2008 Vol. 23, No. 3

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Effect of operating frequency on performance of pulse detonation engine driven ejector
HUANG Xi-qiao, YAN Chuan-jun, WANG Zhi-wu, FAN Wei, JIANG Bo
2008, 23(3): 401-405.
Abstract PDF(467KB) icon1796 icon497
Abstract:
A preliminary experimental investigation of the thrust augmentation performance of a round,straight ejector on a multi-cycle pulse detonation engine(PDE) was performed while using gasoline as fuel and air as oxidizers.The average thrusts of the PDEwith ejector and without ejector were measured with thrust transducer at different detonation frequencies and different length-to-diameter ratios of the ejector.The experimental results indicate that ejector system alone can augment the average thrust obtained from the pulse detonation engine.The maximum value of the average thrust augmentation is found to be about 64.4% when the detonation frequency is 25 Hz.The optimal value of the ejector length-to-diameter ratio is 4.58 when the ejector inner diameter and the operation frequency are constant,which corresponds to the best thrust augmentation performance.
Investigation of supersonic film cooling in flat and convex channels
PENG Wei, JIANG Pei-xue
2008, 23(3): 406-409.
Abstract PDF(779KB) icon1645 icon490
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Film cooling with supersonic,tangential-slot injection of cooling air into supersonic air flow was numerically investigated.The effect of impingement of oblique shock wave was studied and its impacts on a flat surface and on a convex surface were compared.The results indicate that the adiabatic effectiveness of both the surfaces is reduced by the impingement of the oblique shock wave.The adiabatic effectiveness of convex surface is higher than that of flat surface when oblique shock wave is absent whereas the opposite is the case when it is present.
Experimental study in natural convection heat transfer enhancement
WEN Jie, YU Zhao-ji, WU Hong
2008, 23(3): 410-414.
Abstract PDF(540KB) icon1747 icon479
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This paper focuses on study of heat transfer enhancement in natural convection along upright board.Comparing the different effects of heat transfer enhancement by using columned turbulent pins,conical turbulent pins,prisms,pyramids,and LVG(longitudinal vortex generator) arrays,the results show that the performance of LVGin heat transfer enhancement is better than others during simplex pins tests.Furthermore,the mixed configuration of columned turbulent pins and LVGhas the best performance in natural convection heat transfer enhancement,which enhances heat transfer by 24.5 percent.
Numerical and experimental investigation of pressure loss and critical sealing characteristics of straight-through labyrinth seals
JI Guo-jian, JI Hong-hu
2008, 23(3): 415-420.
Abstract PDF(2013KB) icon1626 icon461
Abstract:
Numerical and experimental investigation of pressure loss and critical sealing characteristics of straight-through labyrinth seal has been made.The results show that the RNG k-ε turbulence model is suited to predict the flow of labyrinth seal.The flow of the last tooth is choked when the pressure ratio between the upstream and downstream of the labyrinth seal reaches a critical value.With the increase of the pressure ratio the critical cross moves towards the upstream of the last tooth and the true flow cross area is increased simultaneously,which leads to increase of the leakage.When the total pressure is fixed,the pressure distributed between the teeth decreases linearly along the flow direction and the slope of the curve of the ratio of the pressure between the teeth to the total pressure is related to the total pressure.
Experimental investigation of effect of step axial location and rotating speed on leakage of stepped labyrinth
JI Guo-jian, JI Hong-hu
2008, 23(3): 421-424.
Abstract PDF(538KB) icon1513 icon464
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Experimental investigation of up stepped and down stepped labyrinth seals was made to study the effects of the pressure ratio of inlet and outlet and relative axial location of step and labyrinth on leakage characteristics at rotational and static states.The results show that the sealing characteristics of both up stepped and down stepped labyrinth seals are similar.The leakage coefficient increases with the increase of the pressure ratio.At given inlet total pressure and total temperature,the pressure distribution along the sealing passage decreases almost linearly.The leakage is almost unchanged with variation of the step axial location or the low rotating speed in the experimental range.
Experimental investigation of the temperature gradient and cooling efficiency for effusion wall cooling methods on combustion liner
XU Jian, XU Quan-hong, LIN Yu-zhen, LIU Gao-en, FAN Peng-hui
2008, 23(3): 425-429.
Abstract PDF(1169KB) icon1665 icon460
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Gas turbine combustor cooling has steadily acquired major importance whenever engine performances have to be improved.Effusion cooling is becoming one of the most efficient cooling techniques for protecting metal surfaces against hot gases in combustor liners.As one of the most important influential factors to combustor life-span,the temperature gradient of the effusion wall and the cooling efficiency were investigated experimentally under the guidance of similarity theory.Geometric parameters such as the patterns of holes arrangement and the ratio of the wall thickness to the hole diameter h/d,as well as PS/d2,were varied in four different test models.IRthermograph was used to perform local measurements of the surface temperature field.The experimental results indicated that it had a better performance in both the temperature gradient and the cooling efficiency if P/S=1 as compared with P/S=2;the temperature gradient would be reduced by decreasing h/d or increasing PS/d2,while the cooling efficiency would decline at the same time.
A study on NOX formation for double swirler combustor
DANG Xin-xian, ZHAO Jian-xing, JI Hong-hu
2008, 23(3): 430-435.
Abstract PDF(1432KB) icon1813 icon418
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The influences of various fuel-air ratio,inlet temperature and geometric parameters on two-phase combustion integrated flow fields and pollutant NOx formation in a model gas turbine combustor with a double swirler were investigated experimentally and numerically.Particle image velocimetry(PIV) technique was adopted to measure Profiles of velocity vector of primary combustion zone in model combustor.Multiple-point probes were used to measure radial distributions of outlet temperature and NOx emission.Fluent commercial software was applied to simulate three-dimensional two-phase combustion flows and pollutant NOx formation on unstructured grid system in the model combustor.The calculated results were consistent with the test data,showing that the influences of different fuel-air ratio,inlet temperature and primary holes parameters on two-phase flow fields as well as profiles of outlet gas temperature and NOx are considerable.The outlet gas temperature and NOx increase with fuel-air ratio and inlet temperature.
Effect of discrete spectral resolution on calculation of the infrared characteristics of engine plume
LIU You-hong
2008, 23(3): 436-442.
Abstract PDF(627KB) icon1833 icon488
Abstract:
Finite volume method(FVM) model and its solution procedure were established.And corresponding FORTRANprogram was developed to simulate the plume infrared characteristics,in2～5 μm,of a standard example engine that flies in atmosphere.This study focuses on the effect of the discrete spectral resolution in FVMon the infrared calculation precision.The result shows that the source directional spectral radiative intensity becomes,after absorption along a 0.88 km horizontal sea level path,gradually independent of the discrete wavelength when the discrete spectral resolution increases.When the number of discrete equal intervals of the infrared wavelength of 2～5 μm in FVMis more than150,the infrared spectral radiative intensity emitted from the plume is independent of the discrete spectral resolution.
A porous medium model for simulating leakage flows through brush seals
CAO Guang-zhou, JI Hong-hu, YUAN Yan-ping
2008, 23(3): 443-447.
Abstract PDF(1382KB) icon1810 icon469
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The bristle pack was treated as porous medium.Amomentum source term which was caused by the porous medium was added into the momentum equation.The method to determine porosity of the pack was examined in detail and the porosity was obtained based on the experimental results.So a porous medium model for simulating the leakage through brush seals was built up.The computational results,after correction,show a good agreement with the experimental results.The model was proved to be practicable for predicting the leakage of brush seals.
Numerical analyses of flow field and heat transfer in cavity of straight labyrinth seal at static state
LIU Zhen-xia, ZHAO Hai-gang, ZHANG Li-fen, WU Ding-yi, WANG Xiao-feng
2008, 23(3): 448-453.
Abstract PDF(13738KB) icon2014 icon420
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In order to investigate the performance of straight sealing labyrinth at static state in aero engine,a model of straight sealing labyrinth was established and applied to compute the flow characteristics and heat transfer in the straight sealing labyrinth.With the result of numerical simulation,the effects of Reynolds numbers and T/Con flow field,pressure loss,and coefficient of heat transfer were studied.By comparing some group results of numerical simulation and experiments data,it is found that the numerical results are in agreement with experimental data and the error can be acceptable.The results show that the Reynolds number and T/Caffect the flow characteristics and heat transfer in the straight sealing labyrinth and thus are important factors in deciding the sealing performance of straight labyrinth.
Numerical simulation of three-dimensional combustion flows in annular reversed combustor
HU Hao-sheng, CAI Wen-xiang, ZHAO Jian-xing, JI Hong-hu
2008, 23(3): 454-459.
Abstract PDF(1996KB) icon1657 icon505
Abstract:
Numerical simulations of two-phase reacting flow in an annular reverse flow combustor were developed in a three-dimensional non-orthogonal curvilinear coordinate system.RNG k-ε model,EBU-Arrhenius turbulence combustion model,discrete-ordinates(DO) model and Six-flux model were used for the gas phase flows.The liquid phase calculations were carried out with the Particle Trajectory model.The gas discretization equations were solved with SIMPLEalgorithm.PSICalgorithm was employed to take into account the mass,momentum and energy coupling between two phases.The calculated exit temperature coefficient distributions are in agreement with the corresponding measurements.Predictions show that this numerical method is reasonable;the DOmodel is better than the six-flux model and is therefore more applicable for simulation of two-phase reacting flows of the annular reversed combustor.
Cooling performance induced by film holes with coverage of porous media layer
LIU Yuan-qing, JIANG Pei-xue, Wang Yang-ping
2008, 23(3): 460-464.
Abstract PDF(670KB) icon1550 icon469
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By attaching a layer of porous media coverage to the local zone around film-hole exits,a new cooling scheme which combines the features of film cooling and transpiration cooling was introduced in the present study.The cooling effects of the present scheme and the traditional cylindrical hole film cooling were compared numerically for three kinds of blowing ratio M=0.6,0.91 and 1.22.The results show that the new scheme provides higher wall cooling effectiveness and moderate temperature gradients,which enables it to be a better candidate for blade cooling for future high performance gas turbine.
Fuel deposit experiment on main fuel system of modern military jet engine
LI Min, XIAO Wei-hui, WANG Hong-ming
2008, 23(3): 465-469.
Abstract PDF(599KB) icon1412 icon498
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The relationship between fuel deposit and temperature of Chinese jet fuel RP-3 was measured under crucial thermal condition using weighting method.The results show that,the deposit rate is below that of American jet fuel JP-4,JP-5,Jet-A,but higher than Jet-8.The various degrees of deposit occurred on the filter and the tangential channel of the nozzle swirler.
3-D numerical investigation on supersonic combustion of hydrogen in two different type of scramjet combustors
ZHOU Jian-xing, PIAO Ying, QI Xing-ming, ZHU Jian-hong, CHEN Mei-ning
2008, 23(3): 470-475.
Abstract PDF(1055KB) icon1799 icon547
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The flow fields of hydrogen injected into combustors with step injectors and strut injectors were numerically investigated by solving the 3-Dcompressible Navier-Stokes and species equations with implicit finite volume method.The results show that because of the stronger streamwise and spanwise vortexes induced by the hydrogen flows injected via the strut injectors,hydrogen/air mixing efficiency is greatly enhanced and the mixing length along the channel is shortened.Besides,the cavities in both types of combustors enable the fuel to be mixed more fully and also stabilize the flame,enlarging the combustion area in the rear parts of the combustors.
A through flow inverse design approach for radial and mixed-flow turbines
ZHAO Bin, SHAN Peng
2008, 23(3): 478-482.
Abstract PDF(1843KB) icon1690 icon523
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Acode of quasi-3D streamline curvature was developed through flow method for the inverse design of radial and mixed-flow turbines.This code was used to design a single stage mixed-flow type turbine which served as the turbine of a micro-turbojet engine with a thrust of 500 N.By computational fluid dynamics examination of the turbine stage and intensity evaluation of the blisk,it is proved that the micro-turbine design has achieved all its design goals.To realize consolidation of design schemes for centripetal-,centrifugal-and mixed-flow turbines,S2,m streamline curvature equilibrium equation was written along the directions of both the streamline 'm' and the streamline's quasi-normal-line 'q'.Thus this scheme can also be used in the design of axialflow turbine.The through flow design code utilized the 'whole controllable vortex' method in all computation stations.
Experimental investigations of aerodynamics performance of aspirate subsonic compressor cascade
NIU Yu-chuan, ZHU Jun-qiang, NIE Chao-qun, GE Zheng-wei
2008, 23(3): 483-489.
Abstract PDF(1055KB) icon1652 icon488
Abstract:
Based on the experimental platform-subsonic cascade wind tunnel,the parameters such as cascade suction surface,static pressure distribution on the surface of the cascade and cascade tail,were tested under different Mach numbers,incidence angles and suction flow rates.The results show that,the boundary layer suction could reduce the cascade's total pressure losses,decrease the deviation angles and improve the aerodynamics performance of cascade.With the appropriate suction slot location and suction flow rate,the internal flow of cascade will become more rational.
Spectrum analysis of the characteristic of light emission from dielectric barrier discharge plasmas
LI Gang, LI Hang-ming, NIE Chao-qun, ZHANG Yi, LI Ying-jun, ZHU Jun-qiang, LI Yu-tong, ZHANG Jie
2008, 23(3): 490-495.
Abstract PDF(740KB) icon1328 icon464
Abstract:
The effects of high voltage,frequency,pressure and injection of gases on plasma generation were investigated by measuring the spectra of the plasma.It is found that the relation between light intensity of plasma and the supplied voltage is linear whereas the effect of frequency is not distinct.The variation of light intensity in chord wise direction accords with Gauss function.In lower pressure the light intensity of plasma is enhanced and injection of helium could have the same effect.These results have established necessary basis for further experiments and numerical simulations.
Numerical investigation of dynamic stall control using variable droop leading edge airfoil
HUANG Yong, MOU Bin, CHEN Zuo-bin, LIU Gang
2008, 23(3): 496-504.
Abstract PDF(1547KB) icon1834 icon528
Abstract:
Numerical simulation for the variable droop leading-edge(VDLE) concept proposed to control the compressible dynamic stall of the VR-12 airfoil was presented. Computational results validate that VDLEcan decrease considerably the maximum drag and improve the minimum pitching moment simultaneously while the lift is maintained almost at the same high level.The reason for VDLEhaving achieved these benefits,from the perspective of flow mechanism,is its ability to eliminate completely the dynamic stall vortex occurred on the baseline.Investigation of the effects of parameters shows that the control benefits of VDLEare not sensitive to the variation of Mach number,reduced frequency or drooping control methods,which implies that the VDLEis a robust control method for the compressible dynamic stall of airfoil.
Effect of suctions on maximum backpressure ratios of hypersonic inlets
CHANG Jun-tao, BAO Wen, CUI Tao, YU Da-ren
2008, 23(3): 505-509.
Abstract PDF(791KB) icon1806 icon475
Abstract:
A 2-Dinternal flow field of hypersonic inlets was simulated numerically at different suction rates.The effects of the backpressure on the internal flow field of the isolator were analyzed.The influences of the boundary layer suction on the maximum backpressure were also discussed,showing the variation of the maximum backpressure with the suction rates.The reasons why the maximum backpressure of the hypersonic inlet is improved by the suction technology were analyzed.The results show that,the boundary layer suctions can improve the maximum backpressure of the inlet,which increases the length of the isolator to some extent.The more the suction of airflow is,the stronger backpressure of the inlet will be.
Full range modeling of aero engine systems based on a simplified algorithm
YU Long-jiang, PIAO Ying
2008, 23(3): 510-515.
Abstract PDF(519KB) icon1695 icon585
Abstract:
A simplified gas flow domain model was applied to modeling and simulation of a bypass dual-spool mix flow turbofan engine,and the detailed calculation process and all formulas were presented.According to the engineering experience,a small-scale local iteration was introduced to reduce the time step of calculating the parameters in turbine components and significantly improve the solution.On a comparative basis,this method avoids large-scale iteration for solving non-linear equations,thus ensuring faster calculation of the full range aero-engine simulation program.This method is proved to provide enough calculation accuracy when the simulation results are compared with the test run data of engine.
Three-dimension blade optimization of multi-blade fan/compressor
CHEN Yun-yong, LIU Bo, MA Cong-hui, GAO Li-min, SHI Jian-cheng, WEN Quan
2008, 23(3): 516-521.
Abstract PDF(931KB) icon1563 icon470
Abstract:
With the help of software Fine/Design3Dand a computational fluid dynamics(CFD) method,the optimization design of a three-dimensional blade was carried out for fan/compressor.Then three-dimensional numerical simulation software named Fine/Turbo was used to calculate typical working conditions of both the new fan/compressor and the initial one at design rotating speed.The flow field performance under design speed condition was obtained.Numerical results show that efficiency is increased by 1.05% at design point after optimization of fan blade,without changing the stage total pressure ratio.The optimization obviously improves,especially in the fan stream,the flow structure and parameters of the fan/compressor's main flow.
Experimental investigations of the effect of dielectric barrier discharge plasma on performance of compressor cascade
LI Gang, NIE Chao-qun, ZHU Jun-qiang, LI Hang-ming, ZHANG Yi, NIU Yu-chuan
2008, 23(3): 522-526.
Abstract PDF(902KB) icon1779 icon456
Abstract:
A pair of electrodes attached to the surface of compressor blade were supplied with high voltage and high frequency alternate current and as a result plasma is produced near the electrodes.Tri-hole tube was used to measure total pressure and velocity in the wake.When the incoming velocity was low,total pressure and velocity in the wake were increased greatly by plasma.As velocity increased,the effect of plasma weakened.The effect of plasma could still be observed as velocity increased to 50 m/s.Plasma is not effective in diminishing the trend of flow separation when it occurs.As to the size of separation zone and intensity of separation vortex,further study is needed.
Research of influence of stator blade suction on the stall margin of axial compressor
CHEN Di, GUI Xing-min
2008, 23(3): 527-533.
Abstract PDF(1483KB) icon1491 icon460
Abstract:
Numeca CFDcommercial software was used to simulate numerically the flow field of a high-turning cascade and axial compressor.In order to mitigate the loss from boundary layer separation and expand the working range,a proposal for slot suction on blade suction surface was presented.The influences of position of slots,length of slots and the mass flow of suction on the separation structure and stall margin were investigated.The results show that,the aerodynamic performance could be improved significantly through release of low-energy air current at upstream boundary layer of stator blade,and the flow separation could also be postponed with improved stall margin.
Analysis of deterministic stresses in a centrifugal compressor
LIU Yang-wei, HUANG Wei-bing, LIU Bao-jie
2008, 23(3): 534-540.
Abstract PDF(1038KB) icon1449 icon457
Abstract:
Steady and unsteady simulations were conducted in the investigation of deterministic unsteady phenomenon in a transonic centrifugal compressor with splitter blade.Results from the steady and unsteady simulations were compared firstly and then the distributions of deterministic stresses in the blade passage and the components of deterministic stresses based on velocity decomposition at the impeller/diffuser interface were studied in depth.The study indicates that the deterministic stresses in the impeller and diffuser are of similar magnitudes,and that the stresses in the passage have large gradients in circumferential direction and decrease rapidly from the interface towards two sides in flow direction,and also shows that the spatial correlations have some discrepancies with the deterministic stresses at the impeller/diffuser interface.
Experiment investigation of throttle hole aerostatic bearing of micro turbine engine
HUANG Guo-ping, WANG Yue, LIANG De-wang
2008, 23(3): 541-546.
Abstract PDF(2041KB) icon1723 icon472
Abstract:
Miniature aerostatic journal air bearings used in Micro-turbine engine was studied by experiment in this paper,while the effects of ratio of length to diameter,orifice,clearance of journal air bearing and supply pressure on the characters of journal air bearing were analyzed.The optimum methods for selecting these parameters were presented.An aerostatic bearing for a micro turbine engine(diameter about 11 cm) was designed: diameter: 15 mm,length: 17.5 mm,orifice: 0.35 mm,and clearance: 30 μm.When the air feed pressure is 2.5 kPa,the bearing can load 13.72 N,and the air feed is less than1.0 g/s.The aerostatic bearing designed in this paper can meet the needs of 11 cm micro turbine engine.
Turbine blade displacement transfer based on mesh regeneration method
LI Li-zhou, WANG Jing-chao, LU Zhen-zhou, YUE Zhu-feng
2008, 23(3): 547-551.
Abstract PDF(691KB) icon1786 icon462
Abstract:
In multi-disciplinary design optimization(MDO) of turbine blades,the coupling data between aerodynamics and structural mechanics models must be transferred to consider the multi-disciplinary coupling property.Amesh-regeneration method was proposed to transfer displacement in this paper.Agroup of lines were added on blade surface,and the shape of blades was determined by the shape of these control lines.According to the displacement of blade structure,the position coordinate of the nodes of the lines was adjusted to modify the shape of the blade's control lines,thus achieving the displacement transfer towards geometric model of blade.By re-meshing,the CFDmesh of the deformed blade was generated.
A subsection method to evaluate width of irregular crack
WANG Zhong-yu, LI Meng, GE Le-yi
2008, 23(3): 552-556.
Abstract PDF(465KB) icon1245 icon480
Abstract:
In consideration of the irregular outline of surface crack,a subsection method for width evaluation was proposed.Based on digital image processing,the surface image was acquired and then was divided into several lengthways subsections,the width of each of which was respectively evaluated by Ferret algorithm.For comparative evaluation of diverse sectioning methods,a conception of useful information ratio was put forward for choosing among them an optimal method,by which the quantitative evaluation of crack width was obtained.Experimental data indicate that by using the method proposed in this paper,the width of surface crack can be quantitatively evaluated.The result can provide effective criterion for mechanism surface inspection,and moreover,this method can also be employed in quantitative evaluation for geometric dimensions of irregular graphics.
Investigation on the ultimate strength of unidirectional tapes and plain cloth hybrid laminates
PENG Chao-yi, XIAO Jia-yu, ZENG Jing-cheng, JIANG Da-zhi
2008, 23(3): 557-562.
Abstract PDF(1090KB) icon1424 icon524
Abstract:
Unidirectional-tapes/plain-cloth hybrid laminates are widely applied in fabricating complex composite structures.Atheoretical analysis approach was established in the present paper to predict the ultimate strength of the tapes/plain-cloth reinforced composites based on three dimensional finite element analysis and optimum design method.The tension and compression experiments on the tapes/plain-cloth laminates were done to verify the effectiveness of the theoretical method put forward in this paper.The deviation of the ultimate strength between the theoretically predicted results and the experimental results are within15%.
An investigation of thermal choke in rocket ejector mode
LÜ Xiang, HE Guo-qiang, LIU Pei-jin, LI Yu-fei
2008, 23(3): 563-568.
Abstract PDF(534KB) icon1781 icon513
Abstract:
Thermal choke active control in rocket ejector mode and ramjet mode was investigated theoretically and experimentally for the integral design of RBCCengine.Theoretic model for possibility analysis of realizing thermal choke was set up.The effect of combustor geometry,heat adding scheme,flow parameters of the primary and secondary mixture on thermal choke was analyzed.Aprinciple of critical Mach number for determining the possibility of reaching thermal choke was proposed.Both theoretical results and experimental results show that it's difficult to reach thermal choke at sea level static for HC-fueled RBCCengine,while it becomes more easily under some flight conditions.Thermal choke with active control was achieved under the flight Mach number 1.2 on the direct-connecting test facilities of NWPU,with the adjustable range up to one quarter of the combustor length.
Trajectory control for interceptor missile with combined control of lateral thrust and aerodynamics
YIN Yong-xin, YANG Ming, WANG Song-yan
2008, 23(3): 569-573.
Abstract PDF(468KB) icon1576 icon466
Abstract:
The ability of a trajectory control system to control an interceptor missile with combined control of lateral thrust and aerodynamics was investigated.Adynamical model for interceptor missile with combined control was established.After analyzing differences between various combinations of control for interceptor missiles,impacts of lateral thrust on the motion of interceptor missiles were presented.Amodel of relative movement between the target and interceptor missile was established.Addressing the particularities of combined control for interceptor missiles,a trajectory control algorithm was designed based on the sliding mode control theory.On the basis of which,fire logic was presented for pulse thrusters in order to improve limitation of simple control method.Simulation results show that this method can effectively implement precise guidance for interceptor missiles at the final guidance stage as well as providing preferable robust stability.
Numerical simulation and DFF measurement of ion thruster accelerator grid erosion depth
LIU Chang, TANG Hai-bin, ZHANG Zhen-peng, JIANG Zhi-guo, GU Zuo, LI Juan
2008, 23(3): 574-579.
Abstract PDF(1315KB) icon1819 icon480
Abstract:
Particle simulation of ion thruster grids was carried out via particle-in-cell(PIC) method and numerical method for calculating the erosion depth of the accelerator grid downstream surface was developed.Xenon was used as propellant and Molybdenum was used as grid material.Monte Carlo method was adopted to simulate the charge exchange collisions between Xenon ions and atoms.Distribution of erosion depth of the downstream surface of accelerator grid was obtained,and the erosion pattern agreed with the "pits and grooves" erosion pattern.Depth from focus(DFF)method was used to measure the erosion depth of the downstream surface of the accelerator grid and comparison between the measured and calculated erosion depth was carried out.
On board self-tuning model for aero-engine fault diagnostics
HUANG Wei-bin, HUANG Jin-quan
2008, 23(3): 580-584.
Abstract PDF(764KB) icon1876 icon555
Abstract:
The composite least-square method was proposed for establishing the state variable model.The method was also applied to develop high dimension state variable model with high accuracy.By taking health parameters as augmented state variables,a Kalman filter was then designed to predict the health parameters from the deviation of measurable parameters.To minimize the modeling errors between the self tuning model and real engine,a neural network was built to modify the steady-state modeling errors,thus improving the confidence level of fault diagnosis system.

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