2012 Vol. 27, No. 11

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Impingement characteristics and anti-icing heat load calculation of certain tailplane
ZHAO Yong, YANG Xin-liang
2012, 27(11): 2401-2407.
Abstract PDF(682KB) icon1651 icon550
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To obtain water droplet impingement characteristics by Eulerian method,a math model was built.Also,a computational model of the heat load was established,which was based on the Messinger conservation of mass and energy.Focusing on the three-dimensional tailplane of a certain aircraft,the calculation of impingement characteristics and heat load was performed.It was found that the local water collection efficiency of tailplane raised from wing root to wing tip.The water local collection efficiency distributions of different slices provided a basis for the design of anti-icing system region.The results show that heat load is higher near the stagnation point,top airfoil and lower airfoil.It is concluded from the results that three electricity heating anti-icing regions are designed on the tailplane:the middle continuous heating region and the intermittent heating regions near the stagnation on the top airfoil and the lower airfoil.
Numerical simulation of H2O vitiation effects on kerosene-fueled scramjet combustor performance
XING Jian-wen, XIAO Bao-guo
2012, 27(11): 2408-2413.
Abstract PDF(805KB) icon1961 icon631
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Experiments on the direct-connect dual-mode Kerosene-fueled scramjet engine with two cavities were conducted in the supersonic combustion facility to compare the combustor performance under clean air and air vitiated with H2O conditions.The primary objective was to understand the complicated issues with regard to the effects of air-stream vitiation on scramjet test performance.A set of comparative combustion tests were conducted with the same test gas parameters of nominal Mach number 2,total temperature of about 828K and total pressure of about 800kPa.The simulations of reacting flowfield in the combustor under the same experimental conditions were conducted using flow solver AHL3D.The calculation results were close to experimental data.The final objective was to provide insight into the detail of combustion flow which was not resolved by the available instruments.
Effect of turbulence models on numerical simulation of flow and infrared radiation characteristic of aero-engine exhaust system
HU Ya-ping, JI Hong-hu, BAI Tao-tao
2012, 27(11): 2414-2420.
Abstract PDF(738KB) icon2060 icon665
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The flow field and infrared radiation (IR) characteristics of an aero-engine exhaust system were simulated with three turbulence models, including k-ω shear-stress transport (SST) model,renormalization group (RNG) k-ε model with standard wall functions and RNG k-ε model with enhanced wall functions.The results show that among the three methods, the static pressures are nearly the same,but the distributions of temperature,species and IR are different.The temperature of gas and the inner wall of inner duct,the mass concentration of species and IR are the greatest when RNG k-ε model with enhanced wall functions is used;those are the second when RNG k-ε model with standard wall functions is used,and the results of k-ω SST model are minimal.The comparison of experimental data and those of computation shows that the IR results of k-ω SST model are more reasonable.
Fuel spray characteristic of TAPS/MLDI low emission combustor
XU Rong, ZHAO Jian-xing, LIU Yong, YAN Ying-wen, WANG Suo-fang
2012, 27(11): 2421-2428.
Abstract PDF(1716KB) icon1712 icon531
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A particle image velocimetry (PIV) was employed to measure fuel spray fields of the TAPS/MLDI (twin annular premixing swirler/multipoint lean direct injection) low emission combustor under different inlet conditions.The influences of different fuel flow rates with various fuel injection fashions on fuel spray characteristic of the low emission combustor were experimentally investigated.Results show that:the number of droplet with the size of 40μm reaches maximum under experimental conditions.The number of droplet,which is larger or smaller than the droplet size of 40μm,harply decreases.When the pilot fuel atomizer is operated,the fuel atomization is worsened with the increase of the fuel flow rate.When the primary fuel injector is operated,the fuel atomization is slightly improved with the increase of the fuel flow rate.When the pilot and primary atomizer are operated at the same time,the inlet fuel air ratio is the same,and the effect of the decrease of primary fuel flow rate and increase of pilot fuel flow rate on the fuel atomization is weak.
Numerical simulation of the infrared radiation characteristics and infrared restraining effect of lower wall temperature for two-dimensional plug nozzle
CHEN Jun, JI Hong-hu
2012, 27(11): 2429-2435.
Abstract PDF(1071KB) icon1717 icon531
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A numerical study was conducted on infrared radiation characteristics in the waveband of 3~5μm for two-dimensional plug nozzle of a turbofan engine,which was compared with an axisymmetric converge-diverge nozzle.The results reveal that:compared to axisymmetric converge-diverge nozzle,there is only a limited range of detecting angle,where the two-dimensional plug nozzle has infrared restraining effect.The infrared radiation of two-dimensional plug nozzle decreases 54% as the detecting angle equals to 90° on the narrow detecting side.On the condition that the back wall temperature of plug decreases 300K,the two-dimensional plug nozzle has visible infrared restraining effect on most detecting angle;moreover,its infrared radiation intensity decreases 57% towards the aft-nozzle.
Forced ignition of kerosene spray in supersonic airflow with hot gas injection
XI Wen-xiong, WANG Zhen-guo, LI Qing, LIANG Jian-han
2012, 27(11): 2436-2441.
Abstract PDF(738KB) icon1761 icon535
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Forced ignition of kerosene spray with hot gas injection was investigated experimentally in an expanding scramjet combustor with incoming air total temperature of 800K and Mach number 2 which was related to a typical cold start-up condition of dual-model scramjet.The fuel was injected vertically into the crossflow upstream the flame-holding cavity.The kerosene spray shadow and self-luminosity flame evolvement during the process of ignition were observed using high speed camera.The effects of injection scheme such as position and direction of hot jet on the ignition results and cavity-trapped flame generation were compared and analyzed.Results reveal that the enhanced ignition by hot gas injection is characterized by the far-field diffusive burning between spray and hot jet.The trapped flame within cavity is created due to the flame propagation upstream which is the dominant mechanism of successful flame establishment.
Experiment of performance of interstage turbine combustor
DING Guo-yu, HE Xiao-min, JIN Yi, QIN Wei-lin, WU Ze-jun, JIANG Bo
2012, 27(11): 2442-2447.
Abstract PDF(670KB) icon1806 icon526
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Experiments were conducted to study the interstage turbine combustor performance with different inlet air Mach number and the excess air coefficient of cavity.Experimental result shows that total pressure loss increases from 1.5% to 7% varying with the increase of the inlet air Mach number,the flow drag coefficient is 16 which changes little with the inlet air flow Mach number,and overall temperature distribution factor (OTDF) increases with the increase of the inlet air Mach number;OTDF holds the line as the excess air coefficient of cavity increases while the combustion efficiency decreases;the combustion efficiency is almost between 70% through 85%;the maximal lean blow out(LBO) excess air coefficient is 9.7 at the inlet air temperature of 473K.
Numerical investigation of combination of direct mixing combustion and LPP combustor
LIU Qiang, SUO Jian-qin, LIANG Hong-xia, LI Ming, Li Han
2012, 27(11): 2448-2454.
Abstract PDF(1118KB) icon1670 icon680
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A combination of direct mixing combustion and lean premixed prevaporized(LPP) single-module tubular combustor was designed.Numerical investigation of the combustor was conducted with software fluent.The results show that main flame zone is independent from pilot flame zone;pilot module operates as a direct mixing flame for anchoring main flame.Main module operates as a premixed flame,providing a uniform temperature distribution in combustion zone,which reduces NOx emissions.The contradiction was solved between the low NOx emissions at high power conditions and flame stabilization at low power conditions.
Effect of trench hole depth and momentum flux ratio on film cooling characteristics
WANG Zhen-wei, ZHU Hui-ren, ZHANG Zong-wei, MENG Qing-kun
2012, 27(11): 2455-2461.
Abstract PDF(1301KB) icon1677 icon501
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Film cooling characteristics of trench hole were measured using a transient liquid crystal full-surface measurement technique.The influence of momentum flux ratio (I=0.5,1,2,4) and trench depth (s=0.5 D,0.75D,D;D stands for film hole diameter) were studied comparison between trench hole and cylindrical hole was conducted.The results show that the trench suppresses coolant jet separation,and the trench hole provides greater lateral film coverage compared with the cylindrical hole.An optimum trench depth is s=0.75 D.With a further increase in momentum flux ratio,the cooling effectiveness levels start to plateau,so increased coolant would not be warranted because only a slight increase in film cooling effectiveness would occur.
Aerodynamic stability design method for certain aero-engine in whole engine's flight operating envelope
LIU Yong-quan, SHI Lei, LIANG Cai-yun
2012, 27(11): 2462-2467.
Abstract PDF(336KB) icon2356 icon568
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According to the basic theory of aerodynamic stability and engineering experience,an aero-engine,for example,aerodynamic stability design method in the whole flight envelope was presented on the basis of GJB/Z 224-2005,and some experimental verification were performed.The results show that stability margin required of fan and compressor is larger at high-altitude and low-speed state,stability margin required of fan is larger at right boundary of the engine envelope and basically remains the same,affected by the nozzle subcritical,stability margin required of fan is larger during landing.Therefore,these conditions should be focused in the engine design and use.Engine should be designed to ensure that the stability margin available of fan and compressor is greater than the stability margin required.The design method can effectively meet the demand for complex engineering development.
Research on variable geometry technology of 2-D hypersonic inlet with contract ratio under controlling
YUAN Hua-cheng, TENG Jian, GUO Rong-wei
2012, 27(11): 2468-2474.
Abstract PDF(1171KB) icon1919 icon536
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Based on the two-dimensional(2-D)fixed hypersonic,a new concept of variable geometry hypersonic inlet that the tip moving back off to increase the mass capture ratio was presented.The flow in the hypersonic inlet was analyzed with two-dimensional numerical analyzer,and the inlet performance comparisons were made between the variable geometry hypersonic inlet and fixed inlet at different Mach numbers of inflow.The results indicate that the performance of the variable geometry inlet in the same as that of the fixed one at design Mach number,and the performance of the variable geometry inlet is better than that of the fixed inlet at non design point.All of them indicate that the variable geometry hypersonic inlet is satisfying.
Design and validation of scheme of over/under TBCC inlet
ZHANG Hua-jun, GUO Rong-wei, XIE Lü-rong
2012, 27(11): 2475-2483.
Abstract PDF(1185KB) icon1885 icon553
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Scheme of an over/under type TBCC inlet with variable geometry bleed cavity was presented.The general design methodology of the inlet was introduced and the design Mach number,transition Mach number and flight trajectory were provided.Discussion was conducted concerning the work mode of the inlet under different free stream conditions and the adjustment of the geometry shape of the inlet in the range of flight Mach number,based on which the major aerodynamic parameters and the selection principle of shape parameters were confirmed.Through methods of numerical simulation and high speed wind tunnel experiment,the feasibility of the scheme of the inlet was validated.The numerical simulation results indicate:when the free stream Mach number is less than 2.5,the total pressure recovery of the inlet is beyond 0.8.When the free stream Mach number is from 2.5 to 4.5,the total pressure recovery of the inlet is beyond 0.3.The aerodynamic characteristics of the inlet meet the demands of the scheme.At ramjet mode,the exit Mach number of the ramjet diffuser is below 0.4 and the exit pressure of the ramjet diffuser is beyond 0.5 standard atmosphere pressure.The ramjet diffuser can fulfil the combustion condition of the ramjet combustion chamber.The wind tunnel experiment results indicate:in mode transition,the turbojet diffuser has good matching characteristics with the engine and the turbojet/ramjet diffusers have good compatible characteristics.therefore it can be concluded that the scheme of the inlet is viable.Results of the research would provide scheme reference and technology storage for the combined cycle propulsion evolution in our country.
Design of hypersonic inward turning inlets base on concept of controllable Mach number distribution
LI Yong-zhou, ZHANG Kun-yuan, NAN Xiang-jun
2012, 27(11): 2484-2491.
Abstract PDF(1161KB) icon1825 icon548
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A method has been devised for the design of hypersonic inward turning inlets.On condition that the Mach number distribution along the surface has been given,this method applied the rotational method of characteristics to design the basic axisymmetric flowfield and applied stream tracing techniques to generate an inviscid configuration,and then,designed final inlets with viscous correction.Several categories of typical basic flowfield designed under the same constraint were analyzed comparatively.The hypersonic inward turning inlets with circular shape intake were designed using the basic flowfield of arc tangent Mach number distribution.The numerical simulation results indicate that the category of inlets has good mass capture ratio and compression efficiency.This design method is feasible and extends the scope of basic flowfield,so it deserves further investigations.
Study of novel flow control concept for fix-geometry two-dimensional mix-compression supersonic inlet
WENG Xiao-chai, GUO Rong-wei
2012, 27(11): 2492-2498.
Abstract PDF(842KB) icon1521 icon524
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A novel flow control concept was presented to improve the performance of fix-geometry two-dimensional mix-compression supersonic inlet when the free stream Mach number was lower than the cruising Mach number.This concept is placing a special bypass-slot at the front-end of the second ramp,which can change the configuration of the shock wave system to enhance the performance of the inlet.The numerical results indicate that when the free stream Mach number is smaller than the cruising Mach number,compared with the initial inlet,the flow control can raise the total pressure recovery coefficient and mass flow ratio significantly.Whereas the performance of the inlet declines little at the design point with the bypass-slot shut.In conclusion,the flow control concept is beneficial to the ramjet engine under the speeding up condition.
Improved weighted essential non-oscillatory methods in hypersonic heat-flux simulation
WANG Chao, WU Song-ping
2012, 27(11): 2499-2504.
Abstract PDF(676KB) icon1467 icon522
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Numerical scheme is one of the most important factors for hypersonic heat-flux numerical simulation.Weighted essentially non-oscillatory (WENO) scheme was improved to meet the above requirementsutilizing hypersonic flow characteristics to control the numerical dissipation.The improved scheme can effectively distinguish shock and other regions of large gradients with high resolution,and reduce numerical dissipation to improve numerical high-resolution near the wall.Three numerical experiments indicate that the numerical method proposed here is effective.
Study of environment analysis and thermodynamic on Venus balloon
LEI Yan-peng, YANG Chun-xin
2012, 27(11): 2505-2510.
Abstract PDF(816KB) icon1588 icon497
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The Venus atmospheric environment was described with mathematical model.The Venus balloon thermodynamic model was established.Then,the floating process of a helium prototype balloon,of which the floating altitude was designed as 35km,was numerically designed by this model.The results show that when the Venus balloon is released at the altitude between 30km and 40km,it can reach floating altitude quickly and keep long-term floating,the balloon system should endure the temperature between 440K and 520K,its instantaneous maximum speed is less than 10m/s.This research would provide basis for the further development of Venus balloon further development.
Numerical investigation on unsteady flow structure in supersonic inlet coupled with pulse detonation engine combustor
WEN Yu-fen, TAN Hui-jun, ZHANG Qi-fan, CHENG Dai-shu
2012, 27(11): 2511-2520.
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The flowfield in a supersonic inlet coupled with a pulse detonation engine(PDE) combustor and nozzle was numerically studied by an unsteady CFD method involving chemical reactions.Emphasis was placed on the flow structure of the supersonic inlet which was unsteadily interfered by the detonation wave and its reflected shock.A comparison of the performances of the three models using different coupled methods was also conducted.Results indicate that by injecting premixed fuel and oxidant into the combustor,stable and self-sustaining detonation wave is successfully generated in the combustion process.Due to the pressure perturbation caused by the detonation wave,a shock system and a reflected shock are generated in the duct.Mutual interference between them is observed,and it is found that their transformation in the duct has affected the oscillatory amplitude of the shock system.By comparing the flow characteristics of the three models with different coupled methods,it is noted that due to the buffering effect of the combustor head wall and the effect brought by the reflected shock,the two models which employ the abrupt diverging conjunction of the inlet and the combustor are able to deposit a majority of the compressed air in the combustor,which in turn significantly weakens the interference between the inlet and the combustor and makes a contribution to the stability of the inlet.Furthermore,the concave combustor head introduced can accommodate an extra volume of the high density compressed air,which results in a further reduction of the detonation-induced pressure,and leads to a larger stability margin of the inlet for the pulse detonation engine.
Effect of ratio of radius to thickness on buckling and post-buckling behaviors of metallic spherical-cone diaphragms for positive expulsion tanks
QIANG Hong-fu, ZHOU Suan, WANG Guang, WANG Xue-ren
2012, 27(11): 2521-2528.
Abstract PDF(1569KB) icon1659 icon517
Abstract:
Effects of radius and ratio of radius to thickness on positive expulsion process of metallic spherical-cone diaphragms were numerically analyzed by finite element method (FEM),and analysis results were verified by several typical samples of radius and ratio of radius to thickness.Numerical results were listed as follows:diaphragms of which the radiuses were too large or too small showed apparent scaling effect,and that of smaller radius was more markable;buckling and post-buckling equilibrium configurations of diaphragms of which the radiuses were from 203mm to 403mm were identical;expulsion efficiency of diaphragms of which the ratios of radius to thickness were too large or too small was low because of weak load-carrying capacity or buckling loads of diaphragms increasing as exponential series along with smaller ratios of radius to thickness respectively.However,expulsion efficiency of diaphragms of which the ratios of radius to thickness were from 160 to 400 was high,and post-buckling equilibrium configurations of those diaphragms showed the same trend.At last,numerical results of typical samples testified the above conclusions.
Moving multi-point average method for determining functions of time series mean and variance
WANG Zhi-hua, FU Hui-min, ZHANG Yong-bo
2012, 27(11): 2529-2533.
Abstract PDF(281KB) icon1565 icon545
Abstract:
A moving multiple-point average (MMPA) method was proposed to enhance the determining precision for time series mean and variance functions, and consequently to improve the accuracy for time series modeling, analyzing and forecasting. Non-periodic part of trend item which can be obtained by the MMPA approach, and the periodic part of trend item which can be calculated by sample periodogram method, comprise the whole trend function. We can further determine the series standard deviation function. Monte Carlo simulation study shows that not only the analysis precision but also the prediction accuracy can be ensured by the established methodology.
Implicit stress integration algorithm for Chaboche anisotropic viscoplastic constitutive equations
WANG Qing-wu, ZHANG Shi-hui
2012, 27(11): 2534-2538.
Abstract PDF(525KB) icon1722 icon515
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Chaboche anisotropic viscoplastic constitutive equations were rewritten and the implicit stress integration algorithm was obtained by the governing parameters method.In the algorithm,all the unknowns were expressed by the same parameterwhich forms a governing equation.Therefore,the problem integrating stress was changed into one solving nonlinear equation.This algorithm procedure was embedded in the finite element program Marc, and the experiment examples of uniaxial tension,cyclic loading and relax mean stress relaxation were simulated on single element.From the comparison of implicit algorithm with the explicit one,the results show improvement in steadiness and convergence.The comparisons conducted on component finite element calculations also show that implicit algorithm has higher efficiency than explicit one.
Fault diagnosis for multistage dynamic processes based on signed directed graph
ZHOU Hong, ZUO Hong-fu, SU Yan, BAI Fang
2012, 27(11): 2539-2546.
Abstract PDF(507KB) icon1651 icon546
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After analyzing the dynamic characteristics of multistage processes,new qualitative description model—process dynamic signed directed graph (PDSDG) was proposed by introducing the stage conditions to unmeasured nodes in SDG.The modeling method and a D matrix-based diagnosis method were given.The proposed model can meet the demand of adjustment along with the conditions,and the diagnosis method disposed the nodes that were not online observed.PDSDG had better resolution than static SDG by comprehensive consideration of different stage diagnosis results.Finally,the fault diagnosis model of an aircraft engine bleed system was built with the proposed method.The case results proved the effectivity and utility of this model.)
Effect of blade stagger angle on forced response of bladed disk assemblies
LAN Hai-qiang, ZANG Chao-ping
2012, 27(11): 2547-2552.
Abstract PDF(757KB) icon1725 icon628
Abstract:
Using simplified finite element model and the accelerated Monte Carlo simulation based on extremum principle,the forced response characteristics of bladed disks with stagger angle mistuning were investigated in detail.Six different variations of stagger angle error were simulated and corresponding probability density functions of response magnification factors were calculated separately.By comparing different curves,effect regularity of bladed stagger angle on the forced response of bladed disk assemblies was explored.Results indicate that stagger angle mistuning has small effect natural frequencies,but has a great effect on the blade response.The forced response would increase when stagger angle mistuning strength increases.
Three-dimensional analysis of two-stage high pressure turbine
ZENG Jun, WANG Bin, QING Xiong-jie
2012, 27(11): 2553-2561.
Abstract PDF(1578KB) icon1556 icon477
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The blade profiles of a two-stage high pressure turbine(HPT) were redesigned using 3-D viscous turbine design system developed independently,and the 3-D analysis with cooling air and transition being considered was conducted by commercial software CFX 12.0.A two-equation turbulence model shear stress transportation (SST) was used.The film cooling flow was dealt with using source term modeling techniques.The comparison of calculation results and the test data shows that the predicted efficiency agrees well with the test data,and aft-loaded technique can reduce loss effectively for the cooling blade profile of normal level HPT.
Numerical investigation on flowfield of centrifugal compressor with tandem cascade diffuser
ZHOU Li, WEI Wei, CAI Yuan-hu
2012, 27(11): 2562-2568.
Abstract PDF(1218KB) icon2087 icon543
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The flowfield of the centrifugal compressor with tandem cascades diffuser was investigated numerically,the effects of varying circumferential position of tandem cascade diffuser on a high pressure ratio compressor performance and flowfield in the diffuser was discussed.The comparisons of the compressor stage performance and flow field of 5 tandem cascade diffusers with a conventional single row design of a similar duty were made.Results show that the performance of the stage with the tandem cascade diffuser is superior to the stage with single row diffuser,the efficiency and pressure ratio can increase 1.9% and 2.85% respectively.The circumferential position of the tandem cascade diffuser has an important effect on the stage performance;an optimum circumferential position exists to make the loss in the diffuser minimum.The loss in the tandem cascade diffuser mainly focuses on the region from the middle span to the shroud.
Study of unsteady tip leakage flow characteristic in high pressure turbine stage
WANG Da-lei, PIAO Ying, CHEN Mei-ning
2012, 27(11): 2569-2576.
Abstract PDF(1550KB) icon1727 icon504
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Three-dimensional time-dependent Reynolds averaged Navier-Stokes equations were solved to investigate the unsteady tip leakage flow in a transonic high pressure turbine stage.The changing rules of tip leakage flow as well as the reasons were indicated based on the study of the effect of stator trailing edge wake and shock waves.Results show that the outboard branch of the waves causes the periodic modification of the flow inside the tip clearance,while the stator trailing edge wake and wave make the leakage vortex changes together.The shock wave goes deep into the passage of the rotor and passes through the tip clearance periodically.When the shock wave passes the tip clearance,a strong adverse pressure gradient appears nearby the leading edge of the clearance.In addition due to the adverse pressure gradient, the separation bubble grows and a separation phenomenon appears at the forepart of the tip clearance.Meanwhile,the leakage flowmass increases and reverberates as the result of the shock wave.Because of the effect of both stator trailing edge wave and shock waves,the strength of the vortex attains to a momentary peak value,and the location of the leakage vortex moves front and back,and both of the phenomena indicate that the leakage flow is marked unsteady.
Experiment of self-recirculation tip injection in low speed single-stage compressor
LI Ji-chao, LIU Le, ZHANG Hong-wei, TONG Zhi-ting, LIN Feng, NIE Chao-qun
2012, 27(11): 2577-2584.
Abstract PDF(2866KB) icon1746 icon475
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Experiment of self-recirculation tip injection was performed.The effect of different air-entraining ways on the stall margin improvement (SMI) and efficiency were analyzed.The mechanism of stability range extension was also discussed.It is demonstrated that the self-recirculation tip injection can enhance the stall margin effectively,and can also increase the peak efficiency appreciably.Compared with the tip injection with external air source,the proposed method can save the auxiliary equipment which supplies the external air.The self-recirculation tip injection is simple and practical,and is of great value in many applications.
Effect of location of penny platform in variable stator vane on endwall flow
WANG Jing-yu, YANG Rong-fei, WANG Zhi-qiang, HU Jun
2012, 27(11): 2585-2591.
Abstract PDF(1509KB) icon1504 icon605
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Through experiment and numerical simulation of simplified variable stator vane(VSV) model,the effect of different penny platform locations on the flow in endwall region was studied.The results show that there are two factors affect the loss of endwall flow:the leakage cause by aerodynamic loading and the mixing of flow around the penny platform.Optimization of the location and size of the penny platform which aims at covering the front end of the aerofoil can decrease the leakage and flow loss,thus aerodynamic performance would be improved.
Corrected standardization model of aero-engine parameter based on deviation
ZHONG Shi-sheng, CUI Zhi-quan, WANG Ti-chun, ZHANG Mu-nan
2012, 27(11): 2592-2598.
Abstract PDF(489KB) icon1789 icon601
Abstract:
Considering the effect of atmospheric temperature,atmospheric humidity and fuel heating value,a corrected standardization model was proposed relating gas path parameter deviation based on third similarity theory,the multivariate nonlinear overdetermined equations were established using the historical data as learning sample,and the unknown parameters were solved using Gauss-Newton iterative method.The deviation was solved using the corrected standardization model proposed,and the result was compared with deviation solved by other models.the conclusion is drawn that the correction model proposed is closer to the original factory model with higher accuracy,and it is more innovative and has practical value.
Research on aeroengine's double sensor fault diagnosis logic
KONG Xiang-xing, WANG Xi
2012, 27(11): 2599-2608.
Abstract PDF(1927KB) icon1825 icon637
Abstract:
A fault diagnosis system which utilized a bank of Kalman filters was developed for aeroengine sensor double fault detection and isolation.This approach used multiple Kalman filters,each of which was designed based on a specific hypothesis that fault the has occurred in two of the sensors.In addition,the measurements of the normal sensors were used as the input of the Kalman filter.In the event that a double fault does occur,all filters except the one using the correct hypothesis would produce large estimation errors,from which a specific fault is isolated.Furthermore,if the proper Boolean calculation is designed according to the feature of the estimation errors,the fault diagnosis system can also make detection and isolation to the single sensor fault.In order to validate the diagnosis system,a nonlinear engine simulation for both double and single sensor faults at cruise operating condition was conducted.The results indicate that the proposed fault diagnosis system is promising for reliable detection and isolation of aeroengine sensor fault.
A new rapid response emergency control method for turbo-shaft engines
CHEN Guo-qian, ZHANG Hai-bo, YAN Chang-kai, WANG Jian-kang
2012, 27(11): 2609-2615.
Abstract PDF(1055KB) icon1783 icon489
Abstract:
According to the special need in helicopter's emergency state,a new fast response control method of integrated Helicopter/turbo-shaft engine system was proposed to solve this control problem for helicopter's emergency control.Turbine bleeding was another control input except for fuel flow in this new scheme,and the control law including three control loops was based on multi-variables robust control design theory.Specially in this hybrid control law,not only the helicopter climbing velocity was controlled,the gas turbine speed of turbo-shaft engines was also effectively controlled by turbine bleeding to realize engines' power rapid tracking while keeping the power turbine speed constant.In the final stage,the control law was implemented in an integrated UH-60 helicopter and T700 engine system and the transient performance of the closed-loop system in helicopter's climbing and desending emergency flights.The simulation results show clearly that the response time of the closed-loop system designed by the new fast response control law is much reduced compared with that designed by traditional PID(proportional integration differential) method,and it meets the special need of helicopter's emergency control.
Calculatation method of bearing chamber pressure for aero-engine throttling vent lubrication system
YU Li, LI Guo-quan
2012, 27(11): 2616-2621.
Abstract PDF(580KB) icon1496 icon517
Abstract:
The compressibility of the ventilation in the orifice should be considered in the calculation process.A representative bearing chamber for throttling vent lubrication system was studied,and gas flowing characteristics of bearing chamber of aero-engine throttling vent system was analyzed.The calculation method of bearing chamber pressure was concluded and validated by a real case.Compared with experimental data,the calculation result shows a low absolute error which can meet the requirements of the engineering.This calculation method can be used as a reference for further calculation of the pressure of aeroengine bearing chamber by throttling.
Optimization design and test of stability of contact patterns of spiral bevel gears
SU Jin-zhan, FANG Zong-de
2012, 27(11): 2622-2628.
Abstract PDF(1354KB) icon1926 icon478
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In order to improve the stability of contact patterns of spiral bevel gears,the optimization design method of the sensitivity coefficient of contact patterns was proposed.Firstly,the contact patterns were parameterized,and the effect of equivalent misalignments on the parameter of the contact patterns were investigated.The sensitivity coefficients of the parameter of contact patterns to the misalignments was defined,and the objective function established by the minimum sum of the sensitivity coefficients and the machine-tool settings of pinion were adopted as optimization variables to construct an optimization model for the stability of contact patterns.The simulated results of the numerical example show that the sensitivity of contact patterns to misalignments can be improved by implementing the above methodologies in proper ranges.The contact pattern development tests also validated the stability of the contact patterns under the operating conditions.
Meshing performance of face gear drive based on pinion asymmetric double crowned
WU Cong, LI Da-qing, WEI Bing-yang
2012, 27(11): 2629-2634.
Abstract PDF(835KB) icon1747 icon487
Abstract:
A new modification method for face gear was proposed as the pinion double crowned.The derivations of surface equations of tooth modified pinion and face-gear were obtained respectively.The meshing performance investigation of the local conjugate face-gear pair was presented after the tooth contact anlysis was achieved taking the assembly errors into consideration.Finally,the calculated examples show that it enables the transmission errors to form a parabolic function,and enables the direction of contact path and the magnitude of transmission errors to get good control while the factors are pre-designed.The meshing performance of the local conjugate gear pair can obtain an anticipating controllability by using this method,which is quite important for restraining the edge contact,vibration and noise of face gear drive.
Inverse problem of ultraviolet radiation characteristic parameters in hydrogen-oxygen rocket motor plume
GUO Ai-yan, TANG Yi, BAI Ting-zhu, HUANG Gang, ZHU Xi-juan
2012, 27(11): 2635-2640.
Abstract PDF(726KB) icon1724 icon524
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An inverse radiation analysis was presented for simultaneous estimation of the radiative source term and absorption coefficient distribution in the plume of hydrogen-oxygen rocket motor from the knowledge of a single ultraviolet radiation image captured by the CCD camera.Considering the plume as absorbing-emitting cylindrical symmetry media with transparent boundaries,after applying Abel transform to the image data,the inverse problem was formulated as an optimization problem that minimizes the errors between the radiation intensities calculated and the experimental data with Abel transform,and the conjugate gradient method was used to solve the optimization problem.The effects of measurement errors on the accuracy of the estimation were investigated,and the measured data were simulated by adding random errors to the exact solution of the direct problem.Test results show that the radiation characteristic parameters can be estimated accurately,even for data with measurement error.

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