2012 Vol. 27, No. 3

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Display Method:
RANS calculation and DES analysis of massively separated flows for six typical vehicles
WANG Bao-guo, GUO Hong-fu, SUN Tuo, AN Er, GUAN Chao-bin
2012, 27(3): 481-495.
Abstract PDF(3133KB) icon1919 icon550
Abstract:
A new method for flow field calculation in engineering combining RANS(Reynolds averaged Navier-Stokes) with DES(detached eddy simulation) was proposed,and was applied to the flow field calculation of six kinds of vehicles,such as the first generation of manned spacecraft Mercury,the second generation of manned spacecraft Gemini,the first probe of human that reached over Mars,cruise missiles that posses large quantity of experimental data(with the incoming Mach number from 0.50 to 2.86),Waveriders with large volume efficiency,CAV(common aero vehicle) with high lift-drag ratio,etc.During the flow field calculation,the divided-zone technology was adopted,which means employing the RANS method during the calculation of the whole flow field,but employing the DES analysis method only in the zone characterized by large-scale separation or severe separation.The numerical simulation of 63 cases of the six kinds of typical vehicles finished in this paper suggests:although employing the DES method only in the severely separated zone is not DES exactly,the numerical results (including results of aerodynamic force and aero thermal) of the flow field obtained in this way agree with the experimental data well and the efficiency of the flow field is higher than that obtained in the way applying DES in the whole flow field.
Matching of two-stage supercharging aircraft piston engines
XU Bin, XIA Shao-jun, YANG Shi-chun, JI Fen-zhu, HU Yan-ling
2012, 27(3): 496-500.
Abstract PDF(1095KB) icon1681 icon450
Abstract:
Through the single stage supercharging piston engine’s research,two-stage supercharging applications in this type were applied.The air compressor series and the turbine wheel parallel scheme of arrangement were used to establish the modeling of the engine with GT-Power. According to same-flow method,two-stage supercharger matching was conducted and the waste gate valve flow regulation was calculated.The result demonstrates the turbine wheel and the air compressor in the overall height moves in the high efficiency area,and two levels of supercharging system’s developments have provided the good foundation.
Aerodynamic theory analysis of gas exhausting from concentric canister launcher
YU Yong, XU Xin-wen, FU De-bing
2012, 27(3): 501-507.
Abstract PDF(646KB) icon1948 icon487
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The simplified model of concentric canister launcher (CCL) was proposed according to the gas flowing and exhausting process.The gas from the rocket motor nozzle flows through a stage of reducing cross-area and experiences a uniform section frictional pipe flow.A numerical simulation of a certain CCL case was conducted to verify that the simplified theory model was reasonable.Then some structural factors of optimizing design of CCL were summarized and explained how these factors worked from the analysis of the simplified theory model.According to the basic simplified theory model,a convenient and simple method to estimate the smallest size of gap and the additional eject force of missile has been given.And the simplified theory model also can be used to guide and improve the design of CCL.
Transient performance of the splitter of turbofan engine from maximum to intermediate thrust in the flight
SHI Jian-bang, YAO Shang-hong, WANG Ling-ling
2012, 27(3): 508-512.
Abstract PDF(1078KB) icon1769 icon475
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A flight test has been performed on turbofan engine to get the splitter’s static pressure and distortion with lip width of 1.0mm and 1.5mm from different flight altitudes and velocities.The data show that during the process from maximum rating to minimum augmentation rating,the static pressure difference between the splitter’s inner and outer face will become larger,the quicker of the velocity and the thinner of the splitter,the increase of the pressure difference become faster;the data still show that the pressure difference plays an most important role in the splitter’s distortion,the relationship curve between distortion and the pressure difference has been given in this paper.
Numerical smulation of RCS for 2-D convergent nozzle with different trailing edges
CHEN Li-hai, YANG Qing-zhen, CHEN Ling-ling, CUI Jin-hui
2012, 27(3): 513-520.
Abstract PDF(1930KB) icon1769 icon413
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Combining iterative physical optic (IPO) approach with equivalent edge currents (EEC) method,a program which could calculate the edge diffraction field was developed to simulate the radar scattering characteristics of nozzles with different trailing edges.An efficient algorithm to judge the occlusion relationship between face elements and a method to judge the contour line of trailing edges were proposed.On this basis,RCS (radar cross section) characteristics of the two-dimensional (2-D) convergent nozzles with four kinds of trailing edges were investigated.The results show that the program developed is reliable and the appropriate contour line modification of trailing edge can decrease the RCS of the nozzle in primary attitude angles.
Dynamic response analysis of a small-scale coaxial helicopter to a rapid collective pitch increase
NIE Zi, CHEN Ming, XU Guan-feng
2012, 27(3): 521-527.
Abstract PDF(869KB) icon1595 icon578
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Based on the engineering reality,a calculation model of the rotor unsteady aerodynamics of the small-scale coaxial helicopter had been set up.An airfoil unsteady aerodynamic model was established by introducing a set of Leishman-Beddoes semi-empirical indicial response formula.The induced velocity of the aerodynamic interaction between upper and lower rotors of a coaxial helicopter was set up based on the rigid wake model,free wake model and the dynamic inflow model with interference factors.Considering the teetering rotor’s particular flapping dynamic formula,the Runge-Kutta method was used to obtain the numerical solution of the rigid blade flapping angle.According to the calculation and analysis,the thrust response to a rapid collective pitch increase in both the hovering and forward flight states were obtained,and the blade’s hinge moment of the upper and lower rotors were compared.
Sensibility analysis of gap ratio in rotating cavity
DING Shui-ting, LI Ye, ZHANG Gong
2012, 27(3): 528-535.
Abstract PDF(1801KB) icon1655 icon422
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The sensibility analysis of the gap ratio was investigated on the cooling effect of the rotating cavity with intent of ensuring safety of a turbine disk,one of the life-limited parts in the propulsion system.The cooling effect was evaluated by fluid-structure-interaction numerical method according to resistance evaluation,heat transfer evaluation and stress distribution evaluation.The results show that the gap ratio has a great effect on heat transfer and temperature distribution of the rotating disk.Furthermore,the thermal stress of the rotating disk related to the temperature gradient can be affected.As the rising of the gap ratio,the frictional windage of the rotating cavity has not changed,heat transfer of the windward of the disk takes on up-down tendency,and the stress level and the maximum value enlarged.Therefore,change of the gap ratio has an effect on the failure probability of the turbine disk from two aspects:the material affordability and the working stress.
Reduced chemical reaction mechanism of a surrogate fuel for kerosene
ZENG Wen, CHEN Xiao-xiao, LIU Jing-chen, MA Hong-an, CHEN Ying-tao
2012, 27(3): 536-543.
Abstract PDF(950KB) icon1658 icon443
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The detailed reaction mechanism (including 67 species and 344 reactions) of the ignition and combustion of a surrogate fuel ( n-decane) for kerosene was reduced by adopting net reaction rate analysis and sensitivity analysis,and a reduced mechanism (including 50 species and 118 reactions) was gained.The ignition delay time of n-decane in the shock tube and the process of n-decane premixed combustion in the premixed burner were simulated by adopting the detailed and reduced reaction mechanisms,and the simulated results was compared with the experimental data.The results show that the ignition delay time,the shape of the profiles of the mole fractions of the reactants and the major combustion products simulated by the detailed mechanism and the reduced mechanism agree well with the experimental data.The n-decane can be a surrogate fuel for kerosene,and the reduced reaction mechanism can describe the kinetic characteristics of the ignition and combustion of n-decane.
Numerical simulation of reacting flow field in reverse-flow annular combustor
CAI Wen-xiang, ZHAO Jian-xing, HU Hao-sheng
2012, 27(3): 544-550.
Abstract PDF(1399KB) icon1806 icon571
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In the arbitrary curvilinear coordinates,a computer code was developed for simulating the integrated three-dimensional two-phase reacting flow field in a reverse-flow annular combustor which consists of the diffuser,swirler cup,flame tube,inner annuluses,outer annuluses and bend.The influence of different primary hole parameters on reacting flow fields was studied numerically.Both experimental data and numerical results were in reasonable agreement,and it reveals that these mathematical models and numerical methods are reliable and may be applied to the optimization design and development of the reversed-flow annular combustor.
Numerical investigation on characteristics of CH4/H2O/CO2 reforming reaction in presence of O2 in micro-annular chamber
YAN Yun-fei, ZHANG Li, NIU Li-xiang, RAN Jing-yu, TU Wei-feng
2012, 27(3): 551-559.
Abstract PDF(1117KB) icon1545 icon444
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The effect of component,temperature and flow on characteristic of methane/steam/carbon dioxide reforming reaction in the presence of oxygen in micro-annular chamber was numerically simulated using the surface elementary reaction mechanism.The results indicate that the effect of steam on the yields of H2 is obvious but the effect of carbon dioxide is inconspicuous at low temperature.Increasing the content of steam (carbon dioxide) can improve the conversion efficiency of methane.As the temperature rises,the effect of steam (carbon dioxide) component on the characteristic of reforming reaction becomes more obvious.The content of hydrogen (carbon monoxide) and the conversion efficiency of methane at outlets obviously decrease with increasing flow rate.The effect of steam (carbon dioxide) on the conversion efficiency of methane becomes is no longer obvious at high flow rate.As a product of the reaction,the content of steam (carbon dioxide) at outlets maintains unchanged with increasing flow rate.On the contrary,as a reactant of the reaction,the content of steam (carbon dioxide) at outlets increases with increasing flow rate.
Numerical investigation of thermal radiation characteristics of nozzle cavities with center cone cooled
ZHANG Bo, JI Hong-hu, ZHANG Zong-bin, LUO Ming-dong, LIN Lan-zhi
2012, 27(3): 560-565.
Abstract PDF(862KB) icon1584 icon549
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Numerical investigation was performed on the infrared suppress characteristics of the nozzles with and without cone cooled.In the former,cone and blade were cooled by secondary channel gas,and the temperatures of blade and cone walls were effectively decreased by 21.1% and 46.2% respectively,using only 1.6% of the secondary gas.The radiation of nozzle cavity in 3~5μm was suppressed effectively,the radiation in the small view angle range from behind the nozzle decreased obviously,and the radiation decreased by 30% from straight behind the nozzle compared to the nozzle without cone cooling.
Analysis of the buoyancy-induced heat transfer in a rotating cavity
TIAN Shu-qing, XUE Hang, GAO Chao, LI Ying
2012, 27(3): 566-571.
Abstract PDF(784KB) icon1210 icon417
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In order to get a better knowledge of the heat transfer in compressor cavities of aero-engines, the simplified rotating cavity with two-plane discs, a shaft and a cylindrical rim has been investigated numerically and compared with the available measurements. The numerical results in agreement with the available experiments show large-scale instabilities. The disk local Nusselt numbers show mainly radial rising distributions for the heated disks with radial rising temperature profiles. In the present work, at the Reynolds number of 20000, the disk local Nusselt numbers are the correlations of the local Grashof number to the power of 1.89~2.6, and the value of the power is increased as the rotational Reynolds number goes up. At the rotational Reynolds number of 800000, the local Nusselt numbers are the correlations of the local Grashof number to the power of 0.68~2.6, and the value of the power is decreased as Reynolds number goes up. The area-averaged disk Nusselt number is the correlation of the Reynolds number to the power of 0.479 and the rotational Grashof number to the power of 0.12.
Review of study history and low emission combustion technology development on aero gas turbines fuelling hydrogen
LI Ying-chun, ZHENG Guang-hua
2012, 27(3): 572-577.
Abstract PDF(789KB) icon2088 icon614
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The application of hydrogen is substantial to the development of aero gas turbine technology. According to the hydrogen application studies in aero gas turbine field, the history of the studies was reviewed and low emission combustion technologies were analyzed. The result indicates that the focus of hydrogen application study in aero gas turbine field has been shifted from early military purpose oriented to civil purpose oriented; the lean burning of primary zone is the key of hydrogen low emission combustion technology; the micro-mix non-premixed diffusive combustion has a great potential to be applied in hydrogen low emission combustion.
Application of inter-stage turbine burner on aero-engine
MAO Yan-hui, LIU Cun-xi, LIU Fu-qiang, FANG Ai-bing, XU Gang
2012, 27(3): 578-587.
Abstract PDF(1422KB) icon1522 icon450
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The engine with inter-stage turbine burner was computed in non-ideal cycle with F100-PW229 parameter.The differences of performance and thermal efficiency between inter-stage turbine burner and afterburner were compared;effect of component efficiency on the engine with inter-stage turbine burner was analyzed;combustion efficiency of main burner,inter-stage turbine burner,and after burner were contrasted.The result was different from the computation based on ideal cycle and it shows that thrust specific fuel consumption increases almost the same extent as the specific thrust after using inter-stage turbine burner on subsonic flight and specific thrust increases about 10% on supersonic;the economic performance is worse than base engine,and maneuverability is worse than engine with after burner.Then,the parameter of inter-stage turbine burner engine was optimized.
Optimal design for temperature and structure of the float-wall of flame tube
GAO Jian-hui, WEN Wei-dong, CUI Hai-tao
2012, 27(3): 588-594.
Abstract PDF(974KB) icon1808 icon441
Abstract:
Taking the float-wall structure as the object of study,neural network and genetic algorithm were used to settle synchronistically the optimization of cooling structures and install position.Using genetic algorithm to perform cooling structures and install position optimization,and taking the result of install position optimization as the foundation of cooling structures optimization,thus finally realized the synchronized optimizations of cooling structures and install position.In order to enhance the efficiency of algorithm,neural network was used to perform mapping on the result of install position optimization so as to replace its optimization processes.The result of calculating example shows that the method being mentioned is highly active,accurate and possesses good application value to engineering.
Heat transfer characteristics of hydrocarbon fuel at supercritical pressure in vertical circular tubes
ZHANG Bin, ZHANG Chun-ben, DENG Hong-wu, XU Guo-qiang, ZHU Kun
2012, 27(3): 595-603.
Abstract PDF(1579KB) icon1709 icon480
Abstract:
Experimental results of convection heat transfer to supercritical hydrocarbon fuel (RP-3) in heated vertical tubes were reported in this paper.The effects of heat flux,inlet temperature and flow direction (upward and downward) on heat transfer were studied.In the experiments,the pressure and mass flow rate were maintained at 5MPa and 3g/s the respectively;the heat flux changed from 300kW/m2 to 600kW/m2 and the inlet temperature ranged from 293K to 673K.Test results indicate that heat transfer deterioration appears firstly at the inlet of the heated test section and then increases after thermal boundary layer is developed totally.In addition,heat transfer is enhanced near the critical point of the fuel due to the significant changes of thermalphysics properties;when the inlet temperature of RP-3 exceeds its pseudo-critical temperature,heat transfer deterioration occurs again due to the heat capacity of RP-3 decreases rapidly,Furthermore,the heat transfer coefficient of RP-3 in downward flow is greater than that in upward flow due to the buoyancy effect even if the value of determining factor is lower than 10-5.Based on the experimental data,correlations are developed for the local Nusselt number of convection heat transfer to supercritical hydrocarbon fuel in vertical miniature heated tubes.
Fatigue failure analysis of turbine blade in miniature short-life turbofan engine
HONG Jie, LIU Shu-guo, ZHANG Da-yi, CHEN Meng
2012, 27(3): 604-609.
Abstract PDF(1620KB) icon1624 icon441
Abstract:
For the fracture fault of the high-pressure turbine blade in the miniature short-life turbofan engine during a certain rig test,the blade fractography,the vibration signal and the fault blade dynamics was observed and analyzed.Blades natural characteristics and exciting sources were analyzed in details;the faults mainly stemmed from fatigue for the 1st order,the 2nd order and the coupled mode vibrations due to the instantaneous severe rub impact force.Reasonable control of the clearance and improving the blade root damping can prevent the fault effectively.
Numerical calculation and analysis of arc tooth tenon joint
SHEN Xiu-li, ZHOU Ying-lu
2012, 27(3): 610-616.
Abstract PDF(860KB) icon1515 icon497
Abstract:
Two cylinders contact problem and plan contact problem were analyzed,and feature of convergence was discussed.Some numerical calculations of an arc tooth tenon joint with three teeth were done.Then,the contact stress with ANSYS was analyzed,and the results of trapezoid tooth and arc tooth tenon joint were compared to find that the latter decreased the contact stress,the third principle stress and von Mises stress.Based on this, some optimizations about the arc tooth tenon joint were done,and the stress was decreased again by optimization.
Experiment on ultra-high cycle bending vibration fatigue of titanium alloy TC17
LI Quan-tong, LIU Qing-chuan, SHEN Jing-sheng, CHENG Li, GAO Chao, CHEN Wei
2012, 27(3): 617-622.
Abstract PDF(1155KB) icon1584 icon579
Abstract:
The development of an ultra-high cycle bending vibration fatigue system on the basis of the mechanism of the fatigue failure of aeroengine vanes was discussed,including the design of ultra-high cycle dissymmetrical bending fatigue specimens.Research about TC17 was accomplished by the Ultra-High Cycle bending fatigue system (20 kHz).The fractograph of specimens was analyzed.The result indicates that the crack initiation is independent of interior inclusion and defect,and there are two kinds of mechanism of fatigue crack initiation:arising on surface or subsurface void.In addition, behaviors of interior crack initiation and propagation were not found the image of crack propagation is different from “fish-eye”.
Analysis and experiment on coupled flutter of a wide-chord blade
WU Chang-bo, CUI Hai-tao, XU Tuo, WANG Chun-jian
2012, 27(3): 623-627.
Abstract PDF(734KB) icon1511 icon423
Abstract:
The coupled flutter of a pinwheel wide-chord blade was studied.In view of the pinwheel blade,the theoretical analysis made for the original pinwheel blade showed that some typicaly coupled flutter problems between the first-order bending vibration and the first-order torsion vibration occured on the blade.The blade was re-designed and the frequencies of the first-order bending vibration and the first-order torsion of the modified blade were changed so as to effectively avoid the coupled flutter.The cumulative test of the reliability shows that the cracks are found in the original pinwheel blade after running 80 hours,while the modified blade can run safely over 200 hours.
Analysis technology and experiment for FGH96 disc’s LCF life
FENG Yin-li, WU Chang-bo, GAO Wei-qiang, CHEN Wei
2012, 27(3): 628-634.
Abstract PDF(981KB) icon1860 icon434
Abstract:
Scale effects of FGH96 disc were analyzed.Different LCF (low cycle fatigue) life forecasting methods fitted for FGH96 sub-scale and full-scale disk were analyzed.FGH96 sub-scale disk and FGH96 full-scale crack propagation disk were successfully designed.Two kinds of LCF failure mechanism were showed by LCF life tests.LCF life forecasting methods were verified.FGH96 crack propagation disc’s crack propagation characteristic was gained by crack propagation tests.The objective laws for prominent difference of crack propagation characteristic between FGH96 disc and compact tensile sample were revealed.FGH96 crack propagation disc’s damage tolerance values of 580℃ were obtained.Understanding was made for the high pressure turbine disk’s damage tolerance level.
Aerodynamic design technology in multidisciplinary optimization for turbine
PAN Shang-neng, LUO Jian-qiao
2012, 27(3): 635-643.
Abstract PDF(1593KB) icon1675 icon423
Abstract:
Aerodynamic design technology in multidisciplinary optimization was discussed in this paper through the analysis of multidisciplinary design optimization (MDO) for turbine.Complex three-dimensional (3-D) blade profile generation technique was proposed by incorporating the swept stacking axis method and a two-dimensional cascade parametric modelling method based on cascade characteristic parameters and Bezier spline.General restrictions were given through the analysis of the mathematic model used in aerodynamic optimization.And an optimization method was also proposed according to the aerodynamic design and restrictions at different stages.For 3-D aerodynamic simulation,tgrid generation,modelling,solving and post processing can be completed automatically by further programming based on CFX.The optimization results show that an increase of 2.3% in turbine efficiency has been reached,the number of rotating blades reduces by 13.21% and the overall mass of blade decreases by 8.96%.
Dynamic response analysis of a rotor supported on floating-ring squeeze film dampers
ZHOU Hai-lun, LUO Gui-huo, FENG Guo-quan, CHEN Guo
2012, 27(3): 644-650.
Abstract PDF(1177KB) icon1557 icon567
Abstract:
Characteristics were studied for the floating-ring squeeze film damper.The dynamic model of a rotor supported on the dampers was established.The coupling effect between the rotor and two layers film of the damper was considered in the model.Characteristics of the rotor system responses and other influence factors were analysed making use of numerical integral method.The results of numerical integral show that the bi-stable characteristics of rotor supported on the dampers can be effectively restrained,and the rotor can steadily run if floating-ring mass is appropriate.The results of numerical integral were validated with the experiments of the rotor supported on dampers.
Flow field numerical simulation method and experimentation validation of air cooling turbine stage
WEI Gang, WANG Song-tao, ZHOU Shan, ZHOU Xun, WANG Zhong-qi
2012, 27(3): 651-656.
Abstract PDF(900KB) icon1529 icon463
Abstract:
Using tree order precision Godunoc format with total variation diminishing (TVD) property,free-form surface grid generation technology and divided area grid algorithm,the three-dimensional(3-D)Navier-Stokers (N-S) equations considering cooled air mixing about one type turbine stage were resolved,and the numerical results were comparatively analyzed with the test ones.Through the analysis of the numerical simulation results,the aerodynamic characteristics of the turbine stage were investigated.The results show:the rapid efficient grid generation method considering cooled air mixing and the arbitrary division flow field algorithm can meet the engineering application on the overall performance rapid calculation and flow structure’s detailed description of air cooling turbine stage.
Effect of forward swept blade on rotor stability under inlet circumferential total pressure distortion
SHI Ya-feng, WU Hu, HUANG Jian, YANG Jin-guang
2012, 27(3): 657-665.
Abstract PDF(1935KB) icon1624 icon555
Abstract:
A forward swept rotor was produced on the basis of transonic compressor NASA rotor 11 original geometry.The steady flow fields of this forward swept rotor and rotor 11 have been numerically simulated under design rotation speed,which shows that the performance of forward swept rotor especially the stall margin has been improved.The unsteady simulation of the flow fields of forward swept rotor and rotor 11 indicates that the inlet circumferential total pressure distortion has caused the deterioration of performance.However the forward swept rotor has lower mass flow near stall point compared with the original rotor 11 under the inlet circumferential pressure distortion,because the flow field near the blade tip region benefits from the forward swept rotor.
Investigation of tonal noise in high pressure turbine stage due to non-uniform inlet entropy of inflow
MU Zhong-qiang, QIAO Wei-yang, ZHAO Lei
2012, 27(3): 666-673.
Abstract PDF(1356KB) icon1590 icon432
Abstract:
Through using the flow solver which activated phase-lag method,got the three-dimensional(3-D) unsteady flow field in a high pressure turbine stage which had hot spots in inlet,and then by using the mode matching method in the duct of downstream rotor,the rotor-stator interaction discrete noise which propagated downstream was obtained.After compared with the case without hot spots in turbine inlet,the results show that the total acoustic power level of rotor-stator interaction discrete noise emitted in the downstream direction is increased by 5.9dB at the blade-passing frequency and by remarkably 11.6dB at the first harmonic of the blade-passing frequency.
Analysis of three-dimensional blading influence on highly loaded transonic fan stator
XU Peng-fei, LIU Bao-jie, ZHAO Bin
2012, 27(3): 674-681.
Abstract PDF(2159KB) icon1461 icon447
Abstract:
Under the background of highly loaded transonic inlet fan stage,which produces loading coefficient of 0.42,three-dimensional(3-D) blading influence on transonic stator aerodynamic performance was analyzed as well as its mechanism with numerical simulation technology.The result indicates that the forward sweep is not effective to control the corner separation conducted by shock/endwall boundary layer interaction because of the trend that the shock always tends to remain perpendicular to the endwall.Positive bow modifies the stator performance obviously through adding the blade force to migrate the low-speed corner fluid toward to mid-span.Sweep/bow composition improves the stator performance further,illustrating that the benefit from pure forward sweep is limited and forward sweep can attain optimum effect when combining the positive bow.
Axial compressor performance calculation at off-design conditions
HU Jiang-feng, ZHU Xiao-cheng, OU YANG Hua, QIANG Xiao-qing, DU Zhao-hui
2012, 27(3): 682-688.
Abstract PDF(793KB) icon1765 icon453
Abstract:
The axial compressor performance prediction method was developed,based on streamline curvature method,according to the flow mechanics of transonic axial compressor.This method considered the series impacts of deviation and loss to a certain extent according to the national and international openning research progresses.The internal flow field of NASA(National Aeronautics and Space Administration) TP1659 was calculated,thus obtained the span-wise aerodynamic parameters and characteristic curves at design and off-design points.With the comparison between simulation and experimental value,this method and models are validated to be applicable,and can be used for compressor design and optimization.
Effect of annular chamber radial width on the performance and inner flow characteristics of an after-burning oil pump
XUE Mei-xin, WU Di, PIAO Ying
2012, 27(3): 689-694.
Abstract PDF(884KB) icon1790 icon469
Abstract:
A series of unsteady numerical simulations was conducted for an after-burning oil pump and the effect of annular chamber radial width on the pump performance and inner flow characteristics was investigated.Decrease of the radial width can increase the pump head under different flow-rates and the head increase under small flow-rate condition is larger than that under large flow-rate condition,which improves operation stability under the small flow-rate.Under the large flow-rate condition,annular chamber head loss is reduced by the decrease of circulation flow-rate in annular chamber resulted from the decrease of the annular chamber and following circumferential section area.Accordingly pump head is raised.While,under the small flow-rate condition,decreasing annular chamber radial width makes the incoming flow of the diffuser approach to annular chamber,which reduces the impeller passage head loss.As a result,pump head is enhanced significantly.
Adaptive simulation of gas turbine performance using improved genetic algorithm
LIU Yong-bao, HE Xing, HUANG Shu-hong
2012, 27(3): 695-700.
Abstract PDF(475KB) icon1624 icon490
Abstract:
The precision performance of gas turbine was obtained by synthetically using an improved genetic algorithm and adaptive modeling techniques.Adaptive mechanisms were also added to optimize the crossover and mutation operators,and simulated annealing was also imported.The improved genetic algorithm can approach the optimal solution quickly,and trip out the trap of locally optimal solution.It can insure the solution quality and improve the convergence speed.Considering that previous studies did not take into account the problems that the objective function was impacted by some measuring parameters which had linear correlation and sensor accuracy class,a more maturity adaptive model was established by using the weighted method,and the algorithm was used to search the precision performance.The results show that the improved GA-based performance adaptation method is more robust.
Start-up method of micro turbine engine with closed-loop fuel flowrate control
XU Jian-guo, ZHANG Tian-hong
2012, 27(3): 701-706.
Abstract PDF(679KB) icon1710 icon448
Abstract:
The micro pressure difference method was used to measure fuel flowrate,which has the advantages of low pressure loss,high accuracy and fast response.A new orifice measuring section was designed,and a series of calibration experiments were done with different orifices.The experiments results show that the relation between flowrate and the square root of pressure difference was linear in the flowrate measuring range,which is in accordance with theoretical analysis.On the basis of the measuring method,a single neuron PID (proportion-integration-differentiation)controller was designed and used in the closed-loop control experiments of fuel flowrate.In contrast to open-looped control,this new control method is independent of pump characteristics,power voltage and outlet pressure.It also has good dynamic performance.In the end,the method was used in MTE(micro turbine engine) starting tests,which shows that it improves the quickness and reliability of start-up process dramatically.
Dynamic response capability improvement method for aero-engine temperature sensor
LI Jie, FAN Ding, JI Cang-dun, BU Zhen-peng
2012, 27(3): 707-714.
Abstract PDF(927KB) icon1646 icon621
Abstract:
A problem of engine surge occurred in the process of one aero engine bed test.In order to find out the reason of the engine surge,a mathematical model of the variable stator vanes angle control system of the aero engine high pressure compressor (AHPC) was established,and then joint-simulations were done.Theory analysis and simulation results show that dynamic response delay of a temperature sensor induces the engine surge.Then a dynamic calibration system of this temperature sensor was designed to solve the engine surge problem.The validation simulation results show that the calibration system presented can obviously improve the dynamic response of AHPC’s variable stator vanes,and it can effectively prevent the engine surge without affecting the working of the aero engine.The temperature sensor calibration algorithm presented has a good adaptability and a strong anti-interference capability,and it can provide an important reference to solve the engine surge problem exposed in the aero engine bed test.
Effects of baffle on combustion acoustic characteristics of liquid rocket engine
LI Dan-lin, TIAN Yuan, SUN Ji-guo
2012, 27(3): 715-720.
Abstract PDF(735KB) icon1584 icon467
Abstract:
Cold acoustic tests have been performed to elucidate the effect of baffle on the damping characteristics of the first-tangential acoustic mode in a liquid rocket engine.Different kinds of baffle parameters were researched by acoustic tests.The results agree well with the theory typical example and show that when increasing the axial baffle length and the radial baffle number,the acoustic frequency of the first-tangential acoustic mode decreases and the acoustic damping capacity increases.Injector-forming baffles have some advantages over the typical straight baffles in acoustic damping capability;an optimal acoustic damping capacitance has been achieved in 0.1~0.4mm;axial baffle length can be reduced by using the optimal baffle gap,providing a possible solution of thermal cooling problems.

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