2009 Vol. 24, No. 10

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Mathematical model for calculating effects of target type thrust reverser on turbofan engine performance
WANG Zhan-xue, ZHANG Chen, LIU Chun-yang
2009, 24(10): 2157-2162.
Abstract PDF(803KB) icon1966 icon488
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The target thrust reverser doors are essentially two-dimensional,and the Mach number of reversed jet is between 0.30 and 0.50.By using the simplifying assumptions of inviscid,incompressible and two-dimensional flows,the flow within target thrust reverser was analyzed.In the analysis,a pair of transformations was used to calculate the ejection angle.According to the transformations,the ejection angle can be expressed as a function of reverser geometric parameters,such as door length,endplate height,door sweep angles and endplate angle.For calculating the actual reverser thrust,the model for calculating ejection angle was combined with the turbofan engine performance model.At last,with this model,the reverser thrust of a turbofan engine was calculated and compared with the test results,showing excellent agreement between them.
Effect of blowing and suction on friction drag of wall turbulent boundary layer
WANG Yu-chun, JIANG Nan, XIA Zhen-yan, TIAN Yan
2009, 24(10): 2163-2168.
Abstract PDF(1370KB) icon1246 icon491
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An experimental study was carried out to investigate the effect of local forcing on the friction drag of a turbulent boundary layer.The local forcing was given to the boundary layer flow by means of a sinusoidally oscillating jet issuing from a thin spanwise slot at the wall.The relationship among some inner-scales physical parameters,e.g.the mean-velocity profile,skin friction velocity and fluid dynamics viscosity,and the relationship between skin friction velocity and skin friction shear stress were taken advantage of accurately calculating skin friction drag.The velocity signals were decomposed into multi-scale eddy structures by wavelet transform.A conditional sampling technique for multi-scale coherent structures detection from simultaneous turbulent field was introduced using multi-scale instantaneous intensity factor of wavelet coefficients.Coherent structures for different scales were extracted by this technique and the effect of blowing and suction on friction drag was investigated in flat-plate turbulent boundary layer.The results reveal that friction drag is increased by the local forcing near the thin slot and decreased at downstream region.
Research about the techniques of burst detection in turbulent boundary layer with the mu-level algorithm
HU Hai-bao, SONG Bao-wei, HUANG Qiao-gao, LIU Zhan-yi
2009, 24(10): 2169-2175.
Abstract PDF(925KB) icon1447 icon435
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In order to resolve the problems that the analysis results of mu-level algorithm were influenced easily by measurement and detection parameters,the adaptability of burst-detection in turbulent boundary layer were researched in detail.Through contrast analysis of vertical testing position,sampling frequency,sampling time,boundary-parameter and accessional determinant condition,the influence rules of above factor on burst-detection were acquired,and feasible approaches to enhance burst frequency veracity in turbulent boundary layer were discussed.Finally,a four-step method of detecting burst frequency with mu-level algorithm(fore-sampling,fore-analysis,sampling,detection analysis) was summarized.
Numerical simulations of curved surface sidewall compression scramjet inlets with varied sweep angle and sidewall compression angle
JIN Zhi-guang, ZHANG Kun-yuan
2009, 24(10): 2176-2182.
Abstract PDF(1724KB) icon1617 icon523
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Two generic curved surface sidewall compression scramjet inlets with varied sidewall compression angle or with varied sweep angle and sidewall compression angle were studied to improve the performance of the conventional plane compression sidewall compression inlet.The flow field structures and overall performance were studied comparatively at Much number 4 and 6 by means of numerical simulations,and comparisons were made between this concept inlet and conventional inlet.Results indicate the performance of the curved surface inlet is obviously superior to the conventional inlet.The sidewall compression scramjet inlet with varied sweep angle and compression angle has the advantages of both backward and forward sweep sidewall compression inlet,such as: smaller spillage angle at cowl place,weaker cowl shock waves and more stable boundary layer on the top wall.Numerical simulations also show that,at Much number 6 design point,the mass capture ratio of the new curved surface inlet with varied sweep angle increases by 4.1% than that of the conventional inlet,and the total pressure recovery coefficient increases by 5.3%;at Much number 4 starting point,the mass capture ratio increases by 6.3%,and the total pressure recovery coefficient increases by 5.4%.
Numerical investigation of interaction between asymmetric crossing shock waves/turbulence boundary layer
ZHAO Hui-yong, LEI Bo, LE Jia-ling
2009, 24(10): 2183-2188.
Abstract PDF(1467KB) icon1700 icon466
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The flow field of crossing shock waves/turbulence boundary layer caused by 7°×11° double sharp fins was computed with Navier-Stokes equations and five turbulence models.The main focus was the resolution of wall pressure,heat transfer,adiabatic wall temperature and skin friction lines.The results demonstrate that: the region after the intersection of two oblique shock waves has a high pressure and heat transfer.As compared with the experiment,the computed surface pressure and skin friction lines are very good,the adiabatic wall temperature is moderate,and the heat transfer is poor because its peak is three times of experiment counterpart.Turbulence model has little effect on wall pressure and skin friction lines,whereas it has big effect on adiabatic wall temperature and heat transfer.TNT(turbulent/non-turbulent) and SST(shear-stress transport) models behave relatively well among these five turbulence models.
Micronozzle flow based on simulation of molecule movement
YANG Hai-wei, ZHU Wei-bing, ZHAO Yang
2009, 24(10): 2189-2192.
Abstract PDF(725KB) icon1609 icon503
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In-depth study on micro-nozzle flow field performance contributes to optimization design of micro-propulsion system.Under high Knudsen number conditions,a direct simulation Monte-Carlo method was employed for two-dimensional numerical simulation of the flow field within a Laval micro-nozzle at different inlet temperatures.The results show that along with the increase of fluid temperature at the entrance,micro-nozzle thrust would reduce and specific impulse would increase as the adhesive strength increase.Three-dimensional numerical simulation of micro-nozzle shows that thrust efficiency would decrease with the declining etching depth,and as the etching depth becomes deeper,the influences of three-dimensional boundary wall would reduce.
Numerical simulation of 3-D shock wave/turbulent boundary layer interaction using GAO-YONG turbulence model
YAN Wen-hui, GAO Ge
2009, 24(10): 2193-2200.
Abstract PDF(1165KB) icon1655 icon513
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This paper presented a numerical simulation method of three-dimensional shock wave/turbulent boundary layer interaction generated by a 20-deg sharp fin mounted on a flat plate at Mach number 2.93 and Reynolds number 9.8×105,based on incoming boundary layer thickness.This investigation was conducted based upon GAO-YONG compressible turbulence equations recently developed by GAO Ge and YONG Yan.The equations were discretized using a finite volume method with the convection terms and diffusion terms calculated by the third-order Roe's flux difference splitting scheme and the second-order central difference scheme,respectively.The Runge-Kutta time marching method was employed to solve the governing equations for steady state solutions.Numerical results were compared with available experimental data in the form of surface pressures and boundary layer surveys of yaw angles.The computed three-dimensional flowfield shows most of the features covering λ-structure shock wave,primary vortex,separation region,and high-speed jet impingement;meanwhile,quasi-conical behavior of the surface pressure,surface attachment and separation streamlines exhibited in quasi-conical flowfield model of Alvi and Settles are presented.
Study of flow characteristics for a variable geometry inlet on combined engine
ZHANG Hua-jun, LIANG De-wang, GUO Rong-wei
2009, 24(10): 2201-2207.
Abstract PDF(2075KB) icon1599 icon450
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The 3-D flow fields in a variable geometry inlet on combined engine at different Mach numbers were numerically analyzed.The characteristics of the inlet flow at different Mach numbers were compared and discussed.The results show that the spillage increases and the mass flow ratio decreases with the decline of the Mach number.The first internal shock and its reflective position are important to organize the flow field in the internal passage.With backpressure at the exit of the inlet,the shock train could be formed in the diffuser.The free stream Mach number,backpressure and flow condition in the internal passage determine the form and position of the shock train.The conclusions may be useful to the research for variable geometry inlet on combined engine.
Computational analysis on shock induction control of circular vectoring exhaust nozzle
QIN Ya-xin, YU Jun-li, GAO Ge
2009, 24(10): 2208-2212.
Abstract PDF(1052KB) icon1568 icon456
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Three-dimensional Reynolds average Navier-Stokes equation was solved by using the time marching method in finite volume,and circular convergent-divergent nozzle flow fields in shock induction control vector scheme were numerically simulated.Injection pressure ratio and nozzle pressure ratio were considered in numerical analysis in this paper.The results indicate that,thrust vectoring can be obtained through the shock induction control scheme to turn the main flow.The vector angle reaches 15.35° when the nozzle pressure ratio is 4 and injection pressure ratio is 1.499.Through analysis,the shock surface formed in the circular exhaust nozzle was three-dimensional,and its configuration was complicated.The computational analysis is helpful for better understanding of the flow field structure of vectoring nozzle in experiments.
Study on the blade pitch control of electrically controlled rotor in hover
XIA He-ming, LU Yang
2009, 24(10): 2213-2220.
Abstract PDF(1495KB) icon1470 icon501
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In order to control the blade pitch of the electrically controlled rotor(ECR) accurately,the mathematic models of every part of the ECR system were built based on the improved ECR system.Then the cascade proportion integration differentiation(PID) control method was introduced to design the control law for the blade pitch of ECR in hover based on the mathematic models,and the PID parameters were tuned with the Ziegler-Nichols method.The results of the simulation analysis verified preliminarily the effectiveness of this control method.Based on the method,the open-loop and closed-loop control experiments were carried out for collective and cyclic pitch control in hover.Successful control of the amplitude and phase of ECR blade pitch was realized.And the test results verified the accuracy and effectiveness of the cascade PID control method as well.
Wind tunnel experiment of the influence of dynamic change of attack angle on start property of sidewall compression scramjet inlet
GUO-Bin, ZHANG Kun-yuan
2009, 24(10): 2221-2227.
Abstract PDF(1507KB) icon1545 icon492
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In order to explore how the change of attack angle at different frequencies influences the start property of inlet,this paper conducted a wind tunnel experiment for the sidewall compression scramjet inlet with Mach number 3.85 and attack angle at different frequencies.The sidewall compression scramjet inlet,with designed Mach number 6 and start Mach number 2.5,was subject to several flow tests,when attack angle changed from 0°to 8.15° again down to 0°,with the frequency at 0.8,1.6,3.2 Hz and 6 Hz,respectively.Results show that at each frequency,the inlet in a periodic oscillation succeeds to go through a start-unstart-restart process.With the increase of frequency,attack angle gradually goes up in the first periodic oscillation,and sharply goes down in the proceeding periodic oscillation.
Experiments on infrared radiation characteristics of exhaust system for a turbofan engine
SHAN Yong, ZHANG Jing-zhou, SHAO Wan-ren, SHANG Shou-tang
2009, 24(10): 2228-2234.
Abstract PDF(1771KB) icon1649 icon617
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One fifth scaled model was constructed for the turbo-fan exhaust system according to one-type engine for experimental research.The capability of infrared radiation suppression of the lobed forced-mixer was validated by some model experiments.The experimental data show the lobed forced-mixer can decrease the exhaust system infrared radiation.In detail,the lobed forced-mixer enhances the mixing between core flow and bypass flow to decrease the plume temperature by 11% and infrared radiation intensity by 7.3%～22.6% within 3～5 μm band as compared to confluent mixer.The bypass ratio was enhanced from 0.233 to 0.685,plume temperature reduced by 21% and infrared radiation intensity depressed by 30%～59% at different detected angles within 3～5 μm band.The plume and interior wall temperatures decrease accounts for the depression of exhaust system radiation intensity.
Effect of area ratio of impingement hole to effusion hole on heat transfer characteristics of impingement-effusion composite cooling
ZHANG Bo, LI Ji-bao, JI Hong-hu, SHANG Shou-tang, CHENG Ming, WANG Yan-li
2009, 24(10): 2235-2240.
Abstract PDF(1106KB) icon2070 icon494
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The influence of area ratio to heat transfer characteristics of impingement-effusion double wall was investigated numerically,under the precondition of the same equivalent hole area.Results show that,with the decrease of area ratio of impinging hole to effusion hole,film flow velocity decreases,impinge cooling heat flux increases,and the cooling effectiveness enhances.The heat fluxes of hot side wall,cold side wall and effusion hole wall decrease with the area ratio,but the last one decreases least,and its quotient among the total heat flux increases.
Numerical investigation of influence of swirler on combustion performance in annular combustors
LI Jing-hua, CAI Wen-xiang, LEI Yu-bing, LIU Yong, ZHAO Jian-xing
2009, 24(10): 2241-2248.
Abstract PDF(2303KB) icon1627 icon513
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In this paper,influences of various swirlers on flow fields and combustion performance in annular combustors were numerically investigated.The block-structured grids of annular combustors with swirlers(dual-stage axial,swirl cup and three-stage axial) were generated by solving a system of elliptic partial differential equations with the zone data transmit method.Three-dimensional two-phase combustion integrated flow fields of three different annular combustors including swirler,flame tube,dump diffuser,inner and outer cooling annuluses were calculated in arbitrary curvilinear coordinates.The gas and liquid phases were treated with Eulerian and Lagrangian methods,respectively.Combustor performances were estimated by the empirical-analytical design method.Calculations are in agreement with experimental data.Predictions indicate that the numerical procedures are reliable for numerical investigation of influence of different swirlers on combustion performance in annular combustors.
Experiment investigation on atomization characteristic of an air-blast atomizer with centrifugal nozzle and co-dual-swirl cup
GUO Xin-hua, LIN Yu-zhen, ZHANG Chi, HUANG Yong
2009, 24(10): 2249-2254.
Abstract PDF(843KB) icon1667 icon581
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An air-blast atomizer consisting of a centrifugal nozzle and co-dual-swirl cup was experimentally investigated to obtain atomization characteristics.The radial columnar swirlers were adopted.The experiment was performed in the room temperature and atmospheric pressure to obtain Sauter mean diameter and Rosin-Rammler distribution parameter at different atmosphere pressure drops and fuel pressure.In the experiment,the fuel was RP-3.Sauter mean diameter and distribution parameter of fuel spray were measured by Marlven particle size analyzer in the downstream 50 mm of the nozzle.The experimental results show that Sauter mean diameter decreases and distribution parameter increases with rising atmosphere pressure drops and fuel pressure.Two Sauter mean diameter calculation models were adopted in two different air pressure drops(Δp/p＜3% and Δp/p＞3%).
Piston reshapes study for the air-cooled engine of aerial vehicle
ZHAO Li-feng, LI Yun-qing, WANG Hai-ying, CHENG Chuan-song, HE Peng
2009, 24(10): 2255-2259.
Abstract PDF(1806KB) icon1467 icon540
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The piston's thermal field and deformation of air-cooled engine were studied to solve the problem that piston temperature is difficult to measure in high-altitude environment.The temperature field and thermal deformation of piston were calculated by thermal-solid coupling FEM(finite element method);the contact pair and thermal resistance were applied to couple the multipart.The loads of temperature and gas pressure were applied to the piston.The deformation under gas pressure can be helpful to reshape the piston when the piston structure is designed specially;so the conclusion provides the practical reference for further improving the structure and optimizing the design of piston at high altitude.
Experimental investigation on cooling performance of laminated configuration using infrared thermal imaging technique
Lv Xi-jia, WANG Jian-hua, LIU Qing-dong, WU Xiang-yu
2009, 24(10): 2260-2265.
Abstract PDF(1269KB) icon1572 icon503
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To investigate the geometrical performance of laminated film cooling configurations,the surface temperature distributions of three different specimens with true size of gas turbine components were measured by an infrared thermal imaging system.Experiments were carried out in the hot gas wind tunnel of University of Science and Technology of China(USTC).To describe the overall cooling effect contributed by coolant impingement,heat conduction and convection,an algorithm of digital imaging signal was used,and the two-dimensional temperature drops from initial wall to cooled wall were directly obtained.Through comparisons of the cooling performance of these three specimens,the effects of the number and diameter of columnar ribs,the angle of film holes,the Reynolds number and Nusselt number of free stream on the overall cooling effectiveness were discussed.
Influence of dimple space on heat transfer enhancement and pressure loss in a dimpled rectangular channel
ZHAO Peng, LIU Gao-wen, ZHU Xiao-hua, LIU Yu-feng
2009, 24(10): 2266-2271.
Abstract PDF(854KB) icon1521 icon438
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Heat transfer coefficient and pressure loss measurements were carried out on spheric dimpled test surfaces placed on one wall of a rectangular channel.Three dimpled plates with non-dimensional streamwise space 1.5,1.2,and 0.8,were tested to provide information on the influences of dimple space.Significant local Nusselt number variations were observed at different streamwise and spanwise locations.Comparing the dimpled wall with the smooth wall,globally-averaged Nusselt numbers increase around 45%,friction factors increase around 92%,and globally-averaged thermal performance parameters increase 16%.Decreasing dimple space results in the increase of friction factors,globally-averaged Nusselt numbers and thermal performance parameters.Data also illustrate that the influences of Reynolds number on Nusselt number ratio and friction factor ratio are relatively small.
Experimental study on the influence of fuel supply position of concave cavity on the flow field in trapped vortex combustor by PIV
LIU He-xia, LIU Yu-ying, LI Rui-ming, YANG Mao-lin
2009, 24(10): 2272-2276.
Abstract PDF(1434KB) icon1568 icon528
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The flow field of cavity with fuel supply injection located at the forebody and afterbody in trapped vortex combustor(TVC) was studied using particle image velocimetry(PIV) testing technology.In order to study the influence of fuel supply position on the formation of vortex and vortex stability,different incoming flow velocities and fuel supply locations were analyzed.The results show that,when the fuel supply position is located at the forebody of cavity,the jet flow of fuel supply has certain damage to vortex,and when the fuel supply injection is located at the afterbody of cavity,the jet flow of fuel supply has no damage to vortex.These results provide the fundamental proof for the further studies on the combustion properties of this TVC test rig.
Study on imbalance-misalignment-rubbing coupling faults in aero-engine vibration
CHEN Guo, LI Xing-yang
2009, 24(10): 2277-2284.
Abstract PDF(2191KB) icon1628 icon546
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A new rotor-ball bearing-stator coupling system,including imbalance-misalignment-rubbing coupling fault,was established for aero-engine vibration.In the coupling system,the stator motion was considered,and the nonlinear factors of ball bearing such as the clearance,nonlinear Hertzian contact,and the varying compliance(VC),were fully taken into account;in the process of fault coupling,the imbalance,the misalignment and the rubbing faults were modeled respectively.The numerical integral method was used to obtain system's responses,and the characteristics about the coupling faults were analyzed.The simulation results indicate the correctness and effectiveness of the new model.
Temperature fields calculation of 3-D particle reinforced composite
SUN Zhi-gang, SONG Ying-dong, GAO Xi-guang, MIAO Yan
2009, 24(10): 2285-2290.
Abstract PDF(1977KB) icon1575 icon526
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The higher-order theory was developed to three-dimension,coefficients of temperature function were replaced by surface-averaged temperature to be primary variables of equations,and the concept of sub-cells was canceled.The number of equations was reduced so that computational efficiency was increased effectively.During the thermal analysis of represent volume element,heat exchange equations which were established by the relationship between hear flux and average temperature were used to compute temperature,The comparison of numerical results with finite element analysis demonstrates the correctness and validity of this method.
Analysis of damp trial result of Ti17 simulation blade in air
WANG Mei, LU Shan, Gu Yuan-xing
2009, 24(10): 2291-2295.
Abstract PDF(507KB) icon1873 icon497
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Through simulation blade's damp trial in air,various order vibration model attenuation coefficients have been achieved by the method of free vibration attenuation,then various order vibration model damp ratios were obtained,and the ratio damp coefficients were deduced.These could offer reference for analysis of the relationship between the blade's damp and vibration model in nature and deciding the damp coefficient when calculating the response.
Method for diagnosing rub fault of rotor-stator based on differences of singularly values
HE Tian, LIU Xian-dong, CHEN Ya-nong, LI Qi-han
2009, 24(10): 2296-2301.
Abstract PDF(1252KB) icon1543 icon465
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To overcome the limitation of the methods for diagnosing aero-engine rub fault based on singular value decomposition(SVD),the method for reconstructing abrupt information by using the differences of the singular values was presented based on the reconstructed signal's energy components derived by means of matrix analysis,and the fault diagnosis process was established.The presented method was verified by simulation signals,and the results confirmed the consistency of the presented theory.Finally,the method was applied to process the test data of an aero-engine,and the rub fault was diagnosed successfully.The results show that the presented method is effective to detect rotor-stator rub fault of the aero-engine.
Kinematics modeling and analysis of a military exploration vehicle with wheel-tracks
SHANG Wei-yan, LI Shun-ming, BAO Qing-yong, ZHANG De-man
2009, 24(10): 2302-2307.
Abstract PDF(2042KB) icon1232 icon516
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In order to make the locomotion of the exploration vehicle more controllable,a new method was presented to establish the kinematics model of the wheel-tracked exploration vehicle.By analyzing the structure of the moving system,the kinematics model of exploration vehicle was set up and kinematics equations were deduced.Then the velocity Jacobian matrix between the bodywork and the wheels was established,and least squares method was used to compute the bodywork's velocity to estimate the position and orientation of the exploration vehicle.At last,numerical simulation was made to prove the kinematics characteristics of the exploration vehicle,whilst the adaptability and capability of obstacle surmounting was validated.
Numerical simulation of the disk fragment impacting resistance of plate target
LI Juan-juan, XUAN Hai-jun, HONG Wei-rong, WU Rong-ren
2009, 24(10): 2308-2313.
Abstract PDF(1198KB) icon1811 icon432
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In order to investigate the ballistic resistance and failure pattern of the casing with the impact of disk fragment,and find out structure optimization method,the phenomena of 1/3 disk fragment impacting on single and double layers plate target were simulated using nonlinear dynamical analysis software Dytran.Johnson-Cook material model was introduced for the disk fragment and the plate target,along with Gruneisen equation of state.Based on Lagrange method,impaction was simulated using explicit finite element method.Simulation results show that the major failure patterns of the plate target include plastic deformation,shear and tensile fracture,and that the single-layer plate has greater resistance than any other double-layered plates.Conclusions are also made that the ballistic limit velocity increases with the distance when it is beyond a certain value,and that the greater resistance is obtained in low or high proportion of the first layer with a constant of the total thickness.So,the resistance of double-layered plate targets may exceed that of the single plate,by reasonably arranging the thickness and the standoff distance of two plates.
Experimental investigation on the influence of bowed blade in ultra-highly loaded turbine cascade
ZHANG Hua-liang, TAN Chun-qing, DONG Xue-zhi, ZHAO Hong-lei
2009, 24(10): 2314-2318.
Abstract PDF(1374KB) icon1172 icon454
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An experimental investigation was performed to analyze the influence of bowed blade on the aerodynamic performance of the turbine cascades with high-turning angle of 160° through flow visualization and topological analysis of the flow patterns.The result shows that the influence of bowed blade on ultra-highly loaded turbine cascades with high-turning angle is different from the common turbines.A positive bowed blade deteriorates the flow structure,and the flow loss increases distinctly.A negative bowed blade improves the aerodynamic performance of the turbine cascades,and the flow loss is reduced.
Numerical method of compressible flow on three-dimensional sub-block unstructured grid
WANG Bao-tong, ZHANG Chu-hua, XI Guang
2009, 24(10): 2319-2325.
Abstract PDF(2935KB) icon1739 icon480
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A numerical method for calculation of internal flow in turbomachinery was developed.Firstly,the sub-block unstructured grid generation method was proposed.The complex multiple-connected flow domain was divided into several simple single-connected sub-blocks,and then each sub-block was discretized into body-fitting meshes,finally,each sub-block grid was united to form a whole grid,whose topological connection information was saved by unstructured grid manner.The sub-block unstructured grid not only has the advantage of unstructured grid in dealing with the complex domain,but also avoids the disadvantage of multi-block grid in treating the complicated flow field variable transfer on the interface between sub-blocks.Secondly,a three-dimensional compressible semi-implicit method for pressure linked equation(SIMPLE) algorithm on sub-block unstructured grid was developed by introducing the density correction term in the pressure correction equation.Finally,the proposed methods were used to numerically solve the flow fields around an isolated airfoil and in a turbine cascade.The accuracy of the method was validated by the good agreement between the numerical results and the experimental data.This work is of theoretical significance and applicable value to develop the numerical method for solving the complicated internal flow in turbomachinery.
Three-dimensional viscous numerical investigations on the overall aerodynamic performance of transonic axial-flow compressors
JIA Hai-jun, WU Hu
2009, 24(10): 2326-2332.
Abstract PDF(2356KB) icon1559 icon490
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The internal 3-D viscous flow fields of the transonic axial-flow compressors were numerically analyzed using a time-marching finite difference method.This calculation method was developed by the LU-SGS(lower-upper symmetric Gauss-Seidel) implicit scheme and NND(non-oscillatory,containing no free parameters and dissipative) scheme with Steger-Warming flux vectors splitting technique,and the centered difference scheme was used for the viscous portion.The mixing plane model was employed to simulate the internal 3-D viscous flow fields of multistage axial-flow compressors,so the overall performance for NASA rotor 37,NASA rotor 67 and one stage compressor was obtained and the internal flow fluids were analyzed in detail.As compared with experimental data,the good agreements are found,indicating the model and method are feasible and reliable.
Effect of hub-shape contouring on the corner blockage of compressor stator cascade
YANG Chun, LI Qiu-shi, YUAN Wei, ZHOU Sheng
2009, 24(10): 2333-2337.
Abstract PDF(1402KB) icon1596 icon449
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After analyzing the mechanism of the end wall blockage from stator corner flow separation in compressor,the hub-shape contouring was presented in this paper.The RANS(Reynolds-averaged Navier-Stokes) numerical calculations of real cases of compressor stator show that modifying hub shape can depress efficiently the corner flow separation so as to decrease end wall blockage.Subsequently,the corner blockage of the outlet of stator cascade was decreased by 20.4% and the total pressure recovery coefficient of 10% blade height was increased from 0.89 to 0.948 by the concave profile near the separation point of stator end wall.
Numerical simulation of the aerodynamics performance of swept and curved blade on the compressor stator
FENG Xiu-lian, JIN Dong-hai, GUI Xing-min
2009, 24(10): 2338-2343.
Abstract PDF(1630KB) icon1585 icon574
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NUMECA commercial software was used to simulate some axial-centrifugal compressor with bypass.In order to induce the flow separation on the surface of the core stator,three kinds of blades were used in the design course,i.e.straight blade,backward swept at foot and both backward swept at foot and forward swept at tip,respectively.The results show that,the swept and curved blade can reduce the pile of the low energy flow at corner,and restrain the flow separation,improving the flow at the corner and enhancing the overall performance of the blade.The paper also made some computation about the solidity influence on the cascade aerodynamics.The results show that,reasonable solidity can change the flow field structure,and reduce the secondary loss of the cascade.
Backstepping control strategy for aero-engine using neural networks
PAN Mu-xuan, HUANG Jin-quan, YIN Shi
2009, 24(10): 2344-2348.
Abstract PDF(455KB) icon1473 icon485
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A Backstepping control strategy based on neural network was presented in view of nonlinearity and uncertainty of aero-engine.Radial basis function(RBF) neural network was used to estimate the equations of the unknown system,and a smooth-switching algorithm was proposed to avoid singularity phenomenon.Using Lyapunov stability analysis,the uniformly ultimately boundedness of closed-loop systems was proven.Finally,the compressor speed controller was designed based on a nonlinear model of some turbofan engine.The simulation results illustrate the effectiveness of the proposed approach.
PID decoupling controller for aero-engine based on support vector machines
WU Yong, Xie Shou-sheng, TANG Qi, WU Wei, WANG Hai-tao, MIAO Zhuo-guang
2009, 24(10): 2349-2355.
Abstract PDF(652KB) icon1568 icon496
Abstract:
To solve the coupling problem in aero-engine multivariable control system,a new PID(proportion integration differentiation) decoupling controller based on support vector machines(SVM) was proposed.The SVM was applied to identify the aero-engine model,and then linearized to extract the instantaneous linear model.The PID parameter was obtained based on the linear model.The convergence of PID decoupling controller was proved with the help of Lyapunov stability theorem.Simulation results of certain aero-engine system demonstrate the effectiveness and feasibility of the PID decoupling controller based on SVM.
Condition monitoring of aero-engine based on neural network and fuzzy logic
SHAN Xiao-ming, SONG Yun-feng, HUANG Jin-quan, QIU Xiao-jie, LU Feng
2009, 24(10): 2356-2361.
Abstract PDF(563KB) icon1801 icon484
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The condition monitoring system based on neural network and fuzzy logic for an aero-engine was proposed,which covered data validity and health assessment.According to the validity inspection of dynamic data based on BP(back propagation) neural network,the measurement parameters exceeding normal boundary or otherwise was detected,and the boundary of instantaneous parameter could change along with aero-engine status.Fuzzy logic was used to estimate health parameters,and the abnormity caused by performance degradation was real-time monitored.Digital simulation carried out on a given turbofan engine highlights the validity of the condition monitoring system based on neural network and fuzzy logic.
Stability analyzation of aero-engine distributed control system
PENG Jing-bo, XIE Shou-sheng, WU Wei, SUN Dong
2009, 24(10): 2362-2367.
Abstract PDF(1522KB) icon1775 icon455
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The aero-engine distributed control system(DCS) with time-delay and data-packet dropout was established as an asynchronous dynamical system.Exponent stability of the system was presented using 2nd Lyapunov method and linear matrix inequalities(LMI) formulation,and the state-feedback control parameters of DCS could be obtained according to the stability criterion.Simulation examples show that the stability criterion is feasible.
Software componentization modeling for aero-engines
SUN Long-fei, SUN Jian-guo, ZHANG Hai-bo
2009, 24(10): 2368-2371.
Abstract PDF(939KB) icon1730 icon442
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A methodology was proposed to develop generic aero-engine simulation platform by using software componentization.From the point of view of the engine construction engine model was broken down into several components,from the point of view of software functions the supplementary part of the simulation software was also broken down into multiple components.And a simulation platform of turbofan engines was established,which had achieved good effect.The simulation system based on this method had achieved to be modular,hierarchical,and easy to be maintained and improved.It has strong expandability,and has increased code reuse rate,which reflects the flexibility of the framework of the simulation platform.
Multi-phase flow effect on SRM nozzle flow field and thermal protection materials
SHAFQAT Wahab
2009, 24(10): 2372-2378.
Abstract PDF(1205KB) icon1269 icon462
Abstract:
Multi-phase flow effect generated from the combustion of aluminum based composite propellant was performed on the thermal protection material of solid rocket motor(SRM) nozzle.Injection of alumina(Al2O3) particles from 5% to 10% was tried on SRM nozzle flow field to see the influence of multiphase flow on heat transfer computations.A coupled,time resolved CFD(computational fluid dynamics) approach was adopted to solve the conjugate problem of multi-phase fluid flow and heat transfer in the solid rocket motor nozzle.The governing equations are discretized by using the finite volume method.Spalart-Allmaras(S-A) turbulence model was employed.The computation was executed on the different models selected for the analysis to validate the temperature variation in the throat inserts and baking material of SRM nozzle.Comparison for temperatures variations were also carried out at different expansion ratios of nozzle.This paper also characterized the advanced SRM nozzle composites material for their high thermo stability and their high thermo mechanical capabilities to make it more reliable simpler and lighter.
Method of amorce mass estimation for solid rocket motor
FAN Chao, ZHANG Wei-hua, WANG Zhong-wei
2009, 24(10): 2379-2383.
Abstract PDF(303KB) icon1673 icon463
Abstract:
In order to break through the limitation of traditional engineering empiric formulas for amorce mass estimation,a method was introduced based on the hypothesis of solid phase ignition.The formula was used to estimate the amorce mass for solid rocket motor in different concepts and configurations.The results indicate the estimations agree well with the experiment values.The results show that this method is superior to classic engineering formulas in estimation precision and applicability.
Model and algorithm of optimal embedded sensors placement for gearboxes based on signed directed graph of vibration propagation
CHEN Zhong-sheng, YANG Yong-min, LI Cong, YIN Jian-fei
2009, 24(10): 2384-2390.
Abstract PDF(2472KB) icon1691 icon480
Abstract:
Owing to the fact that sampling ways and propagation paths of vibration signals under embedded ways are much different from those of traditional methods,the fault vibration propagation characteristics in a gearbox under the condition of embedded sensing were studied based on finite element simulations.Then,an optimal placement model was built based on signed directed graph(SDG) of faults vibration propagation in a gearbox,and a solution algorithm was proposed based on particle swarm optimization(PSO).Finally,an example was presented and simulation results demonstrate that the proposed methods are feasible,providing an effective way to embed sensors into a gearbox.
Dynamic response analysis of gear drive with face-gears
CHEN Guang-yan, CHEN Guo-ding, LI Yong-xiang, ZHAO Ning
2009, 24(10): 2391-2396.
Abstract PDF(2042KB) icon1547 icon445
Abstract:
The dynamic model of drive system with a face-gear in helicopter transmission was presented.The excitation analysis of rotor to drive system in the cruise and the hover condition was carried out,while the dynamic load coefficient response between face-gears and a pinion in two flight conditions was computed.In the fixed installation and the floating installation,amplitude variation study of dynamic load coefficient between face-gears and a pinion with change of the non-dimensional rotor excitation frequency was developed.It is theoretically and practically significant to the development of helicopter transmission with a face-gear drive in our country.

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