2011 Vol. 26, No. 4

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Heteroscedastic regression analysis method for mixed data
FU Hui-min, YUE Xiao-rui
2011, 26(4): 721-726.
Abstract PDF(1539KB) icon1388 icon24
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The heteroscedastic regression model was established and the heteroscedastic regression analysis method was presented for mixed data composed of complete data, type-Ⅰ censored data and type-Ⅱ censored data from the location-scale distribution. The best unbiased estimations of regression coefficients, as well as the confidence limits of the location parameter and scale parameter were given. Furthermore, the point estimations and confidence limits of percentiles were obtained. Thus, the traditional multiple regression analysis method which is only suitable to the complete data from normal distribution can be extended to the cases of heteroscedastic mixed data and the location-scale distribution. So the presented method has a broad range of promising applications.
Estimation method for random sonic fatigue life of thin-walled structure of a combustor liner based on stress probability distribution
SHA Yun-dong, GUO Xiao-peng, LIAO Lian-fang, XIE Li-juan
2011, 26(4): 727-734.
Abstract PDF(1074KB) icon1856 icon20
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As to the sonic fatigue problem of an aero-engine combustor liner structure under the random acoustic loadings, an effective method for predicting the fatigue life of a structure under random loadings was studied. Firstly, the probability distribution of Von Mises stress of thin-walled structure under random loadings was studied, analysis suggested that probability density function of Von Mises stress process accord approximately with two-parameter Weibull distribution. The formula for calculating Weibull parameters were given. Based on the Miner linear theory, the method for predicting the random sonic fatigue life based on the stress probability density was developed, and the model for fatigue life prediction was constructed. As an example, an aero-engine combustor liner structure was considered. The power spectrum density (PSD) of the vibrational stress response was calculated by using the coupled FEM/BEM (finite element method/boundary element method) model, the fatigue life was estimated by using the constructed model. And considering the influence of the wide frequency band, the calculated results were modified. Comparetive analysis shows that the estimated results of sonic fatigue of the combustor liner structure by using Weibull distribution of Von Mises stress are more conservative than using Dirlik distribution to some extend. The results show that the methods presented in this paper are practical for the random fatigue life analysis of the aeronautical thin-walled structures.
Research on the dentiform basic parameters of aero-engine turbine joint structure
SHEN Xiu-li, QI Xiao-dong, WANG Rong-qiao, FAN Jiang, LIU Hai
2011, 26(4): 735-744.
Abstract PDF(1582KB) icon2764 icon26
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The impacts on joint structure strength of the dentiform basic parameters,such as wedge angle,blade root neck width,disc groove height,top flank angle,bottom flank angle and skew angle,were studied by lots of finite element and optimization design numerical methods.Based on the calculated results,a new model was established and verified experimentally,indicating that the maximum stress has been reduced.Results show that two-dimensional finite element analysis can be used to study the influence of dentiform basic parameters on the joint structure stress distribution,but this does not reflect changes of the stress in the axial direction.
Optimization design of the turbine blade shroud based on iSIGHT software
FAN Jiang, ZENG Wei-wei, WANG Rong-qiao, SHEN Xiu-li, CHEN Zhi-ying
2011, 26(4): 745-751.
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Based on the established turbine blade shroud parametric model,this article choosed iSIGHT as an optimization platform,and employed the model building software and finite element method (FEM) software to construct the procedure of the shroud optimization.It successfully reduced the shroud's mass (at least 1.0%) on the condition of keeping its structural strength by use of this procedure.In addition,this research shows some relationships among different parameters’ combinations,such as the included angle α and the pressure on the damp faces.It also provides an effective method to design and optimize the similar complicated models.
Faults analysis and solution in ground operation of a micro turbojet engine
CHEN Wei, DU Fa-rong, DING Shui-ting, LI Yun-qing
2011, 26(4): 752-759.
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Based on series of ground operations of a newly designed micro turbojet engine,this paper presented the establishment of engine structure,process of test rig,configurations of measure system,confirmation of engine running plan,and put stress on analyzing the reasons of all the faulty phenomena met in engine operations and their solutions.These phenomena include ignition reliability,flame localization behind the nozzle too much,speed hang-up,rubbing faults between rotor and stator,cracks of welding sews of wing fender in the nozzle,failure of bearing in the side of turbine because of thermal instability,engine surge and debugging of electronic-control programs.The ground operation results show that reducing thermal load of the bearing in the side of turbine,improving mechanical characteristics of the compressor impeller's materials made in China,and promoting manufacturing level are main missions to be finished so far in the design of micro turbojet engine,and other faults stated in the paper can be overcome by appropriate methods.
Mode shape description of an aero-engine casing structure using Zernike moment descriptors
LIU Ying-chao, ZANG Chao-ping
2011, 26(4): 760-770.
Abstract PDF(2111KB) icon1374 icon20
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Vibration mode shape description of an aero-engine casing structure using Zernike moment descriptor (ZMD) was introduced in this paper. The mode shapes of the aero-engine casing structure can be decomposed as a linear combination of a series of Zernike polynomials, with the feature of each Zernike polynomial reflecting a part of characteristic of mode shapes, based on Zernike moment transformation. Meanwhile, the reconstruction of mode shapes with ZMD was explored and its ability to filtering the noise contaminated in the mode shapes was studied. Simulation of the aero-engine casing structure indicated the advantage of this method to depict the mode shapes of a symmetric structure. Results demonstrate that the Zernike moment description of the mode shapes can effectively describe the double modes in the symmetric structure and also has the ability to remove or significantly reduce the influence of noise in the mode shapes. Such feature shows great practical value for further research on the correlation, model updating and model validation of the symmetric structure's finite element model.
Establishment of the threshold of oil spectrum analysis in the aircraft engine based on SVM
LI Ai, CHEN Guo
2011, 26(4): 771-778.
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The probability density of the aircraft engine oil sample spectral data was estimated by using support vector machines(SVM).According to the probability distribution of spectral data,the normal,warning and abnormal threshold of the mass fraction,mass fraction gradient and the mass fraction ratio of aircraft engine were calculated based on spectroscopic diagnosis.This method was also verified by using the actual spectral data in aircraft engine.Through comparison and analysis of the threshold based on the normal distribution assumption,it shows that the actual spectral elements of aircraft engine are not entirely subject to normal distribution assumption,so the results established by SVM-based oil-like spectral threshold method are more genuine and reliable.
Analysis on the influences of the contact gap on the contact response of turbine disc-blade structures
PENG Mao-lin, YANG Zi-chun, CAO Yue-yun, CAO Cheng
2011, 26(4): 779-786.
Abstract PDF(1289KB) icon1705 icon17
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Taking the given fifth disc-blade structures of the gas turbine as an investigation object in consideration of the complex loads, the transient thermo-elastic-plastic finite element analysis of the contact disc-blade structures was completed using ANSYS program designed with ANSYS parameter design language(APDL). The stress and strain of turbine disc-blade structures were calculated respectively under the urgent loads and the typical loads. The disc-blade gap was regarded as a parameter, and the changes of stress and strain of the structures with different contact gaps were analyzed. Meanwhile, the exact value of the contact gap when the stress and strain changed suddenly was obtained. Moreover, the influence of the contact heat transfer coefficient on the stress and strain was discussed. Finally, some constructive suggestions were given for the processing of designing, machining, the improvement of material properties of the disc-blade structures and the operation and management of the gas turbine.
Internal structural optimization of hollow fan blade based on sequential quadratic programming algorithm
YANG Jian-qiu, WANG Yan-rong
2011, 26(4): 787-793.
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Several structural design parameters for the description of the geometric features of a hollow fan blade were determined. A structural design optimization model of a hollow fan blade which based on the strength constraint and minimum mass was established based on the finite element method through these parameters. Then, the sequential quadratic programming algorithm was employed to search the optimal solutions. Several groups of value for initial design variables were chosen, for the purpose of not only finding much more local optimal results but also analyzing which discipline that the variables according to could be benefit for the convergence and robustness. Response surface method and Monte Carlo simulations were used to analyze whether the objective function and constraint function are sensitive to the variation of variables or not. Then the robust results could be found among a group of different local optimal solutions.
Assessment research on damage degree of blade in aero-engine based on back-propagation artificial neural networks
QIAN Zheng-wen, CHENG Li, ZHAO Bing-bing, LI Ying-hong
2011, 26(4): 794-800.
Abstract PDF(937KB) icon1599 icon21
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The internal relationship among damage degree,natural frequency and the location of damage was deduced by simplifying the blade as a cantilever.In view of the problem in the maintenance of damaged blade,the relationship was abstracted into a mapping about damage degree,natural frequency and the location of damage.Then the neural network,which has the ability of self-study and can approach the nonlinear mapping,was used in the prediction of the damage.The damage degree assessment method of blade was built up based on the back-propagation(BP)neural network.Furthermore,this method was validated by using the experimental data of a certain aero-engine blade as the sample and test data.The results indicate that this method is useful to disposal of damaged blade in the project applications and can be applied in the maintenance criterion of blade.
Investigation on impact damping characteristic of interior inlaid steel ball for Euler beam under certain operating condition
WANG Jian-wei, XU Hui, MA Ning
2011, 26(4): 801-807.
Abstract PDF(1273KB) icon1626 icon15
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For an impact system of an Euler beam with interior inlaid freely moving steel ball,under a complicated operating condition,the impact damping characteristic of the steel ball was investigated for residual damped vibrations of the Euler beam acted by inertia forces.A linear spring-damping model was employed to simulate the impact between the steel ball and interior beam walls.Then the linear piecewise dynamic equations for the impact system were established,and the dimensionless state-space equations with finite degrees of freedoms were derived by introducing dimensionless variables,and assuming modes and truncating high order modes.Numerical calculations sufficiently indicate that,under this operating condition, the steel ball has a significant impact damping effect on suppressing the beam residual damped vibrations in amplitudes,and moreover,the impact damping exhibits a strong stage character.The impact damping of the ball is enhanced with increase of its mass.
Experimental and computational investigation into ice accretion on airfoil of a transport aircraft
YI Xian, GUI Ye-wei, ZHU Guo-lin, DU Yan-xia
2011, 26(4): 808-813.
Abstract PDF(1195KB) icon2566 icon28
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Ice accretion characteristics on the airfoil of a transport aircraft were studied with both experimental and computational methods.Icing test was carried out in the icing wind tunnel of 0.3m×0.2m test section,in China Aerodynamics Research and Development Center.The test model is a 0.18 -m-chord laminar airfoil,which is the sub-scale model of the transport aircraft's wing section.Numerical simulation of icing was based on computational fluid dynamics (CFD) method.The flow field of airfoil was calculated by solving time averaged Navier-Stokes equations.Droplet trajectories and impingement characteristics were computed with a Lagrangian method.Ice shape was then obtained after solving the thermodynamic model of icing.Computational results were compared with experimental results.Despite of some geometric differences,the volume,limit and main characteristics of computational ice shape agree well with the experimental results.The study shows that the ice shape on the leading edge of airfoil is streamline at the initial stage of icing,and becomes irregular with increase of icing time.At lower surface of the airfoil,foreside ice is made up of glaze ice,while rear ice,especially ice near the lower impingement limit,is made up of rime ice.At upper surface of the airfoil,icing region is much smaller than that at lower surface,and there is no obvious rime ice even near the upper impingement limit.
Study on heated components mass reduction based on thermal management
FU De-bin, DING Shui-ting, TAO Zhi, LI Guo, ZHANG Gong, LI Ye
2011, 26(4): 814-821.
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The relationship between stress level and disk mass reduction in a rotating disk with heat channel and warming-up in disk root at a fixed flux of cooling air was numerically studied,by using fluid structure interaction (FSI) method based on the thermal management for heated components.The regulation between stress level and disk mass reduction was studied under the boundary condition of disk space and the heat flux of different heat channel configurations’ fixed condition.The rotating speed was also fixed at 10000r/min.Numerical results reveal that there exists a strong relevance between stress level and the construction of heat channel and heat flux.By heating the disk root,the U-temperature distribution can reduce the disk stress level.It means that the method of active thermal management can achieve the disk mass reduction,while guaranteeing the performance of aero-engine and working life.
Characteristics of lean blowout limit for backward step-stabilized flame with centrifugal force effect
LI Lin, LIN Yu-zhen, GUO Xin-hua, SUN Qiang
2011, 26(4): 822-828.
Abstract PDF(1234KB) icon1944 icon19
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Using the centrifugal force effect of a whirl flow through a curved pipe to simulate the working conditions in the rotor combustion system,this thesis investigated the effect of the geometric parameters on lean blowout limit of spray combustion for the backward step flame holder.On the basis of a curved flow channel experiment rig,a backward step flame holder was designed with variable geometric parameters.The geometric parameters include:the height,length and distance between backward step and wall surface.The effect of these three geometric parameters on the lean blowout limit of spray combustion was investigated.Test results indicate that,the height and length have great effect on flame blowout limit.With the increase of the height and length,the lean blowout limit decreases;but the distance between backward step and wall surface has little effect on flame blowout limit.For each backward step flame holder,while centrifugal force effect increases,the flame lean blowout limit is reduced and flameout range is broadened.This research work has laid a foundation for investigation of spray combustion on the rotor combustion system.
Theory and simulation for measurement of molecular sieve adsorption equilibrium isotherm by zero length column (ZLC) method
WANG Hui-dan, LIN Gui-ping, SUN Bing
2011, 26(4): 829-835.
Abstract PDF(1061KB) icon1758 icon44
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The theory for measurement of adsorption equilibrium isotherm by zero length column (ZLC) method was introduced,and a set of mathematical models on ZLC were built.Then,a program was developed based on the equations and simulations were carried out.A good agreement between the simulation results and the experimental data validated the program and models.For the measurement of equilibrium isotherms with the ZLC method,simultaneous measurement of the outlet concentration and flow rate was required,and both of which were coupled by previous investigations.Then,two ways of estimating the true column outlet carrier flow rate were analyzed.With these two estimations,the isotherms were calculated,and compared with the curves from simulation and theoretical calculation.Finally,influential factors to the accuracy and the applicable scope of the ZLC method were discussed,and the accuracy of two revised methods was analyzed,serving as the basis for applying the ZLC method.
Numerical simulation of heat transfer physics of film cooling under rotating conditions
LIU Ning, SUN Ji-ning
2011, 26(4): 836-841.
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Large eddy simulation was used to investigate the effect of rotation on film cooling over flat plate with single hole.The Reynolds number at the jet exit was 2600,and the blowing ratio was 0.5.The flow and heat transfer without rotation and with rotating number of 0.02 were calculated,and the heat transfer mechanics under rotating condition was analyzed through the evolvement of turbulence structure.It was found that hairpin structure determined the heat transfer of film cooling,and the shape and trajectory of hairpin structure was mainly affected by Coriolis force under rotating condition.The film was driven towards high radius side by spanwise Coriolis force,resulting in less mixing between main flow and jet and maintaining low temperature of the film.The Coriolis force normal to the wall reinforced the film attachment and reduced the strength of counter rotating vortex pair,leading to less entrainment of mainflow and better coverage of film.
OH-PLIF measurement of syngas diffusion flame
GUO Pei-qing, ZANG Shu-sheng, GE Bing, TIAN Yin-shen
2011, 26(4): 842-847.
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Planar laser induced fluorescence (PLIF) measurement was conducted on swirling non-premixed flame in a model combustor,firing CH4 and syngas with different C-H ratios,in order to study the combustion characteristics of mid-caloric syngas flame in a gas turbine combustion chamber.Although quite different flame shapes were found between CH4 and syngas flame,instantaneous OH-PLIF images demonstrated the common turbulent flame features.Results also show that both flames are stabilized at the exit of the fuel injector,but CH4 flame burns more steadily.Quantitative analysis of flame reaction core shows that flame stability deteriorates with the increase of C-H ratio.
Study on the feasibility and structural optimization of heat-pipe on board
MING Zhang-peng, DONG Su-jun, WANG Jun
2011, 26(4): 848-853.
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The feasibility and capability of heat-pipe on board was studied by analysis and computation,and the structure was optimized.The results show that the capability of anti axial acceleration of heat-pipe with an effective length of 0.12m is of -1.2g,helping to conquer the disadvantages of changing acceleration and azimuth when the plane manoeuvres.At the same time,the heat transfer capability of the heat-pipe is of 10W/cm2 high with a temperature difference of only 15.303K,so it can meet completely the demand of large flow heat transfer on board.
Cooling efficiency study of impingement pin fin /reversed convection/ film cooling in curved section Part 1: experiments
SHI Rui, XIONG Chun, CAO Jun, XIE Jie, YANG Wei-hua, SONG Shuang-wen
2011, 26(4): 854-859.
Abstract PDF(1107KB) icon1701 icon14
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In order to study the influence of impingement pin fin/reversed convection/film cooling structure on cooling efficiency in curved section of combustion chamber,five different kinds of geometry dimension test pieces were designed and studied experimentally.The test results show that:(1) The efficiency of impingement pin fin/reversed convection/film cooling in curved section with pin fins is better than that without pin fins,especially when the blowing ratio is small.(2) The blowing ratio has great influence on the efficiency of compound cooling;the efficiency of compound cooling increases with the blowing ratio at the same wall position.When the blowing ratio exceeds 1.0,efficiency improvement for blowing ratio is not obvious.(3) The arrangement of pin fins has little effect on cooling efficiency.
Numerical application of nonlinear EASM model to the interaction between shock waves /turbulent boundary layer
ZHAO Hui-yong, LEI Bo, LE Jia-ling
2011, 26(4): 860-866.
Abstract PDF(1196KB) icon1669 icon14
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The nonlinear explicit algebraic stress model (EASM) in k-ω form was used to compute the interaction between shock wave and turbulent boundary layer of supersonic cavity,compression corner and simplified model of side-compression inlet which are usually used in scramjet engine.The main focus was computational resolution of EASM model on wall pressure,friction,Stanton number and skin friction lines.The computational results of EASM model were compared with those of SST (shear stress transport) model.EASM model has better computational resolution on wall pressure,friction and Stanton number so that it can be generalized.EASM model is better than SST model in computation of Stanton number and skin friction lines.
Experimental investigation on airfoil stall separation suppression by multiphase plasma aerodynamic actuation
LIANG Hua, LI Ying-hong, SONG Hui-min, WU Yun, JIA Min, MA Qing-yuan
2011, 26(4): 867-873.
Abstract PDF(1179KB) icon2235 icon18
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Experiments on NACA0015 airfoil stalling separation control based on multiphase plasma aerodynamic actuation were performed in the paper.The effects of the plasma actuation voltage amplitude,phase,input waveform and duty cycle on the lift and drag of the airfoil were examined specifically.The results show that,when the Reynolds number is 4.9 ×105,multiphase plasma aerodynamic actuation can suppress flow separation very well.The critical stalling attack angle of NACA0015 airfoil can increase by 2°.The flow suppression effect is not sensitive to phase difference.The separated flow can be suppressed when the voltage amplitude and duty cycle reach their threshold values.Once the separated flow is suppressed,the actuation voltage magnitude maintaining flow attachment could be reduced significantly.The research can lay a foundation for the mechanism of multiphase plasma flow control.
Research on the optimization design of integrated scramjet /airframe
LI Jian-ping, SONG Wen-yan, XIAO Yin-li
2011, 26(4): 874-879.
Abstract PDF(984KB) icon1879 icon25
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A performance calculation program and an optimization design platform of integrated scramjet/airframe,including three main parts:forebody/inlet,combustor and nozzle/afterbody,were developed in this paper.The hydrogen-fueled,integrated scramjet/airframe configuration optimization design was performed based on the optimization design platform.The integrated scramjet/airframe two-dimensional configuration of optimized design was numerically simulated.The calculation results indicate that the performance calculation program of integrated scramjet/airframe is exact and the optimized design result is reliable.
Three-dimensional Navier-Stokes simulation of flapping wing with pitching elasticity
ZHANG Yun-fei, YE Zheng-yin
2011, 26(4): 880-889.
Abstract PDF(1425KB) icon1744 icon15
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The aerodynamic characteristics of a flapping wing with movements of flapping and pitching were investigated by solving unsteady Reynolds-averaged Navier-Stokes equations.A torque spring on pitch axis was used to simulate the pitching elasticity of bird wings.The influences of the platform of flapping wing,the location of gravity center relative to the pitch axis and the torque spring constant on aerodynamic performances were investigated.The results indicate that there would be a large leading phase between the movements of pitching and plunging.The larger spring constant means greater phase difference.After taking the pitching elasticity into consideration,the amplitude of the lift coefficient and that of bending moment at the root of the wing decreased,contributing much to the steady flight of micro air vehicles.Simultaneously the average drag coefficient was reduced by about 60%.Therefore the pitching stiffness and the location of the pitch axis affect the aerodynamic performance a lot and it's very important to consider the pitching elasticity in flapping wing design.
Numerical simulation and analysis on aerodynamics of three-element airfoil in ground effect
QIN Xu-guo, LIU Pei-qing, QU Qiu-lin, ZHANG Kai
2011, 26(4): 890-896.
Abstract PDF(1152KB) icon1886 icon23
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A three-element airfoil operating in ground effect was investigated numerically.The compressible Navier-Stokes equations were solved by the finite-volume method.Spalart-Allmaras (S-A) turbulence model was used.Slipping wall was used to simulate the relative movement.The effects of flight height on the aerodynamics of the multi-element airfoils were found obviously as compared with clean airfoils.The results indicate that,with the reduction in height,the lift increases for the multi-element airfoil,but decreases for the clean airfoil,while the drag and nose down moment decrease for both airfoils.The cause of the reduction of lift lies in that,the losses of suction at upper surface are more than the increases of pressure at lower surface.The separated region becomes larger with the decline of the height.
Experimental study of static-thrust propeller for mini-vertical takeoff and landing (VTOL) aircraft
WU Da-wei, LI Han-bing, LI Shu
2011, 26(4): 897-902.
Abstract PDF(1040KB) icon2161 icon27
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Systematic experiments about static-thrust propellers' hovering performance with different geometrical parameters for unmanned mini-vertical takeoff and landing (VTOL) aircraft were made to enhance the lifting ability for more payloads. A series of conclusions about geometrical parameters' influence on hovering performance for propellers with constant pitch were summarized based on the test data and propeller strip theory suitable for static-thrust condition.This paper provides the test data of these propellers.The results show that larger diameter can improve hovering performance obviously,and there exist optimal lower medium pitch value,solidity and planform,but the latter two factors don't influence hovering performance obviously.
Numerical investigation of transcritical liquid film cooling in a methane / oxygen rocket engine
YANG Wei, SUN Bing
2011, 26(4): 903-916.
Abstract PDF(1409KB) icon1384 icon20
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Transcritical film cooling was investigated by numerical study in a methane cooled methane/oxygen rocket engine. The respective time-averaged Navier-Stokes equations have been solved for the compressible steady three-dimensional (3-D) flow. The flow field computations were performed using the semi-implicit method for pressure linked equation (SIMPLE) algorithm on several blocks of nonuniform collocated grid. The calculation was conducted over a pressure range of 202650.0 Pa to 1.2×107 Pa and a temperature range of 120.0 K to 3568.0 K. Twenty-nine different cases were simulated to calculate the impact of different factors. The results show that mass flow rate, length, diameter, number and diffused or convergence of film jet channel, injection angle and jet array arrangements have great impact on transcritical film cooling effectiveness. Furthermore, shape of the jet holes and jet and crossflow turbulence also affect the wall temperature distribution. Two rows of film arranged in different axial angles and staggered arrangement were proposed as new liquid film arrangement. Different radial angles have impact on the film cooling effectiveness in two row-jets cooled cases. The case of in-line and staggered arrangement are almost the same in the region before the second row of jets, but a staggered arrangement has a higher film cooling effectiveness from the second row of jets.
Design and optimization of solid rocket motor Finocyl grain using simulated annealing
Ali Kamran, LIANG Guo-zhu
2011, 26(4): 917-923.
Abstract PDF(951KB) icon2589 icon19
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The research effort outlined the application of a computer aided design (CAD)-centric technique to the design and optimization of solid rocket motor Finocyl (fin in cylinder) grain using simulated annealing. The proper method for constructing the grain configuration model, ballistic performance and optimizer integration for analysis was presented. Finocyl is a complex grain configuration, requiring thirteen variables to define the geometry. The large number of variables not only complicates the geometrical construction but also optimization process. CAD representation encapsulates all of the geometric entities pertinent to the grain design in a parametric way, allowing manipulation of grain entity (web), performing regression and automating geometrical data calculations. Robustness to avoid local minima and efficient capacity to explore design space makes simulated annealing an attractive choice as optimizer. It is demonstrated with a constrained optimization of Finocyl grain geometry for homogeneous, isotropic propellant, uniform regression, and a quasi-steady, bulk mode internal ballistics model that maximizes average thrust for required deviations from neutrality.
Steady numerical study of aerodynamic throat formed by round injectors
XIE Kan, LIU Yu, WANG Yi-bai
2011, 26(4): 924-930.
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A three-dimensional (3-D) numerical simulation of aerodynamic throat formed by secondary flow from round injectors,which was applied to solid propellant rocket motors,was performed in this paper.The typical 3-D flow structure and mass flow character of round injectors were reviewed.The influence of different injector area ratios,injector numbers,injection angles,injector types and major nozzle parameter were studied.The results show that the mass control performance of aerodynamic throat can be obviously improved by increasing injector numbers,applying reverse injection or convergence injector type at the same injector area ratio.
Reliability compliance test plans for liquid-propellant rocket engine based on weighting factors
LI Jin, ZHAO Yu, LI Wen-zhao, YANG Jun
2011, 26(4): 931-934.
Abstract PDF(865KB) icon1804 icon25
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The problem of liquid-propellant rocket engine's reliability compliance test plans at present is that ignoring the processes of firing and shutdown or the test taking too long.To solve this problem,considering typical compliance test plans of binomial distribution and Weibull distribution,using the weighting factors,the method of reliability compliance test plan developing was provided.The duration of firing was verified in this reliability compliance test plans developing method,at the same time the processes of firing and shutdowns were also considered.This reliability compliance test plan utilized development information and saved the test time and cost.
Improvement of switch devices of compressor stator blade angle main-backup controller
LI Jie, FAN Ding, PENG Kai, YIN Fei-jia
2011, 26(4): 935-941.
Abstract PDF(1077KB) icon1855 icon16
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In order to ensure the main-backup controller switch reliability of an aeroengine high-pressure compressor variable stator blade angle control system,the original switch devices were improved by adding a new switch component.Simulation results show that,if the fault of digital electronic controller (DEC) occurs,and then if DEC output does not meet the design requirements, i.e .,the output pulse duty cycle of DEC is not 0 but fixed or random,unpredictable signal,the normal work of the original system will be seriously affected,while the normal work of the system with improved switch devices will not be affected,and the switching of main-backup controller is safe,rapid and smooth.Control system's switch performance and aero-engine's functional reliability are improved by the switch devices improvement.
Fuzzy controller design and parameter optimization for aero-engine compressor guide vane system
PENG Kai, FAN Ding, LI Jie, WU Tian-yi
2011, 26(4): 942-946.
Abstract PDF(1084KB) icon1877 icon20
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The hydraulic part of aero-engine compressor guide vane regulator was modeled in AMESim,the fuzzy controller was built in Simulink,and then hybrid optimization algorithms was used to optimize the parameters of the controller in iSIGHT.Co-simulation based on multi-software is highly efficient,the ultimate guide vane regulator formed by numerical simulation is of good static and dynamic characteristics,such as quick response and unobvious overshoot and small disturbance sensitivity,so its performance better than that controlled by standard PID (proportion integration differentiation) is of practical value.
Experimental study for water-lubricated high-speed controllable spiral-groove face seals
ZHANG Guo-yuan, ZHAO Wei-gang, YAN Xiu-tian, YUAN Xiao-yang
2011, 26(4): 947-953.
Abstract PDF(982KB) icon1945 icon21
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Electromagnetic loadable device and testing device for face friction torque were developed,and applied into experimental study of controllable,full water-film lubricated spiral-groove mechanical face seals.Controllable parameters of face seal,such as face temperature,friction torque,and face pressure,were measured,and the influence of axial balancing controlled load on the controllable parameters was studied.Experimental results show that the face pressure increases with increasing rotation speed,and the face temperature is higher with higher speed.The full water-film lubricated face seal has less friction force.The performance parameters of electromagnetic loadable device and testing device for face friction torque were tested in the experiment process,and the target for testing and verifying the controllability of spiral-groove face seals was implemented.The study has the important engineering value for developing real-time monitoring and active control of the spiral-groove face seal.
Experimental investigation of the influence of inlet guide vane prewhirl on the unsteady flowfield in the vaned diffuser
ZHOU Li, ZHANG Xin, CAI Yuan-hu
2011, 26(4): 954-960.
Abstract PDF(1302KB) icon1876 icon20
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Experimental investigation of unsteady flow in the vaned diffuser of a centrifugal compressor stage was performed under different inlet guide vane (IGV) prewhirl angles and directions in this paper.Detailed instantaneous flow was measured at several different measuring positions using a hot-wire anemometer with the phase-locked ensemble-averaged technique,the influence of the IGV prewhirl angle and direction on the unsteady flowfield in the vaned diffuser was studied.In the existence of IGV prewhirl angle,the results show that the turbulence intensity increases at most of the position in the vaned diffuser;the unsteadiness in the vaned diffuser reduces due to the influence of the IGV wake and large size vortice,and the amplitude of the reduction under the negative IGV prewhirl is smaller than that under positive IGV prewhirl angle;the base frequency of the flow in the vaned diffuser decreases under the IGV prewhirl.

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