2006 Vol. 21, No. 2

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Display Method:
Applications of Pressure-Sensitive Paint Technique
LIU Bo, ZHOU Qiang, JIN Jun, MA Chang-you
2006, 21(2): 225-233.
Abstract PDF(1545KB) icon1834 icon550
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Since 1980’s,with the development of Biochemistry,Photophysics,Computer & Information Technology and Image-processing technology,Pressure-Sensitive Paint(PSP) technique has been widely employed in many engineering fields because of its evident advantages,such as easy to operate,lower cost,noninterference in flow field and wide range of pressure measurement.The contents of this paper including basic theory of luminescence molecules and its application to optical measurement,development of PSP technique,applications of PSP technique both to internal and external flow fields were depicted to exhibit the perspectives of PSP technique.The details of the differences of PSP technique applied to internal and external flow fields,the role of Temperature-Sensitive Paint in PSP measurement,the methods and procedures of PSP technique application were introduced as many as possible.
DNS of the Blunt Nose Bypass Transition
XIA Zhi-qiang, YUAN Xiang-jiang, HU Zhen
2006, 21(2): 234-240.
Abstract PDF(740KB) icon1929 icon517
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Bypass transition from laminar to turbulent flow in boundary layer of a blunt nose was studied by means of Direct Numerical Simulation(DNS).The full Navier-Stokes equations were numerically solved,using high-order compact finite difference schemes and high-resolution non-reflecting boundary conditions.The local finite amplitude disturbances were directly introduced into the boundary layer of a curved surface.The common calculating methods,i.e.using periodic boundary condition and curved surface replaced by flat plane,were discarded.The present result shows that transition in the flow field is correlated with the appearance of a kind of elongated structure,which is similar to a "hair-pin".This structure has not been found in other literatures.In addition,there are a lot of differences both in the instable process and in the structure pattern.The present results point out the direction of generalization of the observed transition mechanism to localized disturbances in wall bounded shear flow.
Investigation of Core Engine and Derivative Aero-Engine Development
HUANG Shun-zhou, HU Jun, JIANG He-fu
2006, 21(2): 241-247.
Abstract PDF(438KB) icon2275 icon522
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The investigation of core engine and derivative aero-engine development was presented.The increase in engine thrust can be realized by increasing air flow or cycle power of the core engine.But the margin of rotor speed,flow capacity and power needed of the turbomachinery should be considered early in the design stage.Serial development based on the core engine can be done by keeping the corrected speed of the high-pressure compressor constant,or keeping the maximum gas temperature constant.In practice,both of the foregoing approaches were adopted.Therefore,the margin of the maximum gas temperature,rotor speed and capability of HP compressor are required during the development of core engine and baseline aero-engine.However,the approaches in developing high bypass ratio engine and low bypass ratio engine are different.
Development of Component-Level Startup Model for a Turbofan Engine
ZHOU Wen-xiang, HUANG Jinquan, DOU Jian-ping
2006, 21(2): 248-253.
Abstract PDF(1807KB) icon1875 icon545
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Based on the above-idle component-level model,a two-spool turbofan engine startup model was developed using extrapolated component characteristics.The model can simulate the whole startup process on ground from near static conditions to idle.The influence of the fuel-air ratio on combustion efficiency was taking into account.Heat transfer model was also established to estimate the influence of heat transfer on combustor,high pressure turbine and low pressure turbine.The total pressure loss coefficients of different components varied with the high rotor speed.The method of volume dynamics was used in order to avoid the iterative calculations.Results show that the accuracy of the real-time model is good,and the dynamic simulation error is less than 5%.The model meets the requirements of semi-physical simulation.
Influence of Inlet Boundary Layer on Flow Field Performance of the 2D Compressor Bowed Stator Vane
FENG Guo-tai, ZHANG Yong-jun, CHEN Fu, SU Jie-xian
2006, 21(2): 254-260.
Abstract PDF(849KB) icon1624 icon464
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For several given types of inlet boundary layer,a numerical investigation on flow field of bowed stator vanes under two inlet subsonic Mach numbers was carried out.It was found that the ability of improving diffusion cascade performance was affected by some characteristics of the inlet boundary layer.The characteristics included two aspects:inlet boundary layer thickness and inlet boundary layer momentum loss thickness.When boundary layer is thicker or momentum loss thickness was greater,the flow capacity is evidently increased near end-wall under Mach number 0.2.Consequently,the cascade performance is improved and total pressure loss is reduced near suction corner to a greater extent.Under Mach number 0.7,though the increase of mass flow density is less,because of the high end-wall loss,improvement of end-wall performance will bring more profits to the overall cascade performance.
Numerical Simulation of the Influence of Bowed Blade on the Performance of Turbine Cascade with Film-Cooling
YAN Pei-gang, WANG Song-tao, FENG Guo-tai
2006, 21(2): 261-267.
Abstract PDF(1255KB) icon1657 icon434
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Based on a 3D N-S solver,a computational method was adopted to simulate the flow field in film-cooling turbine,which included a finite difference scheme with 3rd order precision and TVD property,domain decomposition method and arbitrarily curved mesh technique.Air was ejected from 8 locations on the turbine blade surface and the upper and lower endwalls.Both the flow fields in the turbine cascade with straight and bowed blade were simulated.The results show that bowed blade apparently reduces the endwall losses whether with and without cooling.The aerodynamic performance of bowed blade becomes worse when the ejection flux is getting larger in the mid-span.
Numerical Investigation of the Cooling Flow Downstream of a Turbine Guide Vane Trailing Edge Slot
ZHOU Chao, CHANG Hai-ping, CUI De-ping, MAO Jun-kui
2006, 21(2): 268-274.
Abstract PDF(1928KB) icon1684 icon455
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In order to investigate the flow characteristics of cooling flow downstream of a turbine guide vane trailing edge slot,numerical methods of RNG k-ε turbulent model were solved.Two-dimensional model for numerical study was established and boundary conditions were set based on operation conditions.The results show a reversed-flow region is formed at the tip of the pressure side due to the influence of the outside hot combustion gas and the pressure side tip thickness.The pressure gradient makes the coolant flow exit from the trailing edge slot first separates from the trailing edge cut-back,and then affected by the expansion wave,the coolant gas re-attaches the cut-back of the trailing edge after passing a certain distance.This article discusses the influencing factors on the flow of pressure side tip thickness,pressure side angle and the geometric shape of pressure side tip.This article also makes a comparison between considering the combustion gas outside and the case that the flow of combustion gas is not taken into account.
Simulation of Surge Behavior of an Augmented Turbofan Engine
WU Hu, JIANG Jian-jun
2006, 21(2): 275-279.
Abstract PDF(860KB) icon1864 icon447
Abstract:
A numerical computer model with post-stall analysis capability was established to simulate an augmented turbofan engine.The model was based on stage-by-stage compression control volumes.A technique based on steady flow and a pseudo-flow area was developed to simulate the splitter flow at fan exit.Numerical method was established using MacCormack’s explicit difference scheme and characteristic boundary treatment.Reducing nozzle throat area was used to induce post-instability operation and the sequences of events leading to surge were investigated.Afterburner-fuel cutdown transient simulation was established to investigate the elimination of surge.The typical behavior and performance of the turbofan engine during surge cycle and the process of surge elimination were obtained.
Investigation of the Influence of Single Expansion Ramp Nozzle Geometric Parameters on the Flow Field and Performance
WANG Wei-na, WANG Zhan-xue, QIAO Wei-yang
2006, 21(2): 280-284.
Abstract PDF(669KB) icon1643 icon474
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Based on CFD technology,the effects of major geometric parameters on performance of the single expansion ramp nozzle were numerically investigated by solving Reynolds average Navier-Stokes equations and standard two-equation k-ε turbulent models.The results show that upper ramp length,upper ramp angle,lower flap length,lower flap angle have evident effects on flow field structure and the performance of SERN.With the increase of upper ramp length,the expansion in SERN transits from under-expansion to over-expansion,thus an optimal upper ramp length is found to create maximal thrust coefficient.The upper ramp angle,lower flap length,and lower flap angle also have optimal values for SERN performance.
The Low Reynolds Number Effects on the Performance of Some Controlled Diffusion Airfoils
ZHAO Feng, GUI Xing-min
2006, 21(2): 285-289.
Abstract PDF(817KB) icon1852 icon478
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In order to analyze the effect of low-Reynolds number on the performance of some controlled diffusion airfoils,calculations were performed under different Re No.of 1×106,7.7×104,1.6×104,7.2×103,3.4×103with different incidences respectively.The results of numerical simulation show that the total pressure loss coefficient increases with the decrease of Reynolds number.Under the condition of low Reynolds number,the incidence range of low loss becomes narrow.
Experimental Investigation on Film Cooling Effectiveness of Tangential Discrete Holes Configuration
MA Guo-feng, ZHANG Jing-zhou, YANG Wei-hua
2006, 21(2): 290-296.
Abstract PDF(1658KB) icon1707 icon506
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The film cooling effectiveness of the tangential discrete holes film cooling configuration with different hole diameters and arrangement was experimentally investigated using infrared camera.The empirical correlations of cooling effectiveness to blowing ratio and non-dimensional flow-wise distance(X/S) were obtained,which agreed well with the experimental results.The results show that,for the present investigation conditions,the film cooling effectiveness will be increased with the increase of blowing ratios and the diameter of film hole;with the same blowing ratios and porosity of holes,the hole arrangement has little effect on cooling effectiveness.
Simulation Study on Helicopter Nacelle Ventilation Cooling System
XIE Yong-qi, YU Jian-zu, GAO Hong-xia
2006, 21(2): 297-302.
Abstract PDF(889KB) icon2107 icon503
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The physical and mathematical model of the 3D airflow and heat transfer was set up for the helicopter nacelle.Unstructured grids and grid adaptation was applied to the region discretization,taking the characteristic of nacelle configuration and air flow into consideration.For five cooling system design configurations,numerical simulation of the 3D airflow and temperature field was carried out using the standard k-ε turbulent model and finite volume method.The influence of inlet and outlet size and their distribution on velocity field and temperature field was analyzed.The results show that the inlet located in front and the outlet located aft of the nacelle is of benefit to the airflow flow and heat transfer.Air eddy was found in nacelle,and the temperature in the front part of the nacelle was higher than the rear part.
Critical Boiling Heat Flux in Inclined Small Tubes at Zero Inlet Flow
LIU Zhen-hua, ZHANG Tong
2006, 21(2): 303-307.
Abstract PDF(1190KB) icon1810 icon458
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An experimental study was carried out to investigate the nucleate boiling characteristics and the Critical Heat Flux(CHF) of countercurrent boiling in the inclined small tubes at zero inlet flow.Both saturated water and R-113 were used as working liquids.The inner diameters of the tested tubes ranged from 2.1 mm to 4.0 mm,the tube lengths changed from 100 mm to 300 mm,the inclination angles varied from 90° to 0°.The experimental results show that CHF decreases with the decrease of the inclination angle.A semi-theoretical correlation for the CHF of countercurrent boiling in the vertical tube with sealed bottom was modified for considering the effect of the inclined angle.The modified correlation can reasonably well predict the CHF for the inclined tube.
Experimental Investgation on Vaporized-Detonator in Pulse Detonation Engine
FAN Yu-xin, WANG Jia-hua, LI Jian-zhong, ZHANG Yi-ning
2006, 21(2): 308-314.
Abstract PDF(788KB) icon2160 icon450
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Several types of vaporizeddetonator using multiple tubes in pulse detonation engines were designed to obtain successfull detonation in a gasoline fueled aerovalve PDE with 180 mm diameter.A series of experiments with different structures of vaporized-detonator were carried out,which included comparison tests of different diameters of vaporizeddetonator tubes(φ13 mm,φ16 mm and φ29 mm),identical diameter vaporized-detonator tube(φ29 mm) with and without spirals,and spirals with different vaporized-detonator tube sizes(φ29 mm and φ37 mm).The mechanism of detonation engendering and developing in PDE with vaporized-detonator tubes of different size and structure and their influences on detonation pressure and thrust were analyzed.These results show that PDE with such structure can induce detonation successfully.Under same blockage ratio,increasing the diameter of spring and reducing the wall thickness simultaneously for small tubes in multi-tube detonator is of benefit to net thrust.
Effect of Aerodynamic Parameters of Backward-Step Three Dimensional Slots on Film Cooling Effectiveness
ZHU Hui-ren, YUAN He-peng, ZHOU Zhi-qiang, XU Du-chun
2006, 21(2): 315-319.
Abstract PDF(344KB) icon1550 icon433
Abstract:
According to the feature of the turbine blade trailing edge cooling,film cooling effectiveness of backward-step three dimensional slots injection was measured at the slot center line and rib center line.The effects of aerodynamic parameters on the film cooling effectiveness have been studied.The secondary flow Reynolds number based on slot height varied from 5 000 to 15 000 and blowing ratio changed from 0.5 to 2.0.The experimental results show that the influence of secondary flow Reynolds Number on film cooling effectiveness and three dimensional flow mixing region is unremarkable;the influence of blowing ratio on film cooling effectiveness,and the size and performance of the three dimensional mixing flow region is very significant.For lower blowing ratio,secondary flow will flow into mainstream region and the region behind the rib,this will benefit the protected wall;for high blowing ratio,the situation is the contrary.
Application of Discrete-Ordinates Model to the Study of Radiative Heat Transfer
LI Zhi-qiang
2006, 21(2): 320-325.
Abstract PDF(349KB) icon1780 icon446
Abstract:
The radiative heat transfer model,i.e.Discrete-Ordinates(DO) model,was verified by and applied to a combustion chamber and a three dimensional(3D) swirl combustor.For the combustion chamber,the predicted results of pure radiative heat transfer were in good agreement with those of the zone method,while the SHF model gave relatively large deviations.For swirl combustor,the predicted temperature distribution of DO model were in good agreement with those measured by experiment and were better than those of the SHF model.Also,the computation time and boundary treatment,the DO model was better than zone model and six heat flux model.
Flow and Heat Transfer in a Pre-Swirl Rotor-Stator Cavity under High Rotational Reynolds Number
YANG Cheng-feng, ZHANG Jingzhou
2006, 21(2): 326-330.
Abstract PDF(433KB) icon1780 icon458
Abstract:
A three-dimensional numerical study of the flow and heat transfer characteristics of a pre-swirl rotor-stator system equipped with a series of pre-swirl nozzles of circular cross-section was carried out.Pre-swirl nozzles were located on the outer rim of a stator disk with a radius equal to that of the rotor blade inlet holes.The RNG k-ε turbulent model was used for the simulation under the condition of high rotational Reynolds Number and throughflow rate.The convective heat transfer coefficients of the rotor and temperature distributions at the blade inlet holes were obtained for different non-dimensional throughflow rates and rotational Reynolds Numbers under a given swirl angle.The computational data were compared with that of a simple straight air inflow model.The results show that the cooling air total temperature entering the rotor blade holes is obviously lower with the pre-swirl nozzles compared to the straight nozzles without pre-swirl.The convective heat transfer is enhanced inside the cavity by increasing the non-dimensional throughflow rates and rotational Reynolds Number.And the cooling air temperature entering the rotor blade holes decreases with the increase of the non-dimensional throughflow rates,whereas it goes up and then drops down with the increase of the rotational Reynolds Number.
Experimental Investigation of the Local Heat Transfer Characteristics at the Inner Side of the Midchord Region near Film Cooling Holes
XU Lei, CHANG Hai-ping, CHANG Guo-qiang, ZHANG Jing-yang
2006, 21(2): 331-335.
Abstract PDF(407KB) icon1888 icon430
Abstract:
Experimental investigation of the turbine blade local heat transfer characteristics at the inner side of the mid-chord region near film holes was conducted,with and without impingement cooling.Under no impingement condition,the investigation was carried out with different crossflow Reynolds Numbers and different density flow ratios of film outflow to cross flow.The research results indicate that the local heat transfer near the film cooling holes is enhanced with the increase of the cross flow Reynolds Numbers and density flow ratios.The local heat transfer characteristics aft the film holes are better than that ahead the film holes.The closer to the holes the stronger heat transfer will be,regardless of ahead or aft the film holes.A comparison of extraction effect between 30° and 90° film cooling holes was conducted also.Under the condition with impingement cooling,through the experimental data,effect of flow parameters such as impinging Reynolds Numbers and density flow ratios on the local heat transfer characteristics were obtained.
Research of Scramjet Strut Thermal Environment and Thermal Protection Scheme
SUN Bing, ZHENG li-ming
2006, 21(2): 336-341.
Abstract PDF(703KB) icon2013 icon462
Abstract:
The thermal environment of the scramjet strut leading edge is rigorous.In this paper,the thermal environment was studied,and the heat load distribution was obtained.Based on the thermal environment,three thermal protection schemes were put forward,i.e.regeneration cooling scheme,C/SiC thermal protection scheme and gas jet thermal protection scheme.Numerical simulation was employed to obtain the thermal protection effectiveness of these three schemes.The results show that the regeneration cooling scheme can’t protect strut leading edge from destruction;C/SiC thermal protection scheme works well up to flight mach number not exceeding 8,and only gas jet thermal protection scheme can protect strut leading edge from destruction up to Mach 8 and higher.
Bifurcation Analysis of Main Resonance for a Helicopter Drive Shaft with Elastic Multi-Supports
XU Zhao-tang, ZHU Ru-peng
2006, 21(2): 342-348.
Abstract PDF(484KB) icon1851 icon459
Abstract:
A bending motion equation of a tilting helicopter drive shaft with elastic multi-supports was derived by the theorem of motion for center of mass,Galerkin method and Dirac function.A bifurcation equation of the steady state main resonance was obtained based on the multiple scales method.The motion stability,topology structure of amplitude-frequency response curves etc.were analyzed.The results show that elastic intermediate supports plays the role of the limiters,which can improve the motion stability and increase frequency range of non-bifurcation between adjacent orders of main resonance.The bifurcation of main resonance can be removed by reducing the eccentricity and the order of main resonance and increasing damping of the driving shaft and intermediate supports.
Experimental Study on Fatigue Crack Growth Behavior of Direct Aging GH4169 Superalloy
HE Yu-huai, YU Hui-chen, GUO Wei-bin, SHEN Li-li, SU Bin
2006, 21(2): 349-353.
Abstract PDF(1878KB) icon2022 icon514
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Fatigue crack growth tests were conducted on a CT specimen of a nickel base superalloy direct aging GH4169.The effects of thickness,temperature and stress ratio on fatigue crack growth behavior were studied separately.The key results are as follows:thickness has no effect on fatigue crack growth behavior in the thickness range from 4 mm to 10 mm,but as thickness is decreased to 2 mm,the fatigue crack growth rate decreases when stress ratio is 0.1;the effect of stress ratio on fatigue crack growth rate diminishes as stress ratio increases;increasing temperature accelerates fatigue crack growth rate,but the effect of temperature diminishes with the increase of stress intensity factor and the main mechanism for accelerating fatigue crack growth is oxidation.
Research of Aero-Engine High-Speed Ball Bearing
TANG Yun-bing, GAO Ge-ping, LUO Gui-huo
2006, 21(2): 354-360.
Abstract PDF(1266KB) icon2051 icon458
Abstract:
The ball bearing is widely used in aero-engines.Its mechanical properties exert important influence on the dynamic characteristics of rotor systems,especially at high speed.Research on aero-engine high-speed ball bearing has important significance.Considering radial load,axial load,centrifugal force and gyroscopic moment acted on the ball bearing simultaneously,an analysis model based on quasi-dynamic method was set up in this paper.The effects of different structural parameters,such as contact angle,deformation and stiffness and load parameters on bearing mechanical properties were studied.Finally,the method is verified by experiment.
Wavelet Extraction of Impact Vibration Frequency Component and Fault Analysis for a Twine Spool Aero-Engine
HE Wei-feng, CHENG Li, LI Ying-hong
2006, 21(2): 361-365.
Abstract PDF(1448KB) icon1917 icon434
Abstract:
Noise and weak symptom give rise difficulties to aero-engine vibration monitoring and faults diagnosis.The conventional methods in time or spectrum domain are not so effective for it is hard to detect some kinds of fault symptoms.After measuring the data in an aero-engine on the ground,its time-frequency characteristics under different working conditions were analyzed.First,the signals were analyzed using Morlet wavelet and then the frequency component could be extracted from their time-frequency plane.Some impact components were obvious in the time frequency plane which indicated that some faults might occur in the rotor system.They were located in the band of bearing characteristic frequencies.Second,the signal was decomposed using harmonic wavelet whose resolving capability is high in both time and frequency domain in the bearing characteristic frequencies.Then the components of different frequencies were obtained by harmonic wavelet.Energy of the signal was concentrated in some frequency band.From these results of the harmonic wavelet analysis in the bearing characteristic frequencies,the kind of fault can be determined easily.
Non-Linear Bearing Force of the Rolling Ball Bearing and Its Influence on Vibration of Bearing System
TANG Yun-bing, GAO De-ping, LUO Gui-huo
2006, 21(2): 366-373.
Abstract PDF(1819KB) icon2118 icon542
Abstract:
Rolling ball bearing is widely used to support rotors.It is a non-negligible source of vibration in many types of rotating machines,so the vibration characteristics of the rolling ball bearing system is worth to be investigated.Hertz elastic contact theory and bearing kinematics theory were applied to calculate the force caused by the rolling ball bearing.The non-linear vibration of rotors supported by the rolling ball bearing was studied.It was found that the non-linear bearing force excited the varying compliance vibration.Many kinds of periodic(synchronous,sub-and super-synchronous) and non-periodic(quasi-periodic and chaotic) responses exist in the system.The periodic bifurcation behavior of the system was analyzed by means of spectrum diagrams,Poincaré maps and bifurcation diagrams.When non-linear bearing force and unbalance force act simultaneously,combined vibration will be generated.With the Increase of unbalance force,the varying compliance vibration will be weakened.
Analysis of the 3D Unsteady Vortex Flow Inside Axial Flow Compressor Rotor
JI Heng, HOU An-ping, XIONG Jin-song, ZHOU Sheng
2006, 21(2): 374-380.
Abstract PDF(1651KB) icon1975 icon484
Abstract:
Based on the numerical simulation method,frequency spectrum analysis and structure analysis were conducted for the three dimensional unsteady flow inside the compressor rotor.Through the analyses of the time-average flow field and the animated isentropic cartoon,we recognize the characteristics of the flow field,the existence range of the vortex shedding.The interaction of the leading edge and trail edge vortex and corner vortex was investigated,and the rule of their development and their effect to each other were also discussed along with the frequency spectrum analysis.For separated flow,dynamic demonstration graph and spectrum analysis were used to estimate the vortex shedding and corner vortex frequencies.The work can be used as theoretical foundations for active and passive control of compressor to improve its performance.
Research of Altitude Effect on Aero-Engine Ground Test Performance
LIU Zhi-you, HOU Min-jie, MA Qian-rong
2006, 21(2): 381-385.
Abstract PDF(921KB) icon2194 icon428
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The altitude effect on aero-engine ground test performance was analyzed in brief,and the advantages-disadvantages of the two methods used for the analysis of this effect were compared.A method was put forward to study the above-mentioned influence through the inlet pressure’s influence on the engine performance at constant ram ratio with the help of the ATF particular advantage of pressure regulation and control.The test result of an engine shows that its corrected performances agree well with the test results when the inlet total pressure is kept in the range from 70 through 90kPa and the fan corrected rotating speed,94.5% to 96.5% at a constant ram pressure ratio of 1.6.It means that engine Reynolds Number is already higher than the critical Reynolds Number when the ambient pressure is above 70 kPa or the altitude is below 3 km.In this range,the influence of the ambient pressure change on the engine corrected performance can be neglected.Thereby,engine performance at static standard sea level atmospheric condition can be determined through engine ground test with altitude less than 3 km.
Experimental Study of Pre-Stall Pressure Disturbances in a Low-Speed Axial Compressor
LI Chuan-peng, HU Jun, WANG Ying-feng, ZHAO Yong
2006, 21(2): 386-390.
Abstract PDF(346KB) icon1704 icon439
Abstract:
The dynamic pressure on stator surfaces at vane tip,mid-span and root was measured to demonstrate the flow structure in a compressor working close to its stability limit.Unsteady pressure signals show that before stall there exist two kinds of pressure disturbances.The frequencies of these disturbances are approximately in proportion to rotor speed and the relative frequencies are 5 and 8 respectively in terms of rotor rotating frequency.The intensity of the disturbance with relative frequency 5 increases as mass flow decreases until compressor working point reaches stall margin,whilst the intensity of other disturbances increases first and drops suddenly as compressor works at stall point.Thus,the flow field disturbance which leads to rotating stall/surge should be that the relative frequency is 5 and it can be regarded as the warning signal of instability.Setting a value λ as the threshold,establishing a reliable and effective stall avoidance control based on pressure signals detected by high response transducers seems to be promising.
Experimental Determination of Aero-Engine Windmilling Drag
LIU Zhi-you, HOU Min-jie, WEN Gang
2006, 21(2): 391-395.
Abstract PDF(604KB) icon2307 icon512
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Windmilling characteristics are one of the important performance indices to engine design and assessment.It is very difficult to accurately determine engine windmilling characteristics,in particular windmilling drag,for the windmilling state seriously deviates from the engine design point.This paper described the mechanism of the aero-engine windmilling drag,and theoretically deduced the formula for determining it in the simulated altitude test,and finally the experimental method for determining the engine windmilling drag was introduced.The method was satisfactorily applied to the windmilling characteristics test of a turbofan engine.
Numerical Investigation of the Effects of Bowed Compressor Stator Vanes on Variable Incidence Performance at Low Speed
ZHANG Yong-jun, CHEN Fu, FENG Guo-tai, SU Jie-xian, WANG Zhong-qi
2006, 21(2): 396-402.
Abstract PDF(577KB) icon1564 icon404
Abstract:
The effects of the compressor bowed stator vanes on variable incidence characteristics were studied with the method of CFD.It was found that bowed vane had strong impact on flow field under positive incidence.Due to the decrease of diffusion factor near the end-wall and the augmentation of density mass flow close to the suction surface,the bowed blade eliminates or defers the separation formation near suction surface under high positive incidence and weakens the expanding of the separation region.There fore,bowed blade is able to enlarge the operation range of the stator vane.The results show the bowed blade with bow angle of 20° has maximal operation range with critical incidence of 16°.
Fault Simulation and Analysis for the Fluid Systems of LPRE Test-Bed
ZHANG Qing-song, ZHANG Zhen-peng, YANG Xue, CHEN Feng
2006, 21(2): 403-409.
Abstract PDF(1811KB) icon1830 icon492
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According to the static characteristics of the test-bed and the testing LPRE,this paper simulated the main faults effect of the test-bed.Transient characteristics of abrupt faults of the fluid systems were also simulated with the method of characteristic for one-dimensional incompressible transient duct model.Simulation model of the reductor and the pressurized tank were established,and then the fault simulation for the tank pressurization system was carried out with the finite element state-variable model.The aim of this paper is to acquire the static and dynamic faults characteristics of the test-bed.The results indicate that the simulation models and methods are applicable and effective enough to achieve this purpose.The simulation results and analysis can also be used to provide guidance for the test-bed maintenance and amelioration.
Research on Response characteristics of the Full-Flow Staged Combustion Cycle Rocket Engine
HU Wei, ZHANG Zhen-peng
2006, 21(2): 410-416.
Abstract PDF(380KB) icon1863 icon439
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Using the full-flow staged combustion cycle LH2/LOX engine as an example,the engine response characteristics were investigated.The non-linear dynamic mathematical model of the full-flow staged combustion cycle was presented.The variable step Runge-Kutta algorithm for solving the ordinary differential equations was developed.The immunity strategy algorithm and Runge-Kutta algorithm were combined to form this new algorithm.Applying the variable step Runge-Kutta algorithm,the transient performance of the full-flow staged combustion cycle was simulated.Calculating results show that variation of the propellant inlet pressure makes little impact on engine performance parameters,and the engine will transit to a new stable state.The parameter transition curves are smooth.When the engine thrust is adjusted in a small range within a short period,the parameter transition curves are also reposeful.But when the adjusting range becomes large,the parameter transition curves will fluctuate acutely.Thus,when large range adjusting is required,the time of adjusting should be lengthened or the adjusting should be divided into adequate steps.
Fault Simulation and Analysis of the FLPRE Test-Bed Fluid Systems
GAO Fang, CHEN Yang, ZHANG Zhen-peng, CHEN Feng
2006, 21(2): 417-420.
Abstract PDF(519KB) icon1891 icon443
Abstract:
Starting from the transient pipe flow equation of one dimensional compressible fluid and using finite control volume method,the working process of the fluid piping system for liquid-propellant rocket engine testing was simulated.Through the comparison between calculated data and experimental data,the results illustrate that the method used in this paper describes preferably the working process of the fluid piping for the liquid-propellant rocket engine experiment system and can provide guidance for the design of experiment system,fault diagnosis,optimization and performance analysis of liquid-propellant rocket engine.
Research of Hybrid Optimization Method for Aeroengine Performance Seeking Control
ZHU Yu-bin, FAN Si-qi, LI Hua-cong, YANG Chui-bai
2006, 21(2): 421-426.
Abstract PDF(1349KB) icon1908 icon451
Abstract:
According to the optimization control modes of aeroengine Performance Seeking Control(PSC),the aeroengine performance optimization problems which were described as a linear programming problem were studied.In respect that the linear programming may converge to a local minimum and nonlinear method is much more time comsuming,a hybrid algorithm based on Linear Programming(LP) and Model-Assisted Pattern Search(MAPS) was proposed in this paper.The hybrid optimization method was used for aeroengine control.Digital simulations were conducted at maximum thrust mode and minimum fuel consumption mode.Simulation results demonstrate that the engine performance can be improved further and calculation time can be reduced by using hybrid algorithm.
Aero-Engine State Variable Modeling Based on the Genetic Algorithm
LI Qiu-hong, SUN Jian-guo
2006, 21(2): 427-431.
Abstract PDF(1648KB) icon1914 icon444
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Based on the Genetic Algorithm(GA),aero-engine small perturbation State Variable Model(SVM) was proposed.The fitness function of GA was established according to the principle that the aero-engine dynamic responses of the linear model should be in accordance with that of the nonlinear model at the same steady working point.Using the optimization algorithm,the SVM can be obtained.This method has no limitation on the system modes and orders.The SVM of some turbofan engine established with this method turns out to have high accuracy.The performance of the robust controller based on this SVM is quite well,which indicates the validity of this method.
Analysis of Turbo-Shaft Engine Control System Dynamic Performance with Parameter Limitations
HUANG Kai-ming, YIN Ze-yong, HUANG Jing-quan
2006, 21(2): 432-436.
Abstract PDF(377KB) icon1736 icon419
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Effect of limitations of aero-engine parameters was studied.The purpose of the analysis was to achieve better dynamic performance.Limitation rules that may be adopted in turbo-shaft engine control system were presented and a digital controller with multiple limitation loops was designed.Simulation results show that different limitations of parameters bring different effects on engine dynamic performance.Selecting limitations of parameters reasonably can optimize engine dynamic performance.

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