2008 Vol. 23, No. 9

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Performance comparison between　2-D scramjet inlet and　3-D sidewall compression scramjet inlet
JIN Zhi-guang, ZHANG Kun-yuan
2008, 23(9): 1553-1560.
Abstract PDF(1578KB) icon1937 icon470
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Under the same constraints,a conventional 2-Dscramjet inlet and a 3-D　sidewall compression scramjet inlet were designed by using the recently developed advanced methodology.The flow field structure and overall performance were studied comparatively and numerically at Ma=4,5,6.The results indicate that,the flow field distortion of 2-D　scramjet inlet was much weaker than that of the sidewall compression scramjet inlet.The mass capture ratio of 2-D　hypersonic inlet was more greatly affected by incoming Mach numbers than that of the sidewall compression inlet.Numerical simulation shows that,the 2-D　inlet was superior to the sidewall compression inlet at the design point,while under off-design points,especially at the starting Mach number,the performance of the sidewall compression inlet was obviously superior to the two-dimensional inlet.Under the equivalent compression state,the drag characteristic of the sidewall compression inlet was superior to that of the two-dimensional inlet,while the lift force of the 2-D　dimensional inlet was greater than that of the sidewall compression inlet.
Approximate simulation research on the hovering control of an insect flapping flight mimicking bee
ZHANG Xi-jin, FANG Zong-de, YANG Xiao-hui
2008, 23(9): 1561-1567.
Abstract PDF(804KB) icon1649 icon447
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Based on the quasi-state aerodynamic force model,the paper deduced the aerodynamic force and moment approximate equations of an insect flapping flight mimicking bee,and developed kinematic functions of flapping wing.Then,the insect flapping flight mimicking bee was regarded as rigid body moving in the sky,Based on its dynamic equation,hovering control was investigated by means of hierarchical control.External control was position control,PD(proportion differentiation) controller was used for positions of Xand Y,switching controller was employed for position of Z;switching control strategy was also used for internal attitude control,and a set of kinematic parameters were selected for switching control.Finally,hovering control of the insect flapping flight mimicking bee was simulated.The result shows that the proposed control method is effective,when the insect flapping flight is disturbed and departs from balanced position,it can return near its balanced position by means of self-regulation.
Numerical study on the starting characteristics of the pulse combustion wind tunnel
ZHANG Xiao-qing, LE Jia-ling
2008, 23(9): 1568-1572.
Abstract PDF(1158KB) icon1520 icon450
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The starting process of the pulse combustion wind tunnel is unsteady and very complex.It couldn't be investigated by use of the experimental method in existence.In this paper,the starting process was simulated by the Fluent computational fluid dynamics(CFD) code.The current version of this code employs dual-time formulation,second order upwind interpolation scheme,shear stress transport(SST) k-ω turbulence model,and species transport equation.The transient flow structure during nozzle starting process and the establishing process of supersonic flow in the free jet region were analyzed.The results provide a reference for the improvement of the starting characteristics of the pulse combustion wind tunnel.
Investigation of pneumatic characteristics for a ventral S-shaped inlet at high incidence and low speed
WENG Xiao-chai, GUO Rong-wei
2008, 23(9): 1573-1578.
Abstract PDF(921KB) icon1704 icon480
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The pneumatic characteristics of a ventral S-shaped inlet at high incidence and low speed were investigated experimentally.The results show that when the Mach number Mae of the flow at the exit increases,the total pressure recovery decreases,and the circular steady total pressure distortion,turbulence intensity and synthesis distortion increase.When Mae is at 0.45,the total pressure recovery coefficient,circular steady total pressure distortion coefficient,turbulence intensity and synthesis distortion coefficient are 0.881,1.292%,1.513% and 2.805% respectively.At the same time,the power spectrum magnitude of the dynamic total pressure signals has a peak value at 220 Hz,which confirms that a flow separation occurs somewhere in the duct.As compared with the experimental result under ground running,the results at high incidence and low speed have a higher total pressure recovery and although the synthesis distortion is also higher,the inlet is fit enough to the engine at high incidence and low speed.
Numerical Investigation on the transient flow induced by a high-speed projectile
JIANG Xiao-hai, FAN Bao-chun, LI Hong-zhi
2008, 23(9): 1579-1584.
Abstract PDF(2376KB) icon1467 icon452
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The entire process of the quiescent projectile accelerated by high-pressure gas to shoot out at a supersonic speed and fly out of the range of precursor flow field was simulated numerically.The calculation method was based on arbitrary Lagrangian-Eulerian equations and second-order precision Roe method by adopting the chimera grids,dynamic mesh and immersed boundary method.From the predicted results,the coupling and interaction process among the precursor flow field,propellant gas flow field and the high-speed projectile were discussed in detail.
Numerical simulation of flow-field for shock induced axisymmetric fluidic vectoring nozzle
LEI Jin-chun, JIN Jie
2008, 23(9): 1585-1590.
Abstract PDF(1003KB) icon2058 icon418
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Asub-scaled numerical simulation employing RNGk-ε model was conducted to determine the internal flow-field structure of a shock induced axisymmetric fluidic vectoring nozzle with a slot in its divergent section,when the nozzle pressure ratio(NPR) was 3～10,and the flow flux ratio of the secondary flow injection to the primary flow(Ws/Wp)was 2.5%～20%.The results from comparison of computational and experimental data indicate that,the relative tolerance of wall static distribution is less than　10.1%.The flow-field structure is very complicated for the secondary flow injection.The flow structure is characterized in that,a pair of opposite revolving separated vortex exists in the divergent section and a large recirculation region locates between the secondary flow injection and the outlet.The flow field structure changes with NPRand Ws/Wp.
Surface heat flux calculation of variable entropy flow for hypersonic blunt bodies
JIANG You-di, DONG Wei, CHEN Yong
2008, 23(9): 1591-1594.
Abstract PDF(630KB) icon1613 icon429
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Aengineering method,which accounts for variable entropy effects by modifying momentum thickness is described in this paper.Take a blunted 15 degrees half-angle cone for example,the results of calculating surface heat flux were compared with those of experience.The results show that the engineering method consumes less time and is workable.And also,the valuable reference data are supplied for the aero-thermal calculation in initial design and the reasonable choice in thermal protection system of hypersonic vehicle.
Research on self-excited oscillation flows in inlet of ramjet
LIU Zhan-sheng, ZHANG Yun-feng, TIAN Xin
2008, 23(9): 1595-1602.
Abstract PDF(1546KB) icon1613 icon504
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Self-excited oscillation may arise when the inlet of ramjet is under a certain condition.This phenomenon for a supersonic inlet was numerically studied,and changes in fluid flow fields were analyzed.The results demonstrate that,in the occurrence of oscillation,the fluid flow in inlet generates large amplitude,resulting in violent periodic aerodynamic loads on ramjet wall structures.The frequency spectrum of oscillation comprises some characteristic frequencies similar with acoustic modal frequencies,implying a close relationship between acoustic modes and self-excited oscillation.
Numerical simulation of aerodynamic effects of secondary injection positions on fluidic thrust vectoring nozzle
LI Zhi-jie, WANG Zhan-xue, CAI Yuan-hu
2008, 23(9): 1603-1608.
Abstract PDF(1073KB) icon1703 icon494
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The aerodynamic effects on fluidic thrust vectoring of a two-dimensional,convergent-divergent(2DCD) nozzle with fluidic injection were simulated numerically,showing that different fluidic injection positions have bigger influence on the vector angle.In the case of nozzle NPR=4.5,the vector angle of secondary injection position is maximum in relation to the divergent middle section of nozzle,in the case of nozzle NPR≥7.2,the vector angle becomes bigger if the secondary injection position is closer to the outlet.The results indicate that vector angle is sensitive,and thrust coefficient and discharge coefficient are insensitive to the injection position.
Fault diagnosis of rotating machinery based on gray primitive co-occurrence matrix
DOU Wei, LIU Zhan-sheng, MA Xiao-feng
2008, 23(9): 1609-1616.
Abstract PDF(2743KB) icon1612 icon462
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Afault diagnosis method based on gray primitive co-occurrence matrix was analyzed.This method directly extracts the image characteristics about the vibration parameter of rotating machinery by combining ray space distribution characteristics with texture primitive method.While extracting the information of image texture characteristic,it enables fault diagnosis of rotating machinery by using BP(back propagation) artificial neural networks.This method was validated to get high diagnosis accuracy by conducting normal state rotor,unbalanced rotor,misalignment rotor and loose bearing pedestal experiments on　600 MWturbine experimental bench.
Multi-scale constitute model for ceramic matrix composite by high fidelity generalized method of cell
GAO Xi-guang, SONG Ying-dong, SUN Zhi-gang
2008, 23(9): 1617-1622.
Abstract PDF(657KB) icon1929 icon442
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Amulti-scale constitute model for ceramic matrix composite(CMCs) was presented in this paper by using high-fidelity generalized method of cell(HFGMC).Based on the microstructure and damage characteristics of CMCs,a representation volume element(RVE) and damage variables were defined.Then,the evolution of damage variables was calculated by HFGMCmodel to obtain the relationship between global stress and global strain.The numerical example shows that the result predicted by the model is consistent with the experimental result,and the model could simulate the global performance and the damage evolvement of CMCs exactly,thus providing an effective method for the micro-macro analysis of CMCs.
Effect of porosity on the failure strength of porous ceramic materials
YUAN Yi-yun, SONG Ying-dong, SUN Zhi-gang
2008, 23(9): 1623-1627.
Abstract PDF(1771KB) icon1982 icon521
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The failure problems of porous ceramic materials were analyzed using the lattice model and statistical methods.Finite element model of porous ceramic materials was established firstly.Then,the failure process of porous ceramic materials was simulated by using self-adapt load technique.Finally,the simulation results were analyzed statistically.The effects of the pores' size,volume and porosity,etc,were considered easily through 3-Dlattice model.The study shows that the failure process of the brittle porous materials exhibit certain plastic property;the stochastic distribution of the pores causes some differences in the terms of failure strength;the higher porosity means lower failure strength.
Decision-making method for maintenance strategy with mixed data and unknown priority vector
LI Chang-you, XU Min-qiang, GUO Song, WANG Ri-xin, GAO Jing-bo
2008, 23(9): 1628-1632.
Abstract PDF(325KB) icon1299 icon439
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The fuzzy preference programming method was employed to calculate the priority vector from the fuzzy pairwise comparison judgments set,and then ELECTRE Ⅲ based on stochastic dominance and the distance index between the centroid point of a fuzzy number and original point was applied to rank the maintenance strategies in order to select the most appropriate maintenance strategy for a machine.Finally,the proposed method was applied to the maintenance strategy decision making of aeroengine.The result shows that the proposed method is effective.
Small-sample reliability information fusion approach based on bayes-fuzzy logistic operator
FENG Jing, ZHOU Jing-lun
2008, 23(9): 1633-1636.
Abstract PDF(281KB) icon1653 icon475
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In order to solve lower confidence level of reliability assessment results for complex system in aero and aircraft fields caused by little test data,a fusion method based on fuzzy aggregation operator(FAO) was presented to fully embody the degree of redundancy and complementarity of information from multiple sources.The unknown parameters of the fusion operator were estimated by the second maximum likelihood estimation method(ML-Ⅱ).The simulation example shows that the proposed method is effective.
Consistency test method for single expert's information described by fractiles
MA Li-mei, WU Xiao-yue, LIU Qi
2008, 23(9): 1637-1640.
Abstract PDF(350KB) icon1605 icon433
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The definition of expert's consistency was given for expert's information described by fractiles.According to the hypothesis testing theory,the test statistic was constructed,the method for setting critical value was presented,and the procedure was built for consistency testing of single expert's information.Finally,an example was given to show the validation of the method.
Research on failure mode and fatigue life of centering ring of turbine disk
MA Yan-hong, LIU Shu-guo, HONG Jie, DONG Hong-lian
2008, 23(9): 1641-1646.
Abstract PDF(882KB) icon2186 icon394
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The failure mode of turbine disk centering ring was analyzed based on its structure feature and all load forms.The study proved that low cycle fatigue on the high temperature and high mechanical loading condition might have a relatively great impact on its fatigue life.The analysis model was set up for simulating all loads and constrained conditions.In addition,the heat transfer of cooling airflow and the centering ring was simulated to obtain the temperature field.The maximal stress-strain cycles on dangerous location of the centering ring was calculated with the elastic-plasticity finite element method.The fatigue life was predicted according to the maximal stress-strain cycles with different life prediction methods,and these different results were compared.The research result shows that there are two dangerous locations on the centering ring,one is cooling hole-edge subject to axial load,the other one is after edge chamfer of the inner face subject to radial and axial loads.
Experiment of vibration and response of blade with dry friction structure
CHEN Lu-lu, MA Yan-hong, YANG Xin, HONG Jie
2008, 23(9): 1647-1653.
Abstract PDF(1436KB) icon1839 icon485
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Atesting system was set up to measure dynamic response of non-rotating shrouded blades.The loading scheme can achieve continuous adjustment and accurate measurement of contact pressure.The vibration characteristics and response of the shrouded blade with different mounting tightness and pressure angles were measured.The results show that the shrouded blade has nonlinear phenomena-the resonance frequencies are forficate.The effect of mounting tightness and pressure angle were analyzed according to the test data.The results indicate that the selection of pressure angle should be considered according to the proportional relations between relative motion to normal direction and tangential direction based on vibration mode.
Experiment of measure pressure in the same section of detonation tube
ZHANG Peng-gang, HE Xiao-min, ZHANG Jing-zhou
2008, 23(9): 1654-1659.
Abstract PDF(1309KB) icon1818 icon398
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In order to gain the distribution characteristic of pressure in same section of detonation tube,a series of single detonation experiments were conducted to study acetylene-air mixtures in square detonation tube.Four pressure transducers were installed respectively in different positions of two sections to measure the pressure value.The experiment was performed respectively in tube with/without obstacles.The results indicate that the size of pressure wave in same section is different and the detonation wave is not a plane wave.The pressure in tube wall is higher than that in tube center.
Experimental study on cooling characteristics of film cooling with trapezoid tabs
CHEN Li-qiang, YANG Wei-hua, YANG Cheng-Feng, ZHANG Jing-zhou
2008, 23(9): 1660-1665.
Abstract PDF(1152KB) icon1734 icon460
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In order to study the effect of tabs on film cooling,three test pieces with different geometrical dimensions were designed,and the infrared camera was used to measure the temperature distribution on the wall.The cooling characteristics was experimentally studied.The results show that the efficiency of film cooling and the convective heat transfer coefficient of film cooling with tabs have improved markedly in the presence of tabs.The cooling efficiency has an optimal blowing ratio value along the streamwise direction;while the blockage ratio is 0.214,the convective heat transfer coefficient reaches its maximum value in the range of the experiment.
Numerical study of cooling effectiveness of different film cooling holes on stator blade
YAO Yu, ZHANG Jing-zhou, GUO Wen
2008, 23(9): 1666-1671.
Abstract PDF(875KB) icon1716 icon483
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The flow field and film cooling characteristics on the blade surface were numerically investigated using the shear-stress transport(SST) two-equation turbulent model,so as to understand the influences of film-cooling holes on cooling effectiveness.The flow and cooling effectiveness for four configurations of film cooling holes were compared.Results show that the cooling effectiveness for each film cooling hole increases with the increment of the coolant entrance total pressure.Under the same coolant entrance total pressure,the cooling effectiveness of the dustpan and slot film cooling holes are the best,followed by that of the taper film cooling hole.
Numerical investigation on film cooling effectiveness of stator blade with or without heat transfer
YAO Yu, ZHANG Jing-zhou, GUO Wen
2008, 23(9): 1672-1677.
Abstract PDF(1560KB) icon1800 icon420
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The film cooling effectiveness on the blade surface under different coolant entrance pressures was numerically investigated using the shear-stress transport(SST) two-equation turbulent model,so as to understand the influences of film-cooling holes on cooling effectiveness.Three-dimensional turbulent flow in the turbine cascade and the cooling effectiveness on the blade surface with cylindrical film cooling hole were simulated in two cases: with/without heat transfer in the blade.The results show that the cooling effectiveness increases with the increment of the coolant entrance total pressure,and the cooling effectiveness with heat transfer in the blade is better than that without heat transfer in the blade,especially in the leading edge region.
Experimental research on jet impingement inside semi-confined rib-roughed channel
TAN Lei, ZHANG Jing-zhou, YANG Wei-hua
2008, 23(9): 1678-1683.
Abstract PDF(1445KB) icon1760 icon436
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Thermal visualization of jet impingement inside semi-confined rib-roughed channel was tested by thermograph to investigate the effects of impinging Reynolds number,jet-to-surface spacing as well as the ribs arrangement on heat transfer characteristics.The discharge coefficient for jet impingement was also analyzed.Results show that the impingement cooling effectiveness of ribbed surface is affected extremely by the jet-to-surface spacing,and the best effectiveness is achieved under the jet-to-surface space equaling to 1;the rib pattern also exerts great impact on cooling effectiveness,in present research the V-shaped ribs have best performance;the discharge coefficient is enhanced with the increase of impinging Reynolds number and the best result is obtained in V-up channel.
Numerical simulation of flow and heat transfer inside co-rotating disc cavity with de-swirled radial inflow
HUANG Ai-xia, WANG Suo-fang
2008, 23(9): 1684-1688.
Abstract PDF(815KB) icon1861 icon407
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Numerical simulations were carried out to study the flow and heat transfer characteristics inside co-rotating disc cavity.The RNGturbulence model was applied to investigate the pressure loss across the disc cavity and the influences of non-dimensional mass flow coefficient,rotational Reynolds number and turbulent flow parameter on the flow and heat transfer.Results show that flow structure inside the cavity is mainly decided by turbulence flow parameter;under a constant value of rotational Reynolds number and the variation of flow rate,the pressure drop exhibits an "S-curve" behavior in which there are three different values of flow rate for each value of pressure drop;the pressure drop across the cavity can be effectively reduced with the use of de-swirled nozzles;the Nusselt number rises with the increase of non-dimensional mass flow coefficient and rotational Reynolds number.
Investigation on the concept and application of available stagnation pressure in the compressor
HOU An-ping, QUE Xiao-bin, XIONG Jin-song, ZHOU Sheng
2008, 23(9): 1689-1694.
Abstract PDF(658KB) icon1420 icon431
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The aerodynamics design of compressor is definitely required for the flow direction,which,however,isn′t considered in the definition of stagnation pressure.So,the limitation of stagnation pressure appears when describing the performance of unsteady flow in high load fan/compressor.In order to deal with this limitation,available stagnation pressure was presented to consider the influnence on working capability of small flow volume caused by its velocity value and flow direction.And,according to the design demand of flowing in fan/compressor,the concepts of available stagnation pressure and pressure difference coefficent were defined at the level of engneering aplication.The application of available stagnation pressure can reflect more effectively the influence of flow direction on unsteady flow field in turbomachinery,making the performance characters of flow field change more sensitive to the change of quality of flow field.So the available stagnation pressure is useful to analyze the unsteady flow field.
Boundary condition model for unsteady numerical simulation under inlet distortion
YU Chun-hua, LI Qiu-shi, YUAN Wei, ZHOU Sheng
2008, 23(9): 1695-1700.
Abstract PDF(838KB) icon1485 icon433
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The unsteady vortices interactions in different scales of space and time for the compressor flow fields under inlet distortion are major influential factors to the performance of compressor.Aboundary condition model for unsteady numerical simulation under inlet circumferential distortion was presented in this paper.A 3-Dunsteady numerical simulation was conducted based on the boundary condition model.The results show that the model could reveal the unsteady interaction between wide scale total pressure wave resulting from inlet distortion and unsteady separation flow field in the rotor passage.This model provides a simple method for 3-Dunsteady numerical simulation under inlet circumferential distortion.
Numerical investigation of the response of axial flow compressor to circumferential total pressure distortion
HUANG Jian, WU Hu, ZHANG Xiao-dong, DANG Chun-ning
2008, 23(9): 1701-1706.
Abstract PDF(2027KB) icon1927 icon417
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Based on the given circumferential total pressure distortion of steady inlet flow,the response of an axial flow compressor rotor to the circumferential total pressure distortion of steady inlet flow was investigated numerically using 3-Dtime-accurate unsteady algorithm with the help of NWPU-1 axial flow compressor rig.The results show that,at 84 percent of design speed,the overall performance of compressor rotor is reduced due to distortion,with inlet flow circumferential distortion,the efficiency of ompressor rotor is decreased by 0.5 percent and the equivalent weight flow increases by 4.1 percent at near-stall condition if compared with clean inlet flow.Circumferential flow redistribution due to distortion tends to make the load of several blades too high,the blockage zone caused by tip leakage vortex is full of the whole passage,leading to the occurrence of stall.
Effects of blade number on performance of micro slope impeller
CHEN Jie, HUANG Guo-ping, LIANG De-wang, LIU Yu-shi
2008, 23(9): 1707-1712.
Abstract PDF(1100KB) icon1668 icon421
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The results of a study for identifying optimum blade number of a transonic micro slope impeller with splitters were presented.An in-house-developed Navier-Stokes flow code was applied to the study.By increasing the blade,the blade load and separation on suction surface was decreased,and the internal flow was improved,but the low pressure zone was expanded in the entryway.In the event of excessive number of the blades,the full blade cannot work from the leading edge to the trail edge.Along with the augment of the blade number,the impeller performance curves move up and then down.As compared with the experience gained in the study of normal centrifugal compressor,the optimal blade number of the micro impeller is lesser.The lower Reynolds number,the effects of micro-scale and the biggish relative thickness of blade are contributing factors to produce the difference in optimal blade number.
Design of a slot-type casing treatment and its experimental validation
LIU Li-wei, FAN Lin, LIU Huo-xing, NING Fang-fei
2008, 23(9): 1713-1717.
Abstract PDF(946KB) icon1708 icon400
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Steady Reynolds-averaged Navier-Stokes(RANS) of a test rotor with solid casing was simulated,and the flow field near the rotor tip was investigated.Based on several predominant flow features at the blade tip region as the rotor is operate at design state and near stall state respectively,a back chambered axial skewed-slot casing treatment was designed.The performance of the casing was then validated experimentally on a high speed test rig,showing that this casing treatment has notable capability in improving the stall margin of the test rotor,whilst the loss of efficiency is acceptable.This illustrates that the design of the casing treatment could be feasible on the basis of the rotor tip flow field with the solid casing.
Effect of machine tool adjustment parameter errors on spiral bevel gears tooth contact quality
TANG Jin-yuan, LU Yan-feng, ZHOU Chao
2008, 23(9): 1718-1723.
Abstract PDF(1762KB) icon1638 icon438
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Based on the meshing information of the tooth contact analysis(TCA),the influence on the tooth contact quality caused by the machine tool adjustment parameter errors was studied.The effect law between the machine tool adjustment parameter errors and the spiral bevel gears tooth contact was researched.The researched object is a pair of spiral bevel gears processed by SGM(spiral bevel gears,generated,modified roll) adjustment card.The laws of the tooth contact quality caused by the machine tool adjustment parameter errors were obtained.Based on the results,the machine tool adjustment parameters which have great influence on the tooth contact quality are confirmed
Simulation credibility evaluation of the momentum wheel bearing subassembly in the satellite
LIU Xiu-hai, DENG Si-er, TENG Hong-fei
2008, 23(9): 1724-1730.
Abstract PDF(537KB) icon1649 icon436
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The paper discussed the credibility evaluation of the momentum wheel bearing subassembly in a satellite.The simulation credibility evaluation was conducted by calculating the similarity between the simulation output and physical experimental output,which was based on the relationship between the credibility and the similarity.Similarity elements between simulation output and physical experimental output were determined,and a quantitative function was constructed.Then,the paper improved the computational methods of analytic hierarchy process(AHP) that was used to determine the weight of elements.Consequently,the simulation credibility of a momentum wheel bearing subassembly was evaluated through the method.
Nonlinear dynamic characteristics of a rolling bearing-rotor system with surface waviness
ZHANG Yao-qiang, CHEN Jian-jun, DENG Si-er, LIN Li-guang
2008, 23(9): 1731-1736.
Abstract PDF(1626KB) icon1856 icon464
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In consideration of the sources of nonlinearity such as inner and outer race surface waviness,Hertzian elastic contact force and internal radial clearance,an analytical model of rolling bearing was presented.The governing differential equations of motion of a rolling bearing-rotor system were solved by Runge-Kutta-Felhberg algorithm.The nonlinear dynamic behavior of the system with variations of parameters was analyzed by means of bifurcation diagrams,poincaré maps and spectrum diagrams.Simulation results show that the severe vibration occurs when the number of balls is equal to the number of waves.The main route to chaos is doubling bifurcation.There is a definitely functional relationship between the number of waves and frequencies of vibration produced by inner race waviness.
Simulation of cold flow and combustion characteristics of shear-coaxial GH2/GO2 injectors
WANG Xiao-wei, JIN Ping, DU Zheng-gang, CAI Guo-biao
2008, 23(9): 1737-1742.
Abstract PDF(760KB) icon1761 icon433
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Single-element shear-coaxial GH2/GO2 injectors were simulated with non-chemical N-Sequations for cold flow conditions and chemical N-Sequations for combustion conditions.The chemical reaction was modeled with Arrhenius formulation.Detailed 9-step chemical dynamic model was used to describe the reaction of hydrogen and oxygen.The simulated results of typical cold flow fields and combustion fields were compared,showing that the mix ratio of combustion is much smaller than that of cold flow.The influences of velocity-ratio,recess-length and injector-flux for the cold flow condition are consistent with those for the combustion condition,while the influences of injection-velocity are contrary to each other.
Study of methodology for improving cavitation performance of liquid oxygen pump inducer
TANG Fei, LI Jia-wen, XIA De-xin, JIN Zhi-lei, JIA Jian-xin
2008, 23(9): 1743-1747.
Abstract PDF(445KB) icon1854 icon428
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The effect of slotting at the inlet of liquid oxygen(LOX) pump inducer casing on cavitation performance was researched using computational fluid dynamics(CFD).The scheme of blade with dual arcs was analyzed and adopted.In the process of the flow field calculation,the loading of blade inlet under non-cavitating condition was analyzed;the cavitation performance for the inducer was calculated.The calculation results indicate that,the loading of the blades inlet can be suppressed greatly,and the cavitation performance can be improved efficiently with the modified scheme,while the efficiency and head of inducer vary little.
Immune-neural networks model of aeroengine performance monitoring
HOU Sheng-li, WANG Wei, HU Jin-hai, ZHOU Gen-na
2008, 23(9): 1748-1752.
Abstract PDF(1551KB) icon1638 icon469
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Amodel for aeroengine performance monitoring and fault detection was proposed based on immune-neural networks.With immune recognition mechanism of the artificial immune system,this model was combined with artificial neural networks to attain the degrees of engine performance's abnormal state for monitoring engine performance.The approach can sensitively and accurately reflect the whole performance of the engine.Meanwhile,this method improves the rate of identifying whether the performance of the engine is normal or not,finds out the potential forepart fault of engine and prevents the spread of the fault.The validity of this method is testified by monitoring certain type of turbo-fan engine.

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