2008 Vol. 23, No. 2

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Conjugate heat transfer analysis of a high pressure turbine vane with radial internal cooling passages
DONG Ping, HUANG Hong-yan, FENG Guo-tai
2008, 23(2): 201-207.
Abstract PDF(1541KB) icon1799 icon469
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In order to accurately predict aerodynamics and heat transfer between external hot gas and internal cooling passages as well as conduction within metal blade,numerical analysis using conjugate heat transfer methodology for the MarkIItransonic turbine guide vane,which was cooled internally by air flowing through 10 radial round pipes,was carried out.The results show that the flow inside boundary layer is very complex,which includes laminar flow,transition process and turbulent flow.The prediction with M-L(Menter and Langtry) transition model provides the closest agreement with the actual flow conditions inside boundary layer,and the distributions of vane temperature and heat transfer coefficient predicted by this model agree well with the measured experimental data whereas the results with other turbulence models over-predict.However,all turbulence models can well predict aerodynamics of gas outside boundary layer.
Experiment on the breakup process of free round liquid jet
WAN Yun-xia, HUANG Yong, ZHU Ying
2008, 23(2): 208-214.
Abstract PDF(796KB) icon1678 icon410
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An experiment was conducted to investigate the surface stripping and breakup lengths of a round water jet.The process of the main and the satellite droplets in Rayleigh model was further studied under low jet velocity.With the increase of jet velocity,small droplets were stripped off from the jet surface.The surface striping did not appear on the jet surface until the Reynolds number exceeded a critical value.Two jet breakup lengths(the stripping length and the pinch length) were defined and the variations of the two breakup lengths with the jet Reynolds number were plotted,and the correlations fitted for the two breakup lengths were obtained.
Influence of aerodynamic parameters on film cooling effectiveness on the vane leading edge
LI Guang-chao, ZHU Hui-ren, LIAO Nai-bing, XU Du-chun
2008, 23(2): 215-220.
Abstract PDF(744KB) icon1812 icon436
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Film cooling effectiveness on the leading edge with one row of holes is studied experimentally.The model was a blunt body with a half cylinder leading edge and two flat plates.One row of holes was located at the place 2 hole pitches from the stagnation line.Foreign gas injection was used to obtain a density of approximately 1.5.High turbulence intensity was produced by a passive grid.Momentum ratios varied from 0.5 to 4.The result indicates that film cooling effectiveness decreases with increasing momentum ratio.Spanwise averaged film cooling effectiveness is reduced by high mainstream turbulence intensity with momentum ratio of 0.5 and the mainstream turbulence effect is diminished with increased momentum ratio.Film cooling effectiveness along the film cooling hole is significantly reduced by high mainstream turbulence level.Spanwise averaged film cooling effectiveness decreases in the case of low momentum flux ratio and spanwise averaged film cooling effectiveness increase in the case of high momentum flux ratio because of foreign gas injection.
Effect of scale factor on infrared radiation characteristics of helicopter infrared radiation suppressor
SHAN Yong, ZHANG Jing-zhou
2008, 23(2): 221-226.
Abstract PDF(837KB) icon1894 icon408
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A research on the infrared radiation characteristics for the helicopter infrared radiation suppressor consisted of lobed nozzle and curved mixing duct is performed basing on numerical calculation.In the computation,3-D flow field computation and wall temperature computation and infrared radiation computation are combined to investigate the infrared radiation characteristics of the suppressor.Compared with the experimental data,it is indicated that the relative error between the computational and experimental results is about 15%.Spatial distribution of infrared radiation intensity has the same law as that from experiments.And a series of computations on different scale factor model are conducted to obtain the effect of model scale to the wall and plume radiations.The results indicated that the infrared radiation intensity of wall is proportional to power 2 of scale factor and the infrared radiation intensity of exhaust flume is proportional to power 2.32 of scale factor on the case of the velocity,temperature and pressure of the primary flow being keeped the same for different scaled model.
Experimental investigation of free surface MHD flow around a cylinder
HAN Dong, HUANG Hu-ling, ZHANG Yan, LI Hui
2008, 23(2): 227-231.
Abstract PDF(788KB) icon1753 icon411
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The effects of magnetic field on the free surface flow around a cylinder were investigated experimentally using the PIV(particle image velocimetry) under Reynolds number 7767 and 11650.The experimental result revealed that the field enabled the distribution of nondimensional average velocity to deviate from logarithmic distribution of nondimensional average velocity in the boundary layer,and also made the wake become narrower and shorter,and the detachment point move backward.When the Reynolds's number reached up to 11650,the influence of magnetic field was weaken under same strength of external magnetic field.Consequently,the departure degree between the nondimensional average velocity distribution and logarithmic distribution in the boundary layer was reduced.
Applied study of photoelectric detector in detonation wave's measurement
ZHANG Peng-gang, HE Xiao-min, ZHANG Jing-zhou
2008, 23(2): 232-236.
Abstract PDF(682KB) icon1622 icon375
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A measuring tool of high precision and response time is required owing to rapid flame speed and complex structure of combustion flame.The combustion wave was measured in this paper by using photoelectric detector and ion-probe.Based on the high-frequency response pressure transducer,the feasibility and precision of photoelectric detector were validated by measuring the triggering sequence between pressure transducers,photoelectric detector and ion-probes as well as the duration of photoelectric detector and ion-probe signals.The results indicate that photoelectric detector is more suitable to measure the flame speed.
Numerical simulation of jet impingement cooling of turbine steam-cooling vane
DONG Yu, ZHENG Hong-tao, TAN Zhi-yong, MU Yong, LI Zhi-ming
2008, 23(2): 237-243.
Abstract PDF(1372KB) icon1814 icon399
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The present study numerically investigated a conceptual type of internal steam cooling vane with the impingement cooling technology on the basis of plane model and concave model.By changing the inlet Re,distance between the jet and target board and curvature of concave board,a series of temperature value and heat transfer coefficient are obtained.Based on these Results,an impingement cooling vane was designed,which worked on the ANSYSworkbench,and the conjugated heat transfer was studied by means of ANSYS CFX Navier-Stokes code using k-ε two-equation turbulence model for gas field and cooling field.The numerical results of the effects of cooling flow heat transfer in the vane were obtained to evaluate the damage of the vane during steady state operation conditions.
Numerical computation and analysis of the infrared radiation characteristic of missile scarfskin
SHAN Yong, ZHANG Jing-zhou, GUO Rong-wei
2008, 23(2): 251-255.
Abstract PDF(1161KB) icon1840 icon460
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The reverse Monte Carlo method was used in the computer program.And the ideal of program design and the way of realization were introduced particularly.Computer processes and formulas were provided.At a given flight condition,the infrared radiation characteristics of missile scarfskin were obtained by calculation.Brief comparison and analysis of the computing results were conducted.For subsonic missile,the radiation at 2～5 μm can be ignored relative to the radiation at 8～14 μm.For supersonic missile,the radiation at 2～5 μm is a half of the radiation at 8～14 μm.The radiation increases at the detected position of 0°～90° degree and decreases at the detected position of 90°～180° degree.The atmosphere attenuation effect on subsonic missile is strong at low altitude and is weak on supersonic missile at high altitude.The max radiation of supersonic missile scarfskin is 18 times as that of ultrasonic missile scarfskin.
Probability characteristics of vibratory mode of bladed disk assemblies with random stiffness mistuning
WANG Jian-jun, YAO Jian-yao, LI Qi-han
2008, 23(2): 256-262.
Abstract PDF(979KB) icon1587 icon464
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Based on the lumped-parametric model with two-degree-of-freedom per blade disk sector and its Monte Carlo simulation,the vibration characteristics of a typical bladed disk with different random mistuning of stiffness was researched,with particular regard to the subjects of the probability characteristics of natural frequencies and shapes.Alumped-parametric model was built and the natural mode properties of the model without mistuning were discussed.The definition of a modal localization factor was presented to assess quantitatively the behavior of shape localization for the mistuned bladed disk.Then the statistical characteristics of the natural frequencies and mode shapes were simulated and their main properties were explained.Results indicate that the influences of blade and coupling stiffness mistuning on modal characteristics are distinct in that they influence in different frequency ranges.And the localization factor in the frequency ranges affected by mistuning could change abruptly.
Stability and bifurcation of elliptic bearing-rotor systems
WANG Li-gang, CAO Deng-qing, WANG Jin-lin, HUANG Wen-hu, CUI Yin
2008, 23(2): 263-269.
Abstract PDF(2098KB) icon2048 icon396
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The nonlinear dynamic behavior of elliptic bearing-rotor system was investigated by working on 200 MWsteam turbine as an example.The finite element method was employed to establish a dynamical model of the system and a nonlinear model derived from the variational principle was adopted to describe the oil force of elliptic bearings.Then,the nonlinear dynamic system with 608-degree-of-freedom was reduced to a 30-degree-of-freeodm model in terms of the fixed interface mode synthesis method.The Rouge-Kutta method was employed to solve the reduced model numerically,and the frequency-response curve,the bifurcation diagram, and the three dimensional spectral plot obtained were used to analyze the stability of the rotor-bearing system.The effects,on the dynamic behavior of the system,of the eccentricity,the oil viscosity and the length-to-diameter ratio of bearing were discussed in terms of the frequency-response curve.The numerical results show that the stability range of the elliptic bearing-rotor model is larger than that of the circular bearing-rotor system.
Study of failure mode and failure mechanisms on thermal fatigue of plasma sprayed thermal barrier coatings
WEI Hong-liang, YANG Xiao-guang, QI Hong-yu, HAN Zeng-xiang
2008, 23(2): 270-275.
Abstract PDF(1033KB) icon1586 icon441
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Thermal fatigue test was conducted to study the failure process and failure mode of the plasma sprayed thermal barrier coating structures.The controlling factors for failure were also analyzed.Aviscoplastic constitutive model was introduced for the ceramic coat.Moreover,the thermal fatigue behavior of the coating layer was studied numerically.The analysis indicates that: mode Ⅰ crack is easily initiated at the peak position,and mode Ⅱ crack at above middle position of interfaces when TGO(thermaly growth oxides) thickness is 2 μm;the extension of transverse crack is dominated by normal stress when TGOthickness is 8 μm;high strain energy density is formed within TGOof different thickness.The process and mechanisms of crack coalescence within PS-TBC(plasma sprayed thermal grown oxides) were presented.
Modeling of low-cycle and creep fatigue life for DZ125 smooth specimens and small-hole components
ZHOU Tian-peng, YANG Xiao-guang, SHI Duo-qi, HOU Gui-cang, CONG Pei-hong
2008, 23(2): 276-280.
Abstract PDF(569KB) icon1654 icon428
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Alow cycle fatigue and creep life prediction model of DZ125 was established according to the fatigue and creep experimental life data of directionally solidified DZ125 smooth specimens.This model also considered the influences of crystal direction,average stress,strain range,strain ratio and the greatest stress on the life.Then,the relationship of low-cycle fatigue and creep life between smooth specimens and small-hole components was discussed,and a method was developed to predict the low-cycle fatigue and creep life of DZ125 small-hole components from that of directionally solidified DZ125 smooth specimens.The results show that,this model can predict comparatively the low cycle fatigue and creep life,indicating that the error of life prediction results are about two times of dispersion band.
4 theorems on whirl transform of rotor vibration
LIAO Ming-fu, WANG Yu, TAN Da-li
2008, 23(2): 281-285.
Abstract PDF(379KB) icon1743 icon430
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The motion of a rotor can be decomposed into forward whirls and backward whirls. This approach is referred to as whirl analysis or whirl transform.It reveals the relationship between motion of a rotor and forces applied more evidently,therefore this method is widely applied to diagnosing problems in rotating machinery.4 theorems about rotation vibration were established.Theorem 1 states that,an elliptical orbit of a rotor can always be decomposed into a forward whirl and a backward whirl.The area of the elliptical orbit is equal to the absolute value of the difference between the area of the forward whirl and that of backward whirl.Theorem 2 is associated with the circumference of an elliptical orbit and its forward whirl and backward whirl.Theorem 3 states that,the forces applied to a rotor can also be decomposed into forward whirl force and backward whirl force.The forward whirl force can only perform work on the forward whirl but not on backward whirl;vice versa,the backward whirl force can only perform work on the backward whirl but does not on the forward whirl.Theorem 4 states that the work performed by forward whirl force is equal to the dot product of forward whirl force and the displacement of rotor in the forward whirl,similarly the work performed by backward whirl force is equal to the dot product of backward whirl force and the displacement of rotor in backward whirl.The theorems are applied to determine the work performed by unbalance,viscous damping and restoring forces due to skew symmetric stiffness.The results are identical with those obtained from traditional dynamics.However it is found that,when ωy<Ω<ωx,as |r-|>|r+|,the skew symmetric stiffness will act as a stabilizing force suppressing backward whirl of a rotor.
Experiments on damage failure test of single bolted joints in composite laminates
WANG Dan-yong, WEN Wei-dong
2008, 23(2): 286-292.
Abstract PDF(1267KB) icon1848 icon440
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The static-load mechanical properties and fatigue characteristics of 104 specimens were tested on single bolted joints in composite laminates,of which including nine sizes,three types of lay orientations and two types of torques.Dye-Enhanced X-Radiography technique was used to conduct nondestructive test of the progressive damage process of specimens during static and fatigue loadings.The real damage types and failure rules of single bolted joints in composite laminates were also discussed.
A novel method of identifying the imbalance of flexible rotor with one disc
HUANG Jin-ping, REN Xing-min
2008, 23(2): 293-298.
Abstract PDF(623KB) icon1468 icon416
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Based on the transient response of a flexible rotor and the fundamental theory of back propagation(BP) neural network,a novel method for imbalance identification of flexible rotor with one disc was presented.A BPneural network identifying imbalance angle of rotor was established by using the theoretical model of the rotor,thus enabling imbalance identification of rotor through only two accelerations.Firstly,the imbalance angle was identified by BPneural network and the transient response of the first acceleration;secondly,the magnitude of the imbalance was acquired through a second acceleration using the linear relationship between the magnitude of transient flexibility and the imbalance.The experimental result verifies the effectiveness of this imbalance identification method.
Numerical simulation of bird impact on bladed rotor stage by fluid-solid coupling method
JIANG Xiang-hua, WANG Yan-rong
2008, 23(2): 299-304.
Abstract PDF(1881KB) icon1789 icon437
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An aeroengine rotor stage finite element method(FEM) model with aerodynamic load and constant rotational speed was studied by using fluid-solid coupling method with MSC.DYTRANsoftware in this paper to investigate its transient dynamic response while suffering various bird impacts.Results show that great instantaneous impact stress exists in the blades during the swift impact.The peak stress will rapidly increase if the velocity,density and size of the bird increase;nevertheless this ascendant tendency can be blunted after the potential of material hardening and deformation abilities have sufficiently developed.The result also reveal that raising hardening modulus of the blade material can increase the impact stress as well,whereas raising material yield strength will reduce the action time of impact stress.Finally,a more complicated simulation,in which material failure was included,was carried out to investigate the process of blade failure caused by bird impact.
Effect of injector on pressure oscillation amplitude-frequency characteristics from pipeline to combustion chamber
YANG Li-jun, FU Qing-fei
2008, 23(2): 305-310.
Abstract PDF(728KB) icon1708 icon424
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The process of pressure oscillation propagation from pipe-line to combustion chamber was theoretically researched in this paper;the transfer function was also deduced.The dynamic characteristic of combustion chamber linked with various injectors was discussed.The influence of pipe-line pressure,combustion chamber pressure,injector type and configuration on pressure oscillation propagation process of pipe-line was calculated,so the influence rule of injector on propagation process was gained.
Finite volume model for quasi one-dimensional compressible transient pipe flow (Ⅰ) Finite volume model of flow field
CHEN Yang, GAO Fang, ZHANG Zhen-peng, CAI Guo-biao
2008, 23(2): 311-316.
Abstract PDF(1800KB) icon1671 icon414
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Given the fact that there is lack of a uniform deduction process in theory and an all-embracing base equation group for existing one-dimensional dynamic models of flow system,the integral and differential conservative equations of quasi one-dimensional compressible transient flow in pipe with variable section were derived by rational modeling based on integral conservative equations in Eulerian type of specification suitable for control volume of continuous fluid media.The expansion work resulted from variation of control volume was taken into account by reserving the variable volume term in energy equation.With two kinds of finite volume grids which are interlaced in discrete space,a finite volume model was established to describe quasi one-dimensional compressible transient pipe flow field.Actions derived from variable volume,variable fluid properties,axial heat conductivity and gravity were considered in the model.This reinforces and clarifies the theoretical foundation for the numerical system of finite element state-variable model,and also improves the scope of application.On the other hand,the model can be further developed to establish flow field models of common components in pipe system in collaboration with throttling model of valve core.
Finite volume model for quasi one-dimensional compressible transient pipe flow (Ⅱ) Finite volume model of temperature field
CHEN Yang, GAO Fang, ZHANG Zhen-peng, WANG Hai-xing, CAI Guo-biao
2008, 23(2): 317-322.
Abstract PDF(2514KB) icon1979 icon427
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Based on the flow field model,a finite volume model suitable for simulating pipe wall transient heat transfer was established by employing two-dimensional finite control volume grids in axisymmetric cylindrical coordinates which can deal with two boundary heat transfer conditions including convection and radiation.Variable thermophysical properties of wall material and multilayer or vacuum sandwich structure of pipe wall were also considered.The temperature field model is a natural extension of flow field modeling method.The union of both forms the finite volume model(FVM) of quasi one-dimensional compressible transient pipe flow,which is a uniform numerical system of flow and heat transfer.Furthermore, combing with throttling model of valve core,the model can be further developed to establish the flow field and temperature field models of common components in pipe system.The modeling and simulation of a certain liquid rocket engine test-bed LO2 tank pressurization system shows that the FVMhas a wide scope of application and good simulation precision.
Distributed parameter numerical simulation for the transients of cryogenic propellant tank pressurization system(Ⅰ)Finite volume model of tank
CHEN Yang, GAO Fang, ZHANG Zhen-peng, YANG Si-feng
2008, 23(2): 323-328.
Abstract PDF(593KB) icon1692 icon401
Abstract:
Based on the finite volume model of quasi one-dimensional compressible transient pipe flow,a distributed parameter numerical model of cryogenic propellant tank was established by numerical development and integration in which the heat transfer between fluid and tank wall was considered.Two kinds of finite volume grids,which are interlaced in discrete space,were employed to establish the flow field model which can consider actions derived from variable fluid properties,axial heat conductivity,gravity and wall heat transfer.Two-dimensional finite control volume grids in axisymmetric cylindrical coordinates were employed to establish the temperature field model which could deal with two boundary heat transfer conditions including convection and radiation.Variable thermophysical properties of wall material and multilayer or vacuum sandwich structure of tank wall were also considered.The model comprehensively describes the distributed parameter effect in tank and is valuable in tank pressurization simulation field.
Distributed parameter numerical simulation for the transients of cryogenic propellant tank pressurization system (Ⅱ) Numerical model and simulation results of pressurization system
CHEN Yang, ZHANG Zhen-peng, YANG Si-feng, QU Qian, CHEN Feng, ZHU Zi-huan
2008, 23(2): 329-335.
Abstract PDF(1165KB) icon2115 icon439
Abstract:
Based on the distributed parameter numerical model of cryogenic propellant tank, pressurization of a LO2 tank pressurization system during engine firing was simulated by employing the liquid rocket engine test-bed modularization modeling and simulation software-gas system(LRETBMMSS-GS).The simulation results agree well with test data and experiential correlation prediction,which shows that the distributed parameter tank model is more accurate and comprehensive than lumped parameter model in describing flow and thermal stratification phenomena in cryogenic tank.Accordingly,the numerical system of finite volume model and corresponding simulation software have a wide applicability and good simulation precision,which are valuable and can be developed further in pipe system simulation field.
Investigation on the effects of injection structure on kerosene supercritical cooling film
CHEN Jian-hua, LU Gang, ZHANG Gui-tian, ZHOU Li-xin, SUN Hong-ming
2008, 23(2): 336-341.
Abstract PDF(1351KB) icon1671 icon421
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A kerosene supercritical film cooling model for the thrust chamber of liquid oxygen LOX/kerosene staged combustion cycle engine was established,and the effect of the film local injection structure on the local flow and cooling effect near the outlet of film cooling slot was analyzed.Under the supercritical condition, kerosene and its surrounding gas are in same phase,and can be described by the same equation for flow and heat transfer.Numerical simulations for 3 typical injection structures were carried out in this paper.The results show that: the step and angle of the film ring outlet and injection have great influence on the local flow and heat transfer,the step structure with outlet angle less than 90 degree will could reduce the local recirculation in favor of heat protection of the thrust chamber.
Numerical simulation and study of the separation process of missile booster
WANG Li, GU Liang-xian
2008, 23(2): 342-346.
Abstract PDF(530KB) icon1690 icon460
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The overset/Chimera algorithm for structured grids and Favre-averaged Navier-Stokes equations were employed to solve the flow field.Tstion gas jets,were considered in this simulation.Atime profile boundary was employed to simulate the unsteady flow in the tail off duration of the booster.The separating trajectory was ultimately achieved by solving the 6DOF(six degree of freedom) motion models with certain constraints.Moreover,the influence of engine-jet on booster separation was studied.The work provides a reference for accurately simulating the trajectory and attitude of rocket booster.
Numerical study of active flow control using jet-flap for a low-pressure turbine cascade
LUO Hua-ling, QIAO Wei-yang, XU Kai-fu
2008, 23(2): 347-354.
Abstract PDF(1373KB) icon1650 icon406
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Based on Menter's SST k-ω turbulence model coupled with Langtry-Menter transition model,the control mechanism of jet-flap,an active flow control method for PAK-Blow-pressure turbine blade profile,was numerically investigated under different flow conditions including different cascade inlet Reynolds numbers,free stream turbulence levels,and cascade outlet Mach numbers.The results show that the jet-flap effectively reduces flow loss when PAK-Bprofile is stalled.With jet flow mass fraction equal to 2%,relative to the baseline,the energy loss coefficient reduced by about 40%;the flow turning angle increased by about 5%;and the inlet primary flow mass reduced by about 10%.When the flow was not stalled,the control could be ineffective.The results also show that the jet-flap delays boundary layer transition on adjacent blade profile suction side, which in turn delays the boundary layer reattachment.
Influence of inlet distortion on the stall character of a low speed axial compressor
JIANG Hua-bing, LU Ya-jun, YUAN Wei, LI Qiu-shi, HOU An-ping
2008, 23(2): 355-360.
Abstract PDF(988KB) icon1978 icon441
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Flat baffle was utilized to simulate the inlet distorted flow field,and its influence on the stall character of a low speed single stage axial compressor was investigated.The instantaneous characteristic of the compressor,the development process of stall disturbance and the frequency spectrum of the stall disturbance signal were investigated to explore the influence of inlet distortion on the form,intensity and frequency of rotating stall of the compressor.Astall disturbance formed in the distorted flow sector will experience development and damping when it propagates circumferentially,which will effectively influence the stall character of the compressor.Stall inception occurs only when the damping of the disturbance is insufficient to prevent its growth and surrounding propagation.
Plenum chamber casing treatment——numerical research of internal flow and mechanism of stall margin improvements
JIANG Yong-song, WANG Yong-mei, DU Hui, GUO Jie
2008, 23(2): 361-366.
Abstract PDF(1113KB) icon1460 icon391
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The influence of plenum chamber casing treatment on the performance of high loaded and high-speed fan rotor was analyzed through steady simulation.The results indicate that the performance of the same casing treatment differs greatly under different rotational speeds.At the design speed,the casing treatment fails to improve the stall margin of fan rotor,and the efficiency declines by 2.8%.at non-design speed,it enhances significantly the stability of the rotor,without impairment of the rotor performance.The in-depth analysis of the flow field in the casing treatment reveals the inherent mechanism of stall margin improvements by the plenum chamber casing treatment.
Analysis of overall aerodynamic performance of axial-flow compressor with attenuated blade tip
SHAO Wei-wei, JI Lu-cheng, HUANG Wei-guang
2008, 23(2): 367-373.
Abstract PDF(862KB) icon1636 icon406
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Parameter studies for different attenuation thickness(in the tangential direction of blade) and relative height(in the spanwise direction of blade) of pressure surface at tip region are developed,which take ROTOR37 as an example and adopt numerical simulation to obtain the results.Aerodynamic performance curves are obtained at 60%,80%,90% and 100% of design rotate speed working conditions,moreover,detailed analysis of internal flow field is presented for design condition.Results of ten models including the model with unchanged blade element indicate that blade tip attenuation within certain range can advance choke mass flow,total pressure ratio and adiabatic efficiency,and decrease stall margin of the rotor,however,the influence is not so patent.
Comparison of technical characteristics of APU and micro turbine engines for large aircraft
HUANG Guo-ping, LIANG De-wang, HE Zhi-qiang
2008, 23(2): 383-388.
Abstract PDF(1338KB) icon1830 icon600
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The overall design and technical characteristics of micro turbine engines(MTE) and auxiliary power unit(APU) were analyzed comparatively,and their similarities and differences were summarized.The results show that: the output powers of MTEand APUare equivalent.Moreover,the technologies of such two power systems are similar in terms of the designs or manufacturing of engines and their main components.MTEhas higher performance index,and APUpresents higher reliability, economic efficiency and longer service life through conservative design.So,a technical approach to develop Chinese APUbased on the technology of MTEhas been proposed.
Investigation of the restart performance of a mixed-compression two-dimensional supersonic inlet with fixed-geometry
XIE LÜ-rong, GUO Rong-wei
2008, 23(2): 389-395.
Abstract PDF(896KB) icon1923 icon447
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An experimental study was conducted to investigate the restart performance of a fixed-geometry,mixed-compression,two-dimensional supersonic inlet under unstart condition due to raising backpressure,with a designed flight Mach number from 2.25 to 4.0.The test results and two-dimensional unsteady simulation results show that,the inlet performance is consistent in the inlet wall and exit section tests at Mach number of 2.51 and 3.01;the throat area is determined according to the start area shrinkage ratio at Mach=2.25,so that the inlet enables self-start at Ma=2.5 and above.The phenomenon of no hysteresis under stable subcritical condition is because of a high total pressure recovery and a flow pattern of inlet similar to external compression inlet.
FDIA simulation of aero-engine control system sensor FDIA system
CHEN Yi, HUANG Jin-quan, ZHANG Peng
2008, 23(2): 396-400.
Abstract PDF(1094KB) icon1894 icon397
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Based on a bank of Kalman filters,an aircraft engine sensor fault diagnostics system was developed,thus enabling fault detection,isolation and accommodation(FDIA) of individual sensor faults and safe operation of engine control system even in the case of sensor failure.Auniversal graphical simulation platform for aircraft engine sensor fault diagnostics was designed using Simulink software.Simulations were performed on the platform to verify the feasibility of the sensor fault diagnostics system.The sensor noise impact on the performance of sensor fault diagnostics system was also analyzed,offering valuable reference for online aircraft sensor fault diagnostics.

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