2010 Vol. 25, No. 8

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Effect of lobe numbers on the performance of a lobed mixer in the forced mixing exhaust system
LIU You-hong, FAN Chao, XIE Yi, SHAO Wan-ren
2010, 25(8): 1683-1689.
Abstract PDF(2442KB) icon1678 icon453
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Geometric and numerical simulation models of a forced lobe mixing exhaust system with different lobe numbers were created.Though three-dimensional numerical simulation,the principle of effect of different lobe numbers in a forced mixing exhaust system was obtained.The results show that,non-dimensional average streamwise vorticities increase at the trailing edge of the lobe mixer with the growing number of lobe.At the exit section of the forced mixing exhaust system,thermal mixing efficiency declines as the lobe number increases;and the total-pressure recovery coefficient firstly increases when the lobe number increases from 8 to 16,then declines when it augments from 16 to 20 and finally increases when it rises from 20 to 24.
Numerical study of convective heat transfer characteristics of kerosene flowing in a horizontal pipe at supercritical pressure
LI Xun-feng, ZHONG Feng-quan, FAN Xue-jun, HUAI Xiu-lan, CAI Jun
2010, 25(8): 1690-1697.
Abstract PDF(1361KB) icon1537 icon456
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RNG(renormalization group) k-ε turbulent model combined with Wolfstein one-equation model in the vicinity of the wall was used to calculate the convective heat transfer properties of Daqing RP-3 aviation kerosene in a horizontal pipe at a supercritical pressure.A significant secondary flow was generated by the buoyancy effect due to the dramatic changes of the thermophysical properties of the kerosene near the pseudo-critical point.The secondary flow enhanced the turbulence intensity and convective heat transfer on the bottom of the pipe,and reduced the turbulence intensity and heat transfer on the top.Finally,the applicability of two criteria,used for the buoyancy effect on the convective heat transfer of horizontal pipes,was analyzed and compared at the supercritical conditions.
Experiment of the effects of geometrical parameters on internalheat transfer in an impinging contraction channel with liquid crystal transient technique
ZHOU Lei-sheng, ZHU Hui-ren, ZHANG Xia, LI Chun-lin
2010, 25(8): 1698-1704.
Abstract PDF(956KB) icon1691 icon452
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An impinging heat transfer experiment in a contraction channel,obtained by simplifying and magnifying the strut in the inlet of a gas turbine engine,was carried out by adopting narrow-band thermochromic liquid crystal(TLC) transient measurement technique.The effects of the diameter of impingement hole,impingent distance and the height of the channel on Nusselt number distribution and quantities were studied.The results show that the heat transfer in the channel was enhanced with the increasing diameter of the impingent holes and the height of the channel,or the decreasing impingent distance.Meanwhile the distribution change of Nusselt number and the increase of mean Nusselt number on the sidewall and the leading edge are different.In addition,the primary dominating factor for the heat transfer in the channel is the diameter of the impinging holes,and the slightest factor is the height of the channel.
Numerical simulation of fluid-solid-thermal interaction in hypersonic flows
LI Peng-fei, WU Song-ping
2010, 25(8): 1705-1710.
Abstract PDF(864KB) icon2209 icon499
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The unsteady fully Navier-Stokes(N-S) equations were solved by Harten-Yee's TVD(total variation diminishing) and dual time march for the flow field.The 3-D unsteady heat conduction equation was solved for the structure.The coupling was processed as follows: the flow field acquired temperature's boundary condition from the structure and the temperature field of the structure acquired heat flux's boundary condition from flow at the fluid-solid interface.The method proposed here was validated by aerodynamically infinite column.The transformation of head of space shuttle's temperature was analyzed in detail during pneumatic heating process.The results show that the increase of wall temperature strongly affects heat flux.Therefore,solid-fluid coupled iteration is very necessary in the simulation since the influence of the increase of wall temperature can be considered.
Experimental analysis of operating characteristics of a miniature capillary pumped loop
BAI Li-zhan, LIN Gui-ping
2010, 25(8): 1711-1716.
Abstract PDF(889KB) icon1778 icon515
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Miniaturization of capillary pumped loop(CPL) is a developing trend in order to meet the requirement of heat dissipation of miniature high power-density electronic instruments.In this paper,a miniature CPL was experimentally investigated,with focus on the effect of attitudes on the operating characteristics of CPL in gravity and the thermal control characteristics at high heat flux.Based on the experimental results,the following conclusions can be drawn: the CPL can achieve successful startup at different attitudes,and present good thermal control performance during power step-increase tests.The CPL has a maximum heat transport capacity larger than 50W and a maximum heat flux higher than 12.5W/cm2,which can satisfy the requirement of heat dissipation of miniature high power-density electronic instruments.When the heat flux is low,the CPL can realize precise thermal control;however,when the heat flux is relatively high,the evaporator wall temperature fluctuates intensively,making it impossible to realize precise thermal control.
Three-dimensional numerical simulation of continuous rotating detonation engine flowfields
SHAO Ye-tao, WANG Jian-ping, TANG Xin-meng, SHI Tian-yi
2010, 25(8): 1717-1722.
Abstract PDF(761KB) icon1910 icon475
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A three-dimensional numerical simulation of continuous rotating detonation engine(CRDE),which is particularly designed as a coaxial cylinders combustor,was carried out to reveal its physical nature.Numerical results of CRDE's multi-time cycle propagation process agree well with previous experiment qualitatively.Some key problems about CRDE,such as fuel injection,pre-combustion and detonation structure,were also discussed.At last,a propulsion performance analysis about CRDE was made based on a serial of simulation cases.Specific impulses of five different cases about 2200s were given by the present calculation based on the fuel.The mass flux increases linearly with the increase of injection pressure.
Study on fuel spray characteristics of gasoline direct injection reciprocating engine
LI Bo, LI Yun-qing, WANG De-fu
2010, 25(8): 1723-1727.
Abstract PDF(1028KB) icon1765 icon464
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In order to reveal the influences of high pressure fuel injection system on the performance including fuel consumption and exhaust emissions of gasoline direct injection(GDI) engines,the spray characteristics of high pressure swirl type of GDI injector were investigated experimentally and numerically.The experimental analyses had been carried out that the fuel injection into a constant volume chamber within different ambient pressures was visualized by high speed complementary metal oxide semiconductor(CMOS) camera.The spray development,spray penetration,spray cone angle,spray tip velocity and droplet characteristics were measured at various injection pressure,ambient back pressure and at different injection durations.Experimental results show that under the low back pressure ambient conditions,the spray comes out a hollow cone with wide spray angle and initial spray slug at the tip which meet the mixing control concept of homogenous mixture preparation,while the spray exhibits a solid compact cone under high back pressure which satisfy the stratified mixture preparation concept.An obtained empirical equation for spray penetration is validated by experimental results.Vortexes in the opposite direction exist in the rear part of the spray under low back-pressure ambient conditions while the vortexes form in the middle part under high ambient pressure ambient conditions.
Study on the flow of the kerosene in micro tube
LI Zhong-zhou, ZHU Hui-ren, ZHANG Xia
2010, 25(8): 1728-1732.
Abstract PDF(579KB) icon1766 icon459
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Experiments were made to investigate the flow pressure drop and the friction coefficient of the kerosene(RP-3) in micro tube.The result shows that the friction coefficient decreases with the increasing Reynolds number,and the friction coefficient in micro tube is smaller than in traditional channels;the critical Reynolds number of flow from laminar to turbulent in the small tube is much smaller than 2300 in conventional ducts.In addition,the pressure drop increases with the increase of Reynolds number;under the same Reynolds number and same tube length,the bigger tube inner diameter means the smaller pressure drop between the inlet and outlet;the smaller tube inner diameter means the bigger pressure drop between the inlet and outlet.
Experimental investigations of deflagration to detonation transition in toroidal section tube
YU Jun-li, QIN Ya-xin, GAO Ge
2010, 25(8): 1733-1737.
Abstract PDF(722KB) icon1683 icon461
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In order to implement ignition at the same time at closed end of toroidal detonation tube,a way of ignition at a point and several branches of the same length was used.The results show that detonation wave can be formed immediately through shock produced by converging flame at the closed end of tube.With obstacles,the velocity of detonation will be decreased due to flow drag.Without obstacles,the velocity of detonation is close to the theory value.At about equivalence ratio 1.0,the flame velocity without obstacles may generate deflagration or detonation at random.And this random state can be avoided at equivalence ratio 1.1.
Influence of geometric parameters on film cooling effectiveness under adverse pressure gradient
FAN Yi-long, ZHU Hui-ren, LI Yong-hong, LI Guang-chao, FAN Hui-ming
2010, 25(8): 1738-1745.
Abstract PDF(1413KB) icon1496 icon444
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To study film cooling effectiveness of cylindrical hole,fanned hole and bidirectional expanded hole,as well as influences of hole pitches,plane angles and radial angles on film cooling effectiveness,experiments were performed in a low speed closed-looped wind tunnel with scale-up model.The experimental results show that,the film cooling effectiveness of fanned hole is maximum,followed by that of bidirectional expended hole and cylindrical hole.The decrease of hole pitches leads to the increase of film cooling effectiveness,and the smaller the momentum ratio means stronger influence of hole pitch on film cooling effectiveness.The decreasing plane angles lead to the increased film cooling effectiveness.The influence of plane angles on film cooling effectiveness increases with the increasing momentum ratios.Influence of radial angles is complex;when they are less than 30° and are increasing,the decreasing film cooling effectiveness results from the increased momentum ratios;when they are more than 30°,the decreasing film cooling effectiveness results from the increasing radial angles.
Numerical simulation of flow and heat transfer in the co-rotating cavity with de-swirl inflow
CHEN Yang-chun, WANG Suo-fang
2010, 25(8): 1746-1752.
Abstract PDF(1570KB) icon1909 icon521
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In order to investigate the flow and heat transfer performances in the co-rotating cavity with two inner shrouds and de-swirl inflow holes in its left disc,a numerical study was conducted.The effects of de-swirl angle,rotational Reynolds number and non-dimensional flow velocities on the flow and heat transfer characteristics in the co-rotating cavity were numerically simulated.The results show that the total pressure drop in the cavity exhibits an "S-curve" variation with the increase of non-dimensional mass flow coefficient.The heat transfer of the disc surface is enhanced with the increase of rotational Reynolds number and non-dimensional mass flow coefficient.The de-swirl inflow in the co-rotating cavity has better cooling efficiency than the pre-swirl inflow in the rotor-stator cavity.
Experimental investigation on seal characteristics of straight-through labyrinth
ZHANG Xia, ZHANG Xiao-wei, ZHU Hui-ren, WANG Zhen-wei
2010, 25(8): 1753-1757.
Abstract PDF(796KB) icon1836 icon429
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The leakage characteristics of the real-size labyrinth were investigated experimentally.The influences of geometric parameter and rotational speed were analyzed.The results show that:(1) in the experimental range,leakage coefficient increases with increasing Reynolds number.(2) Leakage coefficient decreases with increasing labyrinth number.(3) Leakage coefficient decreases with increasing clearance under the same Reynolds number.(4) Rotational speed has little effect on the leakage coefficient under small clearance(s=0.4,0.5 mm);when clearance is 0.6mm,rotational speed has definite effect on the leakage coefficient,i.e.2000r/min.
Experimental investigation on discharge coefficient of film holes in a longitudinal ripple insulated liner
WANG Yin-hui, CHANG Hai-ping, WANG Yu-mei
2010, 25(8): 1758-1762.
Abstract PDF(830KB) icon1896 icon459
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For a longitudinal ripple insulated liner with discrete film holes in high-powered aircraft engine,the discharge coefficients of the film holes in different positions of the ripple liner were investigated.The discharge coefficients of coolant injection were obtained in a region of Reynolds number Rec=24×104～33×104,and blowing ratio S=0.02～0.07.The results show:(1)The discharge coefficients differ greatly at various hole array positions.(2) For the hole with a low length-to-diameter ratio(L/D≈0.17) in the same position,the momentum ratio of the hole to secondary fluid has an important influence on the discharge coefficients Cd,especially in the case of small momentum ratio,while the Reynolds number of film hole and secondary flow has little influence on the discharge coefficients Cd.
Two effective methods for flow-field performance forecast
WANG Bao-guo, WU Jun-hong, LIU Shu-yan, QIAN Geng, LIU Yan-ming
2010, 25(8): 1763-1767.
Abstract PDF(2141KB) icon1623 icon447
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Based on database established by multi-factor and multi-level design methods,two effective methods of flow-field performance forecast were proposed.One is response surface method,and the other is wavelet neural networks method.The typical examples indicate that two methods can forecast flow-field performance effectively.The results also show that wavelet neural networks method is superior to response surface method in terms of efficiency and precision.
Numerical analysis of multi-mode mixed disturbance wave in a supersonic plane shear layer
GUAN Fa-ming, SHEN Qing, WANG Qiang
2010, 25(8): 1768-1775.
Abstract PDF(1643KB) icon1663 icon409
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Disturbance modes and flow structures were numerically analyzed for a two-dimensional spatial evolving supersonic plane free shear layer at Mac = 1.2.The disturbance modes and the disturbances parameters of streamwise stations were analyzed with linear stability theory(LST) method and disturbance form direct numerical simulation(DNS) method.The disturbance wave evolving of specially designed disturbance frequency was simulated with disturbance form DNS method.It is found that the multi-mode disturbance without phase difference is produced by the specially designed disturbance frequency in the shear layer.
Numerical method for modelling missile turbojet engine windmill start process
YANG Xin-yi, SHEN Wei, LIU Hai-feng, DONG Ke-hai
2010, 25(8): 1776-1782.
Abstract PDF(838KB) icon1708 icon448
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The windmill start process of a missile turbojet engine was simulated and also modeled before ignition using radial basis function networks(RBFN).Under the condition of few sample data,some experiential relations were introduced to reduce the input variable numbers.Compressor characteristic maps were generated with moving least square based on experimental data.Start process after ignition was modeled and the model was solved by particle swarm optimization(PSO) algorithm.PSO can avoid the problem of divergence for nonlinear equations caused by Newton-Raphson(N-R) method when the initial condition is far from real solution.Calculated results show a great agreement with the test data.The presented method provides some reference for the performance analysis and optimization of turbo engine windmill start process.
Research of sidewall effect on binary external-compression inlet flow field
YAN Hong-ming, ZHONG Jing-jun, HAN Ji-ang, FENG Zi-ming
2010, 25(8): 1783-1790.
Abstract PDF(1286KB) icon1617 icon427
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This article mainly researched the influence of sidewall on binary external-compression inlet flow field.The three-dimensional flow fields of two inlet cases,with/without sidewall,were studied with the commercial CFD（computational fluid dynamics） software FLUENT.The performances of the case without sidewall were much worse than the case with sidewall on a comparative basis.Therefore,the performances of the inlet with sidewall between Mach number 2.0～3.0 were studied.As compared with the inlet's two-dimensional flow fields' performances,the three-dimensional flow fields' performances declined once the compressed air passed the sidewall and leaked out.After the analysis of the leakage flow under different Mach numbers,the influence law of leakage from sidewall was induced.
Momentum characteristic of dielectric barrier discharge plasma aerodynamic actuation
ZHAO Xiao-hu, LI Ying-hong, LI Yi-wen, YUE Tai-peng, WANG Xue-de
2010, 25(8): 1791-1798.
Abstract PDF(1762KB) icon1883 icon453
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Momentum characteristic of dielectric barrier discharge plasma actuation was studied from induced airflow velocity and body force.The former one under different actuation parameters was measured and analyzed,and the latter one was compared by the measured and calculated values to consider the variable regular and key factors for body force.Results show that the reference velocity can be enhanced by plasma actuation,but the acceleration effect is weakened with the rise of incoming velocity;the body force values increase linearly with the rise of actuation voltage or frequency,but increase more with the former one;increasing low-layer electrode width can enhance body force better than inner electrode distance.
Influence of height on the starting performance of RBCC engine supersonic sidewall-compression inlet
LIU Xiao-wei, HE Guo-qiang, LIU Pei-jin
2010, 25(8): 1799-1804.
Abstract PDF(1593KB) icon1837 icon478
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The starting performances of two typical supersonic sidewall-compression inlets were investigated from Mach number 1.5 to 5.0 by means of numerical simulation.The influence of height on performance was studied.The investigation shows that the flow features of inlets with different heights differ a lot during the starting process.For a proper height,the inlet performance prior to startup is improved significantly,oscillations of performance parameters become weaker,and the self-starting Mach number is smaller(a minimum value exists).In such case,the inlet with this height has a better starting performance,and can operate well when the incoming Mach number is less than self-starting Mach number.
Research on rotor blade hinge moment of a small-scale coaxial helicopter
XU Guan-feng, CHEN Ming
2010, 25(8): 1805-1810.
Abstract PDF(666KB) icon2058 icon501
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Based on the engineering reality,a calculation model of the rotor blades hinge moment about coaxial helicopter was set up.An airfoil unsteady aerodynamic model was established by introducing a set of Leishman-Beddoes semi-empirical indicial response formula.The induced velocity model of the aerodynamic interaction between upper and lower rotors of a coaxial helicopter was created by introducing an interferential factor into the Pitt-Peters dynamic inflow model;the Runge-Kutta method was used to obtain the numerical solution of the rigid blade flapping angle,and a modal superposition method used to calculate the distortion of the flapping direction.According to analysis of the coaxial helicopter,the total hinge moment is basically the same,although the partial hinge moments of upper and lower rotors are different.In medium and high speed,the hinge moments of upper and lower rotors are accumulated at the lower swashplate to form a moment making the lower swashplate lean forward.
Numerical simulation on thrust reverser based on secondary flow for high-bypass-ratio turbofan engine
LIU Chun-yang, WANG Zhan-xue, FU Peng-zhe
2010, 25(8): 1811-1817.
Abstract PDF(1406KB) icon2330 icon386
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The study for thrust reverser based on secondary flow injection was carried out with the method of CFD(computational fluid dynamics).The two-dimensional flow field of thrust reversers with secondary flow injection was numerically simulated to study the effect of location of secondary injection,angle of secondary injection,total pressure ratio of secondary injection and total fan nozzle pressure ratio on the performance of the thrust reverser.The important parameter is cascade flow ratio,which is in direct proportion to reverse thrust.The results show that the configuration of flow field presented in this thesis is similar to the referenced flow field.Location and angle of injection with optimum values are important factors while the total pressure ratio of injection has a fitting value.Due to the limitation of secondary mass flow,the injection depth is finite,so the new reverse thrust concept can not be adopted by super high-bypass-ratio turbofan engines.
Investigation of two-dimensional supersonic twin inlet with slot-coupled cavity in 90° configuration at venter
MA Xiao-fei, XIE Lü-rong, GUO Rong-wei
2010, 25(8): 1818-1824.
Abstract PDF(870KB) icon1800 icon476
Abstract:
A two-dimensional mixed-compression inlet model with slot-coupled cavity in 90° configuration at venter was investigated by wind tunnel at Mach number from 2.0 to 3.5.The range of the investigation covers angle of attack from-4° to 10° and angle of yaw from 0 to 4°.The performances,including critical pressure,total pressure recovery coefficient and mass flow ratio,were acquired.The results indicate that:with increase of the free stream Mach number or the angle of attack at Ma=3.0,the mass flow ratio increases firstly and then declines a little due to the increase of the total pressure loss around the body nose;and the maximum is obtained at design point.The flow field of two inlets is different at yaw,and the work range is determined by the windward inlet.Besides,the distribution of static-pressure coefficient along the duct validates that a terminal shock can stay around the cavity,so inlets with the slot-coupled cavity can work under wider back pressure.
Numerical simulation of unsteady flow in a vaneless counter-rotating turbine
QI Lei, PAN Shang-neng, LI Wei, ZOU Zheng-ping, LIU Huo-xing, ZHOU Yang
2010, 25(8): 1825-1835.
Abstract PDF(3017KB) icon1796 icon396
Abstract:
In order to investigate the complex flow field in counter-rotating turbine and improve effectively the gas turbine design.A numerical study of unsteady flow in a vaneless counter-rotating turbine was presented in this paper.The steady and unsteady results were contrastively analyzed.It's found that the unsteady effect can decrease the specific work ratio appreciably,and increase the loss by about 0.44% efficiency points.However,the mass flow remains unchanged.The results show that the unsteady interactions from the wake,shockwave,potential field and the tip leakage flow have made great contributions to the unsteady effect.
Effects of local boundary layer suction on aerodynamic performance of highly-loaded compressor cascades
CHEN Shao-wen, GUO Shuang, CHEN Fu, WANG Zhong-qi
2010, 25(8): 1836-1841.
Abstract PDF(1038KB) icon2131 icon423
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The detailed experimental investigations were carried out to analyze the effects of local boundary layer suction on aerodynamic performance of highly-loaded compressor cascade in low-speed condition.The exit aerodynamic parameters were measured by five-hole aerodynamic probe,and the distribution of the profile static pressure on the blade surface was obtained.The effects of local suction type,suction location and suction flow rate on the exit total pressure losses and load capacity of cascades were analyzed in detail.The results show that the effective low-energy fluid removal through side suction and middle suction on suction surface can increase the cascade load capacity,and effectively improve the cascade aerodynamic performance.The influence of the side suction on suction effectiveness is better than that of the middle suction.The cascade aerodynamic performance is obviously improved in the region of middle blade,but the improvement of the cascade aerodynamic performance is not clear near the end wall region.
Influence of rotor blade fillets on turbine stage performance
SHI Yan, LI Shao-jun, LI Jun, FENG Zhen-ping
2010, 25(8): 1842-1848.
Abstract PDF(1121KB) icon1779 icon466
Abstract:
The rotor blade in the first stage of Aachen turbine was added with a fillet structure,and a full three-dimensional viscous numerical simulation was performed to analyze the influence of rotor fillet on the performance of turbine stage and flow fields under the stage environment.The results indicate that the efficiency decreases significantly when the angle between fillet and end wall becomes too small,which should raise more attention in the manufacturing process of rotor blade.The fillet structure decreases the transverse pressure difference near the rotor hub and shroud,and shifts the aerodynamic load to the latter half part of the rotor blade.The fillets at hub and shroud affect the flow field of the rotor mainly at the 0%～55% span and the 70%～100% span,respectively.The upper and lower passage vortexes are close to the midspan of rotor due to the influence of the fillet,leading to increase of the intensity of corner vortex and the loss of second flow near the endwall.
Self-adaptive center-mutation differential evolution and its application to shape optimization design of a turbine blade
CHI Yuan-cheng, FANG Jie, RAO Da-lin, CAI Guo-biao
2010, 25(8): 1849-1854.
Abstract PDF(724KB) icon1526 icon431
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A self-adaptive center-mutation differential evolution(SCDE) was developed for the high-dimension complex optimization problems,and applied to the high fidelity aerodynamic optimization design of the multi-stage oxidizer turbine blade shapes for cryogenic rocket engines.Performances of design candidates were evaluated by the turbine efficiency based on three-dimensional airfoil geometry design and single-channel flow analysis using commercially available CAD(computer aided design) and CFD(computational fluid dynamics) packages.The reasonable solution is finally achieved,namely,turbine efficiency of the optimal design is 5.25% higher than that of the original one.
Reliability assessment and life prediction for very few failure data
FU Hui-min, YUE Xiao-rui, ZHANG Yong-bo
2010, 25(8): 1855-1859.
Abstract PDF(352KB) icon1693 icon449
Abstract:
Aiming at the very few failure data which was usually found in life test of high reliability product,a method of reliability assessment and life prediction was put forward.The one-side lower confidence limits of the service life and reliability were derived under the condition of knowing the lower limit of shape parameter of Weibull distribution.It has the merit of that all the failure data and suspension data can be accumulated.Furthermore,the convert formula of the data among different states was established by the principle of damage equivalence.Thus,the data among different states can be analyzed together and the prediction precision is improved.The presented method is a practical approach with simple calculation and convenient application.
Review of aero-engine case containment research
XUAN Hai-jun, LU Xiao, HONG Wei-rong, LIAO Lian-fang
2010, 25(8): 1860-1870.
Abstract PDF(1650KB) icon2093 icon691
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Development status and trends of aero-engine containment case were reviewed in respect of the containment capability definition,case material,design concept and method,validity testing,numerical simulation,failure and deformation patterns of case and released blade.Requirements of lightweight fan case with high containment capability for the development of high bypass pressure ratio turbofan engine have been illustrated.Therefore,different structure designs of fan case of in-service and developing aero-engine for large airplane were presented,and researches on containment capability of fiber reinforced composite fan case were reviewed.The development directions of containment case for Chinese high thrust/weight engine and low-pollution civilian engine were proposed,respectively,with regard to structure improvement,low-cost manufacturing technology for composite fan case,winding pattern of full composite case,high temperature composite case,multi-disciplinary simulation of engine blade out event and smart containment case.
Fatigue life prediction model for nickel-based single crystal and directionally solidified superalloy
SHI Duo-qi, YANG Xiao-guang, YU Hui-chen
2010, 25(8): 1871-1875.
Abstract PDF(1628KB) icon2028 icon500
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A lifing model was developed to predict the high temperature,low-cycle fatigue-creep(HTLCF-C) life behavior of nickel-based single crystal(SC) and directionally solidified(DS) superalloy.By modifying total strain range with a crystal orientation-dependent function,the mean and maximum stress and its range during a fatigue cycle,as well as dwell time at peak stress or strain level were incorporated into the lifing model using the idea of cyclic damage accumulation(CDA).The model was validated by correlating the fatigue data of DZ125,DD3 and DD6 superalloy under different temperatures,crystal orientations and holding times.Good agreements between predicted and experimental lives were yielded in these two factors for both DS and SC superalloy.The results show that the approach has better adaptability to model the anisotropic and HTLCF-C life behavior of turbine blade materials.
Structural optimization of turbine tenon/mortise
YANG Min-chao, SUN Su-ya
2010, 25(8): 1876-1882.
Abstract PDF(1054KB) icon1613 icon462
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An integrated optimization design system for turbine tenon/mortise has been set up.In this system,contact clearance was used for parametric modeling of turbine tenon/mortise.Nonlinear contact method was used for analysis of finite element by the strong commercial software of ANSYS which could get objective and other stresses by secondary development of language.Meanwhile,multi-island genetic algorithm and sequential quadratic programming were used for optimization in specified space.As a result,the maximal first principal stress and von mises stress decreased obviously under the condition of meeting the geometry and strength requirements.The system exhibits higher stability,feasibility and efficiency for engineering applications.
Experimental study on the relationship between bearing preload and system natural frequency
DENG Si-er, WANG Yan-shuang, LI Xin-ning
2010, 25(8): 1883-1887.
Abstract PDF(599KB) icon2101 icon445
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A special-purpose testing device for bearing preload was developed.The relationship between preload and system natural frequency was researched on this test rig.The test data of bearing preload versus system natural frequency were analyzed.The results show that the preload test rig can reflect the bearing's preload characteristic to a certain extent.The system natural frequency increases with the rising bearing preload.At the same bearing preload,the system natural frequency increases with the increase of bearing's supporting span.The precision of the fitted relationship of preload-natural frequency-bearing span is higher.
Half-modified roll for the optimization of transmission error function of spiral bevel gears
LIU Guang-lei, FAN Hong-wei, GU Ji-hong, JIANG Ping
2010, 25(8): 1888-1893.
Abstract PDF(4866KB) icon1840 icon408
Abstract:
A half-modified roll(HMR) method for the optimization of transmission error function of spiral bevel gears was proposed.Based on local synthesis,the pinion machine-tool settings were firstly obtained,then tooth contact analysis(TCA) was carried out and a contrast was made between the predesigned transmission error function with that of TCA.In order to narrow the differences between these two transmission error functions,the cutting ratio and the third-order modified-roll coefficient were slightly adjusted.By applying HMR to optimize the transmission error function of a pair of spiral bevel gears in aviation,the researches find that the cutting ratio of the pinion has some influence on the magnitude of transmission error function,and the third-order modified-roll coefficient has influences on the whole deflection of transmission error function.The optimized transmission error function agrees very well with the predesigned curve,and the contact pattern meets the design requirement,so the validity of HMR is proved.
Dynamic efficiency investigation of the transmission of tilt-rotor
GUO Jia-shun, WANG San-min, YUAN Ru
2010, 25(8): 1894-1899.
Abstract PDF(954KB) icon1814 icon450
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Based on the transmission structure in the nacelle of tilt-rotor,a lateral-torsional coupling dynamic model and corresponding dynamic equations were built.The dynamic responses in the three flight types were obtained by solving the dynamic equations,then,the gear tooth dynamic loads and the lateral dynamic loads of each component were calculated.Based on the dynamic loads,this paper proposed a method of calculating tooth face dynamic friction wasted powers and bearing dynamic wasted powers,and the dynamic efficiency of the transmission.The dynamic efficiency of the transmission in the three flight types were calculated,and the transmission parameters on the impact of dynamic efficiency in the three flight types were analyzed,laying a foundation for design of highly efficient transmission of tilt-rotor.
Flow modeling of oil film on bearing chamber wall at high-speed
LIU Ya-jun, CHEN Guo-ding, WANG Jun
2010, 25(8): 1900-1905.
Abstract PDF(2108KB) icon1956 icon503
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The analysis model of oil film movement on the bearing chamber wall was proposed based on the experimental work abroad,and the impact analysis of some operation conditions was carried out.The results show that the flow of oil film presents cumulative characteristics in bearing chamber,the film thickness increase between two exports;the increase in speed reduces the film thickness,but it increases the mean velocity of oil film;with the increase of the intake volume flow,the thickness and mean velocity of oil film increases.Theoretical analysis and comparison with the experimental work show that,the proposed method of predicting physical movement of oil film based on the experiment in bearing chamber,is a valuable technical means for the study of movement mechanism of oil film in bearing chamber wall under limited experimental conditions,and for the thermal analysis and lubrication analysis of bearing chamber.
Path planning for maneuver of the satellite based on a multi-objective evolutionary algorithm
SHEN Xiao-ning, ZHOU Duan, GUO Yu, CHEN Qing-wei, HU Wei-li
2010, 25(8): 1906-1912.
Abstract PDF(785KB) icon1622 icon449
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The multi-objective optimization model for the attitude control of the flexible satellite was constructed,and a multi-objective optimization elitist evolutionary algorithm was applied to the path planning for large angle maneuver of flexible satellite,in order to further improve the performance of the attitude control system.Simulation results indicate that the proposed approach could find a diverse set of non-dominated path solutions efficiently in one run,whereby the decision maker can make a choice in the case of different working requirements.Meanwhile,the conflicts among criterions of rapidity,stability degree of the attitude and low vibration of solar panel caused by maneuver of the satellite can be alleviated.
Adaptive model of aero-engines based on error-feedback control
WANG Qian-yu, SUN Jian-guo, LI Qiu-hong
2010, 25(8): 1913-1917.
Abstract PDF(2115KB) icon1749 icon492
Abstract:
A method was presented based on error-feedback control to establish an adaptive model.This method took the real aero-engine's measurable outputs as the reference command,and the deterioration level as the control variables.Then an augmented linear quadratic regulator(ALQR) controller was designed to make the model's outputs adaptively and precisely track the real engine's outputs.Because of the robustness of the controller,the model has good adaptive performance.The controller and the engine model form the adaptive model.The simulation indicates that this method achieves very good performance.
Investigation on dynamic characteristic of recessed region of a gas-liquid coaxial injector with homogeneous flow model
FU Qing-fei, YANG Li-jun, QU Yuan-yuan, GU Bin, WANG Feng
2010, 25(8): 1918-1922.
Abstract PDF(790KB) icon1875 icon450
Abstract:
The dynamic characteristic of gas-liquid two phase flow in the recessed region of a gas-liquid coaxial injector was investigated with the frequency method.Considering the liquid-phase as a lumped-element,the dynamic response of the pressure drop fluctuation in the recessed region to the liquid flow fluctuation was analyzed with the homogeneous flow model.The dynamic characteristics of the injector models were calculated.The calculation results show that,the amplitude of pressure drop fluctuation and the phase-delay between the pressure drop fluctuation and liquid flow fluctuation will increase with the rising fluctuation frequency.A smaller length to diameter ratio recessed region and liquid injector mass flow,or a higher ambient pressure and larger gas to liquid ratio can depress the pressure drop fluctuation in the recessed region.

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