2010 Vol. 25, No. 3

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PIV measurement of flow field for impingement-effusion cooling
YANG Wei-hua, WANG Li, SONG Shuang-wen, HU Hao-sheng, ZHANG Jing-zhou
2010, 25(3): 483-487.
Abstract PDF(1797KB) icon1873 icon467
Abstract:
In order to study the flow field characteristics of impingement-effusion cooling,a kind of impingement-effusion cooling structure was designed,the flow field characteristics of it was studied by PIV(particle image velocimetry).It was found that the flow characteristics between impingement plate and effusion plate is very complex,and the size of eddy between impingement plate and effusion plate is different with the change of blowing ratio.On the side of effusion film,the flow from effusion hole will penetrate gradually main flow when blowing ratio is increased,that destroys the effusion film.There is a pair of "kidney eddies" on the vertical section of the outlet of effusion hole,and the "kidney eddies" will moves into the main flow when the blowing ratio is increased.
Impact of dilution holes on the flow rate distribution and combustion performance of trapped vortex combustor
LI Rui-ming, LIU Yu-ying, MA Wen-jie, ZHANG Rong-chun, LIU Yang, YANG Mao-lin
2010, 25(3): 488-495.
Abstract PDF(1593KB) icon1785 icon443
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The impact of dilution holes with three different areas on the flow rate distribution of a model rectangular trapped vortex combustor was numerically simulated,and the total pressure loss,lean blow-off limit and combustion efficiency of the combustor were experimentally studied under the inlet Mach number was 0.3 and the total temperature was 540K.This shows that,both the flow rate distribution and the performance of the combustor are affected by the dilution holes'areas,and the combustor with larger dilution holes has better combustion performances than the others.
Numerical investigation on gaseous detonation diffraction
LI Hai-peng, HE Li-ming, LUO Jun, ZENG Hao, WU Wei
2010, 25(3): 496-502.
Abstract PDF(1059KB) icon1803 icon458
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Gaseous detonation diffraction in abruptly expanded tube and gradually expanded tubes was numerically investigated at different filling and expanding angles.Detonation tube diameter and critical tube diameter are vital to the successful diffraction.Interaction of the wall reflected shock and the detonation wave produces a high temperature and high pressure region,helping to reduce the detonation inducement time and the distance between transverse waves.The small expanding angle can generate strong reflected shock.If the reflected shock is strong enough,it will separate the detonation wave into 3 parts generating high temperature,high pressure regions at the cut-off points,providing a support to detonation diffraction.
Effect of temperature level on heat transfer on a free disk with laminar flow
ZHAO Xi, XU Guo-qiang, TAO Zhi, LUO Xiang
2010, 25(3): 503-508.
Abstract PDF(1632KB) icon1918 icon460
Abstract:
The effect of density variation caused by temperature difference of cooling air and a free disk on the heat transfer of the disk was simulated numerically.The difference of heat transfer between compressible and incompressible cooling air was compared by the local Nusselt number of the free disk.The following conclusions can be drawn on a comparative basis: the relative difference of the local Nusselt number is dominantly controlled by dimensionless local temperature difference,regardless of the influence of the distribution curve exponent of surplus temperature,dimensionless maximal temperature difference and rotating Reynolds number.A correlation formula of relative difference of local Nusselt number and dimensionless local temperature difference was presented by fitting numerical data.
Simulation approach to the fluid-thermal network and the application
HOU Sheng-ping, TAO Zhi, HAN Shu-jun, DING Shui-ting, XU Guo-qiang
2010, 25(3): 509-514.
Abstract PDF(1322KB) icon1501 icon427
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A new approach combining fluid network and thermal network was developed to predict the characteristic of pressure,temperature and mass flow rate of engine.The simulated system was simplified into nodes and branches.Conservation equations were solved by a newly introduced fluid-thermal method.The program was validated by applying to the benchmark,and then the program was applied to predict the flow and heat transfer characteristics of turbine disk in engine,providing useful reference for design.
Calculation of one-dimensional radiative heat transfer with zonal model in combustor
MAO Wen-yi, LIN Yu-zhen, XU Quan-hong, LIU Gao-en
2010, 25(3): 515-520.
Abstract PDF(2158KB) icon1581 icon410
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A new kind of zonal model for calculating the combustor wall temperature with strict mechanism and high precision was developed in this paper.The Lefebvre model and zonal model were adopted to calculate the radiative heat transfer of a cylindrical combustor without cooling.The distribution of radiative heat flux density and wall temperature was obtained respectively by comparing and analyzing the two different methods.The results show that,there are some shortages for Lefebvre model because gas is partitioned as 1-D directional radiation causing the radiative heat flux density of combustor front and back walls smaller,while the radiative heat flux density distribution tends to be more reasonable with zonal model.
Experiment about heat transfer characteristic of midchord region of turbine blade with pin-fin arrays
ZHANG Jing-yang, CHANG Hai-ping
2010, 25(3): 521-525.
Abstract PDF(982KB) icon1537 icon473
Abstract:
Based on midchord region model of tubine blade whose impinging tube is supported by pin-fin arrays,the heat transfer rules of the wall with pin-fin was acquired,and then the heat transfer characteristic was compared with that of the model whose tube is supported by rib along the flow direction.Various impinging Reynolds numbers,density flow ratios of initial cross flow to impinging jet flow and impinging distance to impinging jet hole diameter were analyzed.The results show that: pin-fin arrays could decrease the negative influence of the initial cross flow on the heat transfer and the initial cross flow could strengthen the efficiency of heat transfer of the region after the cross flow.The heat transfer efficiency of the model with pin-fin arrays is higher than the model with rib along the flow direction.
Improved design method of exhaust ejector mixing tube in cooling helicopter nacelle
CAO Xue-wei, YU Jian-zu, XIE Yong-qi, ZHOU Yi
2010, 25(3): 526-530.
Abstract PDF(427KB) icon1617 icon429
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The conventional design methods of helicopter nacelle exhaust ejector mixing tube were introduced.Based on the characteristic equation and analysis of influence factors,and with a reference to nacelle exhaust systems of a helicopter,an improved design method of helicopter nacelle exhaust ejector mixing tube was established.Based on this improved method,a helicopter nacelle exhaust mixing tube was designed as an example.By comparing with other design results,this method could improve the design efficiency by 30% and maintain design accuracy within 5% to meet the engineering design requirements,demonstrating its availability and significance in engineering applications.
Investigation into effects of axial spacing on performance of a dual-stage counter-rotating compressor
WANG Yan-gang, NIU Nan, LIU Bo, JIA Rui-qi, CHEN Yun-yong
2010, 25(3): 531-536.
Abstract PDF(1046KB) icon1662 icon445
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Seven modules with different axial spacings between two reversed rotating rotors of a counter-rotating compressor were designed,and then the detailed flow structure and performance of them in different rotating speeds was obtained by numerical simulations.The effect of axial spacing on performance of the counter-rotating compressor,inlet flow angle of two rotors and flow structure have been investigated.When the axial spacing between two reversed rotating rotors was changed from 30%C to 70%C,the following observations were obtained:(1)The peak efficiency of counter-rotating compressor decreased approximately 2%,the efficiency of two reversed rotating rotors decreased approximately 4%.(2)At the near stall condition with designed rotating speed,the efficiency and mass flow rate increased firstly and then decreased,and the maximum of the two parameters happened when the axial spacing was 55%C.(3)At the chock condition,the inlet flow angle of the two rotors decreased,contrary to the trend of the chock mass flow rate change.(4)When the axial spacing was bigger than 50%C,it could not affect the inlet flow angle of the two rotors noticeably.(5)Decreasing the axial spacing can improve the performance of the counter-rotating compressor when the loss of mixing is dominating.If the secondary flow loss is the primary loss,increasing the axial spacing is feasible to improve the performance of the counter-rotating compressor.
Investigation of flutter prediction method for transonic fan
ZHANG Zheng-qiu, ZOU Zheng-ping, WANG Yan-rong, LIU Huo-xing
2010, 25(3): 537-548.
Abstract PDF(2836KB) icon1566 icon442
Abstract:
Numerical simulation of three-dimensional unsteady viscous flow around oscillating transonic fan was carried out in the influence coefficient domain with one blade oscillating in various three-dimensional rigid-body modes.Then the stability parameter map was gotten based on the assumption of rigid body mode and mode superposition method.The main result of this paper is that,the shock wave has dominant contribution on the unsteady aerodynamic force,mode shape has an important effect on flutter stability,and the stability parameter of transonic fan and subsonic low pressure turbine has similar pattern.
Research on the effect of centrifugal compressor blade tip clearance distribution on conbustion engine turbocharger performance
GUO Gong-da, ZHANG Yang-jun, XU Jian-zhong, ZHENG Xin-qian, ZHUGE Wei-lin
2010, 25(3): 549-556.
Abstract PDF(1848KB) icon1663 icon408
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Based on three-dimensional computational fluid dynamics method,the flow fields of two opposite impeller blade tip clearance distribution compressor stages with vaneless diffuser were analyzed.The law and action mechanism of tip clearance distribution effect on the high charging ratio transonic centrifugal compressor impeller and vaneless diffuser performance were researched.This proves that non-uniform chord direction blade tip clearance distribution impellers have wider operating range.The pressure ratio and efficiency of compressor stage whose outlet axial clearance height is smaller than inlet radial clearance height are higher than that of compressor stage whose outlet axial clearance height is larger than inlet radial clearance height.The smaller outlet axial clearance height weakens the clearance flow in aft half of impeller passage,improves the impeller aft passage power input and obtains higher impeller pressure ratio and compressor stage pressure ratio.The smaller outlet axial clearance height gets higher efficiency since it reduces impeller aft blade tip clearance leakage vortices intensity and makes the vortices breakdown and dissipation loss less in impeller passage and vaneless diffuser passage.
Aerodynamic design of a small centrifugal compressor
JI Guo-feng, YIN Ming-xia, GUI Xing-min
2010, 25(3): 557-564.
Abstract PDF(1909KB) icon1708 icon524
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An aerodynamic design of a small centrifugal compressor for some pilotless aircraft was presented in this paper.One-dimensional thermal calculation was conducted to configure the flow path.And based on two-dimensional through flow design,the required aerodynamic performance was obtained by adjusting the distribution of velocity circulation of the blade rows.Then three-dimensional blade airfoils can be got by arbitrary camber lines blading.At last,three-dimensional CFD(computational fluid dynamics) calculation was used to analyze the result of the aerodynamic design.All performance parameters of the centrifugal compressor meet the design requirement at design point.And the performance curves at all speeds are really flat.Therefor the work stability of the compressor have a fairly broad scope.
Influence of tip clearance flow on performance of one micro centrifugal compressor
YIN Ming-xia, JI Guo-feng, GUI Xing-min
2010, 25(3): 565-570.
Abstract PDF(1634KB) icon1791 icon437
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In order to research the effects of different clearance widths of small centrifugal compressor,a high speed centrifugal compressor was investigated by numerical simulation.The results show that,the leakage flow is strengthened with the increase of gap width,leading to decrease of impeller'pressurization capacity and efficiency.Thereafter,the stage pressure ratio,efficiency and flow rate decrease correspondingly,and the stable margin of compressor is affected significantly.
Optimization design of a small centrifugal compressor
JI Guo-feng, WANG Wei, GUI Xing-min
2010, 25(3): 571-576.
Abstract PDF(2215KB) icon1725 icon439
Abstract:
Optimization design of some small centrifugal compressor with a small stall margin was discussed in this paper.In the optimization design,a method called arbitrary camber lines blading design method was used for both axial and centrifugal compressors.The optimization design method,beginning with a through flow calculation,and in combination with arbitrary camber lines blading,applied three-dimensional computational fluid dynamics calculation to analyze the result of the optimization design.By changing the control properties of through flow design and arbitrary blading,meridional flow passage and three-dimensional blades were gained satisfactorily.As a result,not only the stall margin has been increased,but also the stage performance of the compressor has been improved significantly.
Numerical optimization of aerodynamics of some 3-D tandem stators
LIU Xiao-jia, NING Fang-fei
2010, 25(3): 577-581.
Abstract PDF(1607KB) icon1533 icon465
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The tandem stators of a high load axial compressor have been optimized by changing three-dimensional(3-D) stacklines near the hub.An in-housed optimization platform for 3-D numerical aerodynamics design of compressors was used and the complex method was adopted.After the optimization,the separation near the hub has been removed,and the performance of the compressor has been effectively improved.
Effect of unsteady cooperative flow on the dynamic response in the rotor of axial compressor
YAN Jia-chao, HOU An-ping, ZHOU Sheng
2010, 25(3): 582-586.
Abstract PDF(1496KB) icon1421 icon423
Abstract:
"Whether the unsteady cooperative flow could induce the dynamic response problem of the rotors" was expatiated in this article.Based on the existing result and modal analysis for spectrum analyzer of three-dimensional unsteady CFD(computational fluid dynamics),the foregoing question was researched by adjusting the wakes of front stator vane.The result of the computation shows that the properly-adjusted number of stators can maximize the unsteady potential while avoiding the sympathetic vibration of the rotors.
Fatigue damage of aero-engine in intensive formation flying
CHENG Li, ZHANG Hai-wei, WANG Li-min
2010, 25(3): 587-591.
Abstract PDF(921KB) icon1574 icon439
Abstract:
Using actual data in typical intensive formation flying,the variance between different aero-engines in almost the same flying conditions was researched.Aero-engine fatigue variance and its statistical rules due to different positions of the chief and the wing aircraft can be elicited,after the data were converted to the standard cycle by quadratic rainflow counting algorithm and the Miner damage accumulation.It is found that it accords with Weibull distribution,namely,single aircraft variance can reach 2～4 times and the maximal variance can reach 9～10 times because of the same reason.Furthermore,the variance of aero-engine fatigue load/damage and the necessity of single aircraft life monitoring are revealed.
Effect of random cell wall thickness on the elastic properties of Voronoi foam with closed-cells
LU Zi-xing, WANG Jian-yue
2010, 25(3): 592-596.
Abstract PDF(806KB) icon1340 icon413
Abstract:
Based on the Voronoi random model for closed-cell foam,the effect of nonuniformity of cell wall thickness on isotropic and anisotropic elastic properties of closed-cell foams was investigated.The combined effect of random cell wall thickness and model irregularity was also discussed.Results indicate that the random cell wall thickness has a reducing effect on the isotropic and anisotropic elastic moduli,and such effect of random cell wall thickness is less than that of model irregularity for isotropic foams,contrary to anisotropic foams;however,the effect of random cell wall thickness on the Poisson's ratio for closed-cell foam is very small.
Effect of interface layer parameters on uniaxial tensile behavior of ceramic matrix composites
SUN Zhi-gang, LI Long-biao, ZHU Bin, SONG Ying-dong
2010, 25(3): 597-602.
Abstract PDF(2046KB) icon1677 icon457
Abstract:
The effect of interface layer parameters on the uniaxial tensile stress-strain behavior of ceramic matrix composites has been investigated using micro-mechanic approach.The simplified micro-mechanic model,which considered the effects of the interface layer on the mechanical properties of fiber reinforced ceramic composites,was proposed based on the classic shear-lag model.The critical matrix strain energy criterion,maximum interface shear stress criterion and the critical fiber strain energy criterion were used to determine the matrix crack space,interface debonding length and the fiber failure fraction.The stress-strain curve was modeled with consideration of the effects of interface layer.And the influences of interface layer volume fraction,elastic modulus and Poisson ratio on the stress-strain curve were also discussed.The stress-strain curve predicted by the present analysis with compared the experimental data,and it was found that the interface debonding and fiber failure part of the tensile stree-strain curve agree well with the experimental data on consideration of the effect of interface layer or interface phase.
Three-dimensional numerical analysis of residual stress field for shot-peening
ZHANG Hong-wei, ZHANG Yi-du, WU Qiong
2010, 25(3): 603-609.
Abstract PDF(2050KB) icon1858 icon583
Abstract:
This investigation is devoted to the modeling and simulation of the residual stress field resulting from the shot-peening process,in which the finite element method was employed.The history of energy change during explicit dynamic analysis was discussed and the solving time for explicit analysis was analyzed by shock wave theory.For the single shot impact model,the study examined the effect of shot velocity,shot size,incident angle and interfacial friction,while comparison was made with the published experimental results.Furthermore,the effect of repeated impacts on the residual stress field and equivalent plastic strain was studied.The influence of peening coverage on the residual stresses field was investigated using a realistic multiple impingement model.
Direct algorithm for variance of random vibration response
KONG Xian-ren, LIAO Jun
2010, 25(3): 610-616.
Abstract PDF(1919KB) icon1456 icon448
Abstract:
By using of extending order and modal transformation of dynamic equation,a Lyapunov equation was established,and the solution of the Lyapunov equation could be used to directly obtain stationary random vibration response variance of large-scale finite element structure.Duffing system was linearized by equivalent linearization method,and the Lyapunov equation was solved to get the variance of random vibration response of duffing system.The precision has been justified by simulation,showing that the presented method is efficient and precise.
Multi-disciplinary aero-dynamic-thermal-structure design optimization for turbine blade
YANG Jun-jie, WANG Rong-qiao, FAN Jiang, SHEN Xiu-li
2010, 25(3): 617-622.
Abstract PDF(1130KB) icon1832 icon509
Abstract:
Design of turbine blades is a typical multi-disciplinary issue on aero-dynamic analysis,thermal analysis and structure design optimization,aimed at ensuring the accuracy of the result and the computing efficiency.Approximate models could simplify data management,improve calculation efficiency and ensure the engineering precision by controlling the number and quality of sample.A framework on multi-disciplinary design optimization for turbine blades,which makes use of some professional tools in the areas,is proposed by analyzing the design process and the data transfer relations.By comparing the optimizations using the Kriging model and accurate analysis for a turbine blade,it shows that the result for approximate models is acceptable in engineering and the efficiency is higher.Furthermore,it also shows that the framework is feasible.
Substructure coupled matrix method for vibration analysis of multi-rotor systems
FAN Ye-sen, WANG San-min, YANG Zhen, LIU Hai-xia
2010, 25(3): 623-628.
Abstract PDF(458KB) icon1621 icon476
Abstract:
A modeling method was presented to analyze the vibration of a multi-rotor system.The multi-rotor system was divided into single-rotor systems at the coupled parts.The coupled forces were regarded as the external exciting forces for each single-rotor system.The vibration equations of the single-rotor system were derived from the lumped mass method and the vibration equations of each node.The coupled matrixes of the multi-rotor system were deduced from the expression of the coupled forces.The global vibration equations of the multi-rotor system were established using the coupled matrixes.The nature frequencies,critical speeds,frequency amplitude diagram and whirling orbit etc.,were obtained by analyzing the global vibration equations of the whole systems.Finally,the feasibility and the reliability of the substructure coupled matrix method for vibration analysis of multi-rotor system were proved though two numerical examples.
Numerical investigation on the unsteady flowfield of the turbine stage under different axial gaps
ZHOU Li, CAI Yuan-hu
2010, 25(3): 629-635.
Abstract PDF(726KB) icon1909 icon400
Abstract:
The unsteady flowfield of the turbine stage were investigated numerically under different axial gaps,and the influence of the axial gap on the flow unsteadiness and the flowfield was discussed.Results show the axial gap L has great influence on the flow unsteadiness in the rotor.The intensity of the stator wake and its influence range increase with the reduction of the axial gap,and the unsteady influence of the stator wake mainly occurs near the leading edge of the rotor.The turbulent kinetic energy of the rotor outlet is minimum under the half of the design axial gap because the recovery effect of the stator wake is directly proportional to the wake intensity of the incoming flow.
Numerical simulation of intercooler flow path for marine gas turbine
DONG Wei, WEN Chao-zhu, ZHENG Pei-ying
2010, 25(3): 636-640.
Abstract PDF(1082KB) icon1761 icon458
Abstract:
With the aid of CFD(computational fluid dynamics)numerical simulation technology,the total pressure loss of the intercooler entire flow path for marine gas turbine was analyzed.The equivalent flow area and equivalent heat transfer methods were used in the numerical simulation,the problem of the modeling entire intercooler flow path was solved effectively.The numerical computation results indicate that the CFD numerical simulation technology can effectively analyze the details of the flow field,helping to improve the intercooler flow path design.The combination of the CFD numerical simulation technology and intercooler design technique can improve the optimal design of the intercooler entire flow path for marine gas turbine.
Design and calibration of a certain aircraft/engine's simulation board
YE Wei, QIAO Wei-yang, HOU Min-jie
2010, 25(3): 641-646.
Abstract PDF(604KB) icon1569 icon459
Abstract:
To satisfy the requirement of a certain aircraf/engine's compatibility test,this paper put forward a half-experience method based on the test data of flashboard for the design of simulation board.On the basis of obtained rough contour of the simulation board and the verifying of resistance coefficient,the given flow field's low pressure range and distortion intensity on the annular surface were compared by the model's blow test.For umpty adjustments of the distortion index of the annular surface element,it makes sure the annular surface holed,numbers and sizes of the holes.The results show that this method is simple and effective.The simulation flow field meets the needs of the certain aircraft/engine's test requirement.
Flow characteristic and aerodynamic performance in elliptic shape isolator at different back pressures
WANG Wei-xing, LI Bo, GUO Rong-wei
2010, 25(3): 647-653.
Abstract PDF(1246KB) icon1481 icon435
Abstract:
Elliptic shape isolators under back pressure were studied with 3-D CFD(computational fluid dynamics) calculation.The results show that the shock train structure and the flow characteristic are symmetrical generally when the upstream Mach number is low under symmetrical free-stream and geometry,but the shock train structure and the flow characteristic become unsymmetrical obviously when the upstream Mach number is too high.As the ratio of major axis to minor axis decreases,the elliptic shape isolator's ability to support back pressure becomes better,but the Mach number and temperature of the isolator outlet are independent of the ratio of major axis to minor axis.As the upstream Mach number increases,the Mach number of outlet varies little once reaching maximum back pressure.
Numerical simulation of heat transfer and fluid flow on marine gas turbine intercooler
WEN Chao-zhu, DONG Wei
2010, 25(3): 654-658.
Abstract PDF(1371KB) icon1662 icon401
Abstract:
On the base of structure features of plain fin rectangular channels,a coupled calculation model of flow field and temperature field was established.One computational fluid dynamics(CFD) program had been used for the simulation on the fluid flow and heat transfer in the physical model.Graphics and trends of temperature,pressure,velocity and local heat transfer coefficients of multiple cross-sections were given and analysed.The performance of intercooling heat exchanger under different loads had been studied.The results could be a useful reference for the optimum design of marine gas turbine intercooling heat exchanger.
Application of trust region filter algorithm to aero-engine online optimization
ZHANG Hai-bo, SUN Jian-guo, WANG Jian-kang
2010, 25(3): 659-666.
Abstract PDF(11611KB) icon1559 icon369
Abstract:
Online optimization method for aero-engine was mainly studied in this paper.Trust region filter algorithm was applied to solve aero-engine online optimization problem in which a relative nonlinear component-level model was used as the optimization model.The algorithm has better optimality and feasibility than the basic trust region algorithm(BTRA).Sub optimization problem infeasibility is escaped by using a restoration algorithm,and the filter algorithm guarantees the algorithm global convergence ability.As shown in a simulation example,the trust region filter algorithm was used in the minimum specific fuel consumption mode for some two-spool turbofan engine performance seeking control,and the simulation results show that it has better optimization effectiveness than BTRA,if it's intended to solve aero-engine online optimization problem.
Startup model of turbofan engine used in a flight simulator
XIONG Hai-guo, ZHENG Shu-tao, JIANG Hong-zhou, HAN Jun-wei
2010, 25(3): 667-674.
Abstract PDF(2977KB) icon1711 icon431
Abstract:
In order to establish the aircraft engine startup model used in a flight simulator,the modeling and simulation methods for turbofan engine startup were studied,the basic rules for establishing the startup model were developed.Accordingly,the main performance models which dominate the dynamic performance of engine startup in normal working condition were developed based on component modeling method,while the typical malfunction models were developed using the designed malfunction factor,so the normal engine startup procedure and malfunction simulation in the starting process were carried out.The comparisons between the simulation results in normal/fault conditions and test data indicate that,the normal startup model reflects the accelerating ability of every startup phase correctly,and the malfunction models represent the fault logic and effects,thus meeting the requirements of flight simulation.
Study on parameter telemetry for rotary machine based on free space optical communication
LIU Dong-dong, ZHANG Tian-hong, MA Jian-gang
2010, 25(3): 675-680.
Abstract PDF(677KB) icon1564 icon478
Abstract:
In order to deal with the high-speed real-time data acquisition problem in the dynamic parameter telemetry for aero-engine rotor,helicopter rotor wing and other rotary machines,a novel non-contact parameter telemetry method for rotary machine based on free space optical communication was proposed,and the overall scheme of parameter telemetry system based on this method was given.The key circuits such as laser diode driver,photodetector amplifier,serializer/deseiralizer of the photoelectric data transmission channel were designed.As a result,a free space optical communication transceiver of a theoretical maximum transmission rate of 622Mb/s was designed,and the actual performance was tested.A parameter telemetry experimental prototype was developed.Data transmission rate of the prototype is reach up to 300 Mb/s in rotational state,which satisfy the requirements of dynamic parameter telemetry for aero-engine rotor.
Research on the iteration methods in aero-engine non-linear model real-time computation
LU Jun, GUO Ying-qing, ZHANG Shu-gang
2010, 25(3): 681-686.
Abstract PDF(1023KB) icon1879 icon407
Abstract:
Considering the rigorous real-time computation of aero-engine non-linear model for on-board application in future,several iteration methods were studied in this paper.Their historical developments were surveyed,and convergence problems were discussed.Then a new improved method was presented in which the Jacobian matrix for a previous state point could be directly applied to the next point's calculation during the transition state simulation.It can improve execution efficiency of the model by reducing the number of aerothermodynamic model computations.Finally,a practical example has been simulated in these iteration methods respectively.The simulation results show that(1) the Broyden rank-one method has highest execution efficiency,so it's more suitable for non-linear aero-engine model real-time computing;(2) the improved method is simple and effective,laying a foundation for the rigorous real-time computation of aero-engine non-linear model.
Flow estimation in fan and compressor characteristic monitoring of turbofan engine
ZHAO Lin, FAN Ding, LV Hong-yan
2010, 25(3): 687-690.
Abstract PDF(1556KB) icon1680 icon419
Abstract:
A method about air flow estimation for fan and compressor characteristic drift monitoring in turbofan engine was presented in this paper.Air flow was estimated by solving four flow balance equations,including balance equation with exit pressure of internal bypass and external bypass,relationship of nozzle flow,relationship of enthalpy increase flow.By calculating and determining the symbol parameter of sensor error,the influences of sensor error on flow estimation can be separated.Two percent of drift either in sensor error or in components characteristic was simulated.It indicates that this method can observe the fan and compressor characteristic drift and separate it from sensor error drift.
Design and experiment of high flowrate single-element gas-gas injectors
WANG Xiao-wei, GAO Yu-shan, JIN Ping, CAI Guo-biao
2010, 25(3): 691-698.
Abstract PDF(1724KB) icon1779 icon424
Abstract:
The GH2/GO2 combustion flow field in a chamber with a single-element typical shear-coaxial injector was numerically simulated firstly.The characteristics of the flow field and the shear-coaxial injector architecture were analyzed to enhance the mixing and decrease the combustion length,some improved designs were made for suiting high flowrate conditions.Numerical analysis and validation experiments were conducted for single-element chambers with these injectors.The improved shear mixing element with high H2/O2 velocity ratio and a flared O2 post tip could maintain a benign heat load environment,and effectively enhance the GH2/GO2 mixing suitable for the combustion in the nominal combustor with high injection flowrate.The results directly contribute to the high flow rate gas-gas injector design and the design methodologies in this paper give references for further studies.
Effect of oxidizer post pattern on characteristic efficiency for gas-gas propellants
DU Zheng-gang, LI Mao, GAO Yu-shan, JIN Ping, CAI Guo-biao
2010, 25(3): 699-703.
Abstract PDF(1361KB) icon1353 icon426
Abstract:
Through the method of numerical simulation and experiment,investigation was conducted on the shear coaxial injector which uses the gaseous oxygen and hydrogen as propellants.The effects of oxidizer post pattern and wall thickness on characteristic efficiency were discussed.The results show that a small scale recirculation zone is produced near the oxidizer post tip,which serves as a flame holder.The radial velocity generated in flared oxidizer post interferes the recirculation zone,making the characteristic efficiency relatively low,while the straight oxidizer post is beneficial to the flame stability,thus achieving a higher characteristic efficiency,and the wall thickness of oxidizer post has no significant influence on characteristic efficiency.
Vibration fault detection method for turbopump in start-up process
XIA Lu-rui, HU Niao-qing, QIN Guo-jun, LI Jian-chuan
2010, 25(3): 704-708.
Abstract PDF(1924KB) icon1734 icon424
Abstract:
In order to completely enhance the safety of liquid rocket engine turbopump,aiming at its start-up process,a method for vibration fault detection was presented.Firstly,the vibration data sampled by equal time interval were resampled and the data of equiangular interval were obtained to drive out the speed fluctuation influence on vibration features.Secondly,the vibration feature was selected and calculated.Finally,the nonlinear relational model between vibration feature and rotational speed was founded by support vector regression.Once the deviation between the new test data and the model is over a limit,it shows evidence of turbopump fault.The detection time of 2.2s test data is 0.0470s.It shows that the model can be used for the turbopump fault detection in start-up process.
Numerical study of the swirl flow effects on the performance of axisymmetric nozzle
LIU Wei, YANG Tao, CHENG Xing-hua, LI Li
2010, 25(3): 709-712.
Abstract PDF(1694KB) icon1635 icon418
Abstract:
In order to study the swirl flow effects on the performance of axisymmetric nozzle,the flow field in axisymmetric nozzle was numerically simulated under both swirl flow and straight flow conditions.The flow coefficient,vacuum thrust coefficient and specific impulse of the nozzle were studied with different air mass flow rates and swirl intensities.It is concluded that the flow coefficient,vacuum thrust coefficient and specific impulse are not changed under different swirl intensities if calculated from the axial mass average total pressure at the nozzle inlet.The tangential dynamic pressure increase at the nozzle inlet with the swirl number enlarged at the combustion chamber inlet,and do not contribute to the thrust,so it should be looked as another type of total pressure loss.
Transient behavior analysis of adiabatic thermal elasto-hydrodynamic lubrication of journal bearing under step load
MA Xi-zhi, ZHU Jun
2010, 25(3): 713-717.
Abstract PDF(812KB) icon1546 icon454
Abstract:
Adiabatic thermal transient behavior of tilted pads thrust bearing under abrupt load change was studied in this paper.The models of oil film and the dynamic parameters of the bearing parts were established,and solved by Newton-Raphson methods because of large cpu consumption and nonlinear oil film force.The responses of the bearing kinetic parameters were acquired.The changes of highest film temperature,minimum film thickness and other parameters of oil film were presented during the transient period.The results indicate that the bearing may be damaged if the design parameters are not properly selected.
Loaded tooth contact analysis of double helical gears and experimental investigation
WANG Cheng, FANG Zong-de, GU Jian-gong, JIA Hai-tao
2010, 25(3): 718-722.
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Abstract:
According to the meshing characteristics of load sharing of double helical gears,the method of loaded tooth contact analysis(LTCA) of double helical gears was proposed.Firstly,tooth surface normal flexibility matrix caused by unit normal force of tooth surface point and the additional matrix caused by the deformation of shafts were obtained through the finite element calculation.The additional matrix was added to the tooth surface flexibility matrix and the normal flexibility matrix of gear system was generated then.Secondly,the loaded tooth contact analysis was completed.In the analysis process,the finite element,the programming method and the axial displacement of pinion were combined.Finally,an experiment that compared the result of tooth surface light contact and loaded transmission error of measure with calculation was provided,which verified the correct of method proposed.

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