2011 Vol. 26, No. 7

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Review of probabilistic risk assessment on aero-engine airworthiness
DING Shui-ting, ZHANG Gong, YU Duo-kui, ZHOU Yan-pei
2011, 26(7): 1441-1451.
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In order to meet the urgent needs of developing large commercial aero-engines which satisfies the airworthiness requirments, the fundamental methodology and development progress of probabilistic risk assessment (PRA) of life limited parts in recent years were discussed. The PRA technologies, including their processes and characteristics, were described to show their compliance with the life-limited parts requirements set forth in section 33.70 of federal aviation regulations (FAR). Moreover, the core methodology and basic database structure of PRA were analyzed. It indicates that the PRA methodology should be established on the basis of combining the probabilistic fracture mechanism with accurate databases.
Influence of blowing ratio on film cooling of rotating turbine blade
DENG Hong-wu, XIAO Jun, LI Guo-qing, XUE Hang
2011, 26(7): 1452-1457.
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Experimental investigations were carried out to study the rotating film cooling characteristics at different blowing ratios in a 1.5-turbine stage.The mainstream Reynolds number Reg is 1.6451×105 in the experiment.CO2 acts as a coolant with mainstream jet density ratio of 1.57.Turbine speed is 475r/min,and the rotation number is 1.901.The blowing ratio varies from 0.5 to 2.0.By using steady-state liquid crystal method,the results show that: (1) On pressure side,the film cooling efficiency and the film coverage increase,the deflection angle of film trajectory decreases with the increasing blowing ratio. (2) On suction side,the film cooling efficiency and the film coverage first increase and then decrease,the film trajectory has no obvious deflection angle with the increasing blowing ratio. (3) The curvature radius of jet flow affects the adhesion of film on the wall.
Influence of orientation angles of branch hole on film cooling effectiveness with one inlet and double outlet hole injection
LI Guang-chao, WU Dong, ZHANG Wei, BAI Shu-sheng
2011, 26(7): 1458-1464.
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In order to investigate the influence of orientation angles of branch hole on film cooling effectiveness with one inlet and double outlet hole injection, the film cooling effectiveness was simulated by commercial code using the finite volume method, on the condition that the orientation angles of branch hole were 30°, 45°, 60° and 90° respectively, the blowing ratios varied from 0.5 to 2.0 . The flow field, the film cooling effectiveness and the spanwise averaged film cooling effectiveness were investigated. The results show that the film cooling effectiveness with one inlet and double outlet hole injection has been improved as compared to that of the cylindrical hole injection. The optimized branch hole angle is 45°, higher by 300% than the film cooling effectiveness of the cylindrical hole injection. The orientation angles of branch hole have an increasing influence on the film cooling effectiveness with the increase of blowing ratios.
Numerical simulation of ice accretions on multi-element airfoils
ZHANG Qiang, GAO Zheng-hong, FU Lin
2011, 26(7): 1465-1470.
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A numerical method based on unstructured grids was proposed to simulate ice accretions on multi-element airfoils. The air flowfield was solved using the Euler equations. Based on air velocity distribution, the governing equations for droplets were solved using an iterative method to obtain the collection efficiency. The different freezing models corresponding to the rime and glaze ice were employed to simulate the freezing process. The process of ice accretions was simulated with the assumption that ice accumulates layer-by-layer, and the ice shape was built with the assumption that ice grows in the direction normal to the airfoil surface. The rime and glaze ice accretions on a typical three-element airfoil were investigated. According to the flowfield around the airfoil, a method of computing the freezing model for glaze ice was presented. The effects of ice accretions on performance of the multi-element airfoil were also analyzed.
Flamelet modeling of two-phase kerosene combustion flow fields using a detailed chemical reaction mechanism
WANG Hui-ru, JIN Jie, LIU Yang
2011, 26(7): 1471-1479.
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Two-phase combustion flow fields in a model combustor were numerically simulated using realizable k-ε turbulent model,particles stochastic trajectory model,flamelet models and the detailed chemical reaction mechanism of aviation kerosene.The detailed reaction mechanism was assembled using the combustion mechanism of surrogate fuel (80% decane and 20% 1,2,4-trimethylbenzene by mass fraction) and NOx formation mechanism.The accuracy of flamelet modeling of RP-3 kerosene combustion flow fields (especially for NO emissions) employing the detailed reaction mechanism was investigated by comparison with the experimental data.The result shows that the temperature and CO2 concentrations predicted using the steady flamelet model are in good agreement with the experimental data,but the NO emissions have a bigger deviation.The use of unsteady flamelet model significantly improves the prediction accuracy of NO concentrations and shows good agreement with the experimental data in condition 1 (inlet Mach number 0.16,inlet temperature 537K,fuel-air ratio 0.0048,atmospheric pressure),but NO emissions are overpredicted in condition 2(inlet Mach number 0.155,inlet temperature 523K,fuel-air ratio 0.010,atmospheric pressure).
Three-dimensional numerical study of supercritical pressure effect on heat transfer of cryogenic methane
RUAN Bo
2011, 26(7): 1480-1487.
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A three-dimensional numerical study of the turbulent convective heat transfer of the cryogenic methane flowing inside a square engine cooling channel under supercritical pressures was systematically conducted. Numerical results indicate that increasing the fluid pressure results in enhanced heat transfer of the cryogenic methane under supercritical pressures. At the pseudo-critical temperature under a corresponding supercritical pressure, drastic property variations cause heat transfer deterioration and sharp wall temperature increase at a high wall heat flux of 7MW/m2. A modified Jackson and Hall heat transfer equation, which can be used for supercritical heat transfer calculations of the cryogenic methane, has been successfully established in this paper.
Numerical simulation and experimental study on flame acceleration and deflagration to detonation transition
QIN Ya-xin, GAO Ge
2011, 26(7): 1488-1494.
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Numerical simulations and experimental study in a detonation duct with orifice plates were carried out to study the phenomena of flame acceleration and the evolutions of deflagration to detonation transition (DDT) and unstable detonation to stable detonation.The results of numerical simulation show that laminar flame is generated by low energy ignition in detonation duct.The laminar flame becomes turbulent flame in the obstruction of orifice plate and under the acceleration action of shock waves and reflected waves.The turbulent flame is strengthened mutually with its induced shock waves.After a few orifice plates,"hot spots" appear between the flame and the sharp shock wave,and then detonate the unburned mixture.Triple-point is formed in the evolution of weak detonation to stable detonation when detonation wave meets orifice plates.The evolution of Mach-pole to incident wave transition was also analyzed.The detonation initiation distances at different equivalence ratios were studied contrastively.Through calculation and analysis,deep understanding of flame acceleration and DDT were obtained,providing useful information for further experiment.
Heat transfer measurements of turn-over channel in turbine blade
WANG Xiao-zeng, ZHANG Li, ZHU Hui-ren, LIANG Wei-ying
2011, 26(7): 1495-1501.
Abstract PDF(1187KB) icon3203 icon38
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An experiment was performed on a facility with ribbed turn-over channel built based on the inner structure of the real turbine blade.A transient liquid crystal was used to measure the heat transfer coefficients of three channels in turbine blade.The influences of Reynolds number and different outlet discharge ratios on the heat transfer of the ribbed walls were studied on the premise that the channel area changes continually.The experiment results show that:the average Nusselt number for the channel increases with the inlet Reynolds number when the outlets discharge ratio is fixed.With the fixed inlet Reynolds number,the average heat transfer of the channel is best when three outlet discharge ratios are 0%,75% and 25%,respectively.Also,the ribs in the corners can significantly enhance the heat transfer.
Numerical study on aerodynamic and infrared radiation characteristics of single expansion ramp nozzle
ZHANG Shao-li, SHAN Yong, ZHANG Jing-zhou
2011, 26(7): 1502-1508.
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Based on computational fluid dynamics/infrared radiation (CFD/IR) numerical calculations,the effects of different structures and nozzle pressure ratio (NPR) on the aerodynamic and infrared radiation characteristics were revealed for a single expansion ramp nozzle (SERN).The results show that:with increase of ramp angle,the thrust-vector angle is enlarged and axial thrust coefficient is decreased rapidly;with increase of nozzle pressure ratio,the axial thrust coefficient increases firstly and then decreases,meantime,the thrust-vector angle reduces;as the length of sidewall increases,axial thrust coefficient improves slightly.The ramp of nozzle can significantly shield the infrared radiation of plume and inner-wall of nozzle.The radiation detected from underside of nozzle is only 10% of that from upside of nozzle.With increase of nozzle pressure ratio,the infrared radiation from underside of nozzle is reduced.
Numerical study on the combustion characteristics of afterburner with chevron mixer
WANG Ya-meng, ZHANG Jing-zhou, SHAN Yong, GAO Jia-chun, XU Xing-ping
2011, 26(7): 1509-1514.
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Based on computational fluid dynamics (CFD),the process of three-dimension and two-phase chemical reaction flow of afterburner with confluent mixer and chevron mixer was simulated with introduction of eddy dissipation (ED) model.The results reveal that the temperature of bypass flow and the oxygen content of core flow are enhanced dramatically by chevron mixer,meanwhile,the combustion efficiency increases by 14.9% compared to confluent mixer under the same fuel supply scheme.
Optimization design of tenon joint structures with an arc contact surface
WEN Wei-dong, XI Zhi-dong, CUI Hai-tao
2011, 26(7): 1515-1521.
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In the foundation of the contact characteristic research for an arc surface to a plane, the structure scheme of the tenon contact surface which is composed of the straight plane and the partial circular arc surface was proposed in this paper. The design results of the scheme were given and compared with that of the contact surface with the typical cylindrical structure. And then, in consideration of the fretting fatigue,the two structure design schemes of tenon contact surface were optimized and analyzed in the selection of minimizing the maximum synthesizing parameter FFD (fretting fatigue damage) and the maximum contact stress respectively as the optimization objective. The results show that minimizing the maximum synthesizing parameter FFD as the optimization objective is better.
Particle swarm optimized Kriging approximate model and its application to reliability analysis
CHEN Zhi-ying, REN Yuan, BAI Guang-chen, GAO Yang
2011, 26(7): 1522-1530.
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Particle swarm optimization (PSO) algorithm was introduced into Kriging modeling process.By taking advantage of PSO's multi-point search ability,the limits of pattern search method's single-point search approach as well as its heavy dependence on the initial guess solution were overcome,so that the optimal correlation parameters in the maximum likelihood sense could be guaranteed under any initial conditions,and the optimal unbiased characteristic for the Kriging prediction could also be assured.A turbine disk low cycle fatigue(LCF)reliability analysis example indicates that the accuracy of the proposed PSO-Kriging in predicting the circumferential strain amplitude of the weakest point is higher than that of neural network on the order of magnitude,i.e.the maximum error decreases from 5.94% to 0.09%,so that it can replace the finite element program in Monte Carlo simulation without sacrificing the accuracy.Meanwhile,the time for PSO-Kriging's modeling and predicting is less than 1/10 consumed by a single finite element run.Due to high-accuracy prediction (the optimal unbiased characteristic assured by PSO) and relative low expense,the proposed PSO-Kriging is valuable for the reliability analysis of real engineering structures.
Bayesian sequential variance test technique based on posterior probability (Ⅰ)
LIU Qi, WANG Nan
2011, 26(7): 1531-1536.
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Based on posterior probability and "small probability event principle",for the Bayesian sequential test on variance in complicated hypothesis conditions,the basic assumptions of Bayesian sequential variance test were presented,the Bayesian sequential variance test (BSVT) model was constructed,the algorithms of solving the critical value of sequential test were designed,and for given censored test number,the judge criteria for hypothesis testing were discussed.At last,the solution and application of BSVT model were illustrated with an example.
Bayesian sequential variance test technique based on posterior probability (Ⅱ)
LIU Qi, WANG Nan
2011, 26(7): 1537-1542.
Abstract PDF(1079KB) icon1647 icon20
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Under the condition of a given theoretical censored test number,it's needed to gain a theoretical largest censored test number and design the experiment for the benefit of the consumers.Based on posterior probability and "small probability event principle" for protecting the customer's profit,the Bayesian sequential variance test (BSVT) model was modified, modified Bayesian sequential variance test (MBSVT) model was constructed,and the algorithms of solving the continuous test region critical value of sequential test were designed.The calculation method of average sample number (ASN) was also given.With an example,the solution and application of MBSVT model were illustrated.
Simulation and experimental investigation of test signal transmission on temperature changing environment
MEN Xiu-hua, LI Shun-ming, YANG Dong
2011, 26(7): 1543-1550.
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The signal transmission theory was applied to circuit network to obtain discrete temperature-time signal transmission model derived by Kirchhoff's law.And then,an iterative algorithm based on voltage and current was proposed,realizing the signal transmission with different temperature change processes.It shows that the amplitude of output signal gradually attenuates with the rise of conductor temperature,by 10% at 300℃.And the amplitude attenuation is more evident due to the coexistence of conductor temperature rise and drop.The corresponding experiment has been conducted,and the results can meet that of proposed model.It provides a new method for improving the accuracy of vibration test signal.
Laser shock peening on vibration fatigue behavior of compressor blade
HE Wei-feng, LI Ying-hong, LI Wei, LI Yu-qin, LI Qi-peng
2011, 26(7): 1551-1556.
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According to the mechanical performance of the 1Cr11Ni2W2MoV stainless steel, the technical parameters of laser shock peening(LSP) were determined. The standard coupons with/without LSP were tested for examining the fatigue performance. It proves that LSP, with the selected parameters, can improve the stainless steel's vibration fatigue life remarkably. From the experiment results of coupons, the vibration fatigue experiment for the compressor blade in one certain aero-engine was designed according to the structure and loads of the blade. The treated zone was designed on the surface where the vibration stress is the most severe. In order to avoid macroscopical deformation, the blades were treated on both sides simultaneously. This confirms that different section parameters after LSP on the blade are within the range of design requests. The vibration fatigue results indicate that the S-N (stress-number of cycles) curve with LSP moves up as compared with that one without LSP. When the max vibratory stress was about 660MPa, the blade fatigue life with LSP was prolonged for 70%. Finally, the reasons were analyzed from the residual compressive stress and micro structure after LSP.
Effects of parameters on blade flutter in turbomachinery
ZHANG Xiao-wei, WANG Yan-rong, XU Ke-ning
2011, 26(7): 1557-1562.
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An aeroelastic stability prediction approach derived from energy method was used to investigate the effects of several parameters on the aeroelastic stability of rotor blades in turbomachinery,and the mechanism of flutter was determined in some details.Taking the first stage compressor rotor of an engine as an example,the aeroelastic analysis was computed under different working conditions for the oscillating cascades with different blade modes.Some parameters,such as mode shape and interblade phase angle,were included to investigate their effects on the flutter in turbomachinery.And the flutter mechanisms were also concluded from the interaction of shock wave on the suction surface and separation area behind shock.The result shows that mode shape and interblade phase angle are key parameters affecting the flutter characteristics,while the shock wave on the suction surface and the separation area behind the shock wave are important factors to induce the blade flutter.
Analysis on bistable response of a disk-rod-fastening rotor
QIAN Zheng-wen, CHENG Li, CHEN Wei, LI Ying-hong
2011, 26(7): 1563-1568.
Abstract PDF(1148KB) icon1959 icon17
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In view of the fault of bistable response appeared in the disk-rod-fastening rotor,the peculiar structure of this kind of rotor was taken into account.By considering the influence of contact effect of discontinuous interfaces on the rotor stiffness,the tie-rod and the contact surface between the wheel disks were equated to a bending resistance spring with nonlinear stiffness.Then the equation of motion of the disk-rod-fastening rotor was established according to this simplification.The vibration characteristics of rotor were calculated by the harmonic balance method with introduction of the predict-correct and homotopy arithmetics.The bistable response behaviors recurred in this simplified model were much closer to the measured results in flight.The study shows that the nonlinear factor of stiffness,resulted from the contact effect of discontinuous interfaces,was a main reason leading to the appearance of bistable response in the disk-rod-fastening rotor.The bistable region can be reduced by the way of adjusting the system parameters to some appropriate values.
Aeroacoustic scattering via the fast scattering method
WANG Tong-qing, ZHANG Li-shuang, YANG Bing, YANG Ming-sui
2011, 26(7): 1569-1574.
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The fast scattering method was developed in this paper, which could be used for predicting the acoustic propagation problems in the varying cross-section ducts with the acoustic liners. The method can handle the complex section relatively easily by using the direct boundary element method. The noise reduction of a real fan with the duct liners was predicted. The influence of the liner impedance and the sound scattering from the moving body was investigated by comparing the results with those given in the literature. The results illustrate that the present method can be used for the design of the duct liner in the engineering.
Statistics and analysis of critical failures of F100 / F110 engine and F-15 / F-16 fighter during operation
LIANG Chun-hua, WANG Zhan-xue, CAO Mao-guo
2011, 26(7): 1575-1582.
Abstract PDF(855KB) icon2423 icon36
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With reference to foreign experience on fighter engine design and development, the critical failures of F-15 and F-16 fighter powered by F100/F110 engine during operation were described based on a great deal of data statistics and analysis. The distribution and respective rules of the failures during operation phases, various components and influential factors were analyzed and concluded. The analysis shows that the failure rate of the engine is high within initial 10 years or 35000 flight hours, then significantly decreases; various engine failures can be exposed during operation, but the failure rate considering the structure integrity is obviously lower than that without considering the structure integrity; the compressor and turbine are main sources of failures; the design, maintenance, support and operation are main influential factors.
Wing optimization of large airplane by adjoint method
WU Wen-hua, TAO Yang, CHEN De-hua, WANG Yuan-jing, HUANG Yong
2011, 26(7): 1583-1589.
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The optimization software was developed to improve the performance of the wing of large airplane.This software include the three main techniques:the aerodynamic configuration parameterization and grid update technique based on Bezier-Bernstein curve parameterization method;the flow solver and adjoint solver based on three-dimensional (3-D) Reynolds averaged Navier-Stokes equations;the optimization method based on sequential quadratic programming algorithm.This paper did series optimization for a wing with many design variables and different constraints and get some excellent results,The analysis to the result shows the optimization method is reliable and efficient.
Performance simulation of large civil aircraft auxiliary power unit
ZHAO Yun-sheng, HU Jun, WU Tie-ying, CHEN Juan-juan
2011, 26(7): 1590-1598.
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By analyzing the structure and aerothermodynamics processes of the typical auxiliary power unit (APU),this paper used object-oriented technology and C++ program to design the classes of APU components.In order to simulate a 150-class civil aircraft APU model,instances of the component classes were assembled.According to the APU operating conditions,the thermodynamic and off-design performance calculations were completed,the design state performance and operating envelope about aircraft environment control and main engine start models,as well as altitude-speed,temperature and load characteristics,were obtained accordingly.
Unsteady numerical investigation of mixing and reacting for transverse injection in HYLTE nozzle
SHAO Yan, ZHOU Jin, LAI Lin, WANG Hong-bo, LEI Jing
2011, 26(7): 1599-1607.
Abstract PDF(1954KB) icon1744 icon16
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A hybrid Reynolds averaged Navier-Stokes/large eddy simulation (RANS/LES) approach was applied to simulate the unsteady mixing and reacting process of the angled transverse injection in the hypersonic low temperature (HYLTE) nozzle,while the influences of different injection angles and distances on the penetration height,mixing and total pressure loss were analyzed.It is found that the penetration height and mixing are enhanced with the increase of the injection angle,but together with the increasing total pressure loss.In addition,when the injection distance increases,the penetration height of the fuel injection increases and the total pressure loss decreases a little,but the counter vortex pairs are too close to produce larger contact regions and better lateral mixing.Optimum incident angle and injection distance are essential to enhance the mixing performance of HYLTE nozzle and optical performance of the deuterium fluoride(DF) chemical laser.Moreover,the reacting flowfield of the coupled region,including 12 chemical species and 23 reactions,was simulated.The small signal gain coefficient reaches the maximum in the vicinity of the centerline.Compared with the method of RANS,hybrid RANS/LES approach is more capable of predicting the changes of flowfield variables.
Multi-objective optimization for aerodynamic shape of helicopter blade
SUN Wei, ZHANG Cheng-lin
2011, 26(7): 1608-1614.
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An aerodynamic model of helicopter rotor was set up based upon free-wake theory,and a surrogate model was created with artificial neural networks.Based on the aerodynamic model and surrogate model,an optimization framework with improved multi-objective genetic algorithm was used to optimize blade aerodynamic shape in hover and large speed level flight.Rotor shaft powers were minimized in these two flight conditions with constraints of figure of merit,effective lift-drag-ratio and maximum drag coefficient of blade element,and Pareto front was generated.The blade of UH-60A helicopter was taken as an example in this paper. The result indicates that the multi-objective optimization framework of aerodynamic shape is feasible and efficient.
Numerical simulation of transonic shock oscillations on a supercritical airfoil
WEI Zhi, TAO Yang, WANG Hong-biao
2011, 26(7): 1615-1620.
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Detached eddy simulation(DES)method was applied to study the self-sustained shock oscillations phenomenon of SC (2) -0714 supercritical airfoil in this paper. The periodic shock motion on the upper surface of the airfoil was predicted using the two-dimensional DES method in present calculation. The effects of Reynolds number (Re) on the reduced frequency of the shock motion, mean shock position and coefficients of fluctuation pressures were also studied in the paper. The results show that Reynolds number has a non-linear influence on shock oscillation motion character. Compared with Re=15×106 and Re=30×106 flow condition, the shock oscillation character in case of Re=6×106 condition is obviously different.
Impact of blade deflection on aerodynamic performance of a transonic fan
ZHENG Yun, TIAN Xiao, YANG Hui
2011, 26(7): 1621-1627.
Abstract PDF(1184KB) icon1923 icon34
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In order to research the impact of blade deflection on aerodynamic performance of a transonic fan,a numeric program was developed to simulate the deflection of fan blades under aerodynamic loads with fluid-structural interaction method.The aerodynamic model of the fluid flow was based on solving the unsteady three-dimensional(3-D) compressible Reynolds averaged Navier-Stokes equation.The blade vibration was predicted with a linear aeroelasticity model by solving the structure dynamic equation simultaneously with aerodynamic equations.The blade deformation under unsteady aerodynamic loads of the NASA(National Aeronautics and Space Administration) Rotor 67 blade was computed,and the impact on the flowfield and aerodynamic performance was analyzed.
IGV wake state, transportation and interaction influence with impeller blade row in centrifugal compressor
CHEN Shan, YANG Ce, LI Du, QI Ming-xu, SHI Xin
2011, 26(7): 1628-1637.
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Numerical investigation was carried out to study the inlet guide vane (IGV) and impeller interaction in a transonic centrifugal compressor.Three blade-row gaps and two rotor/stator(R/S) location settings for each gap model were included in the simulations.The results show that,the R/S location greatly affects the steady calculation performance,but has little effect on the unsteady performance.The IGV-impeller gap barely influences the compressor stage performance,but small gap leads to large pressure pulsation inside the flow field.The existence of impeller shock increases the influence of impeller to IGV several times,even dozens of times for IGV to impeller.And,the formation of pressure pulsation on the IGV pressure and suction side is different due to impeller shock.
Aerodynamic design and numerical investigation of a highly loaded meridian acceleration fan
JIN Hai-liang, JIN Dong-hai, PENG Ze-yan, GUI Xing-min
2011, 26(7): 1638-1646.
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Considering the aerodynamic performance and manufacturing cost of civil fan,the aerodynamic design and three-dimensional numerical investigation of a highly loaded meridian acceleration fan were performed using three design schemes (uniform thickness tandem stator scheme,airfoil tandem stator scheme and uniform thickness single row stator scheme).The results indicate that the utilization of airfoil blade has few improvements on aerodynamic performance.The total pressure ratio and adiabatic efficiency of the airfoil tandem stator scheme are increased only by 0.18% and 0.8% respectively compared with the uniform thickness tandem stator scheme at near design point.The stall margin of the uniform thickness tandem stator scheme is increased by 11% than the uniform thickness single row stator scheme due to the suppression of the corner separation in the single row stator passage and the reduction of the passage blockage by the tandem stator.Considering aerodynamic performance and manufacturing cost the uniform thickness tandem stator scheme is selected as the final scheme of the fan and its performance characteristics at different rotating speeds can satisfy the design requirements.
Analysis and verification of wake / boundary layer interaction model in compressor
YANG Rong-fei, LI Zhi-ping, LI Qiu-shi, ZHOU Sheng
2011, 26(7): 1647-1653.
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A wake/boundary layer interaction model was derived based on negative jet effect of wake transport in turbomachinery,in consideration of the influences of outer boundary layer's viscous force on boundary layer development.Then,the relationship between pressure rise and momentum thickness was established.An experiment was designed to verify this model about effect of wake passing frequency on compressor pressure rise at fixed wake depth and wake width.Comparison of model and experimental results indicates that: (1) The model can be used to predict the effect of wake passing frequency on compressor pressure rise effectively. (2) The key factor of wake/boundary layer interaction is local pressure gradient that changes with wake,which leads to pressure rise finally.
Optimization design of trajectory-control engine of interceptor based on zero-effort-miss
QI Zhao-hui, LIANG Wei, LIU Xue-mei, ZHAI Li-li, GAO Lan
2011, 26(7): 1654-1658.
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To improve the transport and intercepting capability of interceptor considering the relative distance and velocity between target and interceptor, etc, the zero-effort-miss model of interceptor, the internal ballistic model and the mass & size model of trajectory-control engine were established to optimize the trajectory-control engine. The genetic arithmetic combined with Powell method was also adopted in the optimization design of trajectory-control engine. The zero-effort-miss eliminated by trajectory-control engine could improve not less than 17.9% as proved by the optimization design case, and the influence caused by uncertain factors was more explicit, so the method might be applied to the optimization design of interceptor.
Ignition algorithm of solid propellant micro-thruster array for attitude control
LIU Xu-hui, FANG Shu-zhou, LIU Shu-jie, LUO Li, QUAN En
2011, 26(7): 1659-1664.
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The study on ignition algorithm of solid propellant micro-thruster array for attitude control of micro-satellite was made and described in this paper.The performance capabilities of solid propellant micro-thruster array were analyzed and the theoretical model was set up,then two kinds of ignition algorithms, that were combined base value algorithm and array programming algorithm, were proposed and verified by simulation using Matlab/Simulink.The simulation shows that, array programming algorithm is accurate and fast, also can improve the utilization efficiency of thrusters in the array.
Model parameters estimation of aero-engine based on hybrid optimization algorithm
LI Qiu-hong
2011, 26(7): 1665-1671.
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A hybrid optimization algorithm for the time-domain identification of multivariable,state space model for aero-engine was presented in this paper.The optimization procedure runs particle swarm optimization (PSO) and least squares optimization (LSO) "in series".PSO starts from an initial population and searches for the optimum solution by updating generations.However,it can sometimes run into a suboptimal solution.Then LSO can start from the suboptimal solution of PSO,and get an optimum solution by conjugate gradient algorithm.The algorithm is suitable for the high-order multivariable system which has many parameters to be estimated in wide ranges.Hybrid optimization algorithm is applied to estimate the parameters of a 4-input 4-output state variable model (SVM) for aero-engine.The simulation results demonstrate the effectiveness of the proposed algorithm.
Application of neural networks in the test for electronic-controlled gasoline engine of unmanned aerial vehicle
GUO Rong-hua, WU Yu-sheng, CHEN Qing-rong
2011, 26(7): 1672-1680.
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The characters and difficulties in the test for electronic-controlled gasoline engine of unmanned aerial vehicle (UAV) were analyzed in detail.For mending the traditional liner interpolation methods,which are not completely in conformity with nonlinear characteristics of electronic-controlled gasoline engine,a solution was applied in the predication for the manifold air pressure (MAP) of high-altitude calibration of electronic-controlled gasoline engine,by adopting back propagation (BP) neural networks.To avoid the limitation of neural networks in application at present stage,a grouping method of raw-data was put forward to control the feedback of the training error in real-time;this method provided a good solution for the problem that the neural network training result easily leads to the situation of "local optimum" and "over-fitting".The prediction results based on BP neural networks have been studied thoroughly;and the results of the training error and the prediction error reveal that the method is feasible and the result is effective.

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