2012 Vol. 27, No. 6

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Study on disk and blade design based on multi-layer optimization strategy
WANG Rong-qiao, JIA Zhi-gang, YANG Jun-jie, HU Dian-yin, FAN Jiang, SHEN Xiu-li
2012, 27(6): 1201-1209.
Abstract PDF(1158KB) icon1944 icon731
Abstract:
For the turbine multi-discipline optimization (MDO) design,the important principle of MDO firstly extended to component autonomy from disciplinary autonomy.Based on these principles,four kinds of MDO frameworks,which were applied on the turbine design,combining present MDO strategies including BLISS(bi-level integrated system synthesis)2000,CO(collaborative optimization) and ATC(analytical target cascading) were designed.Both the two-layer including double-subsystem strategy and the two-layer including triple-subsystem strategy were built by BLISS2000 strategy as the two-layer framework for turbine design,while the three-layer including triple-subsystem strategy gave the full play to the merits of BLISS2000 and CO strategies.The ATC optimization strategy required huge extra optimization cost,so it is not qualitatively suitable for triple-layer MDO strategy on turbine.After testing,the preponderance of the multi-layer optimization strategies including three subsystems is higher efficiency,while complex interactions between layers always lead to worse optimization accuracy and efficiency on three layers strategy compared with two layers strategy.
Opportunities and challenges of MEMS technology in the environment of intelligent aero-engines
YAN Xiao-jun, ZHANG Kai, WU Xiao-ming
2012, 27(6): 1210-1217.
Abstract PDF(971KB) icon1860 icon624
Abstract:
To develop an intelligent aero-engine,which can adjust its components adaptively based on working conditions,more sensors,actuators,computation processors etc.are needed.Due to their big size and heavy mass,the traditional sensors and actuators will have restrictions when they are used on board considering the compact and limited space inside the aero-engine.This paper reviewed the current statues of MEMS's (micro-electro-mechanical system) application in the environment of intelligent aero-engines.These application fields of MEMS in aero-engine environment included:active flow control,active burning control,health monitoring of structure and lubricating system etc.With the development of MEMS technology,MEMS sensors and actuators will play a more important role in the intelligent engine environment.
Structure optimization design for blisk based on ANSYS
LU Shan, LU Feng-jie
2012, 27(6): 1218-1224.
Abstract PDF(870KB) icon2001 icon721
Abstract:
In order to get the lightest weight of the blisk under the safety working condition,the three-dimensional (3-D) parametric model of the blisk and the mathematical model of the structure optimization design were built.Then the structure optimization design of blisk was completed based on ANSYS platform.In conjunction with the relevant design principles and methods,the disk's meridian plane was firstly optimized to meet the structural design strength criterion,and then the 3-D model of the blisk was built with the chamfer at blade root and 3-D optimization was perform on the design parameters for example,the thickness of the rim,the chamfer at blade root and the dish hub.The effect of each design variable on the Von Mises stress at the chamfer of blade root and at the dish hub was summarized.The whole optimization process only took about three to four hours.
Adaptive incremental Kalman filter method
FU Hui-min, WU Yun-zhang, LOU Tai-shan
2012, 27(6): 1225-1229.
Abstract PDF(523KB) icon1924 icon586
Abstract:
An adaptive incremental Kalman filter (AIKF) method was proposed, of which the concept, model, basic equations and key calculative steps were given. Classical adaptive Kalman filter(AKF)method can effectively estimate the prior knowledge on the statistical characteristics of state noise and measurement noise. Classical AKF method cannot compensate and correct the unknown time-varying system errors that due to environmental factors and the instability of measurement equipments in actual engineering (such as deep space exploration), which produced considerable filter errors and even led to diverge. The presented adaptive incremental Kalman filter method can estimate statistical characteristics of state noise and measurement noise, and also can successfully eliminate these measurement equation's system errors. The method can greatly improve the accuracy of incremental Kalman filter. The method is simple to calculate and easy to apply in engineering.
Study and application on anisotropic multiaxial approximate stress and strain analysis method
WANG Jing-ke, YANG Xiao-guang
2012, 27(6): 1230-1237.
Abstract PDF(1904KB) icon1663 icon813
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The multiaxial anisotropic approximate stress-strain analysis method based on Neuber's rule was used to predict the stress and strain response of notched component machined with directionally solidified superalloy DZ125 and single crystal DD6.Different load directions were considered.The approximate analysis model based on differential Neuber's rule,considering the time-dependent creep-plasticity,was extended to anisotropic multiaxial dwell loading simultaneously.Our results show that,the uniaxial simulation results are close to the experimental data,and cyclic loading and dwell loading predictive results conform to physical facts.So,the approximate stress-strain analysis method based on Neuber's rule can be applied on native directionally solidified superalloy and single crystal material.
Anti-aliasing alternating frequency/time domain method and its application in response analysis of blade systems
LIU Ya-lin, SHANGGUAN Bo, XU Zi-li
2012, 27(6): 1238-1242.
Abstract PDF(632KB) icon1369 icon564
Abstract:
In order to solve the problems of spectrum alias error and spectrum coefficient periodically reiteration cause by using fast Fourier transform(FFT),the fast anti-aliasing Fourier transform was employed to improve analysis accuracy and efficiency of alternating frequency/time domain method.The nonlinear forced response of a real turbine blade was calculated by using the anti-aliasing alternating frequency/time domain method,and the computational accuracy and time were compared with these of the normal method.The results indicate that under certain parameter conditions,the calculation speed of the anti-aliasing alternating frequency/time domain method is about 4 times of the normal one,while the precisions are almost the same.These findings confirm the practicability of the anti-aliasing alternating frequency/time domain method in computing dynamic response of nonlinear systems based on finite element model for high precision analysis.
Experimental and prediction study for bearing capacity of inflatable wing
WANG Zhi-fei, WANG Hua, WANG Wei, JIA Qin-ping
2012, 27(6): 1243-1248.
Abstract PDF(526KB) icon1607 icon538
Abstract:
Experimental and prediction study for bearing capacity of inflatable wing have been done and described in this paper.Firstly,model of aerofoil was established,structure of inflatable wing was analyzed and optimized,then method of orthogonal experiment was used to ascertain the main impact of influence bearing capacity and experimental of inflatable wing was finished for bearing capacity.Artificial neural network was finally adopted to predict bearing capacity.The results show that : (1) In the initial experiment,at the same pressure,the relationship between loading and deflection approximately abides by linearity relations.When reached the fixed pressure,the relationship between loading and deflection is also linearity,but the slope abruptly increases.(2)The relative error between the predicted result and the experiment result is 12%,and standard deviation 0.39%,and show that the bearing capacity prediction model of neural net work can predict the bearing capacity of inflatable wing accurately and rapidly.
Method of structural optimization design for turbine disk/tenon
TAO Ye, LU Shan
2012, 27(6): 1249-1254.
Abstract PDF(1084KB) icon2149 icon788
Abstract:
Considering the effect between tenon joints and meridional section of disk in structure design,a general method of structural optimization design for turbine disk/tenon was presented,including designing tenon joints/meridional section of disk in stages and synthetically optimizing with coordination.Based on ANSYS platform and parametric modeling technique,optimization design variables were chosen and a mathematic model of structural optimization design for turbine disk/tenon was established for the purpose of getting minimum masses with all constrained stresses of turbine disk and tenon joints being met.The results of the structural optimization designs of turbine disk and tenon joints for an aero-engine show that the mass of two-tooth and three-tooth disk/tenon are both decreased obviously after optimization under the condition of meeting geometry and strength requirements,which verifies the rationality of the method;the results also reveal that the structure of two-tooth disk/tenon is less mass and the maximum first principle stress lower than that of three-tooth disk/tenon.This method and platform of structural optimization design for turbine disk/tenon with any number of teeth were applied to structure designs of different turbines,which demonstrated a high engineering application.
Fault diagnostics system for helicopter main gearbox using wavelet neural network
LIU Li-sheng, YANG Yu-hang
2012, 27(6): 1255-1260.
Abstract PDF(984KB) icon1694 icon629
Abstract:
A fault diagnostics system for helicopter main gearbox(MGB) was constructed using discrete wavelet transform(DWT) and neural network,and the DWT was used to extract feature vectors and neural network was used for fault distinguish and classification. Firstly, the theory of DWT, Parseval theorem and GRNN were introduced, and then,the flowchart of fault diagnostics system for helicopter MGB was proposed, finally, the system was verified by the vibration data which were collected during helicopter flying, and both generalized regression neural network(GRNN) and back-propagation neural network(BPNN) were used and compared on the experimental platform. Experimental results indicate that the proposed diagnostics system can distinguish the MGB fault better, which would provide a new technical reference for the further development of helicopter MGB fault diagnostics system.
Quasi-steady flow model of slot-type casing treatments Ⅰ: modeling method and validation
NING Fang-fei, FAN Lin
2012, 27(6): 1261-1269.
Abstract PDF(3001KB) icon1752 icon522
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In order to predict more efficiently the compressor flow with slot-type casing treatment as well as to provide a computationally efficient tool for the design optimization of casing treatment,a quasi-steady flow model of the slot-type casing treatment flows was developed based on the understanding of the unsteady flow physics of the rotor-casing treatment combination.The new model has been coded up and validated against a slot-type casing treatment which was examined by experiment and unsteady RANS(Reynolds-averaged Navier-Stokes) calculations.Results show that the developed model predicts the extension of the rotor stall margin due to the application of the casing treatment quite well.Moreover,as compared to the unsteady simulation results,the model well reproduces the flow field in both the rotor passage and the casing treatment.The computational expenses using the flow model is just about 1% of that using unsteady simulations.This ensures that the model can be used to give fast prediction of the aerodynamic characteristics of a compressor with slot-type casing treatment,and the design and optimization of casing treatment are thus readily applicable.
Experimental evaluation of steady-state effect of inlet radial total pressure distortion under multistage environment
XIANG Hong-hui, HOU Min-jie, GE Ning, WU Sen-lin, YANG Rong-fei
2012, 27(6): 1270-1277.
Abstract PDF(1384KB) icon1903 icon643
Abstract:
In order to evaluate quantificationally the steady-state effect of inlet radial total pressure distortion on a highly loaded multistage axial compressor,the experimental investigation of two types of radial total pressure distortions including hub distortion and shroud distortion effects on the overall and stage performances of the compressor was performed using the pressure distortion mesh and the airfoil-probe technique.The experimental results indicate that both the radial total pressure distortions deteriorate slightly the overall performance and the stability margin of the compressor.The effect of shroud distortion on the overall performance parameters agrees well with hub distortion,while the stability margin loss caused by shroud distortion is larger than that caused by hub distortion(the maximum deviation is equal to 2%).The inlet radial non-uniform airflow mixes quickly in the flowpath of the compressor and produce the corresponding total pressure loss in the mixing process.In addition,both the inlet radial total pressure distortions affect the distribution of stage loading,which results in the improvement of one stage characteristic in comparison to that in the inlet uniform condition.The above physical phenomenon is relevant to the variation range of the attack angles of the rotor blade rows.
Quasi-steady flow model of slot-type casing treatments Ⅱ: design optimization of casing treatment for a transonic rotor
FAN Lin, NING Fang-fei, LIU huo-xing
2012, 27(6): 1278-1287.
Abstract PDF(2617KB) icon1756 icon570
Abstract:
A geometrical parameterization method for the slot-type casing treatment was presented.The relation between a set of key geometrical parameters and the casing treatment performance was obtained based on the numerical simulations of the slot-type casing treatments using the developed quasi-steady casing treatment flow model.Then,an optimized casing treatment was obtained based on the previously designed baseline casing treatment and by the selection of the optimal geometrical parameters.The subsequent experiment shows that the optimized casing treatment can further improve the stall margin over that using the baseline casing treatment.Moreover,the rotor peak efficiency using the optimized casing treatment is also improved the speeds of at 60%,80% and 98% as compared to that of the baseline casing treatment case and even the solid built.Additionally,to investigate the effect of the number of slots,the experimental study of a casing treatment which was the same as the optimized one but with different slot number was also performed.
Numerical study on the rotor solidity characteristics of axial turbine element stages
YANG Jie, QIAO Wei-yang, HOU Wei-tao, WEI Zuo-jun
2012, 27(6): 1288-1296.
Abstract PDF(2461KB) icon1877 icon554
Abstract:
To explore the influence of the rotor solidity on the axial turbine element stage flow status and performance,unsteady numerical simulations on the turbine element stages with five different rotor solidity were conducted,and the rotor solidity influence on the element stage reaction,blade inlet and outlet flow angles,stator and rotor flow fields and loss status was investigated.The research results indicate that the effects of the rotor solidity alteration on the turbine element stage flow status and performance are directly associated with the stator solidity.When the stator solidity remains constant,The rotor solidity alteration changes the turbine element stage reaction by changing the mass flow rate through the element stage.As the rotor solidity increased to a certain extent,shocks will arise from the excessive expansion and acceleration of the gas flow in the stator region,as well as the flow separation caused by the shock interaction with the boundary layer.As the rotor solidity reduced to a certain extent,an large positive flow incidence will occur at the rotor inlet and cause a great range of flow separation on the rotor suction side.When the stator solidity remains constant,there's one best rotor solidity,resulting in the best turbine element stage performance.
Investigation of self-recirculating casing treatment with preswirl blowing for centrifugal compressor
KANG Jian-xiong, DU Qiang, HUANG Guo-ping, ZHU Jun-qiang, WEN Dian-zhong
2012, 27(6): 1297-1302.
Abstract PDF(932KB) icon1714 icon529
Abstract:
Numerical and experimental investigations have been conducted on a self-recirculating casing treatment for a centrifugal compressor.Stall margin improved due to redirecting the low-momentum fluid to increase the mass flow in the impeller passage and decreasing the positive attack angle in the tip region with preswirl blowing.Based on the working mechanism,parametric studies were conducted to design the casing treatment geometry.It was found that the angle of the grooves,the position and the length of overlap were three key parameters for the “best casing configuration” in terms of larger stall margin improvement and smaller lowering of efficiency according to the given range of rotating speeds.The effectiveness of this casing treatment was verified by the single stage centrifugal compressor experiments,and it was observed that the stall margin and efficiency can be improved simultaneously at lower rotating speed.
Design and numerical simulation of pipe diffuser in centrifugal compressor
WANG BO, YAN Ming
2012, 27(6): 1303-1311.
Abstract PDF(1662KB) icon1960 icon602
Abstract:
Parameterized design for three-dimensional geometry of the pipe diffuser was preformed based on programmed model-construct method.The flow field and attack angle characteristics were investigated using time-averaged numerical method,and design parameters of the pipe diffuser were analyzed and optimized subsequently.Compared with the prototype vane diffuser,the performance of a pipe diffuser with traditional circle inlet was evaluated.Further study initiated a pipe diffuser with ellipse-like inlet which would expand the working range of centrifugal compressor,and suggested the mechanism of the improvement.
Implicit algorithm for viscous compressible flow on unstructured grids
WANG Jing-yu, GE Ning, SHENG Chun-hua
2012, 27(6): 1312-1319.
Abstract PDF(1531KB) icon1593 icon523
Abstract:
An implicit algorithm for solving three-dimensional viscous compressible flow on unstructured grids was described.Newton's method and Roe approximate scheme which was used to evaluate the flux Jacobians were chosen to solve Navier-Stokes equations.Three representative flow cases including plate,transonic turbine vane Mark-Ⅱ and CW-22 were simulated.The results of numerical simulation show favorable agreement with exact solution in theory and experimental data,and the flow phenomena such as shock and secondary flow were predicted accurately.These suggest that this unstructured implicit Navier-Stokes flow solver can predict aerodynamic performance correctly.
Implicit coupled solution of the combustion chamber with the spray
ZHENG Qun, LI Yi-jin, SUN Lan-xin
2012, 27(6): 1320-1325.
Abstract PDF(673KB) icon2033 icon641
Abstract:
In unstructured grid,open source was used to simulate the spray combustion process in annular combustor of a certain turbojet engine.At first,the k-ε two-equation model,EBU (eddy break up) -Arrhenius turbulent combustion model,and particle stochastic trajectory model were selected to simulate the physical process of flow field.Then implicit coupled algorithm was described for solving gas flow,the Lagrangian method was used to track the movement of droplets in the fluid region,and two-way coupling was used for the effect between gas phase and droplet phase.Distributions of temperature,mach number,velocity and pressure obtained from simulation experiments were reasonable,and distribution of temperature was roughly in accord with that of the literature.This shows that implicit coupled method can well simulate the flow fields in combustion chamber,and reflect internal flow features of it.
Design and calculation of aircraft nacelle anti-icing system
ZHU Yong-feng, FANG Yu-feng, FENG Wen-chun
2012, 27(6): 1326-1331.
Abstract PDF(1036KB) icon1979 icon573
Abstract:
The structure and theory of engine nacelle anti-icing (NAI) system were introduced.According to the principle that the heat available should be larger than the heat required,the critical design point and required flows of NAI were determining by calculating the required bleed air at complete evaporation and running wet station respectively.The coefficient of water collection of NAI system was determined using Euler method based on the coefficient of water collection of wing and the data similarity rule.According to the theory of allowed maximum thickness of ice,the performance of NAI system was calculated using the VSAERO/ICE software.The result of simulation shows that the maximum thickness of ice can meet at the critical condition.
Separation performance of hollow fiber membrane for on-board inerting gas generating system
FENG Shi-yu, LU Ji, LIU Wei-hua, JIANG Jun-chang, LIU Su-yan
2012, 27(6): 1332-1339.
Abstract PDF(1143KB) icon1846 icon652
Abstract:
The mathematical model of the hollow fiber membrane of on-board inert gas generation system (OBIGGS) is set up in term of the differential method,and solved by the Runge-Kutta method.The comparison between calculating results and experimental data published in literature reveals that the deviation is within 10%.Furthermore,this theoretical model is employed to analyze the influence of the specific feed flux of membrane area,pressure ratio of membrane fiber,the separation factor and the permeability coefficient to the volume fraction of oxygen in production gas and the production efficiency of nitrogen.The study shows that though the increase of the specific feed flux of membrane area could positively promote the production efficiency of nitrogen,the volume fraction of oxygen reduces sharply.Hence,an appropriate process of OBIGGS should be designed to overcome the disadvantage mentioned above.The increase of the pressure ratio and the permeability coefficient of oxygen will decrease the production efficiency of nitrogen and the volume fraction of oxygen,but the influence of the permeability coefficient is slight.Therefore,the increase of the permeability coefficient of oxygen is beneficial to the separation performance.Based on the experimental data and the model,the change of the separation ideal level related to the temperature and pressure is analyzed,the result shows that the pressure ratio will make greater effect on the separation ideal level.When the pressure ratio increases,the actual separation process will deviate from the theoretical one gradually.
Effect of film cooling hole entrance position on film cooling characters in the cross-flow passage with ribs
LI Chun-lin, ZHU Hui-ren, BAI Jiang-tao, DU Xiao-qin, ZHOU Lei-sheng
2012, 27(6): 1340-1346.
Abstract PDF(1481KB) icon1629 icon519
Abstract:
Effect of the relative position between film cooling holes and ribs on the film cooling effectiveness and heat transfer in a channel with cross-flow and ribs was investigated numerically.The effect of position where film cooling holes were close to upstream ribs,downstream ribs and in the middle region of ribs on the cooling effect was studied with blowing ratio of 0.5,1 and 2,with cross-flow ratio of 0.39,0.585 and 0.78.The results show that,in the case of the film cooling hole entrance in the middle of two ribs,the flow in the hole are influenced heavily by the entrance jet,the heat transfer coefficient and film cooling effectiveness are higher.In the case of the film cooling hole entrance near the up-stream rib,the heat transfer coefficient and film cooling effectiveness are lower.
Experimental investigation on cold flow characteristics of afterburner with cavity/strut hybrid flameholders
QIN Wei-lin, HE Xiao-min, JIN Yi, JIANG Bo
2012, 27(6): 1347-1354.
Abstract PDF(2846KB) icon2132 icon559
Abstract:
Particle image velocimetry (PIV) was used to experimentally study the cold flow field of a model rectangular afterburner with cavity/strut hybrid flameholders.The varieties of the total pressure loss coefficient and the cold flow field were obtained.The results show:with the inlet deflective angle (5°~17°) increases,the flow field after the strut flameholders becomes less uniform,indicating worse rectification of the flameholders.As the inlet Mach number (0.18~0.30) increases,the trapped vortexes in the cavity become more stable and the radial penetrating depth of the air from the cavities increases.The width of the recirculation zone and the total pressure loss increase when the inlet Mach number increases.The total pressure loss coefficient of the afterburner is higher than that of an afterburner with V-gutters.
Design and numerical investigation of hypersonic inward turning inlet with water-drop like shape intake
LI Yong-zhou, Zhang Kun-yuan, NAN Xiang-jun, ZHANG Lin
2012, 27(6): 1355-1361.
Abstract PDF(1261KB) icon1830 icon493
Abstract:
The water-drop like shape to circular shape transition hypersonic inward turning inlet has been designed with the technology of streamline tracing and gradual change section,using an axisymmetric basic flowfield with controllable pressure rising distribution.Numerical simulations were conducted on both design point and translation point,and the comparison of performance was performed with the rectangular to circular shape transition inward turning inlet with the same design parameters.The results indicate that two types of inward turning inlet have the roughly equivalent general performance,while the water-drop like shape intake has a more uniform exit flowfield and a better starting characteristic.Furthermore,the flowfiled structure of water-drop like shape intake is asymmetric due to the asymmetric geometry shapes.
Influence of entropy layer on aerodynamics parameters for hypersonic 2-D blunt wedge
CHENG Xing-hua, YANG Tao, CHANG Zhong-dong
2012, 27(6): 1362-1367.
Abstract PDF(737KB) icon1725 icon661
Abstract:
Using thin shock layer theory and mass conservation of stream tube,the entropy distribution of boundary layer exterior margin was analyzed for hypersonic two-dimensional(2-D) blunt wedge,and the influence of entropy layer on aerodynamics parameters such as density,Mach number,and aeroheating,et al.,was investigated.The results show that the entropy of boundary layer exterior margin dropped more quickly in rounding-shoulder region,and the influence of entropy layer on aerodynamics parameters should not be neglectable,which especially augmented the aeroheating 53.6% in transition and turbulent region.So,controling the flow of wall to stay in laminar model is very important for thermal protection of hypersonic vehicle.
Optimum airfoil design on an heavy amphibious aircraft
QIN He-jun, ZENG You-bing
2012, 27(6): 1368-1374.
Abstract PDF(857KB) icon1709 icon530
Abstract:
The research discussed focused upon the optimal airfoil shape design of a heavy amphibious aircraft.A new airfoil with better general performance was attained through the optimal airfoil design,of which the objective was to reduce the drag coefficient on a given airfoil with constant lift coefficient.Restricted the pitch moment,the maximum lift,and the lift drop rate of stalling angle.Made the relative thick,the maximum camber,and the relative position of the maximum thick according with the design request.This design method is fit for the airfoil design on a heavy amphibious aircraft,and is a better optimal airfoil shape design which is suit for the engineering application.
Numerical simulation for magnetohydrodynamic inlets control using electron beam ionization
ZHANG Xiang-hong, WU Yi-zhao, WANG Jiang-feng
2012, 27(6): 1375-1383.
Abstract PDF(1619KB) icon1922 icon510
Abstract:
The magnetohydrodynamic (MHD) controlling of hypersonic boundary layer and hypersonic inlets in off-design conditions were studied by magnetohydrodynamic control system based on electron beam ionization.The governing equations were low magnetic Reynolds number Navier-Stokes(N-S) equations,and the plasma kinetics model coupled with electron beam model was developed to simulate air ionization.Results indicate :(1)The electron beam ionization can improve the conductivity of flow and the control efficiency of magnetic field .(2)The MHD system can effectively control the hypersonic boundary layer and the control efficiency closely related with the electron beam energy .(3)The MHD system can bring oblique shock in off-design conditions back to the location of shock-on-lip(SOL) condition,and the total pressure recovery coefficient and flow mass of inlets would be reduced.
Aerodynamic optimization design of high bypass ratio separate-flow exhaust system based on parallel multi-objective genetic algorithm
XIONG Jian, WANG Xin-yue, SHI Yong-qiang, YAN Zi-guang
2012, 27(6): 1384-1390.
Abstract PDF(919KB) icon1740 icon532
Abstract:
Simple genetic algorithm(GA) was improved with fast non-dominated sort approach,crowded distance estimation and crowded comparison operator.A new algorithm called parallel multi-objective genetic algorithm(PMGA) was developed using the master-slave parallel programming model with the support of massage passing interface (MPI).To establish the aerodynamic optimization design platform for high bypass ratio separate-flow exhaust system,PMGA was combined with profile parameterization of exhaust system and Navier-Stokes solver.With this platform,aerodynamic optimization design of the high bypass ratio separate-flow exhaust system was performed,and a set of Pareto-optimal solutions which was better than the initial design in three objectives was obtained.Detailed comparison and analysis of the Pareto-optimal designs and initial design confirmed the high efficiency and validity of the parallel multi-objective aerodynamic optimization design platform.
Characterization of nozzle thermal and ablation response in dual-pulse solid rocket motors
ZHANG Xiao-guang, LIU Yu, WANG Chang-hui
2012, 27(6): 1391-1397.
Abstract PDF(1511KB) icon1711 icon484
Abstract:
In order to investigate the nozzle thermal and ablation characteristics in dual-pulse solid rocket motors,the transient value of the throat diameter was obtained from the pressure and thrust measurements.Furthermore,the in-depth thermal response,pyrolysis/char profiles and surface recession of the nozzle assembly were predicted through fully coupled fluid-solid analysis using the commercial code FLUENT.Results show that during pulse operation,the insulation material pyrolysis/char profiles expand and the nozzle insert erosion rate increases.During pulse separation,heat conduction in the material leads to the decrease in the material temperature difference.The heat transfer and ablation processes of pulse 1 and pulse separation make the nozzle insert exhibit small heat sink,high surface temperature and large surface roughness,which would result in higher throat erosion rate when pulse 2 operates.
Three-dimensional numerical simulation of hybrid rocket motor operation process
LI Xin-tian, TIAN Hui, ZENG Peng, CAI Guo-biao
2012, 27(6): 1398-1404.
Abstract PDF(1068KB) icon1816 icon628
Abstract:
According to the coupling between the solid fuel and gaseous phases,the solid fuel regression rate model was established.Three-dimensional numerical simulation of a star-shaped fuel grain hybrid rocket motor with hydrogen peroxide(H2O2) and hydroxyl-terminated polybutadiene(HTPB) propellants combination was presented.The flow field and the solid fuel grain regression rate distribution were obtained,and the results were compared with that of two-dimensional axial symmetry engine.The results indicate that the flame layer profile is similar with the star-shaped fuel port,while the thickness and the location of the flame makes differences in the root and the slot of the star-shape.With the axial coordinate increasing,the oxidizer consumes continually,and the flame layer shifts toward the centre of the fuel grain port.The solid fuel regression rate relates with the oxidizer mass flux and solid fuel location.It increases with the oxidizer mass flux growing,and is higher in the root of the star-shape than in the slot.The solid fuel regression rate of three-dimensional fuel grain is larger than two-dimensional axial symmetry under the same oxidizer mass flux.
Static characterization of bump-type gas foil bearing: intergration of top foil 2-D thick plate model
LIU Zhan-sheng, XU Fang-cheng, ZHANG Guang-hui, CAO Zhi-xuan
2012, 27(6): 1405-1415.
Abstract PDF(1731KB) icon2507 icon502
Abstract:
The 2-D(two-dimensional) thick plate finite element model for top foil was developed.By using coupled finite element mothod and finite difference method,the compressible gas lubricated Reynolds equation and the film thickness equation were solved coupling together.Predictions of minimum gas film thickness for increasing static loads at two speeds were obtained for bearing mid-plane and edge of bump-type gas foil bearing.The numerical results of this finite element model were compared with 1-D(one-dimensional) beam model model,2-D shin shell model and test data.The results indicate that the minimum film thickness of three models agree well with test data at bearing min-plane,but at bearing edge,the accuracy of 2-D thick plate model is the highest due to its shear effect.1-D beam model can not reflect film thickness variation along the bearing length direction because it only considers the circumferential direction.The study in this paper established the theoretical foundation of dynamic characteristics research of bump-type gas foil bearing.
Method of stability region determination for planetary gear train's parameters based on nonlinear vibration model
LI Tong-jie, ZHU Ru-peng, BAO He-yun, XIANG Chang-le, LIU Hui
2012, 27(6): 1416-1423.
Abstract PDF(1668KB) icon1697 icon523
Abstract:
A general method of stability region determination for a planetary gear train's parameters was studied based on a nonlinear vibration model.There are five steps in the method,and the first step was threshold determination,the second step was deciding numerical integration time according to the motion state of the system when the parameters discussed changed in their test range,the third step was calculating the maximum displacement of the system when the parameters discussed changed in their test range by using nested loop algorithm,the fourth step was stability judgment by comparing maximum displacement with threshold and the last step was making the stability region map of the system.As an example,the stability region determination of a planetary gear train with errors of transmission,time varying meshing stiffness and gear backlashes was studied,and the stable regions of sun gear's rotational speed,backlashes of the system and relative damping ratio were calculated respectively.
Tooth meshing contact analysis for bevel gears by face hobbing method based on arc blade profile
NIE Shao-wu, DENG Xiao-zhong, LI Tian-xing, ZHANG Hua, DENG Jing
2012, 27(6): 1424-1431.
Abstract PDF(1109KB) icon2248 icon506
Abstract:
In order to improve tooth contact quality of bevel gears by face hobbing method,the straight-line blade profile modified with arc profile and tooth meshing analysis was studied based on generating method of Oerlikon bevel gears.Firstly,the arc blade profile geometry was designed,and the arc blade edge equation was derived.On the basis of mathematical model of bevel gears by face hobbing method,the theoretical tooth surface equation of processed gear was derived.The effect of blade profile modified with arc shape on tooth surface was studied,and the modified quantity of tooth flank was calculated by the use of numerical method.The mathematical model of gears testing with alignment errors was established,and the simplified algorithm of tooth contact analysis was derived.Finally,making tooth contact analysis for Oerlikon bevel gears processed with arc blade profile,the results demonstrate that modifying tooth surface with arc blade profile by selecting appropriate radius not only can reduce risk to edge contact,lower sensitive to alignment errors,and improve bias-in contact quality,but also can revise contact areas for two tooth surfaces,respectively.
Fault diagnosis and isolation of the component and sensor for aircraft engine
QIU Xiao-jie, HUANG Jin-quan, LU Feng, LIU Nan
2012, 27(6): 1432-1440.
Abstract PDF(2759KB) icon1323 icon539
Abstract:
Aircraft engine component and sensor fault detection and isolation approach was proposed,which included fault type detection module and component-sensor simultaneous fault isolation module. The approach can not only distinguish among sensor fault, component fault and component-sensor simultaneous fault, but also isolate and locate sensor fault and the type of engine component fault when the engine component fault and the sensor faults occur simultaneously. The double-threshold mechanism has been proposed, in which the fault diagnostic threshold changed with the sensor type and the engine condition, and it greatly improved the accuracy and robustness of sensor fault diagnosis system. Simulation results show that the approach proposed can diagnose and isolate the sensor and engine component fault with improved accuracy. It effectively improves the fault diagnosis ability of aircraft engine.

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