2010 Vol. 25, No. 10

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Failure mode research on CCF300 and T300 composites under tensile strength
FU Hui-min, YANG Yu-song, ZHANG Yong-bo
2010, 25(10): 2163-2169.
Abstract PDF(1426KB) icon2036 icon529
Abstract:
Five kinds of domestic carbon fiber(CCF) 300 and T300 carbon fiber composites had been tested for tensile property under the condition of 23 ℃ dry,23 ℃ wet,130 ℃ dry and 130 ℃ wet.The failure mode and damage mechanism had been analyzed basing on data,macro character and scanning electron microscope appearance.The result shows that although the tensile property of domestic carbon fiber composites is higher than the T300 carbon fiber composites on the whole,their failure mode is different basically,especially the differences making by the difference of interface property is quit distinct.Therefore,the domestic carbon fiber composites need to improve their interface property to achieve wide application.
Evaluation method on whole engine structural design——structural efficiency
ZHANG Da-yi, MA Yan-hong, LIANG Zhi-chao, HONG Jie
2010, 25(10): 2170-2176.
Abstract PDF(398KB) icon1700 icon502
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An evaluation method named structural efficiency was presented to quantify the benefit of whole engine structures according to the dynamics.The meaning of structural efficiency encompasses engine strength,modal participation and deformation coordination synthetically.Further corresponding elementary numerical method was given.The advantages of structural efficiency on whole engine design were obtained through a rotor/supporting structural optimization case.Besides,the research prospects and research emphases were discussed in detail.
Study on uniaxial tensile strength of unidirectional ceramic matrix composites
LI Long-biao, SONG Ying-dong, SUN Zhi-gang
2010, 25(10): 2177-2187.
Abstract PDF(1212KB) icon2065 icon459
Abstract:
A study on uniaxial tensile strength of the unidirectional ceramic matrix composites was presented in this paper using micromechanical approach.The shear lag model was used to obtain the micro stress field of the damaged composites.The statistical matrix cracking model and fracture mechanics interface debonding criterion were used to determine matrix crack spacing and interface debonding length.After the saturation of matrix cracking,the fiber failure probabilities and fracture locations during tensile loading were determined by fiber statistical failure model based on the assumption that fiber strength is subject to Weibull distribution,and the loads carried by the broken and intact fibers meet the global load shearing criterion.The composites can no longer support the applied load when the total force supported by broken and intact fibers reaches its maximum.The effects of matrix Weibull modulus and characteristic strength,fiber/matrix interface shear stress and interface debonding energy,fiber Weibull modulus and characteristic strength on fiber failure and the tensile strength of ceramic matrix composites were discussed.The predicted results agree well with experimental data,proving the efficiency of the present model.
Investigation and numerical simulation on fretting fatigue of NiTi
HU Dian-yin, WANG Rong-qiao, WANG Xiao-xue, FAN Jiang, SHEN Xiu-li
2010, 25(10): 2188-2194.
Abstract PDF(949KB) icon1774 icon414
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Based on the unique properties of NiTi shape memory alloys(SMA),a new type of dovetail joints was presented in this paper.Finite element analyses(FEA) were performed by using software MSC.Marc to research the fretting fatigue at low cycle fatigue(LCF) and low and high cycle combine fatigue(L-HCCF).Fretting fatigue life was predicted by using nominal stress method,whereby the initiating position of the crack was determined according to fretting fatigue damage(FFD) value.As a consequence,the method of predicting the fretting fatigue life is reasonable and valid,and fretting fatigue-resistance of NiTi-SMA is much better than traditional materials such as TC11.
Civil aero-engine module workscope decision-making
FU Xu-yun, ZHONG Shi-sheng, DING Gang
2010, 25(10): 2195-2200.
Abstract PDF(463KB) icon1788 icon421
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A objective-oriented method for module workscope decision-making was proposed to supply support for the aero-engine module workscope and achieve automatic and intelligent decision-making after analyzing the objectives of aero-engine shop visit.Module workscope was made through two steps from five aspects of life limited parts,airworthiness directive/service bulletin,hardware damage,soft time and exhaust gas temperature margin.To solve the problem of distribution of module performance restoration value in decision-making process,an optimization model based on minimum shop visit cost was put forward and solved by using dynamic programming and heuristic algorithm,respectively.By comparing the results,an applicable environment of the two algorithms was given.Finally,the proposed decision-making method was applied to a prototype system.The test result in an airline shows that the proposed decision-making method is effective and capable of satisfying the requirements of airline companies.
Bayesian sequential testing in reliability growth case
XING Yun-Yan, WU Xiao-Yue
2010, 25(10): 2201-2205.
Abstract PDF(380KB) icon1647 icon428
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For the sequential testing analysis under the reliability growth,a Bayesian sequential testing method in varying population cases was proposed in this paper.The method employed discrete AMSAA(Army Material Systems Analysis Activity) model to describe the growth trend of product reliability and figured out the likelihood function of varying population test data.Furthermore,the Bayesian sequential testing model under the condition of reliability growth was obtained by constructing the posterior probability ratio and decision threshold.The research result shows that the hypothesis testing for reliability index with reliability growth can be solved efficiently by the proposed method.
Numerical simulation of aeroelastic response in compressor rotor blades
XU Ke-ning, WANG Yan-rong
2010, 25(10): 2206-2210.
Abstract PDF(644KB) icon1775 icon424
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A numerical method based on staggered algorithm was used to simulate aeroelastic response in compressor rotor blades.The finite element structural solver was used for structure dynamic analysis,and the unsteady flow solver developed by others was introduced to provide aerodynamic force.The structural solver could transfer the motion of blade to the flow solver,the flow solver advanced the fluid system to obtain new pressure field on blade,and a procedure was used to exchange the interface information between two solvers.Numerical results indicate that staggered algorithm yields transient response of rotor,thus helping to judge whether flutter can occur.
Numerical simulation of bird impact on solid-element hollow blades by using fluid-solid coupling method
LIU Jian-ming, JIANG Xiang-hua, QIN Yin-lei, WANG Yan-rong
2010, 25(10): 2211-2216.
Abstract PDF(1107KB) icon2042 icon486
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In view of the shortages of current fluid-solid coupling arithmetic in simulating the failure of solid-element structures,fluid-solid coupling numerical simulation methods of solid-element flat blade were studied and validated with MSC.Dytran software while considering its integrity and failure.On this basis,in combination with very common and serious bird impact accidents in the working process of high bypass ratio aero-engines,Finite element method(FEM) model of the solid-element hollow blades with transient dynamic load for bird impact was established and the corresponding calculation was performed.Result shows that,huge instantaneous impact stresses will occur in the blades after bird strike,leading to local plastic deformation of the blades.The failure process of the blades after bird strike was simulated finally.
Analytical method for estimating the damping in unidirectional ceramic matrix composites
TANG Bin, SUN Zhi-gang, GAO Xi-guang, SONG Ying-dong
2010, 25(10): 2217-2222.
Abstract PDF(571KB) icon1649 icon452
Abstract:
Based on the stress distribution in the bonded and de-bonded region of ceramic matrix composite(CMC) with matrix cracks,the sliding mechanism of CMC was investigated,and the analytical method for estimating damping capacity in unidirectional CMC was derived.Numerical examples show that:(1) CMCs' inherent damping capacity is very small.The damping of CMC is mostly caused by the frictional energy dissipation along the damaged fiber-matrix interfaces.(2) The damping capacity of CMC will increase with the decreasing interfacial shear stress and the volume fraction of fibers.(3) When the matrix crack spacing increases,the damping coefficient of CMC is decreased.
Load identification of arbitrary positon for composite plates and shells
SONG Zhen, ZHENG Shi-jie
2010, 25(10): 2223-2228.
Abstract PDF(487KB) icon1629 icon454
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A discriminance method was proposed to identify the element with concentrated load,which was judged by the geometrical relationship between the abscissa,vertical coordinates of load point generated from genetic algorithm(GA) and four edges of every element.Furthermore,the load was allocated to nodes of the element by the equivalent distribution principle.Finally,the location of arbitrary concentrated load was identified by finite element analysis and the superior global search capacity of GA.Compared with the identification methods of neural network and inverse finite element analysis method.The presented method is able to identify the concentrated load locating at the interior of a element,and the numerical examples show that this method has higher accuracy.
Numerical simulation research on surface radiation heat calculation of spacecraft in orbit whole course
SUN Bing
2010, 25(10): 2229-2237.
Abstract PDF(730KB) icon1350 icon436
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The surface radiation heat simulation program based on Microsoft VC++ 6.0 for spacecraft in whole orbit course was presented.Due to complexity of spacecraft structure,the spacecraft structures were decomposed to relatively regular parts.Automatic generation of calculation grid was conducted by using structured grid and unstructured technology.Simulation mainly solved automatic grid generation for arbitrary surface and data transmission between arbitrary shape interfaces,and the geometry structure,physical process,calculation accuracy and efficiency were considered.View factors and radiation transfer coefficients were calculated by combining finite element method and ray uniform distribution.According to the position of surface cells,external heat flux was calculated with integral method for non-shaded surface and with ray uniform distribution method for shaded surface.As the spacecraft surface was wrapped with multilayer insulation material,the temperature field of multilayer insulation material was calculated with nodal network method and finite volume method.The temperature of other parts without wrap was calculated with finite element method.The temperature of unconnected regions available with radiation heat transfer relations was analyzed,and the calculation formulae were deduced.Numerical experiment shows that the simulation program is correct and effective.
Numerical investigation on the effect of different anti-vortex hole configurations on film cooling effectiveness
WU Hong, MENG Heng-hui, TAO Zhi, XU Guo-qiang, DING Shui-ting
2010, 25(10): 2238-2243.
Abstract PDF(1088KB) icon1634 icon589
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The flow and heat transfer of the film cooling from the film holes embedded in different space distributions were investigated numerically in several blowing ratios,so as to reveal the effects of span spaces and flow spaces.In the present study,the Reynolds number(Re) based on mainstream velocity and film hole diameter is 4 797,and the blowing ratio(M) alters from 0.2 to 2.0.Results show that:(1)in different span space models,the optimal span space is 1D;(2) better film cooling effectiveness is obtained in the assistant-behind hole model;(3) less influence of the blowing ration occurs in the assistant-behind hole model;and the level of vortex intensity keeps constant under the flow spaces,while the value and direction change sharply.
Experimental investigation of jets turbulence intensity characteristics from rectangular nozzles with different aspect ratios
ZHANG Bo, JI Hong-hu, CAO Guang-zhou, HUANG Wei
2010, 25(10): 2244-2248.
Abstract PDF(690KB) icon1743 icon457
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The distribution of turbulent intensity in the wide and narrow symmetrical planes of the jets from rectangular nozzles was experimentally investigated with hot-wire apparatus.The results show that the turbulent intensity decreases radially,and increases when AR(aspect ratio=W/H,W,nozzle width,H,nozzle height) of nozzle exits is smaller than 8,but decreases slightly when AR is bigger than 8.In the axis line,turbulent intensity increases slowly.The distributions are the same both in wide and narrow symmetrical planes,and the magnitude increases with AR,but decreases as AR is bigger than 8.
Heat transfer investigation of the channels with 90° rib turbulators and double-row bleed holes
GUO Tao, ZHU Hui-ren, XU Du-chun
2010, 25(10): 2249-2254.
Abstract PDF(600KB) icon1794 icon483
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The detailed heat transfer distributions of the wall with bleed holes in a channel with 90° rib turbulators and double-row bleed holes were measured by using transient liquid crystal technique.The effects of the relative positions of rib turbulators and bleed holes,channel Reynolds numbers and bleed ratios on heat transfer characteristics were studied.The results show that:the heat transfer distributions are affected by the combined effect of the flow separation,reattachment and bleeding;the heat transfer characteristics for the bleed holes near the upstream ribs are best because of the heat transfer improvement in backflow region and heat transfer enhancement in reattachment region by bleed effect.For the case of the bleed holes near the downstream ribs,the heat transfer characteristics turn worse since higher heat transfer regions behind the holes are confined by ribs;the change of bleed hole location do not modify the position of the flow reattachment,but affect the heat transfer distribution and intensity in the region;the average heat transfer enhancement decreases with the growing Reynolds number,and slightly increases with the increase of bleed ratio.
Numerical simulation of film cooling effectiveness with one inlet and double outlet hole on leading edge
LI Guang-chao, ZHANG Wei, WANG Cheng-jun, PENG Da-wei, WANG Jian-ming, XU Zhi-hui
2010, 25(10): 2255-2260.
Abstract PDF(923KB) icon1684 icon422
Abstract:
Film cooling effectiveness with one inlet and double outlet hole injection on leading edge was studied by numerical simulation.This hole was of novel concept geometry.Blowing ratios varied from 1.0 to 3.5.Turbulence intensity at the inlet of the tunnel was 30%.The result shows that the distribution of the cooling effectiveness with cylindrical hole injection agrees with the experimental data.The film cooling effectiveness with cylindrical hole decreases with the rising blowing ratios.Film cooling effectiveness is improved by one inlet and double outlet hole injection.The cooling effectiveness increases as the blowing ratios increase from 1.0 to 2.5,but differs little if the blowing ratios are of 2.5 and 3.0.The cooling effectiveness is small at the blowing ratio of 3.5.The spanwise distribution of cooling effectiveness with the double outlet hole is uniform.
Experiment on the breakup of round liquid jets in cross airflows
ZHU Ying, HUANG Yong, WANG Fang, WANG Xiong-hui
2010, 25(10): 2261-2266.
Abstract PDF(696KB) icon1891 icon430
Abstract:
An experiment was conducted to investigate the breakup processes of round liquid jets in cross airflow with a high-speed video camera.The orifice diameter of the nozzle was 0.3 mm and the liquid used in the test was water.The liquid-to-air momentum flux ratio varied from 10.2 to 80.The results indicate that the initial surface waves are sinuous,which will be developed into spiral waves by aerodynamic force.When the spiral waves grow large enough,the liquid column will be either pinched due to surface tension or cut by aerodynamic force,depending on the cross airflow velocity.The amplitude of the spiral wave is increased with the rising cross airflow velocity.The fluctuations of the liquid jets trajectories are larger for higher airflow velocities,and weaker for higher liquid jet velocities.The correlations between the coordinates of the jet breakup locations and the liquid-to-air momentum flux ratio were concluded.The equation of the trajectory like parabola curve was derived for the jet column trajectory before breakup.
Analysis on improvement of film cooling effectiveness with small coolant jets
LIU Xiao-hong, LUO Xiang, TAO Zhi
2010, 25(10): 2267-2272.
Abstract PDF(940KB) icon1631 icon555
Abstract:
The primary focus of this paper is to further understand the flow and heat transfer characteristics of a special film cooling configuration where in the main film cooling hole is accompanied by two smaller jet holes.The adiabatic effectiveness and the interaction between the main hot stream and the coolant jets were simulated and analyzed by comparing with the standard single hole structure at different blowing ratios.It is found that the presence of smaller jets decreases the size and strength of the counter-rotating vortex pair of the main coolant jet and so does its mixing with the main hot stream.The coolant jets remain much closer to the surface.This avoids jets lift-off for the stand single hole structure at high blowing ratio.The surface adiabatic effectiveness value is enhanced as expected.A higher blowing ratio means more obvious improvement of film cooling effectiveness.
Influence of exit flow type on heat transfer of array impingement
WANG Ke-fei, ZHU Hui-ren, LI Zhong-zhou, XU Du-chun
2010, 25(10): 2273-2278.
Abstract PDF(918KB) icon1537 icon442
Abstract:
A transient liquid crystal technique was used to measure the local heat transfer coefficients on a target surface with array impingement hole.The effects of jet Reynolds number(5 000,10 000,15 000,20 000,25 000) and three different exit flow types on the heat transfer coefficients were also investigated.Results show that,the average heat transfer coefficient of target plate with double-sided flow is higher than that with single-sided flow;due to the different strengths of crossflow,the heat transfer coefficients on the target plate are also different.For each exit flow type,the local heat transfer coefficient increases with the jet Reynolds number over entire impingement target plate.
Effects of throat shape design on propulsion performance of micronozzles
LIU Zhao-miao, ZHANG Tan, PANG Yan
2010, 25(10): 2279-2284.
Abstract PDF(1151KB) icon1915 icon445
Abstract:
Characteristics of flow field in Laval micronozzles with 34 μm throat-width were studied numerically by using continuum and direct simulation Monte Carlo(DSMC) method.Three types of micronozzles with different throat shapes were designed,such as:sharp-corner,smooth-corner and flat-corner.Based on the geometric structure design,effects of throat shape and expansion ratio on flow field and propulsion performance were analyzed,respectively.It is discovered from the results that,the comprehensive propulsion performance of the micronozzle with smooth-corner throat is the best,while the micronozzle with flat-corner throat has much better specific impulse efficiency.When the expansion ratio becomes larger,both thrust and specific impulse will increase.
Investigation of thrust balance for the single module scramjet
HE Wei, TONG Ze-run, LI Hong-bin
2010, 25(10): 2285-2289.
Abstract PDF(599KB) icon1632 icon447
Abstract:
A single-component thrust balance using force sensor was investigated and applied to single module scramjet wind tunnel test.When tested in pulse combustion wind tunnel,the oscillation frequency of the balance/model/support system was about 20 Hz,and the signal is steady.The balance can meet the needs of pulse combustion wind tunnel test.Under the same test condition,the results of pulse combustion wind tunnel and long-duration high temperature hypersonic wind tunnel are similar,proving that the balance can be put into application and the results are believable.
Research overview of rain effect on aircraft aerodynamic performance
ZHANG Rui-min, CAO Yi-Hua
2010, 25(10): 2290-2295.
Abstract PDF(406KB) icon2033 icon399
Abstract:
The natural characteristics of rain were studied.The complicated physical phenomena on wing surfaces in rain conditions were analyzed.Emphases were laid on the research progress of experimental tests and numerical simulation of rain effect on aircraft aerodynamic performance at home and abroad.The contents included aerodynamic loss of heavy rain on aircraft wing,the mechanisms of influence of rainfall on aircraft aerodynamic performance and wing sensibility to various influential factors.Some open questions and significant technical challenges in the current research progress at home and abroad involve:natural flight test,scaling laws,the behavior of boundary-layer forced transition in wind tunnel tests and modeling of multi-phases flow in numerical study.
Analysis on bearing capacity and aerodynamic performance of an inflatable wing
WANG Wei, WANG Hua, JIA Qing-ping
2010, 25(10): 2296-2301.
Abstract PDF(1059KB) icon1897 icon458
Abstract:
The approaches of mechanics of both materials and structures were applied to analyze the bearing capacity of an inflatable wing.The criterions of failure were established on the basis of engineering requirements and characteristics of inflatable structure.A mechanical model was presented and proved reasonable by a test.Aerodynamic performance simulation analysis was made for the aerodynamic performance of inflatable wing using FLUENT 6.3,and was compared with the ideal airfoil.Then,the simulated aerodynamic load on the inflatable wing in flying was introduced into Patran,and the stress and deformation was analyzed by infinite element method.
Investigation of aero-engine thrust performance deterioration rules based on fractal theory
YU Jin-lu, HE Li-ming, SUN Dong, LI Tian-liang, SUN Xiao-dong
2010, 25(10): 2302-2306.
Abstract PDF(430KB) icon2142 icon506
Abstract:
Considering the complexity of aero-engine and influential factors,a deterioration model for engine thrust degradation was established with De Wijs fractal theory from the perspective of complex system.Aero-engine thrust deterioration rules was analyzed and investigated based on this model.It's found that the thrust deterioration in full afterburning condition is characterized by aging of organism,and can be modeled by the De Wijs fractal curve with fractal dimension of 0.761 to some extent.
Studies on trims,stability,and controllability of helicopter with slung-load
CUI Li, CAO Yi-hua, LI Guo-zhi
2010, 25(10): 2307-2311.
Abstract PDF(640KB) icon1679 icon459
Abstract:
A rotorcraft with slung-load model was built.Slung-load model with six freedoms was used to simulate the flight process with slung-load.It is assumed that the external slung-load is suspended in a single-point.Trim calculation of the helicopter with slung-load model was conducted and compared with the reference values.Stability of helicopter with slung-load was analyzed in forward flight,and the change of stability was compared when some parameters were adjusted.At last,the dynamic response to the step inputs of the longitudinal,lateral and pedal controls was analyzed in forward flight simulation.
Effect of bowed and swept rotors on stator pressure fluctuation in a transonic compressor
MAO Ming-ming, SONG Yan-ping, WANG Zhong-qi
2010, 25(10): 2312-2318.
Abstract PDF(1363KB) icon1793 icon482
Abstract:
The unsteady 3-D flow fields in a transonic compressor at design point were simulated numerically to study the effect of the bowed and swept rotors on stator surface static pressure fluctuation.The results show that,all three types of bowed or swept rotors,especially the bowed-swept rotor,could weaken the static pressure fluctuation on the top and bottom of stator leading edge compared with the baseline.As a result,the stator surface pressure fluctuation near leading edge area becomes more uniform in radial direction.Expect for the stator leading edge area,the amplitude of pressure fluctuation decreases on the top of pressure and suction surface downstream the bowed and swept rotors,but the effect at mid-span and hub is insignificant.
Dynamic analysis of rotor flow field in the switch processes of injection
ZHOU Jun-wei, HOU An-ping, ZHOU Sheng
2010, 25(10): 2319-2326.
Abstract PDF(1448KB) icon1468 icon428
Abstract:
The purpose of this work is to study the dynamic response characteristic of the rotor flow field during the transition between injection entrance and quit state.The rotor flow field was numerically simulated with an unsteady method.The motion of the tip leakage vortex(TLV) and the dynamic variation of rotor loading distribution were analyzed.It is concluded that,the response of the rotor flow field has two types of time scale,one is small corresponding with a scale of TLV fluctuation,and the other one is large and correlated with the changes of radial distribution of the rotor loading.
Tentative research about pressure measurement on one point of compressor rotor blade surface
WANG Qing-wei, LIU Bo, HOU Wei-min, BO Xiang-feng, XIANG Xiao-rong
2010, 25(10): 2327-2332.
Abstract PDF(749KB) icon1951 icon536
Abstract:
A high response miniature pressure transducer was used for pressure measurement on the rotating blade suction surface of an axial compressor at 50% span,25% axial chord,and the experimental data were compared with the CFD(computational fluid dynamics) numerically simulated results.During experiment,the data acquisition system was fixed on the rotor shaft,enabling to directly sample,amplify and store the pressure signals.The results show that the experimental data are credible,and the blade surface pressures of experimental data are in good agreement with simulation results.It can successfully acquired the unsteady pressure fluctuation of rotating blade surface.The period of pressure fluctuation is almost the same with the cycle time of compressor revolving.
Optimization of axial turbine design by using stator clocking effect
WANG Jian, YANG Bo, GU Chuan-gang
2010, 25(10): 2333-2339.
Abstract PDF(1042KB) icon1570 icon407
Abstract:
According to the effect of clocking in turbo machine,a simple way was suggested to confirm the stator's relative circumferential position.The purpose of this suggestion is to make sure that the axial turbine can reach the best performance.And then,Numeca software was used to make a quasi-3D(three-dimensional) numerical simulation for confirmation of this method.Results show that the method has a certain value in the structural design of turbo machine.
Evaluation of performances of an over-storage solid rocket motor
SHEN Wei, HUANG Wei-dong, YANG Xin-yi
2010, 25(10): 2340-2345.
Abstract PDF(793KB) icon1856 icon415
Abstract:
In order to evaluate the performances of an over-storage solid rocket motor(SRM),the solid rocket motor already stored for 14 years was disassembled.The mechanical property and deflagration performances of the solid propellant were measured.The three-dimensional interior ballistic model for igniting process of the SRM was analyzed by numerical simulation.The finite element model(FEM) of the SRM was developed.Based on the grid face of computational fluid dynamics(CFD) mesh and FEM element,the data transfer method from CFD pressure to FEM load was studied.The structural integrity analysis of the SRM was carried out with the fluid-structural coupling technique.It shows that the modulus of the hydroxyl terminated polybutadiene(HTPB) composite propellant after 14 years has been increased,and ε_m decreased.According to the results of interior ballistic simulation and structural integrity analysis,the structural integrity of the grain could be maintained,and the SRM that had been stored for 14 years is applicable for use.
Thermal structure analysis of liquid rocket engine thrust chamber based on non-coordinated element
ZHANG Jian-wei, SUN Bing, ZHENG Li-ming
2010, 25(10): 2346-2351.
Abstract PDF(910KB) icon1537 icon440
Abstract:
Heat exchange coefficient of gas in thrust chamber and distribution of gas temperature were obtained from Baz formula with data of thermal calculation,and the temperature of thrust chamber was calculated by finite element method.Based on calculation of temperature,the stress of thrust chamber was carried out by Wilson non-coordinated element,in which displacement function was quadratic form.The result shows that,compared with typical element,using Wilson non-coordinated element can get higher calculation precision and more reasonable result in the analysis of high temperature gradient and complex thermal structure of thrust chamber.
Study on pressure wave propagation in two-phase flow in liquid oxygen feed pipe between pumps
WEI Xin
2010, 25(10): 2352-2357.
Abstract PDF(604KB) icon1358 icon376
Abstract:
A study on the character of pressure wave propagation was proposed for the gas liquid oxygen two-phase flow in the pipe between pumps.According to the practical working conditions,the homogenous model based on the compressibility theory regarding a single bubble in an infinite liquid,and Redlich-Kwong gas equation was derived a model for the low temperature and high pressure case,especially considering the change of the ratio of density of gas to one of liquid.The numerical tests were conducted.The results not only show the agreement between numerical simulation for this model and experiment at the normal temperature and pressure is good,but also show that the modifications of the model for the low temperature and high pressure condition are necessary.The study is of reference to further study of oscillation restrain and relative pipe tests.
Effect of gas-particle two-phase flow on jet vane performance
CAO Xi-wei, LIU Yu, XIE Kan, WANG Yi-bai
2010, 25(10): 2358-2362.
Abstract PDF(1091KB) icon1768 icon412
Abstract:
In order to study the effect of gas-particle two-phase flow on the jet vane performance based on the working characteristics of solid rocket motor jet vane,the flow field and aerodynamic performance of jet vane with or without particle was researched by solving the two-dimensional Navier-Stokes equation.In the research,three different diameters of particle 1,10 μm and 30 μm,three different mass fractions 15%,20% and 30%,different vane deflection angles 0°,5°,10° and 15° were considered.The results show that,the pressure of jet vane surface with particles is higher than that without particles,and the difference on the windward and the front part of the jet vane is evident.For the aerodynamic performance,the lift and drag with particles are larger than those without particles,in addition,the difference decreases with the increase of particle diameter,and increases with the growing particle mass fraction under a special particle mass fraction.
Rotor speed changeable cascaded optimization method for helicopter/engine system
ZHANG Hai-bo, YAO Wen-rong, WANG Ri-xian, TIAN Di
2010, 25(10): 2363-2371.
Abstract PDF(552KB) icon2032 icon452
Abstract:
A cascaded optimization scheme by which the main rotor speed can be changed was proposed to solve helicopter/turbo-shaft engine hybrid control problem.Firstly,the minimal power demand of main rotor was found by Levenberg-Marquarat(L-M)algorithm and one-dimensional search optimization algorithm under the helicopter's stable flying state.And secondly,the engine's optimum operating point,i.e.:least fuel consumption state or lowest inlet turbine temperature state,was calculated by optimizing engine's manipulate variables,provided that the engine's constraints were not violated.At last,specific fuel consumption mode control was simulated based on UH-60 helicopter/turbo-shaft engine hybrid control platform;the simulation results show that the cascade optimization scheme is feasible and valid.
Research of configuration modeling technology for aero-engines
TAO Jin-wei, HUANG Jin-quan, ZHOU Wen-xiang
2010, 25(10): 2372-2378.
Abstract PDF(866KB) icon1695 icon558
Abstract:
A component model library,a real-time simulation database,a foreground configuration system and background operating system were designed to establish the aero-engine configuration modeling platform.Steady and transient simulations of variable kinds of aero-engines were successfully conducted on the platform.The results of good precision verify the feasibility for aero-engine configuration modeling technology.
Optimal design of the turbofan engine hydro-mechanical accelerator
WU Wen-fei, GUO Ying-qing, LU Jun
2010, 25(10): 2379-2385.
Abstract PDF(1050KB) icon1734 icon453
Abstract:
A hydro-mechanical accelerator of one turbofan engine was chosen for the research.The decisive cam was designed by multi-optimal method using sequential quadratic programming(SQP) algorithm,wherein the object function was the evaluation function constructed by the rising time of the acceleration,overshoot and stabilization time with full consideration of the constraints in acceleration.The simulation results show that,the optimal design can reduce the overshoot of high pressure rotor speed,shorten the stabilization time and improve the acceleration performance.At the same time the maximum temperature before the turbine has sharply fallen,which is benefit to prolong the lifetime of turbine and other corresponding components.
Analysis on dynamic characteristics of a dual rotor-rolling bearing coupling system for aero-engine
DENG Si-er, HE Feng-xiang, YHANG Hai-sheng, LI Yun-long
2010, 25(10): 2386-2395.
Abstract PDF(1581KB) icon1757 icon433
Abstract:
Based on the bearing dynamics and rotor dynamics models,the nonlinear dynamic mathematical equations were established to describe the dual rotor-rolling bearing coupling system.Newmark finite element method was used to solve the equations.The influences of the rotor speed,intershaft bearing clearance,rollers number and supporting bearing geometry parameters on dynamic characteristics of the dual rotor system were analyzed and verified experimentally.The results shows that:(1) The cylindrical roller intershaft bearing has a significant influence on dynamic characteristics of the dual rotor system,and the stable system operation can be realized when the original clearance is 20 μm.(2) Dynamic characteristics of the dual rotor system can be affected directly by groove curvature radius coefficients of inner and outer rings.(3) The node displacement of coupling between the high-pressure rotor and the low-pressure rotor decreases with the rise of the high-pressure rotor speed,and increases with the drop of low-pressure rotor speed.(4) The theoretical calculation of the coupling node displacement of intershaft bearing is matched with experimental value,and the maximal error is about 18.7%.
Optimization design of spiral bevel gear's dynamic characteristics based on genetic algorithm
ZHAO Ning, KANG Shi-peng, GUO Hui, XIONG Jian-bo, CHENG Chang
2010, 25(10): 2396-2402.
Abstract PDF(516KB) icon1662 icon415
Abstract:
The three-dimensional eight-degree non-linear dynamical model of the spiral bevel gear was established based on the lumped mass method.Time-varying mesh stiffness,non-linear geometric transmission error,gear clearance and non-linear bearing stiffness were considered in this model.The dynamic response for the transmission system was solved by using Runge-Kutta method.Then,by taking meshing cycle root mean square vibration acceleration as an optimizing object,GA(genetic algorithm) was used to optimize these two local control parameters in the local synthesis,meanwhile optimized machining parameters of the gear pair were also obtained.By the way of tooth surface modification,the purpose of reducing gear's vibration and noise was realized.

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