2010 Vol. 25, No. 6

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Display Method:
DSMC algorithm and heat transfer analysis of high temperature and high velocity rarefied gas flow
WANG Bao-guo, LI Xue-dong, LIU Shu-yan
2010, 25(6): 1203-1220.
Abstract PDF(3697KB) icon1659 icon455
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This paper studied 6 kinds of energy transfer of thermodynamic collision and 8 types of chemical reaction on unstructured grids.Subroutine flow charts of the energy transfer and chemical reaction collision mentioned above were proposed in detail.Based on variable hard sphere(VHS) model,Borgnakke-Larsen phenomenological model,chemical reaction model of Bird and Cercignani-Lampis-Lord(CLL) gas surface interaction model,a rarefied gas direct simulation Monte-Carlo(DSMC) code was produced using Fortran,enabling to simulate relaxation of internal energies,thermodynamic nonequilibrium and chemical reaction nonequilibrium.The computation of towed ballute applications of 8 cases was completed in the Earth's and Mars' atmosphere,in which Knudsen number changes from 0.05 to 30.0,flight Mach number changes from 26.3 to 11.2.The results were compared with the computation published by James N.Moss from NASA Langley Research Center in 2007,showing satisfactory agreement.In addition,this paper analyzed thermodynamic nonequilibrium,chemical reaction nonequilibrium and heat transfer efficiency of vehicle wall,by using |T-Tv|/T,Damkhler number and Stanton number,respectively.The analysis is beneficial to thermal protection design of high temperature assemblies. 
Conjugate heat transfer simulation of a high pressure air-cooled gas turbine with transition flow characteristics
ZHOU Hong-ru, WANG Zhen-feng, YAN Pei-gang, LIU Zhan-sheng
2010, 25(6): 1221-1226.
Abstract PDF(1210KB) icon1824 icon514
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The commercial code CFX was used to simulate NASA-MarkⅡ high pressure air-cooled gas turbine under work condition of Run 5411.The simulation ability of different turbulence models for the transition flow region was researched in this paper.As compared with the experimental results,k-ω-shear-stress-transport(SST)-Gamma-Theta turbulence model results were more accurate.In addition,the compiled code employed the Baldwin-Lomax(B-L) algebra model to simulate the same computation model.The results show that the results of B-L model are accurate apart from some temperature error in the transition region.ANSYS can be applied to analyze the thermal stress of solid blade and the results of Von Mises stress show that the temperature results have a great effect on the results of blade thermal stress. 
Experiment of wall temperature in a two-stage swirler combustor
DANG Xin-xian, ZHAO Jian-xing, YAN Ying-wen, LIU Yong, XU Rong, ZHANG Xin
2010, 25(6): 1227-1232.
Abstract PDF(1312KB) icon1694 icon440
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The infrared thermal imager was used to measure wall temperature profiles of the flame tube within the model annular combustor with dual-stage axial swirler under different inlet temperatures,fuel/air ratios and primary holes parameters.The measurements under different experimental cases show that,the different primary holes parameters have a considerable influence on wall temperature profiles of the flame tube.The wall temperature increases with a rise of inlet temperature,but changes of the wall temperature distributions of the flame tube are not obvious.The influences of different fuel/air ratios on profiles of wall temperature are weak,but these influences on the temperature gradient are large.Results of experiments are useful for the optimum design and development of the advanced annular combustor. 
Numerical simulation of cooling effectiveness with injection of double-outlet hole
LI Guang-chao, ZHANG Wei, XIANG Song, WANG Cheng-jun, PENG Da-wei
2010, 25(6): 1233-1237.
Abstract PDF(949KB) icon2084 icon445
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In order to optimize the structure of the film cooling,the film cooling performance of a novel hole with double-outlet was investigated by numerical simulation.The Navier-Stokes equation was solved by Fluent.The realizable k-ε model and enhanced function were used.The numerical effectiveness of the cylindrical hole agrees well with the experimental data.The result of the double-outlet hole injection shows that the lateral spreading of the film is improved as compared to the injection of the cylindrical hole.At the blowing ratio of 0.5,the vortices at the trunk hole outlet are reduced by the injection of the branch hole.At the blowing ratio of 1.0 and 2.0,the vortices at the trunk hole outlet are eliminated by the injection of the branch hole.The optimal blowing ratio is found at blowing ratio of 1.0.The double-outlet hole improves the cooling effectiveness significantly while requiring for easily machinable round hole as compared to expanded hole. 
Experimental study of wall temperature distribution on annular interstage trapped vortex combustor
ZHANG Rong-chun, FAN Wei-jun, XING Fei
2010, 25(6): 1238-1244.
Abstract PDF(767KB) icon2087 icon422
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In order to investigate the validity of the cooling structure and air inlet structure,experimental study of wall temperature distribution on annular trapped vortex combustor was carried out,and the test result was used for computing the structural strength of combustor.The test result shows that the wall temperatures of all test points are lower than the upper limit of materials and the combustor supports long-lasting normal operation.The hot spot temperature of combustor appeared in the lower of fore-wall or in the middle of upper-wall.The wall temperature was greatly influenced by the mainstream air flow rate,cavity air flow rate and oil flow rate,but little influenced by the temperature of the mixing air. 
Numerical investigation on film cooling effectiveness at suction surface of stator blade
YAO Yu, ZHANG Jing-zhou, HE Fei, GUO Wen
2010, 25(6): 1245-1250.
Abstract PDF(1518KB) icon1766 icon481
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The film cooling characteristics of blade surface were numerically investigated using the two-equation turbulence model of the renormalization group.Three-dimensional turbulent flow in turbine cascade and the cooling effectiveness on blade surface were studied under different Reynolds numbers and blowing ratios.The influence of the cooling effectiveness of cylindrical film cooling holes on the blade suction surface with varying location was investigated.Results show that the cooling effectiveness for each film cooling hole increases with the increment of the mainstream Reynolds numbers.The cooling effectiveness downstream the exit of holes changes obviously with the increment of blowing ratio,and away from the downstream the effectiveness keeps increasing with the increment of blowing ratio.Under the same condition the cooling effectiveness of location 1 was higher than other two locations. 
Numerical simulation of the flow field in a single annular concentric staged combustor
LIU Dian-chun, DONG Yu-xi, SHANG Shou-tang, CHENG Ming, SHANG Ming-zhi
2010, 25(6): 1251-1257.
Abstract PDF(1475KB) icon2274 icon483
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Influences of swirler parameters for a single annular concentric staged(SACS) combustor on non-reacting flow field in the SACS combustor were investigated computationally using standard k-εmodel.The computational results indicate that,the influences of swirling directions of the pilot swirlers on the flow field in the SACS combustor are insignificant.Influences of outer swirler on the flow field in the SACS combustor are significant when the vane angles of the three swirlers in the SACS are adjusted.Therefore,the outer swirler is a key factor to the flow structure forming in the SACS combustor. 
Influence of rotation on discharge coefficients of two rows of film holes in channel with rib turbulators
ZHANG Wei, LI Guang-chao, PENG Da-wei, WANG Cheng-jun, XIANG Song
2010, 25(6): 1258-1263.
Abstract PDF(960KB) icon1566 icon453
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In order to understand the bleed performance of the film hole on the internal tunnel within the blade,the influence of the rotation on the discharge coefficients of film holes in rectangular channel with both rib-roughened wall and two rows of film hole suctions was studied by numerical simulation at Reynolds number 60000,rotation number 0,0.11 and 0.22,and suction ratio of 0.22.The numerical results agreed well with the experimental data in the stationary passages.The averaged discharge coefficients of the two holes increase by 90% in the clockwise rotating channel and decrease by 10% in the counter-clockwise channel.The discharge coefficients of the left holes are 4～5 times the right holes in the event of clockwise rotation.The discharge coefficients of the left holes and the right holes differ little in the event of counter-clockwise rotation. 
Experimental study of flow and heat transfer characteristics in silicon-based corrugated microchannels
TANG Hui-min, WU Hui-ying, WU Xin-yu
2010, 25(6): 1264-1270.
Abstract PDF(856KB) icon1673 icon458
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Silicon-based corrugated microchannels used for heat transfer enhancement were fabricated by micro-electro-mechanical-system technology for the first time.The flow and heat transfer characteristics of the deionized water through these corrugated microchannels were studied experimentally,and comparisons were performed between corrugated microchannels and straight microchannels with the same aspect ratio(height-to-width ratio) and hydraulic diameter.Experimental results show that,both flow friction and Nusselt number in corrugated microchannels increase considerably than those in straight microchannels,and this increase becomes more obvious with the increasing Reynolds number.Under the same pumping power,using corrugated microchannels instead of straight microchannels causes the reduction of thermal resistance.The heat transfer enhancement mechanism of corrugated microchannels was also discussed. 
Application of nanofluids in an inclined axial miniature grooved heat pipe
BAO Ran, LIU Zhen-hua
2010, 25(6): 1271-1276.
Abstract PDF(647KB) icon1654 icon389
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An experiment was performed to investigate the thermal performance of inclined miniature grooved heat pipe using water-based CuO nanofluids.The study focused on the effects of the inclination angle and the operating pressure on the heat transfers of both the evaporator and condenser as well as the maximum heat flux of the heat pipe.The nanofluid consists of pure water and CuO nanoparticles with a mean diameter of 50nm.The mass concentration of the nanofluid was fixed at an optimal value of 1.0%.The experimental results show that the inclination angle has a very significant effect on both the total heat resistance and maximal power of the heat pipe using water,and only a slight effect on those of the heat pipe using nanofluids.There exists an optimal inclination angle which corresponds to the best thermal performance,and this angle is 75° for both heat pipes using water and nanofluids.For the inclined heat pipe using nanofluids,not only the evaporation and condensation heat transfer coefficients are greatly increased,but also the maximal power can be almost doubled as compared with those of the heat pipe using water.The present investigation discovers that the thermal performance of an inclined miniature grooved heat pipe can be evidently strengthened by using CuO nanofluids. 
Application of power extraction method in starting process simulation and control law design of turbojet engines
CHEN Yu-chun, WANG Zhao-peng, HUANG Xing-lu, XU Si-yuan, CAI Yuan-hu
2010, 25(6): 1277-1283.
Abstract PDF(1337KB) icon1928 icon580
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In accordance with the character of the turbojet's starting control law,the power extraction model of acceleration and deceleration control law was used to design the starting control law of turbojet engine.In combination with the low speed component character prediction method and the improved power extraction method,the constrain conditions and design procedures were presented.The model could be used to predict the starter power in the crank process,and design the starting control law in the whole flight envelope and all climate conditions.It is shown that the control law designed with the power extraction method coincides with the actual starting control law of the turbojet engine,and the model is of good engineering value. 
Investigation on supersonic flow with γ-Reθ turbulence model and PSE methodinvestigation on supersonic flow
YAN Pei-gang, DONG Xue-zhi, HAN Wan-jin
2010, 25(6): 1284-1290.
Abstract PDF(833KB) icon1605 icon451
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The γ-Reθ turbulence model involved with empirical correlation for transition was adopted to investigate the typical hypersonic flows.Parabolic stability equation(PSE) stability analysis and e-N prediction methods were combined to find the most unstable point of boundary layer,showing that the transition empirical correlation parameters were more appropriate,with less dependency on design experiences.The hypersonic flow field of a blunt cone was simulated,and the computational wall heat flux and boundary layer transition position were consistent well with the experimental results.The shock wave/flat plat interaction and the flow across a compression corner were computed.The analysis of shock wave structure and separated flow shows that the model is also applicable for simulation of complicated flow with shock wave/boundary layer interaction.The results show that the method of this paper is superior to the traditional turbulence models. 
Investigation of surge characteristics and surge eliminating system verification based on a certain engine
QU Ji-yun, MA Ming-ming, WANG Xiao-feng, MA Yan-rong
2010, 25(6): 1291-1296.
Abstract PDF(1438KB) icon2045 icon468
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Ground test of surge inducing based on a certain engine was performed separately by installing disturbed board at inlet and increasing the fuel delivery.Characteristics of the test methods,the engine parameters in the process of test and the reason of surge were analyzed.The test results show that intermittently pushing staff slowly after installing disturbed board at inlet and pushing staff suddenly after increasing the fuel delivery are effective methods,which could reflect impact of influential factors on engine stability.By accelerating after installing disturbed board at inlet,the total pressure distortion and reduction of air flow result in engine surge,and fan surge occurs before the compressor;however,after increasing the fuel delivery,gas oil ratio is always bigger along with engine acceleration so that the stability margin of combustor is lower,and air provided for engine is jammed by high-pressure gas of combustor so that compressor and fan surge occur successively.Surge eliminating system reliably works and critical distortion of the engine is obtained.The studies in this paper have established a necessary basis for surge inducing test in the air and stability assessment. 
Effect of kinetic mechanism of blocker doors on aerodynamic performance for a cascade thrust reverser
XIE Ye-ping, WANG Qiang, SHAO Wan-ren, SHANG Shou-tang
2010, 25(6): 1297-1302.
Abstract PDF(980KB) icon1724 icon461
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Based on the structure and working principle of the cascade thrust reverser,a preliminary research was conducted to analyze the impact of reverser's kinetic schedule on the exit static pressure of the fan and aerodynamic load of the blocker doors.The results show that,the kinetic schedule directly influences the position of fan's working point during deploying/retracting reverser process.Schedule 3 and 4 are suitable separately for reversers installed in engines with relatively small and big surge margin fan.For all kinetic schedules,aerodynamic load on blocker doors increases sharply once it starts operation. 
Three-dimensional numerical simulation of rime ice accretions on an aircraft wing
ZHANG Qiang, CAO Yi-hua, ZHONG Guo
2010, 25(6): 1303-1309.
Abstract PDF(1743KB) icon1775 icon514
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Based on Eulerian two-phase flow theory,the rime ice accretions on an aircraft wing in three-dimensional application were numerically simulated.The governing equations for droplets in three-dimensional application were established according to the droplet pseudo-fluid model.A set of numerical methods for solving the droplet governing equations were proposed.The local collection efficiency and impingement area on the wing were computed from the solution of the three-dimensional droplet flowfield.A method of building three-dimensional ice accretion shape was proposed.The rime ice accretions on an ONERA M6 wing under different angles of attack were predicted numerically and the effects of icing conditions on the ice accretion were analyzed. 
Numerical simulation on performance of variable cycle engines
LIU Zeng-wen, WANG Zhan-xue, HUANG Hong-chao, CAI Yuan-hu
2010, 25(6): 1310-1315.
Abstract PDF(1226KB) icon2443 icon608
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Based on a general gas turbine performance simulation software,a double bypass VCE(variable cycle engine) performance simulation software was developed with introduction of selector valve,forward VABI(variable area bypass injector) and rear VABI and core bypass duct modules.The cycle operating parameters of VCE were given,such as low pressure turbine nozzle area,compressor inlet guide vane angle,fan inlet guide vane angle and core-driven fan stage inlet guide vane angle.A double bypass VCE characteristics were calculated and analyzed with altitude velocity and throttling in this paper.Compared with single bypass mode,the specific thrust and specific fuel consumption(SFC) of double bypass mode were low.The total bypass ratio increased and the SFC decreased with the decline of rotate speed.Under a complicated condition,it is necessary to match the engine with appropriate variable parameters. 
Performance simulation of SteamJet with afterburner
LIANG Zhen-xin, CHEN Yu-chun, HUANG Xing-lu, HU Fu, SHANG Xu-sheng
2010, 25(6): 1316-1321.
Abstract PDF(535KB) icon1688 icon422
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To study the characteristics of SteamJet engine,the mathematical models of water injection pre-cooling heat-exchange computation,corrected computation of physical property and the engine components characteristics were built.With the models mentioned above,the computation model of SteamJet on basis of the two-spool mix-exhausted turbofan engine with afterburner was built,and the corresponding program was developed.The engine characteristic with different fan inlet total temperatures along flight-trace was computed and the effect of pre-cooling on the afterburner outlet total temperature was analyzed,thus the reasonable fan inlet total temperature was selected,and the altitude and velocity characteristics of SteamJet with afterburner were calculated and analyzed.It's shown from the computation results that,the operating range of turbojet can be expanded greatly with introduction of water injection and pre-cooled method.And compared with the SteamJet without afterburner,the SteamJet with afterburner has better thrust characteristics and can meet the need of hypersonic flight. 
Simulation on the scavenging process of the opposite two-stroke diesel engine
CHEN Wen-ting, ZHUGE Wei-lin, ZHANG Yang-jun, YU Hong-sheng
2010, 25(6): 1322-1326.
Abstract PDF(1028KB) icon2450 icon475
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According to the flow characteristics of the opposite two-stroke diesel engine,the suitable flow control equations and turbulence model were chosen to model the high swirl and turbulent flow.The unsteady computational fluid dynamics(CFD) simulation models were developed to simulate the scavenging process under the rated condition.The scavenging efficiency was calculated and the detailed flow fields were analyzed.Results show that a 94% scavenging efficiency can be achieved with the turbocharging uniflow scavenging method. 
Acoustic vibration characteristic of crack gear structure and simulation
SHAO Ren-ping, XU Zhi-feng, CAO Jing-ming
2010, 25(6): 1327-1334.
Abstract PDF(2897KB) icon1528 icon451
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The gear structure was handled equivalent to circinal plate,then the dynamics analysis model and acoustical model of fault gear were established,the sound pressure and the distribution characteristic of sound field of gear elastomer with radial direction crack and arc direction crack were analyzed;and the influence of crack on the radiation characteristic of the sound field of gear structure was studied.With the help of ANSYS and MATLAB software,the distribution of sound pressure in the r=0.5m sphere surface and axial sound pressure of cracked gear structure was obtained,and the influences of various crack types and crack sizes on acoustic characteristic of gear vibration were investigated.Based on analysis,comparison and evaluation of the simulation results,it shows the influence extent and rule of the crack location,crack shape and size in relation to acoustic vibration characteristic of gear structure.These lay a good foundation for gear fault diagnosis using acoustic method. 
Reliability assessment of aero-engine based on the reliability growth forecast module
JIN Xiang-ming, GAO De-ping, ZHAO Yan-yun, NIE Hua-ju, LONG Hai-yue
2010, 25(6): 1335-1339.
Abstract PDF(1536KB) icon2143 icon461
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Reliability assessment for an aero-engine was made in this paper by the reliability growth projection model and based on the data of bench tests and flight tests.The results of the assessment were compared with evaluated values of traditional mean time between failure(MTBF),showing that the method is reasonable,effective and useful. 
Analysis and experimental verification of structure-thermal running stability for micro turbojet engine rotor
ZHENG Dong-ya, DING Shui-ting, DU Fa-rong, HAN Shu-jun, ZHANG Qi
2010, 25(6): 1340-1345.
Abstract PDF(794KB) icon1624 icon501
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For the high speed rotor of a type of micro turbojet engine,thermal running stability was analyzed firstly,then high-precision dynamic balancing and overall dynamic balance checking in thermal state,as well as the damping structure and thermal insulation,were experimentally verified.The results show that,when the rotor imbalance is reduced,the rotor is kept steady with proper external damping.The average temperature of measuring points is reduced with the installation of heat shield for back bearing,which reduces the heat input for rotor support and its effect on the bearing stiffness and damping.The methods consequently improve the structure-thermal running stability of rotor,and enhance the stability and safety of the whole engine. 
Experiment of turbine disc low cycle fatigue life with additional torque
LI Wei, DONG Li-wei, GENG Zhong-xing, ZHAO Fu-xing
2010, 25(6): 1346-1351.
Abstract PDF(870KB) icon2069 icon461
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An experiment technology of turbine disc low cycle fatigue life(LCF) with additional torque was presented.A full-scale turbine disc test model with additional torque for an aero-engine turbine disc was fabricated and debugged,and then was tested for LCF.The test result was different remarkably from the former results on traditional method without torque,and directly validated the conclusion that torque affected LCF of dowel hole connecting disc and shaft. 
Fracture analysis of thermal barrier coating structure with interfacial crack under steady-state thermal loading
HU Hao-ju, ZHANG Jian-yu, YANG Xiao-guang, QI Hong-yu, FEI Bin-jun
2010, 25(6): 1352-1357.
Abstract PDF(587KB) icon1745 icon469
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Considering unilateral interfacial crack in thermal barrier coating(TBC),virtual crack closure technique(VCCT) was used to calculate strain energy release rate of the structure under thermal loading,and unilateral interfacial crack propagation behavior was studied according to the results.During calculation,the stable temperature field was obtained by the given temperature boundary conditions,and taken as the thermal loading in the structure.The temperature-dependent material parameters were adopted.The results show that,in the given conditions,the total energy release rate is greater than interfacial fracture toughness during crack initiation stage,indicating that once the unilateral interfacial crack appears,the unstable propagation will occur subsequently under thermal loading.When the crack extends close to the free end,the total energy release rate decreases rapidly and drops below the interface fracture toughness,leading to stop of crack propagation.The analysis shows that,for the structure of TBC with unilateral interface crack under high thermal loading,the ceramic coat won't flake-off completely. 
Numerical simulation of the three-dimensional flow-path in a ram-rotor
HAN Ji-ang
2010, 25(6): 1358-1365.
Abstract PDF(1314KB) icon1524 icon404
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A kind of three-dimensional flow-path of the ram-rotor was designed in this paper according to the design method of the typical supersonic intake of aircraft and missiles,especially the design method of the compression ramp,the throat and the subsonic diffuser.The design Mach number of the flow-path was based on the averaged relative Mach number,regardless of the change of incoming Mach number along radial direction of the flow-path.Then,the flowfield of the designed flow-path was simulated numerically with computational fluid dynamics software at design point.The purpose of simulation was to obtain the details of the flowfield,including the structure of the shock wave system,position of flow separation zone,and so on.The performance of the ram-rotor was also evaluated.The numerical results show the structure of the shock wave system in the flow-path is similar to that in the supersonic intake.To improve the overall performance of the ram-rotor,the reasonable compromise between the total pressure ratio and the isentropic adiabatic efficiency should be reached.The structure optimization of the flow-path and the configuration of the shock wave system have great influence on the performance of the ram-rotor. 
Numerical simulation of the performance of a four-stage fan
YIN Song, JIN Dong-hai, ZHU Fang, GUI Xing-min
2010, 25(6): 1366-1373.
Abstract PDF(1628KB) icon1177 icon390
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Numerical simulation of the overall performance for a multistage fan was carried out with the computational fluid dynamics(CFD) code developed indigenously.This work was involved with the engine matching and the validation of the code reliability and accuracy.The k-ε turbulence model was introduced,and the source terms in k-ε turbulence model were treated implicitly to relieve the stiffness of k-ε equations.A mixing plane was set for the communication between adjacent blade rows.The code was first verified against a single-stage fan,and then compared with the commercial software and experiments.Further validation was conducted on a four-stage fan.By analyzing the results,it's found that the property of code is good,but the shortcomings caused by the mixing plane need to be improved. 
Numerical study on control method of shock wave intensity based on cool-air injection
WANG Kai, WANG Song-tao, WANG Zhong-qi
2010, 25(6): 1374-1380.
Abstract PDF(1690KB) icon1763 icon450
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The effects on shock wave when cooling air was injected into the stator blade passage were studied in multi-schemes numerical research.The analysis was carried out for the changes of shock wave strength and direction,using the same inlet pressure and same temperature to inject cooling air at 5 different positions around the reflected shock generated point of the stator blade's suction side of high pressure turbine.The results show that it is a feasible method to control the intensity of shock wave by injecting cool-air at shock wave reflection point.Cooling injection has effect on local pressure field,leading to the change of the pressure gradient among the propagation region of shock wave.When the cooling inject position is at the reflection point,the intensity of shock wave can be reduced. 
Optimization of dual stage counter-rotating compressor in multistage environment
WANG Lei, LIU Bo, LIANG Jun, WANG Qing-wei
2010, 25(6): 1381-1388.
Abstract PDF(2324KB) icon1675 icon414
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With the optimization platform of three-dimensional(3-D) design,the optimization design was carried out for rotor 2 of a two stage counter-rotating compressor in multistage environment based on the methods such as: three-dimensional Navier-Stokes(N-S) flow computation,blade section parameterization,artificial neural networks and genetic algorithm.The optimization objective is to maximize the isentropic efficiency while the mass flow and total pressure ratio are controlled.Numerical results show that efficiency is increased by 1.5% at design point after optimization of rotor 2.The gain in aerodynamic performance is largely attributable to the reduction of losses due to flow separation in suction side,as observed through flow field analysis. 
Research on the effects of a transonic compressor rotor with axial skewedslots casing treatment at low Reynolds number
XIA Qin-bin, WANG Ru-gen, ZHOU Min, WANG Long, LI Yong, GUO Fei-fei
2010, 25(6): 1389-1394.
Abstract PDF(1203KB) icon1808 icon463
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The effects of NASA Rotor 37 transonic compressor rotor with 50%,75% and 100% axial congruence skewed slots casing treatment at low Reynolds number were investigated by unsteady numerical simulation.The result shows that the boundary layer radial vortex is well controlled and the blockage zone due to boundary layer separation is notably reduced.It's also found that the blockage zone is caused due to the tip leakage vortex.The stall margin of the compressor rotor with axial skewed slots is obviously improved,contributing to the compressor stability. 
Investigation of the lifter's lift mechanism and efficiency
REN Jun-xue, LIU Yu, JIANG Xing-liu, LE Xiao-yun, WANG Li-ying
2010, 25(6): 1395-1400.
Abstract PDF(869KB) icon1857 icon470
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The lift force of the lifter were measured with different voltage and geometry between electrodes.The ionic wind explanation of the lifter's flying was given and the formulas of the lifter's lift and efficiency was deduced based on it with an one dimensional electrohydrodynamic(EHD) method.The theoretical results agree with the present experimental results.The lift force generation and its magnitude depends on the corona discharge current.When the voltage between the electrodes is not very high,the magnitude of the lift fore is parabolic to the voltage,proportional to the distance between the electrodes,and inverse proportional to the length of the electrodes.The influence of the parameters on the lift force and efficiency of the lifter was analysed according to the theoretical formulas.The lifter's efficiency can be improved by reducing the ion drift velocity while the lifter force is reduced.The lifter's performance is compared with that of the present propulsion systems and it indicates the lifter's thrust power ratio is greater while its efficiency and thrust weight ratio is smaller.Thus the lifter can be only developed as an auxiliary aviation propulsion system. 
Simulation of GH2/GO2 and GH2/LOX combustion characteristics of shear-coaxial injectors
WANG Xiao-wei, CAI Guo-biao
2010, 25(6): 1401-1406.
Abstract PDF(505KB) icon1623 icon390
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Single-element shear-coaxial GH2/GO2 and GH2/LOX injectors were numerically simulated.Two-phase turbulent combustion process of GH2/LOX was simulated with chemical Navier-Stokes equations and discrete particle model.Chemical reaction was calculated with Arrhenius formulation.GH2/GO2 and GH2/LOX combustion flowfields and the influences of some key design parameters on two types of fields were obtained.The combustion completion length of GH2/GO2 injector is longer.The injection flowrate and momentum ratio are key parameters for the both types of injectors,and the influence tendencies of these two parameters are the same.The injection velocity is less influential to both types of injectors. 
Simulation and design of thermal protection of rocket motor in certain detector
ZHANG Tao, SUN Bing
2010, 25(6): 1407-1411.
Abstract PDF(1777KB) icon1713 icon499
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Heat environment parameters of rocket motor were analyzed and computed based on structure and work condition of certain detector.Solid radiation heat flux of rocket motor was computed by finite element method,and thermal protection scheme was designed according to heat flux boundary condition.Multilayer insulation material performance was expressed by equivalent emissivity and temperature field was simulated.As the performance parameters are difficult to determine,the temperature field was computed in wide parameter range.Efficiency and reliability of thermal protection scheme were validated and primary influential factors to thermal protection performance were analyzed,providing a theoretical basis for design and selection of thermal protection scheme. 
Study of thrust stand for solid propellant micro-thruster array
LIU Shu-jie, FANG Shu-zhou
2010, 25(6): 1412-1416.
Abstract PDF(754KB) icon1526 icon419
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In order to test the solid propellant micro-thruster array,a testing stand with four high-precision piezoelectric quartz sensors was designed to measure the main thrust and the coordinates of working thrusters in the array.The static calibration method was discussed,and harmonic analysis was also performed.The X-shaped plate was shrunk by more than 85% in material weight by the means of topology optimization.At last the thrust stand can meet the test requirements in theory. 
Dynamic study of journal gas bearings-flexible rotor coupling system
ZHANG Guang-hui, LIU Zhan-sheng
2010, 25(6): 1417-1426.
Abstract PDF(2014KB) icon1737 icon1203
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The nonlinear dynamic characteristic of journal gas bearings(self-acting gas bearing and hybrid gas bearing)-flexible rotors coupling system was studied theoretically by employing the orbit method in this paper.The multiple degree freedom model of the rotor system was established,solving the coupling with the Reynold equation(including the time terms) by applying alternating direction implict(ADI) method.Through numerical simulation,the nonlinear gas film forces,trajectory diagram,phase diagram,frequency spectrum,power spectrum,bifurcation diagram,vibration mode diagram and the equilibrium position diagram were obtained.As for the characteristic of the orbit method employed in this study,the methods of obtaining the nonlinear dynamic parameters were proposed.It indicates that the dynamic characteristics of journal gas bearings-rotor system and whirling instability of the gas film could be depicted commendably. 
Tooth contact analysis of face gear drive with curvilinear shaped tooth by format cutting
SU Jin-zhan, FANG Zong-de, CAO Xue-mei
2010, 25(6): 1427-1431.
Abstract PDF(1024KB) icon2222 icon451
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The contact characterics and flank modification of face gear drive with curvilinear shaped tooth by format cutting were investigated.An image rack-cutter with curvilinear shaped tooth was considered as a generating tool formed by head-cutter with a tilted angle.The tooth surface of face gear by fotmat cutting and cylinderical gear by generation method were derivated,then,flank modification of face gear was applied by the rack-cutter's parabolic profile.Based on the developed mathematical model of face gear drive,tooth contact anlysis was also established by taking into consideration the assembly errors.Finally,the numerical example results show that the transmission error amplitude can be reduced and the better shape of transmission error curve can be attained,and also the sensitivity of this type gear drive is better than other face gear drives. 
Performance analysis of thin-wall angular contact ball bearings considering the ferrule deformation
NI Yan-guang, LIU Wan-qiang, DENG Si-er, JIAO Yu-jie, LIANG Bo
2010, 25(6): 1432-1436.
Abstract PDF(791KB) icon1742 icon462
Abstract:
In order to calculate accurately the load distribution among the rolling elements of flexible supported bearing,the finite element method was used to research the performance of flexible supported thin-wall angular contact ball bearings in this paper.Ferrule bending deformation under load was considered for flexible supported bearings,and the change law of load distribution,life span and stiffness in different conditions was obtained.The results were compared with those obtained by the quasi-dynamic method and the experiment.It is found that the results of finite element method are close to the experimental values as the ferrule deformation and boundary condition are considered. 
Calculation and analysis of film thickness for slipper pair and valve plate pair in fuel piston pump
HE Bi-hai, SUN Jian-guo, YE Zhi-feng
2010, 25(6): 1437-1442.
Abstract PDF(631KB) icon1597 icon409
Abstract:
The flow features of the slipper pair and valve plate pair were studied in consideration of the influence of the squeezing effect and wedge effect of the films,and then the differential equations of the variation of the film thickness for these two pairs were established.By solution of this equation,the cycle variation laws of the film thickness both for slipper pair and valve plate pair were further obtained,hence the defects of traditional hydrostatic bearing were compensated. 

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