2002 Vol. 17, No. 3

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Assessment of Linear Eddy-Viscosity Turbulence Models in Shock/Boundary-Layer Interaction
YANG Xiao dong, MA Hui yang
2002, 17(3): 273-279.
Abstract PDF(1117KB) icon1718 icon466
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Five popular turbulence models have been tested and validated against experimental data of two turbulent flows.The models are:(1)the zero equation model of Baldwin Lomax;(2)the two equation k ε model of Jones and Launder;(3)the two equation k ω model of Wilcox;(4)the two equation k ω/k ε SST model of Menter;(5)the two scale k ε model.The benchmark flows are two transonic flows over bump geometries with shock wave/boundary layer interaction including separation.The computational results demonstrate that the SST model yields superior performance and the zero equation turbulence model does not provide satisfactory results.
Numerical Simulation of Flow Field in Circularly Lobed Exhaust-Ejector Mixer with/without a Central Plug
LIU You hong, LI Li guo
2002, 17(3): 280-286.
Abstract PDF(432KB) icon1812 icon475
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The role of the central plug in promoting the thermal mixing between the primary and the secondary flows of the circularly lobed nozzle was assessed mainly by the numerical simulation.The fundamental equations were derived in the body fitted nonorthogonal coordinates from cylindrical coordinates for the circularly lobed exhaust ejector mixers with/without a plug in the center of the lobe.These equations were solved using SIMPLEC and a kind of complete pressure correction algorithm in the nonstaggered grids,with the velocity components in physical plane as solving variables and the contravariant velocity components as boundary velocities of the controlled volume.Better agreements have been observed between the numerical results and the experimental values.The numerical results show that there are great differences between the temperature contour in the outer section of the column mixer with the plug in which the low temperature contour lines can reach the center line of the mixer,and that in the outer section of column mixer without the plug in which the elevated temperature contour lines always lie in the central zone.This is the basic reason why the thermal mixing efficiency of the mixer with the plug is much more than that of the mixer without the plug.
LDV Measurements of Three Dimensional Turbulent Flow Field in a Centrifugal Impeller
LIU Zheng xian, JIANG Yin ping, CAO Shu zhen, LIN Mei, MIAO Yong miao
2002, 17(3): 287-291.
Abstract PDF(644KB) icon1853 icon500
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A Laser Doppler Velocimeter (LDV) and shaft encoder was used to measure velocities at the design flow of the shrouded centrifugal backswept impeller.Measurements of the three-dimensional velocity field were acquired at several main planes through the passage.The measurements described both the through flow velocity field along circumferential measurement planes and the velocity vector at radial planes.It was found that the high velocity flow was held near the hub side on the suction surface of blade passage and shifted from the hub to the shroud side on the pressure surface as the fluid approached the exit.The results also provided the evidence of the development of a "wake" of low momentum fluid near the shroud at midpitch at the exit.The velocity vector plots showed that the flow angles on the hub were very differential from those on the shroud side because of the fluid viscosity.The results indicated that the secondary flow generated in vertical direction of the main flow velocity was related to curvature and rotating of impeller.The secondary flow velocity vector plots were also presented at the middle passage and exit.The development of the secondary vortex along impeller blade passage has been clearly observed and recorded.
Numerical Investigation of Base Bleed Effect on Aerospike nozzle
DAI Wu ye, LIU Yu, ZHANG Zheng ke
2002, 17(3): 292-296.
Abstract PDF(336KB) icon1643 icon482
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The numerical simulations of the flow field around aerospike nozzle were completed based on N S equations with second order NND scheme.The attention is paid to the effect of the base bleed on aerospike nozzle at sea level,middle and high altitude.The results indicate that both the quantity of bleed mass flux and the magnitude of base pressure are the causes that induce the swirl in the base area to disappear.Though the bleed can enlarge the thrust of the aerospike nozzle,it lessens the specific impulse except the case that the bleed is small at low flight altitude for the linear aerospike nozzle.
Jameson/TVD Schemes Applied to Simulating the Flow around Rotor Aerofoil
CAO Yi hua, WANG Ji fei, SU Yuan, DENG Dan dan
2002, 17(3): 297-301.
Abstract PDF(312KB) icon1628 icon554
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Two methods based on Jameson scheme and Jameson/flux correction TVD (Total Variation Diminishing) mixed scheme are constructed to simulate the flow around rotor airfoil.By using finite volume approach for numerical approximation and Runge Kutta time stepping advance,Euler/Navier Stokes equations are solved.Through the analyses of examples,the characteristics of these two methods are concluded.Also,these methods can be further developed to simulate the turbulent flow around helicopter rotor and to calculate helicopter rotor drag and power.
Experimental Investigation of Chin Inlet
WANG Xin yue, LIAN Xiao chun
2002, 17(3): 302-304.
Abstract PDF(197KB) icon1525 icon397
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In order to prove the reason of chin inlet/forebody integrated design and the performance of the inlet,the experimental investigation of the chin inlet configuration of a new design was done.In this experiment,Total pressure recovery (inlet efficiency) and pressure distortions at inlet varied with mass flow coefficient were measured.The experimental results show that this new design configuration is reasonable.Total pressure recovery and pressure distortions at the chin inlet are improved.Inlet/Forebody integration design is advantageous for aircraft.In the end,further improvement of the inlet is presented.
Automatic Design Optimization of Compressor Blades
ZHOU Zheng gui
2002, 17(3): 305-308.
Abstract PDF(733KB) icon1579 icon471
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In automatic aerodynamic optimization of blade shapes,the construction of design parameters of blade profiles needs to achieve that the number of the parameters is fewer but the blade profiles possess larger variability.In this paper,blade profiles are formed using blade mean camber lines and distribution of blade thickness along the camber lines.For construction of blade mean camber lines,the combination of a third order polynomial and a multi arc curve are used.The blade thickness is distributed by another third order polynomial.As examples,using above descriptive method,a low speed profile and a transonic blade profile can be satisfactorily reproduced.An automatic optimization algorithm is developed,in which the simplex method is adopted to search for optimal objective;the objective function value for aerodynamic optimization is calculated using the N S equation method.As an example,setting elimination of separation in the blade suction surface as an objective,the automatic optimization algorithm can achieve the objective satisfactorily.
Research on the Combined Cascade
YANG Bo, OUYANG Hua, ZHONG Fang yuan, GU Chuan gang
2002, 17(3): 309-313.
Abstract PDF(284KB) icon1417 icon463
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In this paper,a new design,named combined cascades,which is applied to blade design of reversible axial fan,is put forward based on the assimilating of the previous experience,the advanced technology and the up to date thinking.A new criterion for judging the blade performance in reversible axial fan is presented.NACA0012 airfoil is singled out as the experimental airfoil of the combined cascades.In the two dimensional wind tunnel experiment,the comprehensive performance of the combined cascades is understood through analyzing pressure contours of both the blades and substantive data got from inlet and outlet of cascade at the different overlap ratios,pitch ratios and attack angles.Based on analyzing and comparing results gotten from experiment,it is found that the aerodynamic characteristic of combined cascades is superior to any other cascades.Compared with S type airfoil,which is specifically designed for reversible axial fan,maximum lift coefficient C N+R y max of the symmetrical combined cascades is improved by about 20% and the stall attack angle α N+R C y max about 23 5%.And with NACA0012 single cascade,lift coefficient increases by 8 46% and the stall attack angle 17 5%.The unique flow rules of the combined cascades are understood through analyzing data.The flow in the combined cascades must meet the flow prerequisite i.e.the static pressure must be equivalent along the pitch wise at the outlet of the fan.The overlap ratio B is the one of the most important parameters by which the relative position of two rows of cascade could be determined.As B is chosen within 30%～50%,two rows could be operated respectively at their own stall attack angles and the cascade performance could be improved obviously.The pitch ratio T is another important parameter and could effect cascade performance directly.The smaller T is more suitable to the cascade performance and the optimum range should lie in between 40% and 50%.
The Effect of Blade Bowing on Aerodynamic Parameters with Rotor/Stator Interaction
WANG Song tao, WANG Zhong qi, FENG Guo tai, SUN Xi miao
2002, 17(3): 314-318.
Abstract PDF(653KB) icon1439 icon452
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Simulation of 3D unsteady stator/rotor interaction in turbine stage with bowed and straight vane was presented in this paper.The effect of blade bowing on aerodynamic parameters especially on efficiency was studied in detail.The difference between 3D wake structure and wake mixing process in bowed and that in straight vane stage was discussed.The effect of blade bowing on the inlet condition of rotor was also studied.Efficiency and mass flow fluctuation phenomena and their effects on stage performance were described in detail.Based on the comparison between instant and average efficiency,the contribution of blade bowing to loss reduction in stator and rotor was also studied.
Numerical Simulation of Two-Phase Flow in Impeller
ZENG Zhuo xiong, HU Chun bo, JIANG Pei zheng
2002, 17(3): 319-322.
Abstract PDF(251KB) icon1876 icon430
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The pressure correction equations of particle kinetic pressure and fluid pressure are established in which correction of particle volumetric fraction and fluid density is considered.The turbulent flow is represented by k k ε k θ p model,and the principle of momentum interpolation was applied to the covariant physical velocity components,which were chosen as the dependent variables in the simulation of the two phase flow field of impeller.It is shown that the calculations agree well with the practical matter,and the simulation method is performable.Also,it is shown that pseudothermal temperature on tension side is smaller than that on suction side,and pseudothermal temperature near wall is greater than that in the interior,Furthermore,pseudothermal temperature can be used to describe abrasion level.It supplies foundation for efficient design and property of blade pressure expander.
The Predication of Stalling Recoverability of the Compression Systems
WU Yan hui, LU Zhi wei, ZHU Jun qiang, CHU Wu li
2002, 17(3): 323-326.
Abstract PDF(243KB) icon1486 icon462
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The stalling recoverability of one stage,three stage and nine stage axial flow compression systems is simulated based on a one dimensional unsteady stage by stage model for the dynamic response of a compression system.The validation of the model is verified by good agreement between the simulation results and experimental results in the single stage and nine stage compression systems.The simulation results also point out that some factors (such as in stall stage characteristic,the volume of plenum and compressor shaft speed) affect the stalling recoverability of axial flow compression systems to some extent.Stage matching can have a significant effect on stalling recoverability in high speed multistage compressors.
Effects of Curved Blade Stacking Line on the Aerodynamic Performance of Compressor Cascade
WANG Hui she, YUAN Xin, YUE Guo qiang, ZHONG Jing jun, WANG Zhong qi
2002, 17(3): 327-331.
Abstract PDF(790KB) icon1876 icon467
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The numerical simulation has been carried out to investigate the three dimensional viscosity flow in the compressor cascades with curved blades of different types of stacking lines.The method of the pseudo compressibility was used and the incompressible Navier Stokes equations were solved.The results show that the performance of curved blade is influenced not only by the end angle, but also by the shape and length of the stacking line.
The Energy Analysis in Heat Receiver Cavity
HOU Xin bin, YUAN Xiu gan, CUI Hai ting
2002, 17(3): 332-335.
Abstract PDF(689KB) icon1726 icon504
Abstract:
Solar Dynamic Power System is to be the space energy system in the future.The heat receiver is one of the SDPS key parts.Phase change thermal storage is used in heat receiver.The energy analysis can be used to understand the energy transfer in heat receiver and the thermal storage in PCM.The heat receiver cavity radiation mathematical model and the gas tube heat model were established.Heat loss,energy absorbed by gas,the latent and sensible thermal storage in PCM,tube maximum temperature,gas exit temperature and liquid PCM fraction were calculated.The results were analysed and could be used in heat receiver designing.
Flow Field Measurements Around a Row of Short Cylinders with Jet Impingement
XIANG An ding, ZHANG Li, LIU Song ling
2002, 17(3): 336-340.
Abstract PDF(714KB) icon1663 icon450
Abstract:
Detailed experimental measurements of the flow fields around a row of short cylinders with jet impingement by using a five hole probe have been conducted.The three dimensional velocities and vortex distribution were demonstrated and studied.The experimental data show that the largest velocity was observed at the place very close to the cylinder surface,velocities decreased rapidly in lateral direction from the surface to the symmetric plane of the channel where low velocity flow was found together with reverse flow and vortex.Endwall effect and flow separation result in strong vortices in cylinder array.Interaction of cylinder and endwall boundary layer produces horseshoe vortex at the root of the cylinder.In the wakes turbulent vortices exist.The lateral variation of pressure leads to the producing of channel vortex.As compared with the flow field without jet impingement,the angular position of separation on the surfaces of cylinder moved downstream and the width of wake was reduced obviously.
Investigation of Impingement Heat Transfer of Single Hole in a Limited Space
XU Quan hong, LIN Yu Zhen, LIU Gao en
2002, 17(3): 341-343.
Abstract PDF(220KB) icon1332 icon453
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On the basis of the similarity theory,the local impingement heat transfer coefficient of a single hole impinging on a plate in a limited space was studied with constant heat flux methods.The relationship of various flow and structure parameters with the impingement heat transfer coefficient was summarized,also the fitting equations of average impingement heat transfer coefficient were given according to the linear simulation.The results could be useful for the engineering design and scientific research.
Stability Analysis of the Labyrinth Gas Seals
LI hui, LI Qi han, YAN Li tang
2002, 17(3): 344-348.
Abstract PDF(736KB) icon1812 icon505
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Aeroelastic stability of the labyrinth gas seals is important.Labyrinth seal vibrates as nodal diameter along the circumference,the reducing of aerodynamics damping in some mode makes the stability of the system reduced,even makes the system unstable.We used the double control volume model to calculate the aerodynamics damper and aerodynamics stiffness of the labyrinth seals under nodal diameter vibration,and analyzed the stability of the labyrinth seals according to the complex values which was calculated by the finite element software.
Optimization Design of Friction Damper of Blade
HAO Yan ping, ZHU Zi gen
2002, 17(3): 349-356.
Abstract PDF(423KB) icon2259 icon469
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Friction damper is one of the most useful measures to alleviate the blade vibration stress and to prevent it from failure of fatigue.The procedures of design and optimization for platform friction damper of blades are proposed.Influences of friction coefficient and tangential stiffness of damper on the vibratory response are investigated.Steps which should be taken in design procedures in consideration of these two factors are proposed.One of the most important parameters should be optimized is the normal load after the material and geometry of friction contact are selected.Because of the difficulties encoutered in practice to accurately analyse the aerodynamic excitation and the viscous damping of blades,the effects of the excitation amplitude and viscous damping on the optimal value of normal load are studied based on both the calculation and experimental data.A procedure to optimize the normal load is introduced which is also insensitive to the value of excitation and viscous damping.
Nonlinear Response Characteristics of Cracked Rotor Supported on Squeeze Film Dampers
QIN Wei yang, MENG Guang
2002, 17(3): 357-362.
Abstract PDF(375KB) icon1830 icon452
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In this paper,the nonlinear responses of cracked rotor system supported on squeeze film damper (SFD) are studied.The results show that the squeeze film force can depress non synchronous response effectively and the increase of squeeze film bearing parameter can depress chaotic response.When bearing parameter is small,a certain range of rotating speed and crack depth can lead the system response to non synchronous response and the system response will become chaotic with the increase of crack depth.The system response can be fixed to stable periodic movement by increasing the damping ratio.In general case,peroid 3 movement means that the response will be chaotic.The main route for system response going to chaos is the route of intermittence to chaos and another route is from quasi periodic response to chaos.
Denoise of Rotor Vibration Signal Based on Higher-Order Cumulants
SONG You, LIU Chong kan, LI Qi han
2002, 17(3): 363-366.
Abstract PDF(244KB) icon1827 icon430
Abstract:
The denoise of vibration signal in engine rotor system is proposed,which is based on signal blind separation.Under the circumstance of lighter rub impact,the vibration signal contains instantaneous and high frequency weak information,and frequency mixing with the stochastic noise may take place.The classical filtering is ineffective in terms the denoise.Blind separation of sources based on higher order cumulants is applied to the separation between vibration signal and noise,which is important to diagnosis of rub impact fault.
Strength Analysis of Spiral Bevel Gears with High Contact Ratio
DENG Xiao zhong, FANG Zong de, YANG Hong bin, WEI Bing yang
2002, 17(3): 367-372.
Abstract PDF(804KB) icon1829 icon448
Abstract:
In this paper,the bending stress states of HCR (High Contact Ratio) spiral bevel gears in conditions of various errors and loads have been studied by applying the FEM (Finite Element Method) and stress influencing matrix technique.The calculated results have showed that the high bending strength could be obtained in transmitting of HCR spiral bevel gears in a certain error allowance by optimal design of tooth surface topology,as well as favourable dynamic behavior.
Calculation and Optimization for Tooth Contact Stress of Spiral Bevel Gears
ZHOU Yan wei, FANG Zong de, DENG Xiao zhong
2002, 17(3): 373-376.
Abstract PDF(583KB) icon1938 icon481
Abstract:
On the basis of Tooth Contact Analysis (TCA) and Loaded Tooth Contact Analysis (LTCA),an approach to calculating the maximal tooth contact stress course in the whole meshing period of spiral bevel gears has been provided,by using the theory of elasticity.The effects of tooth surface geometry,load share,tooth deformation and manufacturing errors on contact stress course could be shown by means of the approach.An optimal method for high tooth contact strength was presented,in which by controlling the shape and amplitude of the transmission error curve,that is the curvature on tooth height,the maximal contact stress could be reduced and an improved contact strength could be obtained.
Liquid Rocket Engine Fault Diagnosis Method Based on the Integration of Qualitative and Quantitative Knowledge
LIU Hong gang, WU Jian jun, CHEN Qi zhi
2002, 17(3): 377-380.
Abstract PDF(243KB) icon1715 icon441
Abstract:
This paper first analyzes the SDG method with a view of knowledge description and management,then presents an improved way according to the characteristics of the liquid rocket engine systems.That is,by constructing the SDG containing only the measured variables,the fault modes are diagnosed in advance,and then the modes that can not be distinguished are diagnosed by adding adequate quantitative information.In addition,multi fault mode diagnosis method is proposed in this paper.The test result shows that the method is valid.
A Dynamic Identification Model of Aeroengine Starting Process Based on the RBF Network
JIANG Tao, LI Ying hong
2002, 17(3): 381-384.
Abstract PDF(610KB) icon2720 icon494
Abstract:
In the process of engine start,the airflow of every section is in subcritical condition.It's hard to construct a model with traditional thermodynamics methods.A dynamic identification model is set up in this paper based on Radial Basis Function network using ground test data as learning samples.The simulation results show the model has good dynamic performance and high accuracy,and opens a new way to building the model of engine at low speed.

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