2008 Vol. 23, No. 4

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DNS of incompressible turbulent reacting flows and validation of the RANS turbulence-chemistry model
WANG Fang, ZHOU Li-xing, XU Chun-xiao, HUANG Yong
2008, 23(4): 585-590.
Abstract PDF(1213KB) icon1695 icon515
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The direct numerical simulation(DNS) of well-developed three-dimensional incompressible turbulent reacting channel flows was carried out by using a spectral method.The instantaneous turbulence fluctuation database with the coupling of temperature and mass fraction was gained.The instantaneous results show that both the temperature fluctuation and the mass fraction fluctuation have strip structures in the near wall region.Exact transport equations of the correlations for the second order moment reaction model in the Reynolds averaged Navier-Stokes equations(RANS-SOM) are deducted.As for the correction of the reaction rate coefficient and mass fraction,the dissipation term is key to model closure,and consideration of reaction for the dissipation term of the model equation is necessary.Based on the statistical results of the DNSdatabase,a priori study on the budget of each term in the RANS-SOMmodel correlations transport equations was carried out.It is found that the contributions from the production and dissipation terms are most important,whereas the contributions from the diffusion and reaction terms are rather small.The chemical reaction has obvious influence on the magnitude and distribution of all the terms.Moreover,in the studied cases in this paper,the correlation of reaction rate coefficient and mass fraction which is obtained by DNSdatabase statistical results is close to the value obtained by the algebra second order moment(ASOM) model prediction,affirming reasonableness of ASOMmodel.
Numerical simulation of flowfield and infrared characteristics of an aeroengine exhaust system and its plume
LIU You-Hong, SHAO Wan-ren, ZHANG Jin-xiu
2008, 23(4): 591-597.
Abstract PDF(1408KB) icon1697 icon510
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The flow field of an aeroengine exhaust system including its inner space and outer space was calculated using the Navier-Stokes equations.And then the infrared calculation model of the aeroengine exhaust system and its plume using integration method of the radiative transfer equation(RTE) were established.The corresponding FORTRANprograms for the infrared radiation calculation were written,which can simulate two cases if the after burner is on or not.If the after burner is on the soot absorption and its radiation must be considered except for the gas media radiation of the water stream,the carbon dioxide,the carbon monoxide and the nitrogen monoxide.This paper finally gives the simulated results of the infrared characteristics in the wave of 3～5 μm in the flying condition of high altitude.
Study on the physics of film-cooling effectiveness enhancement by the converging-expanding hole
LIU Cun-liang, ZHU Hui-ren, BAI Jiang-tao
2008, 23(4): 598-604.
Abstract PDF(1288KB) icon2009 icon462
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Numerical simulation was carried out to investigate the flow fields for three types of shaped hole,namely,cylindrical hole,fan-shaped hole and converging-expanding hole,to reveal how the converging-expanding hole enhance the cooling effectiveness.Realizable k-ε turbulence model with enhanced wall function was used.Results show that the jet from cylindrical hole produces strong streamwise coupling vortices due to its strong and concentrated normal momentum.The fan-shaped hole improves the cooling effectiveness by weakening the jet's normal momentum and the coupling vortices.The converging-expanding hole reduces flow separation in the hole and produces a jet with small streamwise thickness and large lateral width as well as large lateral velocity magnitude.These factors make its coupling vortices have an effect to push the jet to the wall,producing the best coverage and the best cooling effectiveness.The average cooling effectiveness of converging-expanding hole is larger than cylindrical hole's and fan-shaped hole's by about 110%and 15%respectively(M=0.5),or 560%and 60%(M=2).
Effect of turbulent combustion model on simulation of hydrogen supersonic combustion
YANG Yang, XING Jian-wen, LE Jia-ling, WANG Jin-nuo
2008, 23(4): 605-610.
Abstract PDF(2096KB) icon1800 icon505
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The equilibrium chemistry model using assumed probability density function(PDF) and the flamelet model were adopted to numerically simulate the reactive flow filed of the supersonic combustor of The Geman Aerospace Center.The calculated results were compared with those of the finite-rate chemistry model and the experiments.Finite volume method was used to discretize Favre-averaged Navier-Stokes equations,and κ-ε turbulence model was employed.The results show:(1)the finite-rate chemistry model and the equilibrium chemistry model using assumed PDFcannot capture fine structures of near-field and far-field from the hydrogen injector,respectively,while the flamelet model can predict the flow field well,and computation time of the latter two models is saved about 38% over that of the finite-rate chemistry model;(2) the interaction between turbulence and chemistry in the reactive flow filed of the supersonic combustor should not be ignored,and the flamelet model may have a bright prospect in engineering practices in terms of efficiency and accuracy.
Numerical investigation on the effect of different transverse trench configurations on film cooling effectiveness
ZHANG Da-hai, CHEN Qiu-yang, ZENG Min, LUO Lai-qin, ZHANG Dong-jie, WANG Qiu-wang
2008, 23(4): 611-616.
Abstract PDF(1252KB) icon1880 icon394
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The flow fields and cooling effectiveness of the film cooling from a row of cylindrical angled holes embedded in different transverse slots configurations were investigated numerically in several blowing ratios,to reveal the effects of narrow trench,wide trench,and inclined trench with the same trench depth on the film cooling performance from the flowing mechanism.The simulation results of inclined trench model were compared with experimental data of shaped holes.It is found that,for the embedded holes,the jet injected into the slot loses momentum at the exit of the slot;the penetration of the film secondary flow into the cross flow is suppressed and the secondary flow is pushed downwards on to the surface,resulting in better coverage.At low blowing ratio,the inclined trench has superior cooling effect,while at high blowing ratio the narrow trench has superior cooling effect.Alateral vortex appears in the wide trench;a pair of taper vortex appear in the narrow trench;and a pair of counter rotating vortex appear in the inclined trench.The trailing edge wall of the trench plays an important role in the lateral diffusion of the cooling film.
Optimization of compact heat exchanger based on 3D distributed-parameter model
ZHANG Li-na, YANG Chun-xin
2008, 23(4): 617-622.
Abstract PDF(1076KB) icon1677 icon433
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With the mesh generation method based on fin passages and element control equation,a new three-dimensional distributed-parameter model for compact heat exchangers was developed.On the basis of this model and the principle of minimum entropy generation,an optimization methodology was realized with genetic algorithm(GA),by which the geometry dimension of the heat exchanger and the fin surface type and sizing can be optimized simultaneously.The distributed-parameter model which takes account of the variation of local fluid physical properties in the heat exchanger can be applied to wet conditions or phase-change conditions.Moreover,because it avoids the complexity of CFDmethod and shortens the computer execution time greatly,the optimization based on distributed-parameter model is very practical.This optimization methodology can be extended to other kinds of heat exchangers and heat sinks.
Analysis of the effects of temperature distribution on stress level in a rotating disk
FU De-bin, DING Shui-ting, TAO Zhi, DU Fa-rong, XU Guo-qiang, WU Hong-wei
2008, 23(4): 623-628.
Abstract PDF(930KB) icon1823 icon471
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The effects of temperature distribution on stress level in a rotating disk at a fixed flux of cooling air was numerically studied using coupled thermal-elastic method based on the finite element technique.The rotating speed is fixed at 6000 r/min,and the temperatures of inner rim and outer rim are 600 ℃ and 650 ℃,respectively.Detailed information of stress level change with surface temperature distribution of rotating disk was discussed.Numerical results reveal that there exists a strong relation between the surface temperature distribution of rotating disk and stress level inside the rotating disk.The V-shape temperature distribution can significantly reduce the stress level.
Numerical simulation on the temperature field of a helicopter accessory cabin
XIE Yong-qi, YU Jian-zu, WANG Xian-wei, LI De-qiang
2008, 23(4): 629-634.
Abstract PDF(880KB) icon1535 icon443
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In order to test the thermal control ability of a helicopter accessory cabin with forced ventilation cooling and free cooling,the temperature field was analyzed based on the finite element software.Unstructured grid and finite volume method were applied for region and governing equation discreteness,and standard k-ε model was used as turbulent model.The influence on temperature distribution by changing size and position of cooling air inlet as well as heat dissipating capacity from accessories was discussed for 3 cooling schemes.And the temperature field was calculated for the close cabin under free cooling.The calculation and test results show that the forced cooling scheme can meet the cooling requirements.
Wall temperature calculation on an axi-symmtrical converging-diverging nozzle considering heat conduction,convection and radiation
LIU You-Hong, LI Jiang-Ning, CAI Juan
2008, 23(4): 635-641.
Abstract PDF(2301KB) icon1928 icon497
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The flow field and the wall temperature distribution calculation models on a converging-diverging nozzle considering the heat conduction,heat convection and radiation heat transfer are established and computed.The flow field is governed by the Navier-Stokes equations and the equations are solved based on the density solver.The wall temperature distribution calculation model is based on the heat transfer mechanism and the heat flux equilibrium.And the corresponding FORTRANprograms for the three layer wall temperature calculation of the nozzle are written.Many flight cases are calculated in which the properties of the burning gas mixture are calculated by a series of formulas and methods considering them varied with the pressure,the temperature and the ratio of oil to air.The results show that the heat shield temperature and the converging-diverging nozzle cylindrical wall temperature increase along the flow direction and decrease in the expand segment of the nozzle.The maximum wall temperature happens around the nozzle throat position.The outer adjustment plate temperature outside of the nozzle cylinder reaches its maximum some little before the nozzle throat position.The best agreement between the calculation and the given data can be observed in the paper.
Numerical study on the flow and heat transfer characteristics of coupled synthetic jets
TAN Xiao-ming, ZHANG Jing-zhou
2008, 23(4): 642-646.
Abstract PDF(1325KB) icon1703 icon428
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Numerical study on the flow and heat transfer characteristics of coupled synthetic jets was carried out.The results show that: Near the slot exit,three synthetic jets couple to one jet and move downstream.Two synthetic jets on both sides are limited and rolled by the middle synthetic jet until they merge together into one centrosymmetric synthetic jet.The synthetic jet spreads rapidly along the minor axis direction of the orifice with bigger spread-angle;while along the major axis direction,the synthetic jet contracts firstly and then spreads slowly.At the target surface impinged by the synthetic jet,the temperature field is symmetric with the lowest filed in center.The heat transfer coefficients also take on the same trends with centrosymmetric waves,which means that the best cooled area is the stagnation.The distribution of heat transfer coefficients along different directions of the target surface is basically uniform.
Influence of aerodynamic parameter on the temperature gradient and cooling efficiency for effusion wall cooling method
XU Quan-hong, XU Jian, LIN Yu-zhen, LIU Gao-en
2008, 23(4): 647-650.
Abstract PDF(555KB) icon1592 icon468
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As one of the most important factors influencing the combustor life-span,the temperature gradient of the effusion wall,as well as the cooling efficiency were investigated experimentally under the guidance of similarity theory.The effects of the temperature ratio of the main flow to the cooling air,the speed ratio of the cooling air to the main flow and the speed of the main flow were analyzed and discussed.IRthermograph was used to perform local measurements of the surface temperature field.The results reveal that these parameters which are investigated in this paper have strong influence on the temperature gradient and the cooling efficiency.
Numerical simulation of infrared radiation characteristics for exhaust system of an UAV with engine installed on the back of the fuselage
SHI Xiao-juan, JI Hong-hu, LUO Ming-dong
2008, 23(4): 651-656.
Abstract PDF(1466KB) icon1928 icon527
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Anumerical study was conducted on infrared radiation characteristics in the waveband of 3～5 μm for exhaust system of an unmanned aerial vehicle(UAV) with engine installed on the back of its fuselage.The flow field of the exhaust jet was calculated with commercial software FLUENT.The infrared radiation characteristics were calculated by using the software developed by the authors based on discrete transfer method.In the computation,multiple effects were considered,which included the emission and reflection of the nozzle wall,the absorption and emission of species of combustion gas,e.g.CO2,H2O and CO,the shelter of fuselage,and the absorption of atmosphere.The results show that by installing the engine on the back of the fuselage,sheltering the nozzle from its underside and forward shifting the nozzle exit relative to the aft-fuselage,the infrared radiation of the exhaust system to under hemisphere is reduced evidently,but on the other side the infrared radiation to the top hemisphere is increased;and the absorption effect of atmosphere on infrared radiation for the front hemisphere is stronger than that for the aft hemisphere.
Experimental Investigation of the cooling performance of lamilloy using infrared thermal imaging technique
MA Long, WANG Jian-hua, WU Xiang-yu, DU Zhi-neng
2008, 23(4): 657-661.
Abstract PDF(826KB) icon1682 icon493
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To investigate the cooling performance of laminated configuration,an infrared thermal imaging technique was used in the experiments with true size configuration.The diameters of film hole,columniation and impingement hole were 0.5,0.8 and 0.8mm respectively,the chamber height and total thickness of the configuration were 0.8 and 2.6mm respectively,the ratio of the hole and culmination was 1∶4∶1.To measure surface temperature exactly,a thermocouple with high accuracy was used,and a correction relationship was established.To describe the integral cooling effect,an algorithm of thermal imaging signal was used for processing image digital signal.The experiments were carried out at a hot gas wind tunnel,and the results present the influence of coolant injection rate on the cooling performance of the laminated configuration.It is demonstrated that the infrared thermal imaging technique is effective method to study cooling performance of laminated configurations.
An experimental investigation of rotating stall margin improvement with unsteady casing treatments
SUN Da-kun, HOU Rui-wei, SUN Xiao-feng
2008, 23(4): 662-670.
Abstract PDF(1384KB) icon2214 icon507
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Casing treatments are widely used to enhance the stall margin of fans or compressors of aircraft engines.However,the existing design of casing treatment is generally on the basis of trial and error method and its application always results in efficiency loss of fans or compressors.So,how to understand the mechanism of stall margin improvement with casing treatments and how to design better casing treatments have long been an area of vigorous research activity.Based on the knowledge of the unsteady characteristics caused by casing treatment,it is verified that recessed casing treatment can be modeled as a wall boundary condition,which can be calculated by means of vortex sound theory.In the present work, a series of experimental investigations were conducted with emphasis on the effect of unsteady casing treatments on the stall margin and efficiency of three different low speed fan/compressor facilities.The results show that the unsteady casing treatments do improve the stall margin without incurring recognizable efficiency loss of the concerned fan/compressor.
An experimental study on inhibition of unsteady casing treatment on stall inception
SUN Da-kun, SUN Xiao-feng
2008, 23(4): 671-679.
Abstract PDF(2142KB) icon1768 icon516
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A kind of unsteady casing treatment was used to enhance the stall margin of an axial flow fan,which did not result in any recognizable efficiency loss.So,it is quite important to understand the mechanism of stall margin improvement with such casing treatment.The present investigation firstly developed a technical method for measuring and analyzing the inception wave,and then made some detailed comparisons with the existing results.The experimental results show that the unsteady casing treatment will delay the non-liner development of stall process by suppressing the propagation of inception wave in comparison to the evolution of the inception wave without casing treatments,while the inception point will not be changed with the application of the unsteady casing treatment.
Further verification of nonlinear harmonic method
ZHAO Jun, LIU Bao-jie
2008, 23(4): 680-686.
Abstract PDF(2610KB) icon1805 icon425
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A two-dimensional steady,unsteady and nonlinear harmonic method(NHM) RANScode was developed based on Denton steady code.Then the code was used to simulate a two-dimensional transonic compressor cascade by the above three methods and the results were compared on deterministic stress fields,blade surface velocity and other aspects.The comparison indicates that NHMpresents high precision on modeling deterministic stresses and mixing-plane treating plays an important role in the simulations.The shortcomings of NHMwere also discussed,including main unconquerable origins of modeling error and long computational time.
Investigation of off design performance of a transonic compressor with circumferential grooves
ZHU Jian-hong, PIAO Ying, ZHOU Jian-xing, QI Xing-ming
2008, 23(4): 687-692.
Abstract PDF(1102KB) icon1693 icon431
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A case with circumferential grooves was designed for a transonic compressor.And 3-D numerical simulations were carried out for stall mechanism in three operative modes at representative speed.Comparison study between compressors with and without casing treatment shows that: with the rotation speed rising,stall margin gain increases dramatically under the help of casing treatments;and the case with middle grooves has better compromise between stall margin and efficiency.Under low speed,the gain reduces,and the last grooves on the chord of blade tip have greater influence on the stall boundary.Further investigation shows that there is a translation in the mechanism of compressor stall when its speed reduces: the stall margin gain mainly results from suppression of tip leakage vortex by casing treatments under high rotation speed;whereas under low rotation speed,the gain benefits more from reduction of the boundary layer separation on suction side of blade tip.
Analysis of stall in vaneless diffuser based on wavelet neural network
GAO Chuang, GU Chuan-gang, WANG Tong, SHU Xin-wei
2008, 23(4): 693-698.
Abstract PDF(646KB) icon1529 icon431
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Wavelet neural network(WNN) was trained with experimental data collected from a variety of literature and then was utilized to study influences of geometries of impeller and diffuser on rotating stall in vaneless diffuser,and the results were presented in graphs.Results show that diffusers with different width ratios exhibit distinct responses to geometry variation,proving that different stall mechanisms exist for wide diffuser and narrow diffuser.The conclusions provide reference to the design of vaneless diffuser.
Effects of the forebody boundary layer state on flow structure and performance of hypersonic inlets
CAI Qiao-yan, TAN Hui-jun
2008, 23(4): 699-705.
Abstract PDF(1472KB) icon1856 icon512
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Influences of the forebody boundary layer state on shock pattern,characteristics of shock/boundary-layer interaction,mass capture capability and total pressure recovery of axisymmetric hypersonic inlet were studied with the aids of CFD.The performance trend in accordance with the forced transition position was obtained at different Mach numbers.As a forced transition device,two-dimensional roughness was introduced to examine the disturbance it made to the flow field.Differences between specific inlet design schemes were also compared in the study.
Mathematical model and snatch force prediction for the lines-first parachute deployment
XU Hong, CAO Yi-hua, LI Dong
2008, 23(4): 706-711.
Abstract PDF(664KB) icon1793 icon447
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Prediction method for the lines-first parachute unfurling process was provided, in which the viscoelasticity of suspension lines was taken into consideration.The fundamental equation of the mathematical model of parachute unfurling process was formulated.The effect of viscosity term in fundamental equation on spreading of tensile wave along suspension lines was emphatically analyzed.The viscoelastic tensile wave not only causes delay of tension spreading from the canopy sleeve end to the other end,but also makes the tension at the two ends different due to absorption and dispersion during the parachute unfurling process.The present model was used to calculate unfurling loads and motions of a parachute deployment.The dynamic change of snatch force was analyzed and it shows that the max snatch force borne on the load end is related not only to max tension produced at the moment when the parachute skirt being drawn out,but also to the load tension produced after skirt is drawn out.
Error correction for cylinder probes measuring the flow with velocity gradient
WANG Hong-wei, FANG Jian, WANG Zhi
2008, 23(4): 712-717.
Abstract PDF(881KB) icon1700 icon403
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Cylinder pressure probes deliver biased data in measuring flow with transverse velocity gradient.Numerical and experimental simulations were contrived to investigate this error.The results show that the effect of velocity gradient is to introduce an angle bias and make the measured velocity magnitude greater.Correlations between the angle bias and velocity gradient were deduced from the numerical simulation and were verified in the experiment.The correlations were used for the measurement result in a cascade experiment and improvement was achieved.
Analysis on thermodynamic performance of partially-fueled pulse detonation engine
QIU Hua, YAN Chuan-jun, FAN Wei
2008, 23(4): 718-723.
Abstract PDF(763KB) icon1855 icon462
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Ideal partially-fueled detonation cycle model was established based on FicketJacobs cycle.It is shown that partial fuel filling will cause decrease of total thermal efficiency,which means that this work mode is not adequate to the application of detonation for power output.However,as energy exchange between combustion products and purge gas occurs during the expansion of the detonation products under this mode,it can be used to enhance the propulsive efficiency of PDE.
Experimental and numerical simulation of atomization of liquid jet in supersonic crossflow
LIU Jing, WANG Liao, ZHANG Jia, WEI Bao-xi, XU Xu
2008, 23(4): 724-729.
Abstract PDF(928KB) icon1773 icon531
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The liquid jet atomization in supersonic crossflow was investigated experimentally in a supersonic wind tunnel and the present experiment was numerically simulated.The Mach number of the supersonic flow was 2 and dynamic pressure ratio varied from 1.6 to 11.7,and water was used as test liquid.Schlieren method was used to study the structure of liquid jet in supersonic flow field and the correlation for penetration height was developed.Numerical simulation used EulerianLagrangian method to describe the two-phase flow.Anew hybrid K-H(Kelvin-Helmholtz) and R-T(Rayleigh-Taylor) atomization model was used to describe the atomization process.
Studying for low-cycle fatigue fractal damage evolution on TC11 Ti alloy welded joint
WU Qi, QIU Hui-qing, GUO Hai-ding
2008, 23(4): 730-736.
Abstract PDF(1350KB) icon2030 icon469
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Based on damage mechanics and fractal theory,a damage evolution equation of welded joints is built up which it involves surface factal characteristics of fatigue fracture suface based on statistical self-similarity of surface profiler of fatigue fracture surface.Two dimensional fractal dimension and Parameters in damage evolution equations of fracture surface in Titanium alloy Ti-6.5Al-3.5Mo1.5Zr-0.3Si(TC11) is obtained according to the related experimental data.So damage evolution equations of low-cycle fatigue life under three levels loads in TC11 is established and these models are compared with damage evolution equations abased on line fractal charactertistic in fracture surface.
A integral parameter-based modeling method for 3D crack
TANG Jun-xing, LU Shan
2008, 23(4): 737-741.
Abstract PDF(960KB) icon1843 icon452
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Aparameter-based and geometry independent general method was developed for the simulation of 3Dplanar crack propagation by using finite element method(FEM). This method,on the basis of introducing a crack model containing whole crack surfaces,has a capability of creating cracked block automatically and simulating crack propagation in a multiple degree way.The accuracy,efficiency and versatility of the method were demonstrated by comparison with other analytical or experimental results available in the literature.
Investigation on probabilistic model for fatigue-creep failure of alloy GH30
HU Dian-yin, WANG Rong-qiao, HONG Jie, LI Qi-han
2008, 23(4): 742-746.
Abstract PDF(843KB) icon1733 icon433
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Aprobabilistic model for fatigue-creep reliability analysis was studied based on the deterministic fatigue-creep failure function,and the corresponding approach was proposed.Fatigue-creep failure function of alloy GH30 at 600 ℃ was established by using the experimental results under continuous cyclic creep.With consideration of random variables,probabilistic analysis for fatigue-creep of alloy GH30 was performed.The calculations show that random variables do great contributions to the failure probability.Furthermore,the effect of different variables on failure probability can be revealed through the sensitivity analysis,helping to improve the components' life.
An investigation of flow induced blade vibrations at the transonic operating condition
LI Run-ze, LI Lin
2008, 23(4): 747-753.
Abstract PDF(1192KB) icon1478 icon397
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The unsteady flow field of the same transonic fan at both transonic and subsonic operating conditions was simulated numerically.The periodic unsteady aerodynamic forces of the flow field at both transonic and subsonic operating conditions were analyzed by Fourier Transform Algorithm,and then compared to obtain the unsteady aerodynamic characteristics at tansonic operating condition.The forced response of the rotor blade was analyzed with ANSYSby using the method of transient response analysis.The forced response of the rotor blade between transonic and subsonic operating conditions was analyzed comparatively to find out the characteristics of the forced response.
The design of tooth face width of the face-gear drives with helical pinion
SHEN Yun-bo, FANG Zong-de, ZHAO Ning, GUO Hui
2008, 23(4): 754-758.
Abstract PDF(1568KB) icon1830 icon441
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A voidance of undercutting or pointing in the toe and heel of the face-gear drives with helical pinion was mainly discussed in the paper.The expressions of inner radius and outer radius able to prevent undercutting or pointing under arbitrary shaft angle that formed by shaper and face-gear were also presented.Anew method was developed for solution of critical point of undercutting on the shaper tooth surface.Three unitless coefficients of inner radius,outside radius and tooth width were defined.The results show that these three coefficients depend on the magnitude of helix angle of the shaper and the number of teeth of spur helical pinion.
Study on a new shape-curve of finger seal with low-hysteresis and low-wear
LI Er-sheng, CHEN Guo-ding
2008, 23(4): 759-764.
Abstract PDF(800KB) icon1668 icon392
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Considering the present unsolved problem of improving hysteresis and wear in multi-objective optimization of finger seal,Stackelberg theory is introduced to construct finger seal mathematical model with hysteresis and wear characteristics by treating curve as elements to be optimized.With the lead-follow Stackelberg game mechanism,the controllable optimization of finger seal characteristics is performed based on genetic algorithm combined with backward propagation(BP) network and finite element analysis(FEA) methods.Then the finger seal of up-concave curve with low hysteresis and wear characteristics is obtained.Finally,the FEAsimulation reasonably explains to reason that this type of finger seal has the better characteristics and also show its future in engineering field.
Design of robust adaptive trajectory linearization controller for aerospace vehicles based on RBFNN
XUE Ya-li, JIANG Chang-sheng, ZHU Liang
2008, 23(4): 765-770.
Abstract PDF(1884KB) icon1671 icon432
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This paper presents a novel robust adaptive trajectory linearization control(TLC) method based on radial basic function neural network(RBFNN) and introduces its application to an aero-space vehicle(ASV) flight control system.Firstly,the TLCcontroller was designed based on an analytical model of the control plant.Secondly,RBFNNwas utilized to approximate the system's uncertainties,and based on which,a robust adaptive controller as well as an adaptive law were designed.Then,Lyapunov's direct method was used,and a rigorous poof was demonstrated in order to guarantee the ultimate boundedness of all the signals in the closed loop system of the provided method.Finally,the proposed method was applied to the flight control system design of ASV,and its effectiveness was verified by simulation results.
Effects of gap between nozzles on plug heat transfer characteristics
HAN Fei, LIU Yu
2008, 23(4): 771-776.
Abstract PDF(1213KB) icon1643 icon416
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To understand the effects of gap between nozzles on plug heat transfer characteristics,three dimension computational models of plug nozzle were established and studied numerically.Heat transfer characteristics of plug with different ambient pressure and different coolant flow rate were investigated.The results of coolant heat pick-up and pressure loss,wall temperature,pressure and heat flux distribution were obtained,especially the effects of gap between nozzles on plug heat transfer characteristics.The results show that: due to the effect of gap between nozzles,the distribution of pressure,heat flux and temperature along the width of plug is different.With decrease of ambient pressure,this effect becomes weaker.

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