2011 Vol. 26, No. 9

  Previous Issue | Next Issue 
Display Method:
Influences of vitiation air from ethanol-fueled heating on kerosene-fueled supersonic combustion
HOU Ling-yun, YANG Jin, MA Xue-song, LIU Wei
2011, 26(9): 1921-1927.
Abstract PDF(960KB) icon2088 icon15
Abstract:
The influences of vitiation air generated by ethanol-fueled combustion heating on the performances of kerosene-fueled supersonic combustion were studied numerically when the inflow Mach number at the inlet of combustor is 2.5.Premixed burner-stabilized flame model and ethanol-air reaction mechanism with 61 species and 388 steps were used to simulate the combustion in the heater,helping to obtain the components of high-enthalpy air fluid.The reduced reaction mechanism with 17 species and 30 steps were used to simulate the kerosene-fueled supersonic combustion.The contributions of seven main vitiated species such as H2O,CO2,O,OH,H,CO,H2 to the performance of the supersonic combustion were analyzed.Comparing with the cases of electric-heating on the ground and high altitude at the height of 25km,vitiation air causes the increase of combustion efficiency and internal thrust because of the free-radical's function,decrease of averaged molecular mass and increase of averaged specific heat at constant pressure.
Lattice Boltzmann simulations of rotating channel turbulent flow
WU Hong, WANG Jiao
2011, 26(9): 1928-1934.
Abstract PDF(1196KB) icon1951 icon15
Abstract:
The large eddy simulation based on the multiple relaxation time lattice Boltzmann method (LBM) was used to simulate the fully developed turbulent flow in a rotating channel at Reynolds number equaling to 194. The rotation number varied from 0 to 5.0 based on the friction velocity. The dynamic subgrid stress model was performed to model the non-closure term after filtering; the modified second moment force model was used to compute the pressure gradient and the Coriolis force. The statistical quantities such as: mean velocity, root mean square velocity fluctuations, Reynolds stress and the turbulence structure were calculated to elucidate the effect of Coriolis force on turbulent flow. The result shows that the profile of the average streamwise velocity becomes asymmetric and the turbulence intensity increases on the pressure side, while on the suction side the flow has a tendency to become laminar. The comparison results between the direct numerical simulation and present work show that the ability of LBM to simulate rotating turbulence is confirmed.
Numerical study on mixing enhancement of lobed injector
SHAN Yong, ZHANG Jing-zhou, ZHU Hua-ping
2011, 26(9): 1935-1940.
Abstract PDF(1225KB) icon1819 icon12
Abstract:
The mixing characteristics of two different kinds of fluids with non-reaction in the lobed injector were numerically studied by using FLUENT CFD(computational fluid dynamics) software. The primary flow (CO2) was injected from the lobed slot between two corrugated plates, and then mixed with the coflowing secondary flow (air) in the mixing duct. The velocity fields, streamwise vortice structures and species distribution were obtained to analyze the effects of lobed injector parameters on the circulation intensity of streamwise vortices. The streamwise vortices induced by the lobed injector are helpful to improve the mixing efficiency of the two coflowing fluids, and make the species distribution more uniform.
Effect of the shape of divider wall on heat transfer and flow resistance characteristic of passage
LI Li, XU Guo-qiang, DING Shui-ting, DENG Hong-wu
2011, 26(9): 1941-1946.
Abstract PDF(1090KB) icon1907 icon11
Abstract:
Numerical simulation was performed to obtain heat transfer and flow resistance characteristics in a channel with zigzag divider wall in the trailing edge passage of turbine blade.One traditional divider wall and three configurations of zigzag divider walls with different angles were applied to research the effect of angle on the heat transfer and flow resistance.The calculated results indicate that the heat transfer is improved with decrease of the angle of the zigzag shape.For the first passage,the highest improvement was nearly 30 percent.At the same time,the passage with small angle divider wall encountered bigger flow resistance.By comparison of integrated effect of heat transfer,the configurations with smaller angle divider walls have higher values than those with larger angle divider walls.
Effect of microencapsulated phase change material absorbing nanoparticles on heat transfer
WANG Liang, LIN Gui-ping
2011, 26(9): 1947-1952.
Abstract PDF(1003KB) icon1868 icon13
Abstract:
By numerical simulation of the heat transfer among nanoparticles, microencapsulated phase change material(MPCM) and liquid, the factors such as nanoparticle amount, diameter and thermal conductivity, which affect the MPCM-liquid heat transfer Nusselt number, were analyzed. When MPCM absorbed nanoparticles, the effect of the increase of the MPCM-liquid heat transfer coefficient on the phase change period was also studied numerically, providing a theoretical basis for the mechanism of enhancing the heat transfer with nanoparticle.
An icing model for simulating three dimensional ice accretion on the upwind surfaces of a plane
CAO Guang-zhou, JI Hong-hu, HU Ya-ping, PANG Li-gang, SI Ren, FENG Xiao-xing
2011, 26(9): 1953-1963.
Abstract PDF(1166KB) icon2059 icon20
Abstract:
A three-dimensional (3-D) icing model was built for the ice accretion on the upwind surfaces of the plane.The methods and steps for solving the model were also presented.The model can simulate both the ice accretion in the glaze ice,rime ice and no ice conditions and the water film flow on the ice surface.The model can also estimate which kind of ice accretion occurs when the super-cooled water droplets impinge on the surfaces.The 3-D ice accretion on airfoil-plane intersecting wall was simulated with the model.The two-dimensional (2-D) section of the 3-D ice on the airfoil was compared with National Aeronautics and Space Administration's (NASA's) ice shape.Good agreement proves the icing model is logical.
Investigation of the grid dependency from the spray simulation
CHENG Chuan-song, LI Yun-qing, WANG Yan-hua, ZHAO Li-feng
2011, 26(9): 1964-1969.
Abstract PDF(1032KB) icon1881 icon13
Abstract:
Based on the discrete droplet model, the grid dependencies of the original spray model and revised spray model were compared. The results show that the apparent grid dependency exists in the simulated results with original spray model due to the application of O'Rourke collision model and momentum coupling algorithm with nearest node. However, the separate Lagrangian collision mesh is utilized to reduce the mesh dependency from the collision prediction, and the Lagrangian interpolation coupling algorithm and the gas-jet model are combined to cut down the mesh dependency from the momentum coupling calculation. Therefore, the revised spray model successfully achieves significant lower grid dependency so that the simulated accuracy of coarse grid is improved.
Experiment on discharge characteristics of straight-through labyrinth
ZHANG Xiao-wei, ZHU Hui-ren, ZHANG Xia, ZHANG Wen-cun
2011, 26(9): 1970-1974.
Abstract PDF(845KB) icon2018 icon13
Abstract:
Experimental investigation was conducted on the discharge characteristics of the straight-through labyrinth,which was applied widely in aero-engines,under different configurations and operating parameters.Influences on the nominal discharge coefficients of the inclination angle,the clearance of the labyrinth pins and the revolving speed of the shaft were considered.Discharge flow rate and pressures at the entrance and the exit of the labyrinth were measured,and then nominal discharge coefficients and a correction equation were acquired.Moreover,comparisons of experiment data with data calculated from the classical correction equation were done.The results show that nominal discharge coefficients increase with the rising ratio of the inlet total pressure and the outlet pressure,and then tend to a certain constant for each configuration at each operating point.However,they decrease with the decreasing inclination angel and clearance of the through labyrinth in this study.Also the optimum value of inclination angel is in a range of 45°~60°.For the shaft revolving speed of the labyrinth disc,it works complicatedly,and nominal discharge coefficients decrease with its increase clearly.
Heat transfer study on a turbine rotor endwall by an improved transient experiment method
YU Kun, LUO Xiang, WEN Jie
2011, 26(9): 1975-1980.
Abstract PDF(1064KB) icon1847 icon9
Abstract:
Based on a new scheme of transient experiment,the test item has a linear initial temperature distribution between the upper and lower surfaces,so the equipment and operation could be simplified.Studies were done on the flow and heat transfer of a turbine rotor endwall.Results show that the endwall heat transfer is determined by the mainstream Reynolds number,together with the complex secondary flow pattern in the cascade passage.The overall heat transfer rate of the endwall is intensified with the improvement of the mainstream Reynolds number,while the secondary flow induces locally higher heat transfer rate in some regions,including:the region of horseshoe vortex near the leading edge,region where branches of horseshoe vortex pass by,the region downstream near the suction side where passage vortex occurs,and the region where corner vortex occurs.Results show good accordance with current knowledge of the endwall secondary flow.
Experimental investigation on a six-tube air-breathing pulse detonation engine
YUAN Cheng, FAN Wei, PENG Chang-xin, ZHANG Qun, CHEN Wen-juan, YAN Chuan-jun
2011, 26(9): 1981-1985.
Abstract PDF(1103KB) icon2112 icon15
Abstract:
A experimental system for six-tube air-breathing pulse detonation engine (PDE) with the single tube's inner diameter of 68mm was designed.Using gasoline as fuel and air as oxidizer,multi-cycle experimental study was successfully performed.The results show that all of the six tubes can obtain continuous detonation waves.The interaction among the tubes is not obvious and the engine can work synchronously and stably.The research results are very helpful to engineering applications of multi-tube PDE.
Numerical simulation of flow field in pressure-swirl injector based on VOF interface tracking method
LIU Juan, LI Qing-lian, WANG Zhen-guo, WU Hai-yan
2011, 26(9): 1986-1994.
Abstract PDF(1390KB) icon2035 icon20
Abstract:
Interface-tracking method volume of fluid (VOF) was used to simulate the flow process in pressure-swirl injector.The process of liquid phase filling injector was exhibited:pucker appears at first,then distinguishes with the increase of liquid.Velocity and pressure distribution were especially analyzed in different sections of injector.As both liquid and gas phase coexist in the injector,the flow field is highly complex.Total pressure loss lies mostly in the convergent and columned sections,so increasing convergent angle helps to reduce total pressure loss.Setting a divergent angle at injector exit can increase liquid phase velocity and reducing liquid sheet thickness can get better atomization finally.
Numerical comparison of three ullage models for the tank pressurization process of liquid rocket during outflow
WANG Lei, LI Yan-zhong, LI Cui, ZHAO Zhi-xiang
2011, 26(9): 1995-2001.
Abstract PDF(886KB) icon2016 icon21
Abstract:
In view of the process of helium pressurization in a liquid oxygen tank during outflow,the numerical methods of zero-dimensional integrated model,one-dimensional stratification model and two-dimensional computational fluid dynamics(CFD) model were adopted to study the variation law of ullage physical field,respectively.An empirical formula was set up to solve the heat transfer rate between ullage and tank wall in the zero-dimensional model and in the one-dimension model,while the low Reynolds number k-ε model was selected to calculate the coupled heat transfer rate between fluid and tank wall in the two-dimensional CFD model.The helium density was calculated by the ideal-gas model.The ullage pressure,ullage average temperature and temperature distribution were forecasted by these three models,respectively.The computational results show that the forecasted ullage pressure and ullage average temperature of three models show reasonable distribution,and the results of different models can be confirmed one another.In addition,the calculated axial temperature distribution in the ullage gas and in the ullage wall of the one-dimensional model is close to that of two-dimensional model in the main region,while the forecasted temperature distribution inside the ullage top nearby gas injector obviously deviates in different models.Moreover,the higher inlet velocity of the pressurized gas means more obvious radial temperature distribution inside tank top.Thus the two-dimensional CFD model should be selected to present the physical field distribution in the ullage when the inlet velocity is high.
Design and analysis of GH2/GO2 fired gas multi-injectors orthogonal optimization
CHEN Tao, LI Mao, JIN Ping, CAI Guo-biao
2011, 26(9): 2002-2008.
Abstract PDF(825KB) icon2034 icon9
Abstract:
Orthogonal design methodology was applied to investigate the design parameters' impact on multi-objectives,including flame length,wall temperature and injector panel temperature of GH2/GO2 fired gas shear coaxial multi-injectors chamber.Variance analysis and range analysis indicate that ratio of hydrogen-rich gas velocity to oxygen-rich gas is a dominant factor for flame length and wall temperature,and small thickness of injector is beneficial for reducing injector panel temperature.The interaction effect of the design parameters varies sharply for different objectives.The result of response surface shows that low pressure drop of oxygen-rich gas,high velocity ratio and appropriate injector thickness are advantageous for balance performance.
Optimal design of hybrid rocket motor for sub-orbital vehicle based on improved particle swarm optimization
CHI Yuan-cheng, ZHU Hao, FANG Jie, CAI Guo-biao
2011, 26(9): 2009-2014.
Abstract PDF(888KB) icon2016 icon10
Abstract:
An improved particle swarm optimization(PSO),called as dynamic target particle swarm optimization (DTPSO),was proposed to use dynamic target strategy for solving complex multi-dimensional optimization problems by analyzing the position between individual particles,personal best and global best.As a specific example,the DTPSO was applied to the optimal design for hybrid rocket for a certain hybrid rocket motor of sub-orbital vehicle.The optimization results show that algorithm has strong search capability,and can also reach convergence rapidly and solve such problem effectively.All those can provide a theoretical reference for the research of sub-orbital vehicle engine's optimal design.
Thermal characteristics of liquid film in a film regenerative cooling system
YANG Wei, SUN Bing
2011, 26(9): 2015-2020.
Abstract PDF(887KB) icon2005 icon18
Abstract:
Computation method on film regenerative cooling in liquid rocket was studied in this paper.To integrate the factors such as chemistry,evaporation,entrainment,convection,thermal conductivity and radiation,the liquid film was divided into three areas-temperature increase area,evaporation area and steam area to be calculated.Length and thickness of the film were computed,and effects of these factors on film were analyzed.The results show that: (1) Length of liquid film and cooling effectiveness is obviously enhanced with the increase of the film coolant mass flow,and the associated cooling effectiveness is up to 0.57 .(2) Length of liquid film is short in hot combustor,but the cooling effectiveness is up to 0.9 in this area .(3) The film in the head of combustor protects the whole wall even if the liquid has disappeared.Low temperature border area covers the whole combustor .(4) Sensible heat absorbed by the liquid film,evaporation heat of the film and convection heat from hot gas to liquid film are most important elements in liquid film area.However,mass loss and heat transfer caused by entrainment should not be ignored.
Simulation and experimental analysis of structure improvement for nitrous oxide micro-thruster
HAN Yue, LI Mao, FANG Jie, SUN Wei, CAI Guo-biao
2011, 26(9): 2021-2026.
Abstract PDF(960KB) icon1814 icon13
Abstract:
Many investigations were made on micro-thruster using nitrous oxide (N2O).Based on the obtained results,the impact of the temperature on the specific impulse of the thruster was analyzed.An improved solution was presented to optimize the structure design of the former thruster.Both flow field simulation and experiment test of the improved device were carried out to compare with the result of the previous one,whereby the correlation between the structure and specific impulse was acquired.The results can provide some references for the research of the nitrous oxide micro-thruster.
Investigation on plume interference effect of solid propellant micro-thruster
ZHANG Bin, MAO Gen-wang, HU Song-qi, CHEN Mao-lin
2011, 26(9): 2027-2031.
Abstract PDF(848KB) icon1434 icon9
Abstract:
The three-dimensional numerical simulation of two-phase plume flow of solid propellant micro-thrusters was developed. Then it was used to investigate the plume interference effect by combining the direct simulation Monte Carlo (DSMC) method for multi-component gas flow with the two-way coupling model for two-phase rarefied flow. At different space between the two micro-thrusters and different wall temperature,the plume interference effect was analyzed specifically. The results show that under the plume interference effect the gas is compressed and the flow direction is changed,which resulted in the increasing of gas pressure and temperature; solid phase made no significant effect on the flow parameters of gas phase; with the rising of the space between the two micro-thrusters,the maximum pressure decreased and the maximum temperature increased in the domain under the plume interference effect; the wall temperature could influence the temperature of the gas which is extremely close to the wall,but not the gas pressure.
Hexahedral mesh regeneration method for MDO on complex aero-engine components
WANG Rong-qiao, JIA Zhi-gang, FAN Jiang, HU Dian-yin, SHEN Xiu-li
2011, 26(9): 2032-2038.
Abstract PDF(1028KB) icon1657 icon17
Abstract:
A set of hexahedral mesh regeneration modeling method was presented in this paper based on the tools of both the parametric model and topological characteristic.The parametric fixed points were designed on the local where the optimized parameters exit,while their function was to constraint the meshing topology boundary and then ensure the orthogonality of the grid and the quality of mesh regeneration.Further,the feature-based parametric finite element (FE) modeling method was developed from the mesh generation algorithm of ICEM.Finally,testing the case of the MDO (multidisciplinary design optimizationon) on the low pressure turbine shrouded blade,the method of the mesh regeneration showed in this paper is effective.
Analysis method for the stress fatigue probability life of a disk considering size effect
LU Shan, ZHANG Hong, TANG Jun-xing, WANG Chun-guang
2011, 26(9): 2039-2043.
Abstract PDF(852KB) icon1960 icon14
Abstract:
Considering the flaw of precision in forecasting the medium-long and long life of disks and simulation specimen with volume method based on the strain life model, volume method based on the stress life model was proposed to compute the life of disks, which considered the size effect. The maximum stress and stress ratio have been taken into the life reliability computation of the disk as parameters. Then the fatigue life reliability of a disk simulation specimen was analyzed by the method given. The difference between computational median life in the method and the experimental median life is only 14%, and they fit well with each other. While the computational median life in the strain based method is only sixteenth of the experimental median life. It is shown that volume method based on the stress life model which considering the size effect can be used to estimate the probabilistic life of the medium-long and long life of disks and simulation specimen.
Fracture mechanics analysis for rotating blade model of aero-engine
CHEN Ai-jun, CHEN Cheng, ZHANG Ding-guo, LIAO Lian-fang
2011, 26(9): 2044-2048.
Abstract PDF(872KB) icon2187 icon12
Abstract:
An analysis model for the cracked plate of blade was established using fracture mechanics method.Firstly,the weight function for blade containing a single edge crack was derived from one reference stress intensity factor under uniform load.Secondly,the stress intensity factor at the tip of crack of rotating blade was calculated using weight function method.Finally,critical rotate speed of blade was inferred on the basis of fracture criterion.The analysis of examples shows that the depth and position of crack in blade have much influence on the stress intensity factor and critical rotating speed.
Progressive prediction method for failure data with small sample size
WANG Zhi-hua, FU Hui-min, LIU Cheng-rui
2011, 26(9): 2049-2053.
Abstract PDF(792KB) icon1540 icon10
Abstract:
The small sample prediction problem which commonly exists in reliability analysis was discussed with the progressive prediction method in this paper. The modeling and estimation procedure, as well as the forecast and confidence limits formula of the progressive auto regressive (PAR) method were discussed in great detail. PAR model not only inherits the simple linear features of auto regressive (AR) model, but also has applicability for nonlinear systems. An application was illustrated for predicting the future fatigue failure for Tantalum electrolytic capacitors. Forecasting results of PAR model were compared with auto regressive moving average (ARMA) model, and it can be seen that the PAR method can be considered good and shows a promise for future applications.
Research method of cyclic stress-strain analysis of narrow brazing seam zone of DZ125 alloy brazed joints at high temperature
DONG Cheng-li, SHI Duo-qi, YANG Xiao-guang, ZHANG Lei, QI Hong-yu, HOU Jin-bao
2011, 26(9): 2054-2060.
Abstract PDF(952KB) icon1488 icon11
Abstract:
A back-calculating method for solving difficult measurement of cyclic stress-strain of the narrow brazing seam zone (less than 150 μm) at high temperature was presented based on following two types of data: the first one was cyclic stress-strain data of DZ125 alloy base metal at high temperature,which was obtained by the finite element software ABAQUS coupling user material subroutine (UMAT) embedded into Chaboche viscoplastic model;the second one was cyclic stress-strain data of brazed joints obtained by the high-temperature cycle test;after data processing and MATLAB programming,the cyclic stress-strain of the brazing seam zone at high temperature was obtained concisely.The results show that the deformation of the brazed joints at high temperature has obvious heterogeneous and localized properties,and as compared to the base alloy metal,the brazing seam zone is relatively 'soft’,and also a weak link in brazed joints which should be given adequate attention.By extension,the proposed back-calculating method provides a new way for studying the general mechanical behavior of narrow seam of the welded joint.
PSP experiment of global surface pressure distribution on suction surface of compressor cascade with large curved angle
GAO Li-min, GAO Jie, WANG Huan, ZHOU Qiang, LIU Bo
2011, 26(9): 2061-2067.
Abstract PDF(1253KB) icon1946 icon16
Abstract:
Based on the home-made PSP (pressure sensitive paint)system and ICCAS's (Institute of Chemistry,Chinese Academy of Sciences) PSP,the pressure distribution on the compressor cascade surface was performed on a subsonic cascade wind-tunnel while the conventional pressure scanner was employed to validate the PSP measurement.Comparison between the PSP and the pressure scanner indicates: (1) Pressure distribution on the suction surface of with use of PSP is quantitative,continuous and global,and that with use of pressure scanner is discrete and limited.(2) Compared with the results of pressure scanner,there is a good agreement on the pressure valley and the maximum measuring error near the leading edge and trailing edge,which does not exceed to 4.48%.(3) The maximum measuring error is decreasing when Mach number of the inflow is increasing.
Experimental investigation of boundary layer suction effects on a transonic cascade
WANG Yan-gang, GUO Rui, REN Si-yuan, JIANG Zheng-li
2011, 26(9): 2068-2074.
Abstract PDF(1155KB) icon1906 icon12
Abstract:
To explore the effects of boundary layer suction (BLS) on a transonic cascade,several experiments were carried out on an intermittent cascade wind tunnel.The results of different locations in relation to the point for passage shock wave projection of various suction coefficients have been investigated.Experimental results show that:when the location of BLS slot is in front of the point for passage shock wave projection,the local Mach number around the suction slot is increased and cascade performance is deteriorated.The loss coefficient increases with the enhancement of suction coefficient for both higher subsonic and supersonic inlet flow conditions,and when the suction coefficient is greater than 0.2%,the loss coefficient increases rapidly.When BLS slot is located behind the shock wave,the cascade performance is significantly improved,and the positive effect of BLS increases by the suction coefficient.Compared with the condition without suction,the loss coefficient reduces by 8% and the total pressure recovery coefficient increases by 5% when suction coefficient is 0.8%.
Influence of the root fillet on the flow pattern of an axial turbine rotor
WANG Da-lei, PIAO Ying, CHEN Mei-ning
2011, 26(9): 2075-2081.
Abstract PDF(1369KB) icon2101 icon13
Abstract:
The influences of the root fillet on the aerodynamic performance and vortex patterns of an axial turbine rotor were investigated by numerical simulation,and different root fillet radii were taken into account.Results show that the efficiency of the turbine rotor could decrease due to the root fillet.And the efficiency could further decrease with bigger fillet radius.The root fillet could make a significant influence on the cascade secondary flow patterns.In the case of small radius of the fillet,the separation bubble before the rotor leading edge near the endwall could increase markedly,resulting in the intensification of horseshoe vortex and lower passage vortex.And the lower passage vortex could move away from the rotor suction side.The pressure distribution near the trailing edge region changes due to the strengthening passage vortex;pressure at the region of the lower passage vortex reduces;meanwhile the pressure at the upper passage increases,leading to the decrease of the upper passage vortex for the fillet rotor compared with the unfilleted rotor.The fillet near the trail edge could increase the turbine rotor wake and induce more wake losses.However,comparisons of different fillet radii indicate that,as the fillet radius increases,the separation bubble decreases along with the correlative horseshoe vortex and lower passage vortex,and the upper passage vortex increase along with the rotor wake.
Numerical investigation of rotor-stator interaction noise in a turbine stage
MU Zhong-qiang, QIAO Wei-yang, ZHAO Lei
2011, 26(9): 2082-2088.
Abstract PDF(1252KB) icon1714 icon14
Abstract:
By using the unsteady computation which employed phase-lag method to get the fluctuation pressure in a high pressure turbine stage with real blade amount,and also using the mode matching method in the duct of downstream rotor,the non-physic reflection in the duct end and other non-sound pressure fluctuations were extracted.The rotor-stator interaction noise propagating downstream was obtained.The results show that the dominance azimuthal mode m=3 isn't cut-off for the blade passing frequency, m=6 and m=-64 aren't cut-off for the second blade passing frequency.
Study on the flow mechanisms of casing treatment on a transonic single stage axial-flow compressor
DU Hui, TENG Jin-fang
2011, 26(9): 2089-2094.
Abstract PDF(1253KB) icon1634 icon13
Abstract:
The influences of axial skewed slot casing treatment on the performance of a transonic single stage axial-flow compressor were investigated through three-dimensional(3-D) numerical method. The numerical results indicate that the stable operating range of axial compressors is enlarged and the compressor efficiency is increased with casing treatment appreciably. The flow mechanisms of affecting compressor performance were obtained by analyzing in detail the flow-filed in compressor rotor with casing treatment. It was found that the starting location of flow separation near rotor blade suction was moved backward by the back flow formed in the slots, which weakened the adverse influence rooted in interaction of separated flow and tip leakage flow and improved the current ability of blade tip passage. So the compressor stall was suspended.
Research on control method of surge in auxiliary power unit
SU San-mai, CHANG Bo-bo, LIU Tie-geng, LIU Mei-feng
2011, 26(9): 2095-2100.
Abstract PDF(1011KB) icon2087 icon29
Abstract:
The surge mechanism of auxiliary power unit (APU) with load compressor was analyzed.To ensure load compressor's working stability,the method of controlling exit corrected flow less than the minimum stable work flow was put forward.When load compressor exit flow is less than 2%,compared with minimum stable flow,the surge control valve (SCV) used to avoid surge was opened.Proportion-integral-differential (PID) controller was designed to control the opening angle of SCV so as to avoid surge of load compressor,and make exit pressure of air meet certain requirements.Compared with APU actual test data,numerical simulation results show that the method can be used to ensure the load compressor's working stability.
Diagnosis method of aero-engine fault based on fuzzy inference and evidence theory
WANG Gu-chang, CHENG Jian, BAO Chuan-mei, SUN Ye
2011, 26(9): 2101-2106.
Abstract PDF(943KB) icon1999 icon17
Abstract:
A diagnosis method of aero-engine fault based on fuzzy inference and evidence theory was proposed in this paper.According to the fault symptoms,the proposed method inferred the probabilities of fault causes with experts' experience,so as to resolve the fuzzy problem of fault diagnosis.Then the results of fuzzy inference were regarded as basic probabilities of evidences to insure the veracity of evaluation.Finally,all evidences were aggregated and analyzed according to the combined rules to reduce the uncertainty of fault diagnosis and eliminate the inconsistency among evidences,so as to locate the fault cause accurately.The results of experiment show that the method is feasible and effective.
Development strategy and key prognostics health management technologies for military aero-engine in China
WEI Xun-kai, FENG Yue, LIU Fang, YANG Li, ZHAN Li-guang
2011, 26(9): 2107-2115.
Abstract PDF(830KB) icon2727 icon50
Abstract:
The development strategy and key prognostics health management (PHM) technologies for military aero-engine in China were proposed.First,the development history and corresponding representative features of PHM was briefly reviewed.Then,several key relationships and important issues in PHM technology development worth emphasizing were minutely analyzed,which include the relationship between PHM technology development and the air force military requirements,the relationship between PHM technology development and the technology readiness level,developing PHM technology based on the third generation aircraft platform,introducing PHM into aero-engine full-life management system,and the proposed PHM architecture and composed functions for China air force,etc.After that,the key technologies which should be focused on with high priority in China were proposed.Finally,the factors that constrain the domestic developments of China military PHM technology and the aimed technology developing targets are shortly concluded.
Life extending control of aircraft engine based on adjusting acceleration schedule
CHEN Xiao-lei, GUO Ying-qing, LU Jun
2011, 26(9): 2116-2121.
Abstract PDF(852KB) icon1956 icon19
Abstract:
The acceleration schedule of engine which influenced the thermo-mechanical fatigue (TMF) of turbine stator blade was analyzed. Through additional acceleration limit to the original control schedule, the acceleration schedule was optimized by genetic algorithm, in consideration of the acceleration performance and life of blade. The simulation results show that the improved acceleration schedule can provide significant life extension of blade while keeping the rise time unchanged during the acceleration process.
Model and numerical simulation of auxiliary power unit
CHANG Bo-bo, SU San-mai, LIU Tie-geng, LIU Mei-feng
2011, 26(9): 2122-2127.
Abstract PDF(1065KB) icon2129 icon47
Abstract:
In order to supporting auxiliary power unit (APU) design,the widely used APU with load compressor in structure was discussed and modeled.Firstly,the structural characteristics and regulation law are introduced and then how the load compressor works on APU was analyzed.Finally the mathematic model of APU was established based on components.Take a kind of APU as the object for numerical simulation and then compare with the actual test data.The results show that the dynamic simulation error is less than 5%.The mathematic model of APU is suitable for engineering usage.
Numerical simulation on bypass transition of variable cycle engines
LIU Zeng-wen, WANG Zhan-xue, CAI Yuan-hu
2011, 26(9): 2128-2132.
Abstract PDF(853KB) icon2365 icon37
Abstract:
Based on a double bypass variable cycle engines,a bypass transition process was given.Using multi-components control method,the performance of variable cycle engine mode transition was numerical simulated by a steady state model.Compared with general turbofan engine,the variable cycle engines could change obviously the bypass ratio,and the SFC(specific fuel consumption) is depressed on subsonic cruise condition.
Experimental investigation on flow characteristics of a submerged inlet with high offset
WENG Xiao-chai, XIE Wen-zhong, GUO Rong-wei
2011, 26(9): 2133-2140.
Abstract PDF(1030KB) icon1745 icon18
Abstract:
Experiments of a submerged inlet with high offset were made and described in this paper.The study was carried out in a high speed wind tunnel.The results show that:(1) Under cruising condition,the Mach number at the exit has little effect on the inlet performance.(2) According to the experimental results,when the free stream Mach number increases,the total pressure recovery decreases and the synthesis distortion rises.The rising incidence is favorable to the inlet performance,but on which the yaw has little influence.(3) At the matching point of the inlet with engine,the power spectrum of the dynamic pressure signals in the duct generally presents the characteristics of white noise;however at high incidence or yaw the power spectrum has some narrow band peak value.
Study on matching method for core and bypass mass flux of 2-D convergent nozzle of mixed flow
LI Na, JI Hong-hu
2011, 26(9): 2141-2147.
Abstract PDF(1091KB) icon2202 icon16
Abstract:
A design method of two-dimensional (2-D) convergent nozzle was developed to meet core and bypass mass flux requirements of mixed flow turbofan engine.A matching method for core and bypass mass flux based on three-dimensional (3-D) viscous numerical simulation was proposed.Non-linear dimensionless mass flux matching equations for core and bypass channel with 2-D nozzle were formulated.Solving procedure of the non-linear equations was presented.Numerical simulation and matching results for some nozzle cases indicate that : (1) The method for solving the non-linear mass flux equations is effective,geometric parameters could be determined quickly for 2-D convergent nozzle.(2) Nozzle length and throat area properly play a key role for the required nozzle gross thrust.A nozzle with greater length and smaller throat area has greater gross thrust and better efficiency.
Numerical simulation on effects of variable specific heat capacity on internal flow field of jet vector nozzle
SONG Ya-fei, GAO Feng, WEN Ke, HE Zhi-lin, JIN Nan-nan
2011, 26(9): 2148-2153.
Abstract PDF(1110KB) icon2038 icon11
Abstract:
Given certain variable specific heat capacity and constant specific heat capacity,two-dimensional Reynolds average Navier-Stokes equation was solved by using time marching method in finite volume,and the internal flow of jet vector nozzle was studied.The results gained from different cases were compared.The results show that:as compared with the specific heat capacity,when the shock wave generated by second injection moves toward downstream divergent section,the thrust vector angle and thrust coefficient decrease.With the increase of temperature,the gap between the results from two methods became wider.The influence of variable specific heat capacity must be take into consideration when studying the internal flow field of jet vector nozzle by the method of computational fluidic dynamic.
Optimization of rotor-bearing system with nonlinear dynamics considering internal clearance
HU Qing-hua, DENG Si-er, TENG Hong-fei
2011, 26(9): 2154-2160.
Abstract PDF(817KB) icon1918 icon18
Abstract:
In view of existing problems in optimization of a rotor-bearing system with dynamic performance constraints, the following improvements were made. Firstly, influence of clearance was considered in the optimization model. Secondly, a hybrid algorithm based on evolutionary algorithm/line search method was proposed. In the proposed algorithm, there were two optimization processes, global searching process using evolutionary algorithm to obtain an optimal solution and local searching starting with the optimal solution by line search method. Numerical results show that: the clearance has great influence on optimization results. The proposed algorithm overcomes the difficulty in choosing initial value for line search method, with higher success rate under the same calculation accuracy.

Copyright © 《Journal of Aerospace Power》 All Rights Reserved.

Supported by: Beijing Renhe Information Technology Co., Ltd.