runge-Kutta method.The unsteady flow fields of different flight conditions were calculated and the effect of propeller slipstream was analyzed.Some calculated results were compared with experimental data,showing good agreement with each other.
Numerical simulation on jet flow field of separate flow nozzles with chevron trailing edge
KANG Guan-qun, WANG Qiang
2011, 26(1): 154-160.
Abstract PDF(1678KB) icon1940 icon17
Abstract:
Three-dimensional numerical simulations for the jet flow field of separate flow nozzles with/without chevrons on core nozzle were carried out.Calculation was conducted by employing second order upwind discretization scheme and RNG(renormalization group) k-ε turbulent model.As compared with baseline axisymmetric separate flow nozzle,addition of chevrons can strengthen the jet mixing since chevrons introduce streamwise vortices and increase the length of the mixing layer between core stream and fan stream,resulting in obvious reduction of hot potential core length and the decay of jet maximum velocity near the centerline.Moreover,increment of chevron deflection angle greatly enhances vortex strength so as to decrease jet velocity and total temperature substantially in a certain axial range.Relatively,reinforcement of jet mixing with increment of chevron length is not evident.
Experiment investigation about drag reduction of riblet structure on large-scale cylinder
LIU Zhan-yi, SONG Bao-wei, HU Hai-bao, HUANG Qiao-gao, JIANG Jun
2011, 26(1): 161-166.
Abstract PDF(966KB) icon1771 icon15
Abstract:
Experiments of large-scale cylinder model with smooth and riblet surfaces were carried out under different speeds and attack angles in wind tunnel,providing a reference for engineering application of drag reduction technique about riblet surface.Results from comparison and analysis are as follows:wind speed has a great influence on drag reduction effect of riblet surface.Drag reduction effect increases first,then decreases with increasing wind speed,and reaches to peak at certain speed.The drag reduction effect could exceed 20 percents.Attack angle has limited influences on drag reduction effect of riblet surface.The riblet structure has almost no influence on the lift coefficient and pitching coefficient of model.
Analysis of trajectory divergence characteristics for double-seat escape system
MAO Xiao-dong, LIN Gui-ping, YU Jia
2011, 26(1): 167-172.
Abstract PDF(1052KB) icon1696 icon15
Abstract:
In order to analyze the trajectory divergence characteristics for double-seat escape system,a solver was designed based on MSC.EASY 5 fundamental platform in this research.Subsequently,the trajectory divergence characteristics were numerically calculated and analyzed with the solver,including trajectory divergence performance evaluation,analysis of the influence of divergence on trajectory height and seat stability.The analysis results show that the trajectory divergence technology could effectively prevent the double-seat from interference at low speed.Although the trajectory height is somewhat reduced and the seat stability is affected a little,the integrated performance of the double-seat escape system is improved.The results provide a theoretical guidance for the engineering application.
Multiple regression analysis method for mixed data
FU Hui-min, YUE Xiao-rui
2011, 26(1): 173-177.
Abstract PDF(1371KB) icon1773 icon13
Abstract:
Aiming at the mixed data composed of complete data, type-Ⅰ censored data and type-Ⅱ censored data which are very common in accelerated life test, a multiple regression analysis method were developed. The multiple regression model was established, and the best unbiased estimations of regression coefficients and the standard deviation were given. Furthermore, the point estimation and confidence limits of percentiles were obtained. The presented method is applicable to not only the normal distribution but also the Weibull distribution, the extreme value distribution and some other location-scale distributions. The traditional multiple regression analysis method which is strictly suitable to the complete data is extended to the mixed data composed of complete data and censored data. Compared with the traditional method, the presented method can reach a high precision and a great number of specimens can be saved.
Forced response characteristics of bladed disks with random mistuned non-linear friction damping
WANG Ai-lun, LONG Qing
2011, 26(1): 178-184.
Abstract PDF(1217KB) icon1839 icon16
Abstract:
Based on various difficulties in study on vibration localization mechanism of bladed disks with mistuned non-linear friction damping,especially the problems like establishment and solution of non-linear mechanical model,the mechanical model of bladed disks with random mistuning of hysteretic dry friction damping was established in this thesis,and an incremental harmonic balance method was used to analyze the effects of parameters of bladed disks like degree of mistuning of dry friction force,coupled stiffness,viscous damping ratio and friction strength,on the forced response of bladed disks.Studies reveal that tuned bladed disks with non-linear friction damping may also cause vibrational energy localization phenomenon,and the random mistuning of dry friction force intensifies its vibration localization.
Estimation of fatigue safe lives of 7050-T7451 aluminum alloy samples
REN Xu-dong, JIANG Da-wei, ZHANG Yong-kang, ZHANG Tian, LUO Xin-min
2011, 26(1): 185-190.
Abstract PDF(1122KB) icon1639 icon17
Abstract:
Laser shock processing of three categories of 7050-T7451 aluminum alloy samples was carried out,and their seven groups of fatigue life values were studied.To obtain the values of fatigue safe life of 7050-T7451 aluminum alloy specimens,the unilateral tolerance factor statistical analysis method and two-dimensional Weibull distribution method were used to predict the values of fatigue safe life,respectively,and these two kinds of calculation results were compared.The results show that:the fatigue life of aluminum alloy samples is enhanced greatly by laser shock processing,and in consideration of the confidence and reliability,the unilateral tolerance factor method can get an exact estimation value of the fatigue safe life,while the two-dimensional Weibull distribution method can get the range of values of fatigue safe life;considering different requirements of capital and safety,etc,on the fatigue safe life,the two-dimensional Weibull distribution method is more suitable for engineering applications.
Application of time domain method in aeroelastic computations for compressor rotors
XU Ke-ning, WANG Yan-rong
2011, 26(1): 191-198.
Abstract PDF(1290KB) icon1747 icon14
Abstract:
An aeroelastic analysis system(AEAS) was been designed to perform aeroelastic analysis for three-dimensional turbomachinery rotor blade models.A time-marching method was applied in AEAS for transient displacement and dynamic stress responses of rotor blades,thus simulating aeroelastic phenomena in compressor rotors.Forced response and flutter analyses modules are two major aeroelastic modules in the AEAS code.In forced response analysis,periodic unsteady pressure field was applied to rotor blades at possible resonances on Campbell diagram to compute the amplitudes of dynamic stresses,therefore dangerous conditions of rotors were assessed.In flutter analysis,the structural solver and the unsteady flow solver were invoked alternately; transient responses of blades were provided to determine whether flutter occurs.Numerical results show good agreement with experimental measurements,indicating that it is possible to obtain dynamic stresses in fluid induced vibration analyses using the time-marching method.
Optimization design and test investigation of squirrel cage elastic support
FENG Guo-quan, ZHOU Bai-zhuo
2011, 26(1): 199-203.
Abstract PDF(1023KB) icon1932 icon37
Abstract:
Optimization design and test investigation of a squirrel cage elastic support was performed.An optimization software,which is used to achieve structure parameters optimization of squirrel cage elastic support of an engine,was developed based on the genetic algorithms and MATLAB.The test of flexibility and stress was accomplished.The results indicate that the fatigue stress is decreased to approximately 40% of the original scheme,the errors between the optimization and test results are less than 6%,so the optimization design is validated.
Application of genetic algorithm in optimizing arrangement of engine blades based on initial unbalance
JIA Jin-xin, LI Quan-tong, GAO Xing-wei, CHEN Wei
2011, 26(1): 204-209.
Abstract PDF(955KB) icon2001 icon13
Abstract:
A method to reduce turbojet engine vibration was introduced by optimizing initial arrangement order of blades.This method gave an optimal blade arrangement sequence to obtain least unbalance volume.Based on this GA(genetic algorithm) scheme,the experience for fan blades show that it provides much better results than those given from both the simple pair method and common experience method,and therefore should be adopted to balance the engine rotor.
Flow visualization of gas-gas injector mixing flowfield
JIN Ping, DU Zheng-gang, YANG Li-jun, CAI Guo-biao
2011, 26(1): 210-216.
Abstract PDF(1442KB) icon1683 icon23
Abstract:
Flow visualization technology with particle image velocimetry system was applied in the paper to study the mixing flowfield of gas-gas injector. The method of tracing two different flows separately was adopted and three typical injectors, such as coaxial shear injector, coaxial swirl injector and triple impinging injector, were selected to conduct out a series of tests. The experimental results validate the way to trace the two flows separately credible and show the different mixing mechanisms of three typical injectors with axial and cross-section images, which reveal the major impact factors of mixing process and distribution features of mixing flowfield.
Numerical simulation of a continuous wave laser powered thruster with argon propellant
LI Xiao-kang, ZHANG Yu-lin, CHENG Mou-sen, YAN Chang-yu
2011, 26(1): 217-222.
Abstract PDF(1130KB) icon1529 icon14
Abstract:
The heating and flow process in a continuous wave laser powered thruster using argon as propellant was modeled numerically.A model of physical mechanisms including laser absorption,chemical reaction,high-temperature thermodynamics properties,viscosity,diffusion,heat conduction and the effect of radiation was built up.The two-dimensional axisymmetric flow filed described by Navier-Stokes equations was solved by pressure-based SIMPLEC(semi-implicit method for pressure-linked equations consistent) algorithm.The thrust was computed by integrating the pressure and viscosity stress all over the wall,and the value was consistent with the experimental result of a similar configuration.Then the characteristics of the filed of a thruster under different mass flow rates were analyzed,and the methods for performance improvement were presented.
Strategy of thermo-structure coupled computation for composite nozzle
ZHENG Xiao-ya, CHEN Feng-ming, CAI Fei-chao
2011, 26(1): 223-227.
Abstract PDF(1028KB) icon1698 icon13
Abstract:
Temperature field on flow and heat transfer process for composite nozzle was simulated based on fluid-structure coupled method.While the interface program of computational fluid dynamics (CFD) and finite element method (FEM) were complied,the temperature load and mechanical data transfer was realized rapidly.Then a strategy of thermo-structure coupled computation for composite nozzle was put forward.Direct constraint procedure solved the boundary nonlinear problem caused by carbonization of component interfaces under high temperature.The results show that temperature field computation by coupled method is reasonable and the boundary nonlinear problem has strong influence on the deformation character and stress fields.
Simulation of lubricating system for control momentum gyroscopes in spacecraft
SHENG Ming-wei, CHEN Wei-shan, LIU Jun-kao, SHI Sheng-jun
2011, 26(1): 228-233.
Abstract PDF(1033KB) icon1843 icon13
Abstract:
To obtain a longer longevity of control momentum gyroscopes in spacecraft,a positive-feed on-demand lubricating system was proposed.The system consists of an oil container and a piezoelectric lubricating device based on drop on demand technology.To solve the interface movements with continuing topology changes during the ejection process,volume-of-fluid method along with the piecewise linear interface construction technique was implemented to describe the interfacial movements.A computational approach based on VOF(volume of fluid) method was applied to analyze the ejection process of lubricating oil droplet.In simulations,the ejection process of lubricating oil was examined by varying diameter of nozzle and temperature in the aerospace.The experimental results show that it is difficult to form droplet with larger nozzle,and the variety of space temperature has impact on the lubricating oil droplet velocity,but little effect on the formation time.
Design of the IP soft core of JTAG controller for electronic engine controller
YANG Sheng-kui, ZHANG Tian-hong, DENG Zhi-wei
2011, 26(1): 234-240.
Abstract PDF(1022KB) icon1637 icon18
Abstract:
It is feasible to realize on-line test by designing an intellectual property (IP) soft core of JTAG (joint test action group) controller which is based on filed-programmable gate array (FPGA).Through analyzing the state machine of test access port (TAP) controller and the principle of some application specific integrated circuit (ASIC) for boundary scan controller,the IP soft core of JTAG controller was designed for digital signal process (DSP) which was used in an electronic engine controller (EEC).Meanwhile the hardware of testing and verification system for boundary scan was designed,and the tests of main instructions were completed.This IP soft core,which can be used in many fields such as scan test and fault injection,can load the scan vector flexibly to realize on-line test.

Copyright © 《Journal of Aerospace Power》 All Rights Reserved.

Supported by: Beijing Renhe Information Technology Co., Ltd.