2006 Vol. 21, No. 3

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Display Method:
Response of an Transonic Two-Stage Compressor to Steady Circumferential Total Pressure Distortions
WU Hu, JIA Hai-jun, HUANG Jian
2006, 21(3): 437-441.
Abstract PDF(308KB) icon1985 icon444
Abstract:
An important component of the gas turbine engine is its axial flow compressor system.With the advent of high maneuvering aircraft with weapon release in the vicinity of the engine inlets,there will always exist inlet total pressure distortions.So,in today’s military turbine engines,their axial compressors must be capable of stable operation despite of severe inlet total pressure distortion.Many experimental and analytical investigations have been conducted in the past four decades to quantify the effects of distorted inlet flow on axial compression system stability.A transfer matrix model was used to predict the response of a transonic two-stage axial flow compressor to steady circumferential total pressure distortions.The effects of multistage environment on the response of an axial flow compressor to steady circumferential total pressure distortion were found.Comparison with those of the two-stage compressor,great attenuation of the total pressure distortion,static pressure distortion and the weakening of the incidence angle changes were produced by isolated single stage.A good agreement was obtained by comparing the numerical results with experimental data.Suggestions were also made to utilize this method for the design of distortion-tolerant multistage axial compressors.
Low Diffusion TVD Schemes and Simulation of Low Mach Number Flow in Turbomachinery
LI Xue-song, XU Jian-zhong
2006, 21(3): 442-447.
Abstract PDF(349KB) icon1472 icon450
Abstract:
The preconditioning matrix in conservation variables was derived from the primitive variables of pressure and entropy,and the resultant eigenvalues and eigenvectors of the preconditioned system were deduced in three dimensional curvilinear coordinates.Specially,the feature matrix given in three dimensional curvilinear coordinates was simple and could be inversed in any case.Then,the low diffusion Harten-TVD scheme in the curvilinear coordinates was obtained based on preconditioning,and the method enforcing the pressure/velocity coupling was discussed.Using schemes with and without preconditioning,low-pressure turbine blade T106 at low Mach number flow,i.e.inlet mach numbers were 0.1,0.01,0.001 respectively,was simulated.The convergence histories were considered firstly.It could be noticed that the convergence rate increased obviously with preconditioning.The convergent results indicate that low diffusion scheme with preconditioning can recover features of low mach flow but scheme without preconditioning can’t.The reason was that the modified eigenvalues of preconditioned system were proportional to the particle velocity approximately,not acoustic velocity,that agreed with real flow characters in low speed flows.However,high convergence rate and high accuracy were gained because of low diffusion and low equation stiffness.It was also noticed that the distribution of equi-pressure contours for these three inlet mach numbers were almost undistinguishable for inviscid flow.
Numerical Simulation of the Flow Inside Radial Inflow Turbine
FENG Tao, ZHOU Ying, ZOU Zheng-ping, LI Wei, DING Shui-ting, XU Guo-qiang
2006, 21(3): 448-454.
Abstract PDF(470KB) icon2027 icon458
Abstract:
Three-dimensional numerical simulation of the flow inside a radial inflow turbine was presented.Preliminary analysis of the aerodynamic characteristics of the island shaped blade,secondary flow and development of vortex and impact of tip clearance were conducted.Results show that island shaped blade has little sensitivity to flow direction in certain range;secondary flow is evident near the inlet of the impeller and close to the suction surface of the passage;along with the reduction of shroud radius,tip clearance flow of the rotor becomes strong.Appropriate tip clearance flow can improve the flow in the tip region.
Investigation of Unsteady Flow Control in an Annular Compressor Cascade Using PIV
GONG Zhi-qiang, LU Yajun, GE Jing-dong
2006, 21(3): 455-460.
Abstract PDF(1232KB) icon1824 icon478
Abstract:
A synthetic jet generator was used as an active control method to control the flow in an annular compressor cascade.It was found that the total pressure loss of the cascade could be reduced effectively.2D Particle Image Velocimetry(PIV) was used to measure the flow field around the blades.Flow fields were acquired under different incidences,jet frequencies and intensities.It was found that synthetic jet had huge impact on the flow field.With proper jet frequency and intensity,flow separation on the blade suction surface was suppressed evidently,and the blade wake intensity and width were reduced.Streamlines around the blade were smoother.These changes were consistent with the decrease of total pressure loss.The mechanism of this active control method was analyzed.
PIV Investigation of the Internal Flow in an Axial Flow Compressor Rotor under Inlet Distortion
LI Mao-yi, LU Ya-jun, GONG Zhi-qiang, YUAN Wei
2006, 21(3): 461-466.
Abstract PDF(1668KB) icon1706 icon489
Abstract:
Flow field structure in the rotor blade passage of a low speed axial flow compressor both under uniform inlet flow and distorted flow simulated by adding baffles with 50% blocking ratio was investigated using PIV(Particle Image Velocimetry) technique.Experimental results indicate that there are four different flow field structure types in the compressor rotor passage at different circumferential positions under inlet distortion.Inlet distortion makes the intensity of vortex disturbance,velocity decrement and separation in the rotor passage rise greatly.This will affect the performance of compressor heavily.The experiment also testifies the limitation of the classical parallel compressor theory.
Maximizing Three-Dimensional Clocking Benefit by Applying Edge-Matching
JI Lu-cheng, YAN Zhao, CHEN Jiang
2006, 21(3): 467-473.
Abstract PDF(1352KB) icon1388 icon437
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Considering "why the benefit of two-dimensional(2D) clocking is always larger than that of the three-dimensional(3D) clocking",a general way of maximizing 3D clocking benefit by edge matching was put forward.On the basis of experience and knowledge accumulated from investigations on clocking,a further simplified method was presented and emphasized.Aachen 1.5 stage low speed subsonic axial turbine was used as an example of maximizing 3D clocking benefits by applying edge matching.The result shows that 3D clocking benefit can be maximized by routinely using edge matching with only little computation resource requirements,and the benefit is good enough to be paid more attention.
Experiment and Numerical Simulation Investigation of Turbine Blade with Trailing Edge Ejection
WANG Yan-gang, LIU Bo, JIANG Jian, CHEN Yun-yong
2006, 21(3): 474-479.
Abstract PDF(527KB) icon1888 icon510
Abstract:
Numerical simulations and tests were carried out to investigate the effect of ejection from different trailing edge slots of a turbine cascade.The detailed flow field of ejection cascade was obtained by using a compact ejection model coupled with the calculation of main flow field.Numerical and experimental results show that the ejection ratio has little effect on the distribution of Mach number and exit flow angle of the two slot types.However,the energy degradation coefficient increases at first and then it has a decreasing tendency with the increase of ejection ratio.The ejection from the symmetric slot blows away the vortex at the blade trailing edge and strengthens the mixing of the wake with the main flow.The ejection from the half slot only blows away the vortex on the slot surface,and has little effect on the flow field near the trailing edge.
Numerical Optimization Design of Circumferentially Curved Transonic Compressor Rotor
YI Wei-lin, HUANG Hong-yan, HAN Wan-jin
2006, 21(3): 480-484.
Abstract PDF(477KB) icon1790 icon423
Abstract:
A flowfield simulation code was developed based on Reynolds-averaged Navier-Stokes equations and validated by experimental data.A numerical optimization code was developed and applied to the optimization design of a circumferentially curved transonic compressor rotor.Results indicate that the circumferential curving can effectively change the three dimensional shock wave structures and weaken wake losses.Optimized blades improve adiabatic efficiency approximately 0.59% and possess fine off-design performance.
The Experimental Research on a New Method for Extending the Axial-Compressor’s Stall Margin
LI Zhi-ping, LI Qiu-shi, YUAN Wei, LU Ya-jun, JIANG Hua-bing
2006, 21(3): 485-491.
Abstract PDF(391KB) icon1716 icon454
Abstract:
Firstly,investigating the influences of unsteady disturbance on compressor’s aerodynamic stability by exterior excitation,and then exploring the new method’s outlook for engineering application by utilizing the unsteady wake impact cooperative effect in adjacent blades of compressor.Furtherly,the model experiment proved that the goal which increasing the compressor’s aerodynamic performance and aerodynamic stability can be realized by optimizing the unsteady aerodynamic circumference configuration technique in compressor.The experiment results indicated that the stall margin can be increased greatly when excitation amplitude exceeded the threshold value and excitation frequency cooperated with the typical vortex shedding frequency,the stall margin can be increased 22.1% relatively.On the other hand,the cooperative effects of WIE(Wake Impact Effect,WIE) at different correct rotating speed were investigated in detail.
Design of the Active Anti-Surge Fuzzy Controller for Axial-Flow Compressors
GAO Yong, LI Ben-wei, XIANG Jin-wu
2006, 21(3): 492-496.
Abstract PDF(707KB) icon1738 icon426
Abstract:
To realize the active antisurge control of axial-flow-compressors,simulation of the compressor transition process was carried out,and the influence of the variation of adjustable parameters on the compressor working characteristics was analyzed.Based on the simulation and analysis,the active control of compressor surge with fuzzy control technology was proposed,and a fuzzy controller was designed and simulated.Results show the controller’s effectiveness.
Parallel Computation for Large-Eddy Simulation of a Model Afterburner
SHAO Mao-min, YAN Ying-wen, LIU Yong, ZHAO Jian-xing
2006, 21(3): 497-501.
Abstract PDF(315KB) icon1476 icon422
Abstract:
Large-Eddy Simulation(LES) of turbulent chemically reacting flows in the model afterburner with V-gutter flame holder was carried out using parallel algorithm based on the MPI(Message Passing Interface) library.The k-equation subscale grid model was used to simulate the turbulent viscosity.The chemical reaction rate was determined by the subgrid EBU combustion model and the heat flux model was employed for the heat flux.In the computer cluster,overlapping grid method was applied to treat the staggered grid in the common boundary.The dynamic memory allocation was used to reduce memory usage.The parallel computing and sole computing results were compared.It shows that parallel computation procedure can correctly simulate the chemically reacting process in the model afterburner.Also,the computation time consumed is dramatically reduced.Parallel computation is proved to be an effective way to simulate the turbulent flows and combustion process in the complex geometry combustor.
Experimental Studies of Flow and Combustion with a Flame-Holder and LES of the Flow
WANG Fang, XU Chun-xiao, WANG Jia-hua, FAN Yu-xin, HAN Qi-xiang
2006, 21(3): 502-506.
Abstract PDF(901KB) icon1590 icon486
Abstract:
Flow and combustion in a combustor using a V-gutter flame-holder with pre-vaporization for afterburners are studied by experiments and the cold flow is also studied by large-eddy simulation.The results indicate that this kind of flame holder can create multiple recirculation zones which lead to increasing the range of flame stabilization.
Experimental Investigation on Thermo-Driving Heat Transfer in Porous Medium in a Centrifugal Force Field
XIA Jie, CHANG Hai-ping
2006, 21(3): 507-511.
Abstract PDF(402KB) icon1567 icon420
Abstract:
Based on the research of turbine blade super cooling technique,experiments have been carried out to investigate the thermo-driving heat transfer phenomenon in a new cooling configuration filled with porous medium in a centrifugal force field.The heat transfer effectiveness of the new cooling configuration was compared to that of the configuration with no porous medium.The results show that the thermo-driving heat transfer effectiveness of the cooling configuration filled with porous medium can be enhanced by increasing the rotating speed,heat flux and cooling air speed.The heat transfer effectiveness of the new cooling configuration is strengthened with the installation of porous medium.
Effect of Rotation on Heat Transfer in a Rotating U-Shaped Passage
LIU Chuan-kai, TAO Zhi, DING Shui-ting, XU Guo-qiang, DENG Hong-wu
2006, 21(3): 512-517.
Abstract PDF(450KB) icon1890 icon446
Abstract:
The influence of rotation on convective heat transfer in a rotating two-pass square channel was investigated experimentally for Reynolds number from 6100 through 25 100 and the rotation number from 0 through 0.26.The square channel has a length-to-hydraulic diameter ratio of 23.The mean rotating radius to the channel hydraulic diameter ratio was kept at a constant value of 24.The results show that the values of Nusselt number reveal an increase with the increase of Reynolds number,keeping the ratios of local Nusselt number to Dittus-Boelter correlation at all locations the same as stationary state.As the channel rotated,the Nusselt number of the first pass was found to increase on the trailing wall and to decrease on the leading wall,the reverse was true in the second pass.The effect of rotation on the heat transfer is most significant in the middle part of the first pass.The geometry of the sharp turn dominates the local heat transfer distributions in the turning region and the upstream of the second pass.
Experimental Investigation on Flow in Pin-Fin Trapezoidal Duct
ZHANG Li, ZHU Hui-ren, LIU Song-ling, WANG Xue-wen, XU Du-chun
2006, 21(3): 518-522.
Abstract PDF(358KB) icon1616 icon460
Abstract:
Experiments were conducted to determine the distribution of static pressure and lateral mass flow rate in a pin-fin trapezoidal duct that modeled the cooling passages in the gas turbine blades.The ratio of lateral-to-total flow rate was 1.The flow Reynolds numbers were varied from 1.5×104through 9×104.The results show that the pressure drops along chordwise passages are much larger than that along radials.The lateral flow rates near the root and the tip of the blade are larger than that in the middle part by 5%～30%.
The Effect of Different Clapboards Structure in Turbine Blade Trailing Edge Complex Passages on Heat Transfer Characteristics
DING Shui-ting, LIU Li-yan, LI Li, TAO Zhi, XU Guo-qiang
2006, 21(3): 523-527.
Abstract PDF(434KB) icon1627 icon473
Abstract:
The experiment mainly aimed at to investigate the effect of different aperture in different clapboard structure in the turbine blade trailing edge complex passages on heat transfer and pressure drop characteristics.A thermochromic liquid crystal method was used to measure the detailed heat transfer coefficients on the end wall surfaces.Comparison of end wall heat transfer and pressure drop characteristics was made between two kinds of rectangular clapboards and two kinds of waved clapboard in the turbine blade trailing edge complex passages.It was found that the rectangular clapboard with aperture of 2.5 millimeter produces higher heat transfer with relatively less pressure drop than that of the rectangular clapboard with aperture of 1.8 millimeter;the heat transfer of the waved clapboard with aperture 1.5 millimeter in trough and aperture 2.1 millimeter on ridge was higher than that of the waved clapboard with aperture 2.1 millimeter in trough and aperture 3.0 millimeter on ridge.Comparing the four structures,the two waved clapboards performed the higher endwall-averaged heat transfer and in the meanwhile pay the lower pressure drop penalty than the two rectangular clapboards.
Numerical Investigation of Jet Impingement Cooling with Non-Uniform Crossflow
TAN Lei, ZHANG Jing-zhou, TAN Xiao-ming
2006, 21(3): 528-532.
Abstract PDF(407KB) icon1942 icon491
Abstract:
Three-dimensional numerical computation of the flow and heat transfer for the jet impingement cooling with non-uniform initial crossflow was conducted to investigate the effects of the jet-to-surface spacing,the impinging holes and crossflow holes arrangement,as well as the crossflow to jet Reynolds number ratio on the heat transfer characteristics.When the crossflow to jet Reynolds number ratios are equal or greater than 0.5,the jet impingement Nusselt numbers are obviously lower than that without crossflow under the same total cooling massflow rate.Under the action of non-uniform crossflow,the temperature distributions take complicated feature for both staggered and inline arrangements owing to the interaction of jet and crossflow.Compared to the case of staggered arrangement between jet holes and crossflow holes,the stations corresponding to peak Nusselt numbers for inline arrangement move downstream.
Experimental Investigation on the Film-Cooling Adiabatic Effectiveness with Different Slot Inlet Hole Pitches
ZHANG Chi, XU Quan-hong, LIN Yu-zhen
2006, 21(3): 533-537.
Abstract PDF(484KB) icon1558 icon449
Abstract:
The film-cooling adiabatic effectiveness was investigated by the heat-transfer experimental method with different pitch between inlet holes of the slot film.The adiabatic wall temperature was measured to calculate the important parameter for film-cooling effectiveness,defined as adiabatic effectiveness.The slot film configurations featured no convergence and inlet holes perpendicular to slot lip.The main stream turbulent level was higher than 10% in all experiments.The experimental results indicate that the pitch between inlet holes plays important role in film-cooling effectiveness.The adiabatic film-cooling effectiveness increases with the decrease of the pitch between the inlet holes and the slot geometric parameter MIXN.
A multiaxial Low Cycle Fatigue Damage Parameter for Single Crystal Nickel-Based Superalloys
DING Zhi-ping, CHEN Ji-ping, YIN Ze-yong, YANG Zhi-guo, CHEN Xiao-ming
2006, 21(3): 538-544.
Abstract PDF(398KB) icon1914 icon448
Abstract:
Strain energy release ratio,being known as thermodynamics generalized force,was applied to describe fatigue damage course of orthotropy materials.From the definition of strain energy release ratio,a triaxiality factor for single crystal superalloy that contains three elastic constants was defined.Not only may the triaxiality factor show the multiaxial complex stress states as well as the coupling effect of the tensile and torsional stress in orthotropy material while the applied loading deflects from the principal axes directions of material coordinate system.It is a prolongation for triaxiality factor of isotropy material.By using the triaxiality factor to modify strain range as a failure parameter and introducing a cyclic characteristic parameter for damage force to take account of alternately changed characteristic of cyclic loading,a low cycle fatigue damage model for single crystal superalloy was proposed.The low cycle fatigue test data correlation to DD3 and CMSX-2 single crystal superalloy with the parameter by using multivariate linear regression analysis is good and the all test data fall into the factor of 2.0 and 2.5 scatter band respectively.
Luster Polish Strengthening for Race Surface of the Mainshaft Bearings of Aeroengine
DENG Si-er, TENG Hong-fei, ZHOU Yan-wei, MA Fu-jian, ZHANG Zhi-hua
2006, 21(3): 545-549.
Abstract PDF(293KB) icon1891 icon478
Abstract:
The technology of surface modification was an efficient way to increase fatigue life of the mainshaft bearing of the aircraft engines.On the basis of theoretical analysis of the surface modification,this paper proposed a new strengthening treatment technology of the raceway surface for the mainshaft bearings(i.e.luster polish strengthening treatment),and designed a corresponding special machine for luster polish strengthening treatment(the centrifugal strengthening machine).The experimental results show that the surface hardness of the raceway is increased and the surface roughness is improved and the residual compression stress is produced on the surface of the raceway,the method of luster polish strengthening can increase notably the fatigue life of the mainshaft bearings and decrease the degree of dispersion of fatigue life.
Response Time Measurement of a Cantilever Rotor with a Disk-Type Magnetorheological Fluid Damper
ZHU Chang-sheng
2006, 21(3): 550-555.
Abstract PDF(677KB) icon1930 icon421
Abstract:
The response time of a cantilever rotor with a disk-type magnetorheological(MR) fluid damper operating in a shear mode were measured at different excitation modes,rotational speeds and magnetic flux densities of different MR fluids.It was shown that the response time of the MR fluid damper rotor system consisted of the initial response time,rapid response time and last slow response time.The initial response time was less than 100 milliseconds;the rapid response time was about 50～400 milliseconds and both were impossible to be within a few milliseconds.The initial response time and the rapid response time were related not only to the magnetic flux density,magnetic particle weight ratio in the MR fluid and rotational speed,but also to the operating mode of the power supply.The response time of the rotor system during switching the step current off was longer than that during switching the step current on.There was an initial delay time at either switching the step current on or off,which was caused by the magnetizing or de-magnetizing process.
Experimental Investigation on Dynamic Characteristics and High Speed Dynamic Balance of a Cantilever Flexible Rotor
DENG Wang-qun, GAO De-ping
2006, 21(3): 556-562.
Abstract PDF(865KB) icon1802 icon417
Abstract:
More than 20 dynamic characteristic experiments of rocket engine oxygen turbopump rotor with different combination of elastic support and metal-rubber damper(combined bearing) were conducted.High speed dynamic balance and repeatability check experiments of the rotor were also conducted with an optimum combined bearing.The results show that the dynamic characteristics of cantilever flexible rotor can be improved by optimum combination of elastic support and metal-rubber damper.The dynamic deflection of the rotor and the dynamic stress of the elastic support can significantly be reduced by single plane high speed dynamic balance technique,and additional unbalance caused by disassembly and assembly will not materially destroy the original balance so long as the accuracy of balancing and the quality of assembly are ensured.
Analysis and Experimental Study of the High Speed Flexible Rotor Dynamic Behaviors
WU Guo-fan, CHEN Guo-zhi, TU Meng-pi
2006, 21(3): 563-568.
Abstract PDF(386KB) icon1585 icon463
Abstract:
A gas turbine rotor working speed is higher than the first critical speed of bending.For this rotor,the high-speed rotor dynamic behaviors and the sensitivity of the balance plane were calculated and analyzed.According to the calculated result the rotor supporting configuration was adjusted,and extensive dynamic experiments were carried out with a simulated rotor.The result of the calculation and experiment shows that appropriate supporting configuration and vibration depressing device can make the rotor cross the first bending critical speed smoothly and run steadily at working speed.
Analysis of the Multileaf Foil Journal Bearings with Large Preload Effect
GENG Hai-peng, QI She-miao, YU Lie
2006, 21(3): 569-574.
Abstract PDF(364KB) icon1661 icon441
Abstract:
According to the structure characteristics of the multileaf foil journal bearing with large preload effect,the nonlinear Finite Element contact model of the foil bearings was established through introducing the assistant parts.The performance of the foil bearings were investigated using Finite Element Method.The assistant parts were used to help form the last contact relationship of foil bearings in the numerical simulation process.These assistant parts were dealt with as rigid bodies without strain.Through modifying the moving contact relationship between the foil bearing parts,the large preload effect of foil bearing was dealt with using the nonlinear contact Finite Element analysis between rigid bodies and flexible bodies.Solution of the governing hydrodynamic equation dealing with compressible fluid was coupled with the structure resiliency of the foil bearing surfaces.In this paper,a typical five leaves foil bearing with large preload effect was analyzed as a successful case to prove the analysis feasibility and accuracy.
Fault Diagnosis of Roller Bearings Based on EMD and SVM
CHENG Jun-sheng, YU De-jie, YANG Yu
2006, 21(3): 575-580.
Abstract PDF(1550KB) icon1808 icon452
Abstract:
A roller bearing fault diagnosis method was proposed in which Support Vector Machine(SVM) and Auto-Regressive(AR) model based on Empirical Mode Decomposition(EMD) were combined.EMD method was used to decompose the roller bearing vibration signal into a finite number of Intrinsic Mode Functions(IMFs),then the AR model of each IMF component was established,finally,the auto-regressive parameters and the variance of remnant were regarded as the fault characteristic vectors and served as input parameters of SVM classifier to classify working condition of the roller bearing.The experimental results show that the proposed approach can classify working condition of roller bearings accurately and effectively even in the case of small number of samples and the atomization of the roller bearing fault diagnosis can be implemented.
Study on Comprehensive Fault Injector for BIT Verification of the FADEC System
Qin Hai-bo, ZHANG Tian-hong, SUN Jian-guo
2006, 21(3): 581-587.
Abstract PDF(372KB) icon1912 icon412
Abstract:
In order to verify the BIT(Built-In-Test)ability of the EEC(Electronic Engine Controller),the design idea of a kind of comprehensive fault injector was proposed in this paper.The fault injector was based on ARM processor,and injected faults to digital and analog electronic nodes by back-driving and voltage summing technique respectively.According to the electronic characteristics of the sensors and actuators of a FADEC(Full Authority Digital Electronic Control) system,the realistic simulation interface circuits were designed to make a FADEC running system with an EEC.Fault injecting experiments to a principium EEC swatch show that the fault injector is a viable tool for BIT verification.
Theory of Similarity Based Aeroengine Multivariable Control Method
YANG Gang, YAO Hua
2006, 21(3): 588-594.
Abstract PDF(1715KB) icon1744 icon454
Abstract:
The procedure of applying the theory of similarity to LQR method in aeroengine control systems was developed.The method was analyzed and the shortcomings were pointed out:(1) the closed-loop system responds slowly at high altitude and low Mach number,which can not meet the swift respond requirement;(2) the closed-loop system requires too much control energy at low altitude and high Mach number.On one hand,this is very likely to cause aeroengine actuator saturation.On the other hand,this would degrade the performance of the closed-loop system under disturbances such as noises and delays.Hence,an improved procedure of applying the theory of similarity was developed and it solved the above problems reasonably well.Further more,the stability of the proposed method was proved.It was also extended to the augmented LQR method.Finally,the design procedure of a turbofan engine control system exemplified the above results.
Application of Median Filter in Gas Turbine Sensor Data Validation
TANG Ya-juan, CHENG Mou-sen
2006, 21(3): 595-600.
Abstract PDF(333KB) icon1296 icon420
Abstract:
The filtering requirements of engine measurement signals are analyzed.A center weighted median filter and fast algorithm for sensor data validation are presented,and the filtering function and algorithmic efficiency are evaluated with numerical experiments.The simulated test signals are composed of steep edges and slopes that representing abrupt faults,linear deterioration and/or regime transitional response,superimposed with simulated random noise and high-amplitude impulsive noise.Results show that median filter is good at removing impulsive noise and outliers.In addition,random noise is suppressed to great extents while preserving the final details.Practical application to gas turbine experimental sensor data validation confirms the above conclusions.
Switching Stability Analysis of Multi-Control Loops for Turbofan Engine
LIU Xiao-feng, SUI Yan-feng, HE Bao-cheng, YU Da-ren
2006, 21(3): 601-605.
Abstract PDF(1442KB) icon1654 icon438
Abstract:
The stability of the turbofan engine control loops(which commonly includes speed control,acceleration/deceleration control and temperature protection control) was researched in this paper.The research showed that the turbofan engine control system was a special multi-switch control loops.A sufficient condition was given that made multi-control loops for turbofan engine control system be stably switched through every stable control loop and continuous switching.
Elimination of Coupling Instability Using Few Parallel Connection Notch Filters for Helicopter Rotor/Power Train
LI Sheng-quan, YANG Zheng-shan, SUN Jian-guo
2006, 21(3): 606-609.
Abstract PDF(261KB) icon1432 icon384
Abstract:
A solution was proposed which eliminated the coupling instability between helicopter power transmitting train torsional vibration system and power control system.A combination of notch filters in parallel and filters selected according to engine working modes have been used to achieve torsional vibration filtration.The modification of the notch filter made the extra phase-shifting introduced to the control system passband reduced and so the control performance was improved.The method was demonstrated successfully on a helicopter integrated test-bed.
Thrust Determination of an Engine with Laval Nozzle with Large Simulated Ambient Pressure Deviation
LIU Zhi-you, HOU Min-jie, GONG Xiao-qi
2006, 21(3): 610-614.
Abstract PDF(294KB) icon1749 icon445
Abstract:
The particularity of the altitude simulated test of an engine with Laval nozzle was analyzed in brief.The engine thrust determination and correction in altitude test with large deviation of simulated ambient pressure was put forward.The test result shows that maximum tolerance of the simulated ambient pressure deviation is about 14% under which the engine thrust uncertainty remains less than 1.0%.Where there is a limitation of the test facility capability or for other reasons the large deviation of simulated ambient pressure may occur.The presented method can be used to determine the thrust of the engine with Laval nozzle.
Study of Monitoring Parameter Selection Based on AHP for LRE in Ground Test
YANG Xue, ZHANG Zhen-peng, YANG Si-feng
2006, 21(3): 615-620.
Abstract PDF(532KB) icon1711 icon408
Abstract:
It is an important and basic issue to choose monitoring parameters of Liquid propellant Rocket Engine(LRE) monitoring system in ground test.According to the statistic characteristics of steady parameters and the faults frequently happened in LRE ground test,after analyzing the sensitivity and correlation of monitoring parameters to faults,usability of the sensors and the correlation of measured parameters,the hierarchy models consisting of project layer,criterion layer and object layer for selecting monitoring parameters were established.Based on the Analytic Hierarchy Process(AHP),and with the help of the models,monitoring parameters to monitor the operation condition of LRE in ground test were evaluated,compared and optimized.Finally,the monitoring parameters were determined.The verification with the test data and simulation data of LRE ground test faults shows that the monitoring parameter set determined can supervise satisfactorily the change of LRE operation condition,and also shows that it is reasonable and practicable to use AHP selected monitoring parameters for LRE monitoring system in ground test.

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