2012 Vol. 27, No. 7

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Three-dimensional simulation and analysis of five-stage low pressure turbine
ZENG Jun, WANG Li
2012, 27(7): 1441-1447.
Abstract PDF(1533KB) icon2365 icon704
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In order to understand the five-stage LPT(low pressure turbine) aerodynamic design characteristic,full three-dimensional simulation of the five-stage LPT was conducted by the CFD(computational fluid dynamics) software CFX12.0.Three-dimensional Reynolds averaged N-S(Navier-Stokes) equations with SST (shear stress transport) turbulence model were used to predict the LPT internal flow.The results were compared with the experimental data.It is proved that the turbine blades are all designed by fore-loaded or uniform-loaded,and the CFX has high precision on simulating aerodynamic flowfield.Besides,the results provide some references for civil aerial-engine turbine design.
Validation of nonlinear harmonic method in dual-stage counter-rotating compressor
WANG Lei, LIU Bo
2012, 27(7): 1448-1455.
Abstract PDF(1271KB) icon2283 icon687
Abstract:
NLH (nonlinear harmonic) method implemented in Fine/Turbos code was evaluated for unsteady rotor-rotor interaction analysis of the NWPU (Northwestern Polytechnical University) dual-stage counter-rotating compressor.Strengths and weaknesses of the NLH method were first highlighted through direct comparison with experimental data and reference classic time-domain unsteady simulation close to the design point.Then its ability to correctly capture rotor-rotor interactions of the counter-rotating compressor was investigated in detail to enhance the understanding of the flow physics involved.The results show,on one hand,the good behavior of the NLH method and its ability to correctly predict global quantities as well as local flow pattern,on the other hand,for the present case,the NLH method is about one order magnitude faster than the classic unsteady simulation.
Experimental investigation on the stall process of a transonic compressor rotor
WANG Zhuo-qi, YUAN Wei, SONG Xi-zhen, LI Mao-yi, LU Ya-jun
2012, 27(7): 1456-1463.
Abstract PDF(1792KB) icon1900 icon659
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An experiment with static and dynamic acquisition were carried out on a transonic compressor rotor at three rotating speed.The analysis was performed on the original signal,the FFT(fast Fourier transform)and the wavelet method.The results show that the stall inception is spike type of whole span.Only one stall cell exists in the flow field,the spreading direction of which is the same as the rotor rotating.And the relative rotating speed of the stall cell decreases when the rotor speed increases.
Neural network reconstruction method of compressor characteristics with continued fraction expanded data
WANG Xing-bo, LI Ben-wei, WANG Yong-hua, YANG Xin-yi
2012, 27(7): 1464-1471.
Abstract PDF(1471KB) icon1812 icon611
Abstract:
Original two-dimensional constant rotating speed curve data points of aero-engine compressor were expanded using continued fraction interpolation.Rotating speed characteristic data through twice network training was increased and BP(back progagation) neural network model reconstruction in three-dimensional space was performed.According to the space distribution of compressor characteristics data,pressure ratio function was introduced,computational domain was adjusted,input and output data were defined and dimension of hidden layer was determined by cut-and-try method.Particle swarm optimizing algorithm based on seek advantage and avoid disadvantage principle was used to optimize the initial weight and threshold of neural network,and to establish the integral surrogate model of compressors was taken pressure ratio and efficiency characteristics.In the end,some aero-engine low pressure compressor for example to conduct the model reconstruction method.The check and verification results indicate the surrogate model established by the method proposed is more accurate than traditional two-dimensional interpolation and common BP neural network model.The reconstruction model can increase computational accuracy and boost iteration speed when used in solving aero-engine mathematic model based on general characteristic curve of compressor such as trial and error procedure,coordinate method and components method,therefore it is of engineering value.
Investigation of three-dimensional viscous model for compressor with distortion inlet
SHI Pei-jie, QIAO Wei-yang, WEI Zuo-jun, CHEN Ping-ping
2012, 27(7): 1472-1478.
Abstract PDF(1153KB) icon2043 icon673
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A three-dimensional model for predicting compressor performance and stability was developed by solving N-S(Navier-Stokes) equation with source terms to annulus duct without blades.The source terms were calculated by flow field parameters which were generated by conventional three-dimensional computational fluid dynamics(CFD) solver at different operation conditions.A transionic single-stage compressor was investigated by the model with clean inlet.The three-dimensional flow field and performance of CFD results agreed well with those of the experiment,which indicat that the model is reliable and correct.Finally,the effect of circumferential total-pressure distortion on the compresser flow and performance was studied with the model.The compressor stability was further analyzed by introducing the stall criterion.
Effects of vortex generator application on the wing-body juncture horseshoe vortex
WANG Jian-ming, LIU Wei, ZHU Kui, AI Yan-ting, TANG Ji-tao
2012, 27(7): 1479-1483.
Abstract PDF(877KB) icon1719 icon757
Abstract:
A typical wing-body junction region was presented.In order to modify the horseshoe vortex,the vortex generator was placed upstream of the wing on the flat plate.Numerical simulation was conducted to investigate the effects of the vortex generator's heights on the turbulent junction flow.The results show that any vortex generator can weak the horseshoe vortex.The modification is best with 2mm of the vortex generator's height.The vortex legs congregate round the wing with the increasing of the heights.The proposed method is a kind of passive control method.The modification of junction flows with vortex generator application presented is promising since it is very simple and applicable.
Two-dimensional cascade test on flow control using jet-flap for turbine blades
WANG Pu-wei, QIAO Wei-yang, CHEN Ping-ping, WEI Zuo-jun
2012, 27(7): 1484-1492.
Abstract PDF(1333KB) icon1820 icon614
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Control of jet-flap on turbine cascade flow was studied.An experiment was conducted to study the impacts of the jet-flap which were blown out by a row of jet holes which were in diameter of 1mm and were near to the trailing edge on the pressure surface of gas turbine blade.The experiment adopted different shapes of jet-flap with different mass flows under various flow conditions.The experiment results show that jet-flap can effectively control the mass flow and the turning angle.When Reynolds number is 71742,Mach number is 0.048,turbulence is 1%,and the jet flow reaches to 4% of the mass flow,the mainstream mass flow is reduced by 13.32%,and the turning angle is increased by 6.34%.Along with the increase of the jet flow,the loading coefficient decreases and the total pressure loss coefficient increases.
One and three-dimensional designs and analyses of small radial turbines
XI Zhong, FU Jing-lun, LIU Jian-jun, ZHANG Xiao-dong
2012, 27(7): 1493-1502.
Abstract PDF(761KB) icon1813 icon791
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A reasonable method of choosing speed ratio and degree of reaction for small radial turbines was described,and a one-dimensional design code OCC(one-dimensional computer code)was programmed by analyzing all kinds of restriction factors on the speed ratio and degree of reaction.The code OCC was used for the design of nozzle and rotor blade of a 600kW simple cycle gas turbine taken from the literature.The OCC results were compared with the results of the design and analysis code OFC(one-dimensional computer FORTRAN code)in the literature.The results were in agreement,and the total static isentropic efficiency of the radial turbine designed by OCC was larger than that designed by OFC.The comparison between the CFD(computational fluid dynamics) simulation resulted that and the OCC results for the radial turbine shows the discrepancies were lower than 10%.In conclusion,the present design method and the one-dimensional design program are appropriate to the preliminary design of micro radial turbines.
Effect of U-grooves on high-lift low pressure turbine profile's incidence characteristics
ZHANG Bo, LI Wei, DU Qiang, HUANG En-liang, LU Xin-gen, ZHU Jun-qiang
2012, 27(7): 1503-1510.
Abstract PDF(1321KB) icon1762 icon618
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The high-lift low pressure turbine blade profile incidence characteristics under low Reynolds number were investigated.The modification used recessed U-grooves to improve the profiles’ incidence margin.The numerical simulations suggest that compared with high incidence flow condition,lower incidence does not induce large separation which appears on the suction surface of the profile and hence lessens profile loss.The recessed U-grooves delay the separation location,accelerate reattach location,decrease the turbulent wetted area,thereby the separation bubble is suppressed and the profile loss decreases.Whether or not the recessed U-grooves can improve the incidence margin is related to the depth and location of the U-grooves.With±15 incidence degrees,the U-grooves located in 72% axial chord length showed lower profile loss,and when the depth was 0.40mm the profile loss was the lowest.
Rising velocity of Taylor hydrogen bubble in upward vertical slug flow
SONG Jian-jun, DU Xiao-ping, ZHAO Ji-guang
2012, 27(7): 1511-1516.
Abstract PDF(737KB) icon1734 icon757
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Aiming at the difficulties of gas-liquid flow experiment in the vertical pipe,the modeling and simulation methods were conducted to investigate the dynamic model of slug flow and the rising velocity of Taylor hydrogen bubble in upward vertical slug flow.Simulation results show that the velocity of the developed Taylor hydrogen bubble is 0.2265m·s-1.In flowing liquid,the velocity coefficient is insensitive to the liquid Reynolds number.As the Reynolds number based on the liquid velocity,the Reynolds number increases from 220 to 6400,and the velocity coefficient decreases from 1.83 to 1.14.In developing Taylor bubble,the rising velocity increases with the shortening distance between consecutive bubbles.
Experimental study of atomization performance on a fuel slinger
XIONG Chun, SONG Shuang-wen, CHEN Jian, LI Zhi, LI Wen-gao
2012, 27(7): 1517-1522.
Abstract PDF(719KB) icon2196 icon639
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An experimental study was performed to investigate the atomization performance on a rotating fuel injection system in a fuel slinger test rig.Performance parameters such as fuel droplet size Sauter mean diameter (SMD) and spray cone angle etc was measured by using phase Doppler particle analyzer (PDPA) system under different slinger rotary speeds.The test results indicate that during the given rotational speed ranges,the fuel atomization cone angle of the slinger is gradually decreased with increasing shaft speed,the fuel droplet size of the slinger is gradually decreased while the rotational speed increased.Over than 25000r/min,SMD is not changed and kept constant,under the same rotary speed,the droplet size increased when the distance away from the fuel slinger hole increased.
Effect of central plug on performance of forced mixing exhaust system
XIE Yi, LIU You-hong
2012, 27(7): 1523-1531.
Abstract PDF(1358KB) icon1806 icon769
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Geometric models with respective changes of plug radius at lobe exit and plug length in the lobed forced mixing exhaust system were established.Then these models were numerically simulated based on Navier-Stokes equations.The results show that when plug length is constant,the thermal mixing efficiency increases at first and then declines with plug radius at the lobe exit augmenting,and when ratio of plug radius at lobe exit to lobe height is equal to 0.55,the lobed mixing exhaust system has the biggest thermal mixing efficiency at the nozzle exit among the models researched.Generally speaking,the total pressure recovery coefficient declines as radius increases.Moreover,the thrust coefficient at the nozzle exit firstly increases and then decreases sharply.When plug radius at lobe exit keeps constant,with plug length rising,the thermal mixing efficiency and total pressure recovery coefficient vary little and the thrust coefficient at the nozzle exit augments quickly in the beginning and then declines slowly.
Research on wind cooling disperse heat of micro electric vehicle power cabin
XU Xiao-ming, ZHAO You-qun
2012, 27(7): 1532-1536.
Abstract PDF(422KB) icon1742 icon582
Abstract:
Air-inlet of micro electric vehicle can be arranged in a plurality of positions. It is worth researching whether the air-inlet arranged in the front of micro electric vehicle power cabin can improve disperse heat efficiency.It is also important to choose a finer air-inlet & air-outlet pattern to improve disperse heat efficiency.The results indicate that the temperature of power cabin is affected evidently by the battery heat,environment temperature and air-inlet temperature,whereas is affected less by air-outlet pattern,number and speed of the air-inlet;when the intake air temperature is lower than the ambient temperature,increasing the number of air-inlet quantity and vehicle speed can improve the cooling performance,and when the intake air temperature is above the ambient temperature,reducing the number of air-inlet quantity and vehicle speed can improve the cooling performance.Then the reference basis for choosing disperse heat project was provided.
Effect of various fuels used on turbocharger experiment
HUO Lei, WANG Hong-ming
2012, 27(7): 1537-1541.
Abstract PDF(414KB) icon1633 icon603
Abstract:
Effect of various fuels used in gas generator on the performance of turbocharger was investigated by theoretical analysis and experiment.The results show that in the turbine test,the performance of the turbine is uncertain due to the uncertain water capacity of the alcohol fuel.The combustion products lead to extra corrosion of turbine components,which is a hidden danger to the turbine.The petrol can lead to certain turbine performance and the corresponding test result can provide evidence for the improvement of turbine performance.
Effect of splitter on performance of inlet particle separator
KUANG Kai-xin, WANG Suo-fang
2012, 27(7): 1542-1548.
Abstract PDF(1264KB) icon1790 icon543
Abstract:
In order to investigate how the position and the size of splitter affect the performance of integral particle separator (IPS),a numerical simulation was conducted by using the Realizable k-ε turbulence model.The simulation came out with the effects of splitter movements in axial direction and radial direction on flowfield,separation efficiency and total pressure loss in IPS.On this basis,the ratio of axial distance to radial distance at splitter lip,the highest point of inner wall surface,and the shape of the splitter's effect on IPS were studied.The results show that:When the ratio is large,with the increase of the axial distance,total pressure loss declines with a large gradient descent.When the ratio is small,total pressure loss tends to decrease at first and then increase;after the shape of the splitter changes,the total pressure loss becomes much lower while the separation efficiency getting much higher,and the highest Mach number at the splitter lip also decreases.
Reduced mechanism for oxygen/methane combustion based on sensitivity analysis
HOU Jin-li, JIN Ping, CAI Guo-biao
2012, 27(7): 1549-1554.
Abstract PDF(764KB) icon2821 icon630
Abstract:
To investigate the oxygen/methane combustion in liquid rocket engine,a new set of reduced mechanism was developed for oxygen/methane based on sensitivity analysis.The reduced mechanism was then used in perfectly stirred reactor (PSR) of CHEMKIN 4. 1. The results show that the proposed kinetic mechanism shows good concordances with the detailed mechanism in the prediction of equilibrium temperature and major components concentration.The proposed reduced mechanism well reflects the oxygen/methane combustion in a wide range,laying the foundation for further efficient and accurate study of methane in the combustion chamber flow field.
Numerical sumulation on optimization design of contraction section in icing wind tunnel based on droplet trajectory
CONG Cheng-hua, PENG Qiang, WANG Fu-bo, FU Cheng
2012, 27(7): 1555-1561.
Abstract PDF(1011KB) icon1645 icon624
Abstract:
Performance of icing wind tunnel's contraction section was investigated by numerical simulation.For several typical wall contours were provided by former researchers,the flow field calculation using simplified 2-D (two-dimensional)model was performed,and the pressures along the centerline and the velocity distribution at the test section entrance were obtained.The numerical simulation results show that all contraction curves can prevent the separation of boundary layers,and the difference of fluid dynamics parameters is negligible except for cubic curve and fifth power curve(xm=0.4) which can't provide a specified degree of uniformity.Then droplet trajectory was studied by numerical simulation when different diameter water-liquid that the droplets were released.The numerical results state droplet accretion using Witozinsky curve is less compared with that designed by other curves.By comparing of several contraction curves' effect on flow field and droplet trajectory,it can be concluded that convergent section designed by fifth power curve (xm=0.5) has higher efficiency.
Structural parameter design of slot injection control for rectangle mix-compression inlet
YOU Jin, XIA Zhi-xun, LIU Bing, LV Zhong
2012, 27(7): 1562-1570.
Abstract PDF(2072KB) icon1672 icon668
Abstract:
Numerical simulation on structural parameter design of slot injection control restarting characteristics of rectangle mix-compression supersonic inlet was conducted.Effects of the slot position,width and injection angle on restarting characteristics were researched.A few unsteady numerical simulations were performed to verify the steady results.The steady calculation results show that new restarting flow impress such as movable pneumatic throat appears,and the supersonic mass spillage increases with the injection.Inlet restarts with the injection mass flux of 4.5%~11% inlet mass flux as 5% inlet mass flux spills out with the injection mass flux of 1% inlet mass flux.When the distance between lip and slot is 35~65mm,inlet would restart and has same restarting characteristics.With the increase of injection angle,spillage efficiency of injection enhances,and the range of injection mass flux for restart reduces.However the effects of slot width on spillage efficiency of injection and restarting characteristics of inlet is slight.
Experimental and numerical investigations of shock induced thrust vectoring nozzle
LI Wei-qiang, SONG Wen-yan, LUO Fei-teng
2012, 27(7): 1571-1578.
Abstract PDF(2119KB) icon1903 icon595
Abstract:
By inducting a secondary stream injection into the expanding part of a two-dimensional convergent-divergent nozzle model in the experiment, shock induced thrust vectoring technology was investigated. As the wall pressure distribution of the nozzle was measured and density field of the outflow was captured by schlieren, the effects of main stream pressure, secondary stream jet pressure and jet geometry(holes or a slot)on the performance of thrust vectoring nozzle was investigated. Numerical simulation method was used to calculate the flow field of the nozzle under different test conditions, and significant flow field data and performance parameters which were hard to capture by experimental method were obtained to analyze the test results as aid method. The investigation results indicated that: in the present conditions, with the increase of the main flow pressure, the angle of thrust vectoring is decreased and the thrust coefficient is added; with the increase of the secondary jet pressure, the angle of thrust vectoring is augmented and the thrust coefficient is descended; Compared with the jet hole, when the slot is applied, the separation point on upper wall is moved upstream due to induced shock. Moreover, the pressure is increased observably after the separation point, and the penetrabitity of secondary jet is strong, the effect of secondary jet on the main flow is intensified.
Research on two-dimensional hypersonic inlet based on dual-mode combustion
LI Hang, LI Bo
2012, 27(7): 1579-1587.
Abstract PDF(1548KB) icon1431 icon722
Abstract:
Design and study of a two-dimensional hypersonic inlet based on dual-mode combustion was conducted.The duct was divided into a supersonic duct and a subsonic combustion duct by a splitter plate.The influence of the geometry parameters on the inlet performance was mainly studied by using numerical method.The geometry parameters included the profile of the shoulder,the height and position of splitter plate,the turning position and expansion angle of transition duct,the height of subsonic combustion duct and the shape of the head of splitter plate.Results indicate that the profile of the shoulder,the height and position of splitter plate,the turning position of transition duct have great effects on the total pressure recovery coefficient,while the height of splitter plate,the shape of the head of splitter plate,the expansion angle of transition duct and the height of subsonic combustion duct have great effects on characteristics of back pressure.
Numerical simulation of wing/nacelle/pylon aerodynamic characteristics and their changes under powered condition
LI Qiang, WANG Ming-sheng
2012, 27(7): 1588-1594.
Abstract PDF(1170KB) icon1981 icon706
Abstract:
Based on DLR-F6 model,the wing -nacelle-pylon (W-N-P)configuration dynamic characteristics were calculated by computational fluid dynamics(CFD) method under through flow condition and powered condition respectively.The results show that the interference configuration passage shock wave and nacelle vortex would increase nacelle overall drag and reduce wing lift.The resistance would be lower under power condition compare with that under through flow condition.
Performance recovery control method for aircraft engine
HUANG Jin-quan, QIU Xiao-jie, LU Feng, LIU Nan
2012, 27(7): 1595-1603.
Abstract PDF(1556KB) icon1882 icon579
Abstract:
The performance recovery control system of an aircraft engine was designed for deterioration compensation due to aging.The system switched among the conventional speed control mode,steady state performance recovery control mode and acceleration performance recovery control modes,based on the engine operation condition and healthy condition.Steady-state performance recovery control mode is an outer control loop added on the conventional speed control mode to recover the deteriorated engine performance through adaptive adjust engine compressor speed command at steady state.Acceleration of recovery control modes ensures the air stability of the engine and fully taps the potential of the engine by integrating conventional speed control and surge margin control.Simulation results of different states under different components deterioratation show the validity of the proposed system.
Aero-engine fault diagnosis applying new fast support vector algorithm
XU Qi-hua, GENG Shuai, SHI Jun
2012, 27(7): 1604-1612.
Abstract PDF(714KB) icon1737 icon586
Abstract:
A new fast learning algorithm was presented to solve the large-scale support vector machine (SVM) training problem of aero-engine fault diagnosis.The relative boundary vectors (RBVs) instead of all the original training samples were used for the training of the binary SVM fault classifiers.This pruning strategy decreased the number of final training sample significantly and can keep classification accuracy almost invariable.Accordingly,the training time was shortened to 1/20 compared with basic SVM classifier.Meanwhile,owing to the reduction of support vector number,the classification time was also reduced.When sample aliasing existed,the aliasing sample points which were not of the same class were eliminated before the relative boundary vectors were computed.Besides,the samples near the relative boundary vectors were selected for SVM training in order to prevent the loss of some key sample points resulted from aliasing.This can improve classification accuracy effectively.A simulation example to classify 5 classes of combination fault of aero-engine gas path components was finished and the total fault classification accuracy reached 96.1%.Simulation results show that this fast learning algorithm is effective,reliable and easy to be implemented for engineering application.
Identification method based on support vector machines for turbofan engine steady state control in full flight envelop and various working conditions
LIU Jian-xun, LI Gang, LV Meng-jun, WEI Xun-kai
2012, 27(7): 1613-1618.
Abstract PDF(537KB) icon1671 icon556
Abstract:
To accomplish steady state optimal control of turbofan engine in full flight envelop and in different working conditions,nonlinear estimation methods based on linear steady state models of turbofan in all operation points were presented.The principle and algorithm realization of support vector machines for nonlinear controller approximation were improved.Then,the method used the improved support vector machines to establish the identification model of many linear optimization controllers designed for turbofan engine in some representative flight conditions.The controller design results for other operation points in the flight envelope can be conveniently educed by the model.For the identification model,the inputs were the steady rotation speed,the flight altitude and the flight Mach number,and the outputs were the parameters of the synthetic controller.The application examples show that the identification errors of the method in the whole flight envelop and various working conditions can meet the control precision need.
Research on cold start fuel flow control of aero-piston engine burning kerosene
WANG Chun-feng, WEI Min-xiang
2012, 27(7): 1619-1624.
Abstract PDF(816KB) icon1780 icon583
Abstract:
In order to solve the problem of cold start fuel flow control of an aero-piston engine fueled by kerosene,a fuel film compensation model based on fuel film theory was presented,and a discrete control algorithm running on microcontroller was given.What's more,a fuel flow control model for cold start which was based on fuel film compensation was simulated on Matlab/Simulink platform.The simulation result shows this control model can ensure sufficient kerosene flowing into the cylinder.Finally,the prototype burning kerosene experiments were performed,which shows that without changing fuel feeding and ignition system,the cold start capability of kerosene engine has been improved by cold start fuel flow control.
Unscented incremental filter method
FU Hui-min, LOU Tai-shan, WU Yun-zhang
2012, 27(7): 1625-1629.
Abstract PDF(380KB) icon1631 icon530
Abstract:
The unscented incremental filter(UIF)model and analysis method were put forward, in which its concept, basis equations and the recursive calculative steps were established, and special concern was given to UIF with additive noise. In practice, the measurement data have unknown system errors, for the environmental factors, the instability of measurement equipments and the improper models and parameters. Under these conditions, the classic unscented Kalman filter(UKF)have greater filtering error, and even lead to diverge. The presented UIF can successfully eliminate these unknown system errors and improve the filtering accuracy. The method is simple to calculate and easy to apply in engineering.
Optimization design of resin-based composite fan blade
HU Dian-yin, PENG Miao-jiao, WANG Rong-qiao, FENG Xiao-nan
2012, 27(7): 1630-1637.
Abstract PDF(1531KB) icon1941 icon545
Abstract:
Based on the study of the material properties and design criteria of resin-based composite,a structural design method of the resin-based composite material hollow fan blade was proposed,and then,the strength and vibration of the fan blade were studied.The results show that the resin-based composite material fan blade has better strength property and lighter weight than the traditional metal fan blade.Then an optimization design process of the resin matrix composite fan blade was established,during which the information transmissions of disciplines and application softwares were solved.Thus,the stacking sequence optimization design of the composite fan blade was achieved.It was verified that compared to the metal fan blade,the weight of the resin-based composite material fan blade decreased by 78.88% and the vibration margin increased by 8.44%.
Experiments on fatigue failure test of single-row multiple bolted joints in composite laminates
ZHU Yuan-lin, WEN Wei-dong, CUI Hai-tao
2012, 27(7): 1638-1645.
Abstract PDF(962KB) icon1643 icon532
Abstract:
The static tensile strength and fatigue characteristics of double-lapped three bolted joints of T300/BMP-316 composite laminates were tested,which included three sizes and two types of torques.In order to compare the differences in mechanics properties of three joints and single joint,the mechanics properties of single joints were also tested.To understand the double-lapped bolt hole's deformation with increasing load,the hole's deformation was measured.Experimental results show that the damage type is closely related to its size,and there are some errors in using mechanics properties of single joint to characterize mechanics properties of multiple joints,and the curve of bolt hole deformation-load is obtained.
Experiment on effect of gas film constraint on natural frequency of gas bearing-rotor system
HAN Dong-jiang, YANG Jin-fu, ZHANG Zhan-yi
2012, 27(7): 1646-1651.
Abstract PDF(620KB) icon1584 icon542
Abstract:
Experimental modal analysis (EMA) was presented on the 10kg rotor in free constraint state and gas film constraint state.The experimental results were given including rotor translation,conical moving and the first bending natural frequency and modal shape.The effect of gas film constraint on natural frequency of gas bearing-rotor system was analyzed by the experiment.EMA under gas film constraint was closer to the raising speed experimental results.The results provide a basis to determine the natural frequency of the gas shaft and to choose the control parameters.Also,it lays a foundation for vibration controlling of the gas bearing-rotor system.
Portable measurement and control system of rocket motor ground experiment
LI Xin-tian, YU Nan-jia, LI Jun-hai, CAI Guo-biao
2012, 27(7): 1652-1658.
Abstract PDF(785KB) icon1853 icon537
Abstract:
A set of portable measurement and control system of rocket motor ground experiment was proposed.It was designed according to the requirements of rocket engine ground test.Based on NI (National Instruments) USB (universal serial BUS) data acquisition device development,the system,portable and universal,was integrated with both measurement and control functions.Using the LabVIEW as the development environment,the software of the system,adopted with modularization ideology,gave a friendly human machine interface and was easy to expand.The system has been successfully used in several experiments and it can satisfy the requests of different types of rocket motor experiments.
Reusable technology for liquid rocket engine thrust chamber
KANG Yu-dong, SUN Bing
2012, 27(7): 1659-1664.
Abstract PDF(908KB) icon1911 icon595
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To validate the reusable technology for liquid rocket engine thrust chamber,the fluid-structural coupling method was adopted to simulate the effect of thrust chamber inner wall material,closeout thickness and regenerative cooling channel aspect ratio on the usable life of thrust chamber inner wall.Through computation,the stress and strain distribution of thrust chamber wall at different stage of each cycle under different inner wall materials,closeout thicknesses and cooling channel aspect ratios were obtained,and a post processing method was applied to predict the damage of the thrust chamber inner wall.The results show that the use of high yield strength inner wall material with reasonable ductility,low-stiffness closeout and high aspect ratio cooling channel can decrease the damage of thrust chamber inner wall and extend the usable life the thrust chamber.
Research on deflection of nozzle spray direction
WANG Yan-zhong, NIU Wen-tao, TANG Wen, GUO Mei, GUO Xia, ZHAN Peng, ZHAO Zhi-shu, SHEN Rong
2012, 27(7): 1665-1670.
Abstract PDF(722KB) icon1927 icon668
Abstract:
The jet flow deflection of aero-engine lubrication system was researched.The deflection mechanism was analyzed firstly.Then a three-dimensional numeric model of the nozzle was established based on the method and application of computational fluid dynamics(CFD).Then the spray direction with different inlet velocities and nozzle slenderness ratios was computed.Finally,the influential factor of the deflection and its rule were obtained through the comparison of the results.The study found that the radial velocity causeed the deflection of the spray direction.The greater ratios of radial velocity to normal velocity as well as length to diameter,the higher level the deflection.The results also show that the suitable match of inlet velocity and ratio of length to diameter result in no deflection.
Effect of different elastic ring installation locations in catcher bearing system on rotor drop dynamic responses
ZHU Yi-li, JIN Chao-wu, XU Long-xiang
2012, 27(7): 1671-1680.
Abstract PDF(1460KB) icon1841 icon573
Abstract:
Catcher bearings serve as the temporary support of the rotor once active magnetic bearings fail.Focusing on the huge impacts and vibrations after rotor dropped methods of,fixing an elastic ring on the rotor and outer race of the catcher bearing were separately adopted to buffer the series of impacts.The dynamic models of rotor drop for the two structures were established.Then,the established dynamic functions were numerically simulated to compare the different effect of the two proposed structures on the following impacts,rotor orbits and inner race speed after rotor dropped.On the basis of theoretical analysis,the corresponding experiments were performed.Both simulation and experimental results show that adding the elastic ring to the rotor is more effective to reduce the vibration amplitudes and impacts.

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