2008 Vol. 23, No. 10

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Improved simulation of electrothermal de-icing system
CHANG Shi-nan, AI Su-xiao, HUO Xi-heng, YUAN Xiu-gan
2008, 23(10): 1753-1758.
Abstract PDF(1347KB) icon1686 icon446
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A two-dimensional rectangular geometry used to simulate the electro-thermal de-icing system was modeled.The enthalpy method was appliled to establish heat conduction governing equations considering the phase chang.The control volume method was adopted to discretize the governing equations,as well as initial and boundary conditions.The block-correction technique was used to improve the solving of the difference equations system.Comparison was made with previous studies of foreign paper and excellent agreement was achieved,documenting the validity of the improved numerical codes.The effects of time step and grid on the results of the simulation were analyzed.
Numerical studies of the effects of shaped holes on cooling effectiveness of flat plate film with conical shrink entrance and conical diffuser exit
LI Zhi-qiang, TIAN Tao
2008, 23(10): 1759-1764.
Abstract PDF(1373KB) icon1586 icon449
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The numerical simulation was used to study the film cooling effectiveness of plate with jet holes by increasing the heat transfer of wall of hole and enlarging the cooled area of plate in the side of hot gas stream.By studying different shape of jet holes,a new shaped hole(conical shrink entrance and conical diffuser exit shaped hole) was proposed.The computational results show that,the conical shrink entrance of the new shaped hole can efficiently enhance the convection heat transfer of wall of hole,and the conical diffuser exit of the new shaped hole can efficiently enlarge the cooled area of plate in the side of hot gas stream.If comparing with the conical diffuser shaped hole,it is found that,when the shrinkage hole is used,the film cooling effectiveness of plate is enhanced with low blowing ratio,and the film cooling effectiveness is inferior with high blowing ratio.However,when compared with the cylindrical hole,when the new shaped hole is used,the film cooling effectiveness of plate can be improved in any case.
Film cooling experiment of row of expanded shape holes
YANG Cheng-feng, ZHANG Jing-zhou, CHEN Li-qiang, WU Shi-xun
2008, 23(10): 1765-1771.
Abstract PDF(1632KB) icon1601 icon489
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Three types of expanded shape film-cooling holes were designed to study the change of the film cooling efficiency,heat transfer coefficient at the wall and flow discharge coefficient with the blow ratio.The result shows that: the film cooling efficiency and heat transfer coefficient of the expanded film cooling holes are higher than the typical round film cooling holes,but the flow discharge coefficient is lower.The effect of the streamwise expanded angle on the film cooling effectiveness and heat transfer coefficient is more remarkable than the laterally angle,which expands the area of the low pressure near the edge of the holes,leading to lower flow discharge coefficient.
Numerical investigation on improvement of film cooling effectiveness with console hole
YAO Yu, ZHANG Jing-zhou, ZHOU Nan
2008, 23(10): 1772-1777.
Abstract PDF(1630KB) icon1579 icon470
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The film cooling characteristics of console hole were numerically investigated using the shear-stress transport two-equation turbulent model to understand the effects of blowing ratios on cooling effectiveness.The cooling effectiveness for three configurations of film cooling holes was also studied comparatively.Results show that the cooling effectiveness for console film cooling hole increases with the increment of the blowing ratio.Under the same blowing ratio,the cooling effectiveness of the console hole is better than cylindrical hole,and lower than slot.Under the condition of low blowing ratio,the film cooling effectiveness of console is equivalent to the slot.
Combustion characteristics of self-stabilized dual-swirler cup in the unconfined case
ZHANG Chi, WANG Zhi-qiang, LIN Yu-zhen
2008, 23(10): 1778-1782.
Abstract PDF(625KB) icon1576 icon437
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The combustion characteristics of the self-stabilized dual-swirler cup in the unconfined case,which is suitable for the tangential trapped vortex combustor,were investigated experimentally.The self-stabilized dual-swirler cup is characterized in that,the dual-swirler with radial holes is employed,and the fuel sprays from a pressure nozzle in the center.According to the different swirl numbers and air flux distributions of the swirler,different layouts are developed.In the experiment under normal temperature and pressure,RP-3,for example,was used as the fuel.Results show that,the flame stability increases and the length and shape of the flame remain unchanged with the decrease of the air flux distribution of the internal swirl and increase of its swirl number.
Design and study of annular combustor for micro-turbine engine
LI Cong, FANG Shu-zhou, ZHANG Ping
2008, 23(10): 1783-1787.
Abstract PDF(1246KB) icon1868 icon481
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A micro annular combustor was designed based on research both inland and oversea,and simulated the combustion in the annual combustor.And then,according to the simulation result,the design of combustor was optimized and re-computed.All case including chemical reaction,heat radiation,evaporating of fuel and secondary breakup of spray was comprised in numerical simulation,the boundary condition of inlet was gained through computing and the parameter of spray was gained through experiment.The result of computation can reflect the reality case exactly.At last,the numerical simulation result of two combustor was compared,the result indicate the optimized design is reasonable,fuel can combusted sufficiently in chamber and the performance parameter is satisfied the design requirement.All data can provide numerical foundation for better performance in combustion chamber.
Experimental research on the cooling characteristics of an afterburner fuel injector with double-wall construction
YAN Bao-hua, FAN Wei-jun, LI Rui-ming, YANG Mao-lin
2008, 23(10): 1788-1794.
Abstract PDF(1036KB) icon1581 icon462
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A new afterburner fuel injector with double-wall construction was presented to meet the actual requirements.8 test pieces of new fuel injector casings with different sizes were designed in this research.The heat transfer characteristics and cooling air flow performance were tested based on previous flow characteristics research.In view of the air extraction and cooling performance,an optimum cooling case was selected.Then,this casing of fuel injector was researched with respect to the distribution of injector temperature,change of injector temperature with cooling flow inlet total pressure and change of injector temperature with Re of cooling flow inlet.The results show that: this new afterburner fuel injector can extract enough cooling air from the fan stream(When Δp is 850 Pa,extracted air flow flux is 9 g/s) and decrease effectively the temperature of the wall of fuel injector(cooling efficiency is not less than 0.7).
Application of nanofluid in thermal performance enhancement of horizontal screen heat pipe
SHU Tao, LIU Zhen-hua
2008, 23(10): 1795-1799.
Abstract PDF(932KB) icon1663 icon500
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The heat transfer characteristic of horizontal screen heat pipe using nanofluid was studied experimentally.The nanofluid consists of water and CuO nanoparticles having a mean diameter of 50 nm,the mass concentration of nanofluid ranges from 0.5% to 2.0%,and the operational pressures of the heat pipe varies from 7.45 kPa to 19.97 kPa.The experimental results show that the effect of the particle concentration on both evaporating and condensing heat transfer coefficients and the maximum heat flux is very significant.At the pressure of 19.97 kPa,the evaporating heat transfer coefficient rises from 170% to 410%.The operational pressure yields very significant effect on the heat transfer enhancement for the heat pipe.The lower operational pressure indicates more significant thermal performance enhancement of the heat pipe.The heat transfer characteristic improves with the rise of mass concentration,and then drops after reaching a certain value,while the optimal mass concentration is 1%.
Investigation of the wall temperature distribution and cooling efficiency for impingement/effusion cooling scheme
HU Chao, XU Quan-hong, XU Jian, LIN Yu-zhen
2008, 23(10): 1800-1804.
Abstract PDF(883KB) icon1921 icon448
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In order to meet long-duration requirements of high-temperature combustor liner,impingement/ effusion cooling scheme was investigated experimentally in the following aspects: the influence of the hole arrangements,the ratio of the wall thickness to the hole diameter,and the opening rate per unit area on the overall cooling effectiveness and wall temperature distribution.The condition of cooling air was under atmospheric temperature and pressure.The velocity of the main flow was 20 m/s.The velocity ratio of the cooling air to the main flow was 0.63,and the temperature ratio of the main flow to the cooling air was 1.6.The experimental results indicate that it has a better performance in the cooling efficiency with the long rhombus hole arrangement,while little influence on wall temperature distribution,and reducing the opening rate per unit area has the same result.The wall temperature distribution becomes more uniform when the ratio of the wall thickness to the hole diameter increases,and the cooling efficiency will decrease at the same time.
Torsional vibration analysis of helicopter power transmission system by the multi-shaft transfer matrix method
WANG Jian-jun, MAO Zhen-zhong, QING Li-wei, LI Qi-han
2008, 23(10): 1805-1812.
Abstract PDF(1025KB) icon1625 icon431
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The multi-shaft transfer matrix method(TMM) with differential gear mesh and the torsional vibration characteristics of the helicopter power system have been investigated.Firstly,the analytical model for the helicopter power system was built by the transfer matrix method.Next,the 'mesh transfer matrix' for the two-shaft and three-shaft gear pair,and the planetary gear pair were established using transfer matrix method.Then the torsional vibration characteristics of the helicopter power transmission system were obtained using the multi-shaft transfer matrix method.Lastly,the natural frequency and vibration mode properties was discussed
Experiments on dynamic response of labyrinth air seals with damping-ring/sleeves
ZENG Liang, LI Lin
2008, 23(10): 1813-1820.
Abstract PDF(1113KB) icon1812 icon448
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The experimental results of dynamic response for the shell with different damping-ring/sleeves verified the validity of the proposed simplified model and the numerical simulation results in this paper.The influences of variable parameters on the dynamic response,such as the width,thickness,gap size and installed position of damping-ring/sleeves were also discussed.The region of installation of damping-ring has great influence on its effect of vibration control.With the effect of "frequency-transfering" and friction damping,the damping-sleeves reduce the peak of the vibration notably.When the shell vibrates in different circumferential waves,even for the same damping-ring/sleeve,its effect of vibration control is different.
Research on a smoothing method for engine removal rate
BAI Fang, ZUO Hong-fu, REN Shu-hong, SHEN Shi-song, GENG Duan-yang
2008, 23(10): 1821-1828.
Abstract PDF(2499KB) icon1477 icon431
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Considering the characteristics of condition based on maintenance policy,a mixed integer nonlinear programming model for the cost of aero-engine fleet was formulated.At the same time,a new method was proposed to smooth the engine removal rate named shifted shortest procession time(SSPT) algorithm,which was compared with other three algorithms by using the data of CF6 engine as an example for the case study.The results show that the scheduling made by SSPT algorithm can gain lowest cost,highest support level,lower average removal rate and better effect of peek smoothing.
Design and experimentation of simulation specimen for aero-engine compressor disk slot used in low cycle fatigue test
YANG Xing-yu, DONG Li-wei, GENG Zhong-xing, LIU Xin-ling, ZHAO Fu-xing
2008, 23(10): 1829-1834.
Abstract PDF(889KB) icon1654 icon480
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The number of specimen in low cycle fatigue test of aero-engine component is small,making it difficult to confirm the reliable life.On the basis of before-mentioned circs,the factors affecting the component low cycle fatigue life were investigated.A new type of method combining with simulated specimen and tests of a few components was researched to evaluate the real component life and reliability.With this method,simulated specimen of 1st compressor disk slot of aero-engine was designed and low cycle fatigue life was assessed.The result shows that,the experimental simulation technology of low cycle fatigue life and reliability provides a new method for evaluation of life and reliability in real aero-engine component.
Damage failure analysis for composite bolted joints with tightening torque subjected to static loadings
WANG Dan-yong, WEN Wei-dong
2008, 23(10): 1835-1841.
Abstract PDF(1198KB) icon1582 icon430
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A damage failure method was developed to predict the static strength and failure modes of composite bolted joints along with three-dimensional finite element technique.The damage status for different types of joints,the whole process of failure initiation,propagation and catastrophic failure of the structure were also simulated.The predicted results and X-radiographs of specimens were compared.The results of experiments and simulation are very consistent,showing the successful ultimate strength simulation capability of the model.
Aeroengine fault diagnosis based on variable precision rough sets
SUO Zhong-ying, ZHU Lin-hu, WU Hua, SU Qiang
2008, 23(10): 1842-1846.
Abstract PDF(750KB) icon1668 icon436
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According to the practical conditions of aeroengine fault diagnosis,the paper firstly analyzed limitation of rough sets,then processed the samples set from experts experience by introducing variable precision rough sets model.And the samples sets of history faults were analyzed by the received decision-rules.The rate of identification was high.The result proves the effect of this method and the applicability of the decision-rules received from the small samples set.
Dynamic response of damped gyroscopic system with complex modal method
ZENG Liang, LI Lin
2008, 23(10): 1847-1853.
Abstract PDF(1036KB) icon1742 icon445
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The dynamic response of damped gyroscopic system was researched by the complex modal method,and the concept of gyroscopic damping ratio was also put forward in this paper.With the method proposed in this paper,it is possible to analyze the dynamic characteristics of rotating thin-walled structures such as the rotating thin-walled shaft and shell.The characteristics of traveling wave vibration of shell under different load condition(single-point harmonic load and the harmonic load with k circumferential waves) were also discussed.
Modeling behavior of cross-ply ceramic matrix composites under quasi-static loading
XU Ren-hong, SONG Ying-dong, LI Long-biao, SUN Zhi-gang
2008, 23(10): 1854-1858.
Abstract PDF(1204KB) icon1677 icon451
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The stress-strain response of cross-ply fiber-reinforced ceramic composites laminates under quasi-static loading was discussed by using a micromechanical approach.The cross-ply modified shear lag model was used to analyze the micro stress field of the damage composites.The critical matrix strain energy criterion and the Nair de-bond criterion were used to determine the matrix crack spacing and interface de-bonded length.At last,the tensile stress-strain curves were modeled by combining laminated shear-lag theory and failure criterion.The results from the present analysis match well with experimental data.
Numerical simulation of the flowfield around the seat/occupant system
SONG Bao-yin, ZHANG Zhong-gang, MOU Jie, YAO Qiu-ping
2008, 23(10): 1859-1867.
Abstract PDF(1889KB) icon1482 icon470
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The seat/occupant system was modeled geometrically and mathematically in this paper.The modified geometry model was closer to the real body.A numerical investigation using CFD technique was conducted.A three dimensional Reynolds-averaged Navier-Stokes code with standard turbulence model was used to describe the turbulent compressible flow field around the seat and occupant.The CFD code used was FLUENT,which is based on the control volume finite-difference approach.The results were presented in the form of force and moment coefficients,and agree well with the experimental data obtained from wind tunnel test.The dynamic characteristics of the seat / occupant system for Mach number of 0.2,0.6,and 1.2,at angles of attack from 0 to 60 degrees and the angles of sideslip from 0 to 30 degrees were investigated respectively.The results reveal that high Mach number,zero angle of the attack and large sideslip angle are the most dangerous state for the escaping pilot.
Research on aeroengine performance margin design considering performance deterioration in utility
ZHOU Mao-jun
2008, 23(10): 1868-1874.
Abstract PDF(1159KB) icon2082 icon474
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The purpose of this article is to study the impacts on engine performance caused by the engine deterioration after long time use,and the result was used in the engine performance margin design in new developing engines.Method is to use data acquired in special arranged performance-deterioration engine tests as well as the ones collected from overhauling engines,to analyze the impacts on engine performance caused by module efficiency loss,and to find out the difference between new delivered and deteriorated engines.This difference is used to the engine performance calculation after deterioration in development engines.Conclusion: the performance margin of 100 ℃ in engine gas temperature(EGT) and 7% in specific fuel consumption(SFC) need to be maintained in subject new development engines in order to guaranty the safety use within the time between overhaul,and development engines can meet the higher performance requirement of new generation aircraft relying on the efficiency improvement in modules.
Normal mode analysis for the sound propagation in a lined annular duct with mean swirling flow
GUAN Ying, WANG Tong-qing, ZHAO Xiao-jian
2008, 23(10): 1875-1881.
Abstract PDF(1052KB) icon1886 icon482
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Sound propagation in a lined annular duct with mean swirling flow was investigated via the normal mode analysis of three-dimensional(3-D) Linearized Euler equations,and was calculated as a generalized eigenvalue problem by a spectral collocation technique.Axial eigenmodes spectrum which are mainly composed of nearly/purely acoustic modes and nearly/purely convected modes with mean swirl and relative unsteady disturbances can then be determined.Mean swirl may even change the number of the propagating acoustic modes,and consequently affect the cut-on/cut-off characteristics of sound propagation.After validation of the approach,the effects of flow parameters and liner on the acoustic modes and convected modes are discussed.
Numerical simulation of helicopter rotor-fuselage-engine aerodynamic interactions
HU Li, CAO Yi-hua, ZHAO Ming
2008, 23(10): 1882-1887.
Abstract PDF(2253KB) icon1762 icon499
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The rotor-fuselage-engine aerodynamic interactions were studied using computational fluid dynamics numerical tools.The body-fitted structural grid was generated through multi-block grid technique.The finite volume method was adopted and incompressible Navier-Stokes equation was solved.The flow field and performance of the helicopter in forward flight were analyzed.Firstly,the accuracy of viscous simulation was investigated for the isolated fuselage configuration.Then,the rotor-fuselage aerodynamic interactions using the actuator disk model were obtained by discussing the influence of rotor on fuselage pressure distribution.Finally,the effect of the helicopter engine inlet and outlet was analyzed using a simplified engine model and the rotor-fuselage-engine interactions were obtained.
Comparison of four turbulence models in diffusing S-duct
ZHANG Li-fen, LIU Zhen-xia, Lü Ya-guo
2008, 23(10): 1888-1891.
Abstract PDF(937KB) icon1759 icon459
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Four turbulence models: Realizable κ-ε,S-A(Spalart-Allmaras),SST(Shear stress transport) and RSM(Reynolds stress equation model),were compared by simulating separated flow in a diffusing S-duct.The numerical results show the capability of each turbulence model in dealing with separation.Before separation,the predicted results agree well with experiment for four models,but in separated region,the turbulence model has important effect in simulating separation.SST model is compared to RSM in simulating separation and pressure coefficient,however not as clearly as RSM.S-A model under predict the separation and the separated region is smaller than experiment.Mach number is higher than experimental data for four models.Pressure recoveries are similar for different models,and are within 0.7% agreement with experimental data.
Thrust analysis and experimental study of the flexible wings of a flapping-wings aircraft
XU Yi-cun, BI Shu-sheng, ZONG Guang-hua
2008, 23(10): 1892-1895.
Abstract PDF(1271KB) icon1707 icon476
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A method of calculating the aerodynamic force on the flexible wing of mini flapping-wings was presented based on the Euler equation and finite element analysis.And the experiment was conducted to measure the thrust of a prototype.The results prove that the calculation can reflect the character of thrust during a flapping period.This method can gain not only the thrust and the flapping drag on the whole wing,and also the force map on different flapping characters.This is useful for the optimization design of the flexible flapping-wings.
Numerical simulation of the flow-field and performance of amicro-flowrate centrifugal compressor impeller
HUA Yan-hong, YUAN Wei-xing, YUAN Xiu-gan, YANG Chun-xin, CHEN Jiang
2008, 23(10): 1896-1902.
Abstract PDF(817KB) icon1728 icon487
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A 3-D impeller for a micro-flowrate high-speed centrifugal air compressor(MHCAC) was designed and the performance of flow field was numerically studied.The results show that the ratio of outlet to inlet area of MHCAC impellers is less than 1.0,the efficiency of a micro-flowrate centrifugal compressor can be improved by high rotating speed;the optimum number of blades of MHCAC impellers is less than that given by empirical formula originated from the theory of high-flowrate-low-speed centrifugal compressor;the outlet angle of a MHCAC impeller is generally bigger than 60°;the overall pressure ratio and efficiency of the impeller decrease with the increase of tip clearance.The methods and results of this paper provide valuable reference for engineering design of a MHCAC in aircraft air-cycle or vapor compression refrigeration systems.
Design of transonic centrifugal compressor for vehicle
ZHENG Xin-qian, ZHANG Yang-jun, GUO Gong-da, ZHANG Ji-zhong
2008, 23(10): 1903-1907.
Abstract PDF(989KB) icon1550 icon420
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As internal-combustion engine power density has increased,turbocharger with high pressure ratio is required.With a Fully three-dimension CFD technology,a transonic centrifugal compressor with pressure ratio 4.0 for vehicle was designed and also applied to micro gas turbine.The design methods and principle of transonic centrifugal compressor were analyzed.The engine-matching test shows that,the performance of the engine improved significantly with the new designed compressor as compared to the prototype compressor.The engine fuel consumption was reduced by 4.1 g/kW·h and the inlet temperature of turbine was decreased by 35 K.
Numerical optimization of transonic axial compressor by bowed blades
ZHANG Xiao-dong, WU Hu, HUANG Jian, MA Cong-hui
2008, 23(10): 1908-1912.
Abstract PDF(1010KB) icon1723 icon470
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A compressor automated optimization system was investigated,which composed of software ISIGHT,NUMECA and a sophisticated blade-design program.For testing its validity,a single-stage transonic compressor was optimized by changing circumferential stacking line of blade.The results show efficiency and pressure ratio is improved in whole characteristic curve;the investigation indicated the negative bow of rotor tip can improve flow structure and validated the compressor automated optimization system.
New intelligent neural network adaptive control scheme research for aeroengine
ZHAO Jun, CHEN Jian-jun, WANG Ling-gang
2008, 23(10): 1913-1920.
Abstract PDF(1802KB) icon1508 icon638
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In view of complicated,undetermined and strongly nonlinear aeroengine object,a novel control scheme integrating the merits of fuzzy inference,neural network adaptation and simple proportional-integral-derivative(PID) method was presented.Based on the improved fuzzy-PID controller,a novel intelligent neural network controller was designed.The parameters of the controller were optimized by the mixed learning method integrating offline chaotic ant colony optimization and online error back propagation(BP) algorithm.By applying least square support vector machine for system identification,with its fine nonlinear mapping ability,Simulation results at the design point show that the control system has good robustness and better performance than conventional control methods.The feasibility and validity of the control scheme are proved.
Reusable launch vehicle pitch attitude control system research by trajectory linearization
SUN Chun-zhen, HUANG Yi-min, GUO Suo-feng
2008, 23(10): 1921-1926.
Abstract PDF(1857KB) icon1615 icon476
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To improve the performance of terminal area energy management control system for reusable launch vehicle,the pitch attitude control system architecture based on trajectory linearization was developed,which includes two parts: pseudo-inverse model and feedback control system.Using the concept of instantaneous equilibrium,the pseudo-inverse model was designed by trimming the whole profile and the pitch attitude control system architecture was built.Take example for the flight phase of high altitude and super sonic,the system was designed and compared with traditional feedback control system.The results show that the control system by trajectory linearization can improve the transition performance,offload the feedback loop,and reduce the possibility of integrator saturation.
Tooth contact analysis of face gear drive with helical pinion and simulation of the tooth face
ZHAO Ning, ZENG Xiao-chun, GUO Hui, SHEN Yun-bo, FANG Zong-de, WEI Bing-yang
2008, 23(10): 1927-1932.
Abstract PDF(1735KB) icon1982 icon494
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The coordinate systems for the processing and driving of the helical pinion and the face gear were established,the tooth face equations of face gear and the helical pinion were deduced,while the tooth faces were simulated for visualization.Tooth contact analysis was conducted for the alignment error of the driving system.The tooth contact path and the transmission error of the face gear drive were computed through tooth contact analysis.Besides,different tooth faces and the tooth contact paths between the dextral face gear and the sinistral face gear were investigated in the paper.At last,the method of restoring the shift of contact path through axial displacement of the face gear was studied.
Analysis of data mining of clustering and its application to mechanical transmission fault diagnosis
SHAO Ren-ping, HUANG Xin-na, HU Jun-hui
2008, 23(10): 1933-1938.
Abstract PDF(1610KB) icon1693 icon443
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For mechanical fault in the gear transmission system difficult to diagnosis,an improved clustering method was presented based on the DBSCAN(Density-based spatial clustering of application with noise) by using the concept of grid processing.The faults of gear transmission system were detected and the styles of gear faults were estimated by the improved clustering method,which also calculated spectral entropy of vibration signal of gear transmission at different rotate speed,and showed the spectral entropy distribution in Two-dimension and Three-dimension domain by grid plotting.So it enables better clustering and identification of gear faults such as natural,cracked and attrited faults,etc.The method is verified experimentally to be capable of distinguishing reliably gear transmission signals at different work conditions for gear transmission system,with clustering rate up to 96%.It indicates that the method is feasible for classification and diagnosis of gear faults.
Vibration fault diagnosis method based on gray level-gradient co-occurrence matrix for rotating machinery
DOU Wei, LIU Zhan-sheng, WANG Zheng-xian
2008, 23(10): 1939-1943.
Abstract PDF(1121KB) icon1580 icon476
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A diagnosis method based on gray level-gradient co-occurrence matrix was researched in this paper.This method was used to directly extract the features from graphics of rotating machinery by gray level-gradient co-occurrence matrix.And,fault diagnosis of rotating machinery was achieved by using artificial immune system.The test proves that this method can get high diagnosis accuracy.
Internal ballistics calculation of solid rocket motor under high overload
GUO Yan-hong, LIANG Xiao-geng, CHEN Bin
2008, 23(10): 1944-1948.
Abstract PDF(709KB) icon1855 icon506
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High overload yields great influence on the grain combustion of SRM(solid rocket motor) in working process.Under nonuniform combustion of grain,a nonparallel combustion model of complicated grain was developed.The level set method was applied to calculate burning face location and internal ballistics property at different intervals.The computed results show that overload has little effect on SRM internal ballistics,since local burning rate of grain increases greatly in overload direction,leading to exposure of thermo-protection layer in high temperature gas and enhanced erosion in this position.
Experimental investigation on once injecting water in metal fuel/water ramjet
HU Fan, ZHANG Wei-hua, XIA Zhi-xun, HU Jian-xin, LI Shi-liang, HUANG Li-ya
2008, 23(10): 1949-1952.
Abstract PDF(473KB) icon1750 icon539
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The experimental system of metal fuel/water ramjet was introduced.The unchoked ramjet of metal fuel containing magnesium can burn steadily after once injecting water.In the experiment,the mass flux of water was stable and the pressure of chamber changed similarly with the secondary chamber.The effect of once water/fuel ratio and fuel burn rate for the ramjet was studied through experiments.The results show the combustion and injection efficiency for ramjet firstly increase,and then decrease with the increase of water/fuel ratio in a define range of ratio;also,the combustion efficiency and the operation performance are improved observably by increasing the burn rate of fuel metal whose variation must under the need of the long time operation for the ramjet.

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