2010 Vol. 25, No. 2

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Display Method:
Effect of elliptical and compositive cut at trailing edge on the performance of a lobed mixer
LIU You-hong, XIE Yi, GUO Nan
2010, 25(2): 243-250.
Abstract PDF(1165KB) icon1805 icon479
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The principal effects of different elliptical and compositive cut at trailing edge of a practical lobed mixer on the thermal mixing efficiency and total-pressure recovery coefficient were studied by three dimensional-computational fluid dynamics(3D-CFD) numerical simulation.The results show that the thermal mixing efficiency declines while the total-pressure recovery coefficient increases as the cut size of the elliptical sector augments.As for the models of compositive cut at trailing edge,the thermal mixing efficiency is lower than that of the original models except for the model with half sector arrangement,but the total-pressure recovery coefficient is usually higher than that of the original model.Among all the models with compositive modification,the model with half sector arrangement has the best performance.
Numerical investigation on diffraction characteristics of detonation wave from pre-detonator
ZHANG Yi-ning, HAN Qi-xiang, CHEN Wei, WANG Jia-hua, TANG Hao
2010, 25(2): 251-257.
Abstract PDF(1750KB) icon1593 icon444
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In order to achieve successful transition of detonation wave from the pre-detonator to main detonation tube,numerical simulation was performed for the exits of different geometry shapes,and the diffraction characteristics of detonation wave were obtained from pre-detonator to main tube.The results show that when the pre-detonator has a straight nozzle,the detonation waves cannot propagate upstream from the interface between the main combustor and pre-detonator exit;when the pre-detonator exit has a 45-degree nozzle,the detonation wave can diffract to both sides in main combustor.These results have been proved by laboratory experiments.
Fuel temperature analysis of advanced fighter aircraft during supersonic cruise
ZHANG Xing-juan, ZHANG Zuo-qi, GAO Feng
2010, 25(2): 258-263.
Abstract PDF(681KB) icon1908 icon448
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Fuel is widely used as a heat sink for heat components of fighter aircraft.With the development of the integrated thermal management technology,fuel is utilized more efficiently to cool off especially for advanced fighter aircraft.Heat balance method has been used to build heat transfer mathematics modeling,and the time-dependent fuel temperature changes during supersonic cruise were analyzed in this paper.The results show that,the recirculation of the fuel and the flight Mach number are major influential factors to the fuel temperature during supersonic cruise.The computation and simulation of the temperature of fuel in the fuel tank was carried out by using the program based on C software.
Interaction between bubble jet flows on thin wires
LU Jian-feng, PENG Xiao-feng, DING Jing
2010, 25(2): 264-269.
Abstract PDF(1351KB) icon1446 icon386
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Both visual experiment and numerical simulation were conducted to investigate the interaction between bubble jet flows on thin wires.The attractive interaction appeared between nearby bubble jet flows,and bubble jet flows would combine into one jet flow under strong interactions.A physical model was proposed to understand the mechanism of the interaction between bubble jet flows.The temperature in the adjacent region of the bubble sharply decreases due to the bubble growth,which induces unsymmetrical thermocapillary force around and/or in adjacent region of a bubble.As a result,the attractive interaction exists between nearby bubble jet flows,while the adjacent bubbles trends to separate from each other.The numerically simulated temperature and flow fields are in a good agreement with experimental results.
Numerical simulation on vortex shedding and combustion oscillation in aero-engine afterburner
ZHANG Cheng-yu, SUN Xiao-feng
2010, 25(2): 270-277.
Abstract PDF(2837KB) icon1790 icon518
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The flow field and combustion oscillation in the aero-engine afterburner were numerically simulated.The mean parameter and vortex structure were obtained.The combustion model is very important for the shear vortex accreting the flame holder lip.The periodic process of vortex shedding and periodic change of recirculation zone after the flame holders were observed as an important factor for the afterburner buzz and combustion oscillation.The applicability of Rayleigh rule was validated by the harmonious wave in the afterburner.
Thermoacoustic oscillating calculation of longitudinal equivalence frequency and stability in aero-engine afterburner
ZHANG Cheng-yu, LI Lei, SUN Xiao-feng
2010, 25(2): 278-283.
Abstract PDF(2188KB) icon1684 icon465
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Firstly,the thermoacoustic oscillation coupling theoretical model between the duct acoustic propagation and instability heat release was presented in this paper.Secondly,this model was used to analyze and predict the longitudinal equivalence frequency and stability in an aero-engine afterburner.The average flow parameters of the afterburner were gained by computational fluid dynamics(CFD) simulation,providing conditions for the application of thermoacoustic oscillation theory of the afterburner.By analyzing the results of calculating cases for heat release position and perforated rate of heat shield,some reference criteria were provided for the engineering design of the aircraft afterburner instability and the control method was disclosed.
Water droplet impingement prediction for three-dimensional complex surfaces
YANG Sheng-hua, LIN Gui-ping, SHEN Xiao-bin
2010, 25(2): 284-290.
Abstract PDF(1736KB) icon1828 icon403
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An Eulerian two-phase method was presented to predict water droplets impingement for three-dimensional complex surfaces such as multi-element airfoil and engine inlet under icing conditions.The air-droplet two-phase flow was considered one-way coupled,and the airflow field was solved independently from the Euler or Navier-Stokes(N-S) equations.A treatment of boundary conditions of the droplet phase at the impingement surfaces was given.An adaptive numerical diffusion model was proposed to avoid divergence in higher order simulations caused by the singularity of droplet volume fraction in localized regions.Validation cases were performed for typical two or three dimensional bodies,including a cylinder,a MS(1)-0317 airfoil,a sphere,a multi-element airfoil and an engine inlet.Cases with droplet sizes in certain distribution were also calculated.In comparison with published experimental results,the present computational method is accurate and effective,and applicable to three-dimensional complex surfaces.
Experiments on improving film cooling effectiveness with transverse slots
CHEN Xin, HE Li-ming, YU Jin-lu, HU An-hui
2010, 25(2): 291-294.
Abstract PDF(524KB) icon1736 icon472
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To investigate the influence of transverse slots on film cooling effectiveness,an experimental study was employed with three different film cooling experimental plates in several ratios,two of which have different transverse slots.And the distributions were compared with the baseline holes' to reveal the good effects of the transverse slots on the film cooling performance.The results show that,the penetration of the film secondary flow into the cross flow is suppressed under the action of the transverse slots,so the film effectiveness is higher with better coverage on the hot side.And SCASE 2 of sloped downstream slot outperforms the other cases with respect to the cooling effectiveness.
Experiments of heat transfer characteristics for swirl microchannel under acceleration environment
YANG Sheng, YU Jian-zu, GAO Hong-xia, XI You-min
2010, 25(2): 295-301.
Abstract PDF(1750KB) icon1549 icon386
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The experiment of heat transfer characteristics in rectangular cross section swirl microchannel test pieces under acceleration environment was conducted with ethylene glycol solution of 30%(volume concentration),and the acceleration environment was simulated in test by centrifugal acceleration test machine.Heat transfer characteristics of swirl microchannel under different acceleration environment situations were investigated with various conditions of fluid flux and heating power,and the influencing factors were analyzed.The results show that,the acceleration direction has significant effect on the heat transfer of swirl microchannels,and the ability of swirl microchannel against the influence is as larger as the Dean number get higher.
Research on error analysis and correction of infrared temperature measurement for curved surface
CHANG Guo-qiang, CHANG Hai-ping, WANG Yin-hui, SHAN Xue-qing
2010, 25(2): 302-307.
Abstract PDF(892KB) icon1600 icon523
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Experiments and theory analysis were carried out to investigate the characteristics of temperature measurement using thermal imager for curved surface.According to the theory of infrared thermometry techniques,the infrared radiation characteristics of curved surface essentially have no difference with flat surface,both of which can be described by the same mathematics expression.The essential reason which induces the measuring error of infrared thermal imagery for curved surface is that equivalent face of the measured surface no longer satisfies the diffuse body hypothesis,owing to too large included angle of the normal direction of curved surface and the measuring direction of infrared thermal imagery.The temperature measuring accuracy can be improved by measuring the local emissivity for the region where the diffuse body hypothesis is invalid for its equivalent face.
Numerical investigation on film cooling effectiveness of rotating blade with multihole
LI Guo-qing, DENG Hong-wu, XIA Hui-xia
2010, 25(2): 308-313.
Abstract PDF(1485KB) icon1534 icon424
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The multihole film cooling effectiveness on rotating blade surface of an on-design turbine was numerically studied by k-ε turbulence model.Cases of 60°,30°,0°,-30°and-60° multihole were compared under different blowing ratios when the main flow Re was 670000.Results show that the rotating film cooling effectiveness can be greatly improved on pressure side with multihole,where the effectiveness of the multihole toward the low-radius is better than that of the multihole toward the high-radius because of the coriolis force.But the effectiveness isn't increased greatly on suction side with multihole.
Numerical simulation of three-dimension combustion in an annular combustor during a transient state
WANG Hui-ru, JIN Jie, LIU Da-xiang
2010, 25(2): 314-319.
Abstract PDF(978KB) icon1537 icon386
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A numerical investigation of an annular combustor in a transient state(from idle to maximum) was conducted with commercial software FLUENT by adding the UDF(user-defined function) subroutines.Temperature field was studied by comparing with traditional method(which used steady simulation at some discrete operation conditions to approximate the transient state).The results show that:(1)there are large differences between transient and steady simulation at corresponding operation condition,the outlet temperature distribution of steady simulation is higher than the transient simulation;(2) the time step is a critical factor affecting the accuracy of transient simulation,a small time step could account for the close interaction with flow filed parameters of different times;(3) a hysteresis phenomenon during the transient state exists at the averaged outlet temperature in relation to fuel-air ratio.
Effects of cooling channel parameters on flow and heat transfer in regenerative cooling channels
KANG Yu-dong, SUN Bing
2010, 25(2): 320-325.
Abstract PDF(1352KB) icon1775 icon446
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To study the effects of wall roughness,sudden expansion/contraction,inlet turbulence intensity and cooling channel curvature on heat transfer and fluid flow in cooing channel,three-dimensional turbulent fluid flow and heat transfer were numerically investigated with RSM model,which was used to represent the turbulence;the coolant was gas hydrogen,whose thermophysical properties varied with both temperature and pressure.The results show that,the increase of wall roughness will increase not only the heat transfer but also the pressure loss;the vortex appears on the nearby sudden expansion/contraction point,the turbulence intensity and local pressure loss increase due to the vortex,while the wall temperature decreases at the place where the vortex appears;the coolant inlet turbulence intensity has no effects on the development of flow in cooling channel;the secondary flows which develop due to centrifugal force on the coolant will cause the mass redistribution,leading to heat transfer enhancement at the concave cooling channel but deterioration at convex cooling channel.
Study of active particles' influences on combustion of H2/Air mixture
LAN Yu-dan, HE Li-ming, DING Wei, GUO Xiang-yang
2010, 25(2): 326-330.
Abstract PDF(852KB) icon1912 icon447
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The chemical kinetic model of H2/Air mixture combustion was established in this article.With the non-equilibrium plasma,this paper calculated and analyzed how the active particle(O,H) and radical(OH) produced by gas discharge influenced the components in the combustion,the temperatures and pressures at different equivalent ratios.Therefore,this paper can provide a theoretical foundation for the experimental research and practical application of plasma assisted combustion(PAC) in the aero-engine combustion chamber.The results show that PAC can improve reaction efficiency,combustion temperature and flame spread velocity,reduce the rise-time of combustion and strongly influence H2/Air mixture combustion.
Enthalpy measurement and heat transfer investigation of RP-3 kerosene at supercritical pressure
ZHANG Chun-ben, DENG Hong-wu, XU Guo-qiang, HUANG Wen, ZHU Kun
2010, 25(2): 331-335.
Abstract PDF(718KB) icon2101 icon467
Abstract:
A method of measuring the enthalpy of China's No.3 jet fuel RP-3 at supercritical pressure was proposed based on the principle of energy conservation.At the same time,the enthalpy of RP-3 at different supercritical pressures between 323K and 834K was measured.The results indicate that,the enthalpy of RP-3 at different pressures is almost the same when the fuel temperature is lower than its critical temperature.When the fuel temperature is higher than its critical temperature,the difference of enthalpy at different supercritical pressures declines with the growing pressure.In addition,the temperature of RP-3 calculated by the curve of enthalpy had been compared with the measurement value,showing that the measurement of enthalpy is accurate and reliable.At last,the influence of heat flux on heat transfer of RP-3 was studied.The test results indicate that the Nusselt number increases with heat flux if the bulk fuel temperature Tb/Tc is lower than 1.179(760K).
Experimental and numerical investigations of boundary layer performances on curve structure surfaces with transpiration cooling function
JIA Shan, WANG Xiao-chun, WANG Jian-hua
2010, 25(2): 336-342.
Abstract PDF(1539KB) icon1730 icon383
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With the combined approach of experimental investigation and numerical simulation,the fluid flow and heat transfer performances within the boundary layers of a curve structure with transpiration cooling function were studied.The specimen used in the experiments was made of sintered refractory steel,which has a porosity of 0.37 and a character length of 20μm.The temperature and velocity of free stream were controlled by two control systems of a hot gas wind tunnel,and the Reynolds number of gaseous coolant was given by a digital mass flow rate controller.The surface temperature on the specimen was measured by an infrared thermal imaging system,NEC TH5104.Using a two-dimensional,steady and local thermal equilibrium model of the commercial software FLUENT 6.3,the transpiration cooling performance of the specimen was numerically simulated under the same conditions with the experiments.Through comparison of the numerical results with the experimental data,the numerical program was validated.With the help of the validated program,the fluid flow and heat transfer performances within the boundary layer of the curve structure were discussed.
Transient test of aerodynamic heating for hypersonic vehicle
HOU Yu-zhu, ZHENG Jing-liang, DONG Wei
2010, 25(2): 343-347.
Abstract PDF(992KB) icon1655 icon465
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To design a thermal protection system of the hypersonic vehicle and verify the numerical computations,an aerodynamic heating transient test system together with its control software was designed and developed.The test system can measure the real-time heat flux and temperature on the surface,directly produce heat flow and temperature curve,according to hypersonic vehicle's trajectory.To simulate the heat transfer conditions at different altitudes and understand the effecting of the pressure,the test system used a vacuum chamber.To ensure that the conditions of the lower side of the thermal protection system could be simulated in a vacuum environment,a cooling bed was used,making the transient test method more reasonable and accurate.
Trimming and maneuvering control of a helicopter flight near the ground
SU Yuan, CAO Yi-hua, FANG Zhen-ping
2010, 25(2): 348-353.
Abstract PDF(1093KB) icon1355 icon427
Abstract:
Based on a nonlinear flight dynamics model for a single rotor helicopter with ducted tail rotor,a mixed(Newton method/Gradient method) numerical method was proposed to solve helicopter trimming and maneuvering control laws.The effects of ground on trimming and maneuvering control were studied.Taking a typical helicopter as an example,the trims for steady flight with different velocities and altitudes were first solved.Then control laws for lateral jink maneuver were obtained for helicopter NOE(nap of earth) flight.The calculation results conform to the ground effect theory,and load factor and control variation of the maneuver can be used for reference.The theoretical method here can provide the references for the analyses on dynamics and unsteady control in helicopter maneuvering flight near the ground.
Influence of sunroof on flow field and aerodynamic noise inside the passenger compartment of the car
KANG Ning, WANG Xiao-chun
2010, 25(2): 354-358.
Abstract PDF(1264KB) icon1657 icon382
Abstract:
Numerical simulation and analysis of flow field inside a simplified Golf 1.6 car and aerodynamic noise at the receiving point around the driver's left ear were conducted by using large eddy model of computational fluid dynamics(CFD) software FLUENT.The velocity and pressure fields on the symmetry plane of the driver and sound pressure level at the receiving point were obtained.The results show that sound pressure level becomes smaller with the backward shift and widening of the sunroof.The sunroof of case 1 is the most reasonable.
Frequency domain method for predicting sonic boom propagation based on Khokhlov-Zabolotskaya-Kuznetsov equation
CHEN Peng, LI Xiao-dong
2010, 25(2): 359-365.
Abstract PDF(2461KB) icon2002 icon457
Abstract:
A fast frequency domain method for predicting sonic boom propagation was proposed based on classical Khokhlov-Zabolotskaya-Kuznetsov(KZK) equation.Furthermore,the sonic boom properties along the normal direction to the shock front were obtained by augmenting the Mach angle into the equation.To demonstrate the feasibility of the method,the results were compared with the experimental data of the model C presented in NASA TD N-161.The flow field of the supersonic moving vehicle was first calculated by a computational fluid dynamics(CFD) method with different grids.Then,the sonic boom propagation was computed based on the proposed KZK model with the input of the Fourier analysis results from CFD.The prediction results are in good agreement with NASA experimental data.It is also shown that the sonic boom decays rapidly in the near field due to the nonlinearity effects.In the far field,the sonic boom becomes axisymmetric gradually due to the effect of sound diffraction.After long distance propagation,the sound energy is concentrated on low frequency component.
Computational analysis on the nozzle performance of pulse detonation engines
QIN Ya-xin, YU Jun-li, GAO Ge
2010, 25(2): 366-372.
Abstract PDF(1704KB) icon1948 icon449
Abstract:
Two-dimensional axisymmetric numerical simulation was carried out using single-cycle and detailed chemical reaction kinetics of hydrogen/air mixture,so as to investigate different nozzle effect on the performance of pulse detonation engines.The simulated results of detonation wave parameters are close to the value of a chemical equilibrium solver named STANJAN.The results of numerical simulation with four single-nozzles and four combined-nozzles indicate that,the largest instantaneous thrust and specific impulse are obtained in divergence nozzle;the average thrust generated by the combined-nozzle with ejector is larger than that by the single-nozzle.Furthermore,the mechanism of unsteady ejection was analyzed,offering references to augment the performance of pulse detonation engines.
Vortex evolution in supersonic air free diffused mixing layers
LI Feng, CHENG Xiao-li, WANG Qiang
2010, 25(2): 373-378.
Abstract PDF(693KB) icon1492 icon433
Abstract:
The vortex formation and evolution in a supersonic air/air free diffused plane mixing layer were investigated numerically by forcing four different harmonic disturbances without phase differences.The two-dimensional compressible Navier-Stokes equations including the diffusion effect of air components were solved by using a high accuracy finite difference method.The convective terms and transport terms were discretized by a third-order upwind compact scheme and a sixth-order symmetric compact scheme,respectively.The unsteady time marching method is a third-order compact storage explicit Runge-Kutta algorithm.Some phenomena of large-scale primary vortex growing and interacting were revealed,such as saturating,paring once and twice,and triple-vortex pairing.For low convective Mach number of Mac=0.3,primary vortices are fatter,but their streamwise lengths are shorter.Under the influence of air real-gas characteristics,the vortex-shocklet structure is not discovered in the case of high convective Mach number of Mac=0.8.
Method for match of two-stroke piston engine and set propeller
TANG Zi-jie, DING Shui-ting, DU Fa-rong, HAN Shu-jun, ZHANG Qi, ZHANG Wan-bing
2010, 25(2): 379-383.
Abstract PDF(564KB) icon1737 icon575
Abstract:
Based on the working characteristics of the long-endurance UAV(unmanned aerial vehicle),and in combination with the power output characteristics of the engine and the power absorption characteristics of the set propeller,as well as external characteristic curve of the engine and propelling characteristic curve of the propellers,the method for matching of set propeller of the two-stroke piston engines was presented.This indcates that this method can be employed practically to select most suitable set propeller for one two-stroke engine under the conditions of ground and low altitude.
Method of reliability analysis for time truncated zero-failure data based on normal distribution
FU Hui-min, ZHANG Yong-bo
2010, 25(2): 384-387.
Abstract PDF(1507KB) icon1834 icon440
Abstract:
The term'time truncated zero-failure'means the product under experiment does not fail at the end of the experiment,and this is a pressing problem in engineering to solve problems related to time truncated zero-failure data.In this paper,a method of reliability analysis for time truncated zero-failure data based on normal distribution was presented,providing reliability assessment of a product with high confidence using the information from time truncated zero-failure data.The one-side lower confidence limits of liability and life were calculated in this paper when the standard deviation or its higher limit was known.Then,time truncated time zero-failure data from some satellite thrust tests with normal distribution,were analyzed.The results indicate that the method in this paper can make full use of both the information from these data and the higher one-side lower confidence limits of lognormal distribution.The method provided in this paper can be easily realized for the benefit of engineering application.
Local creep buckling analysis method of combustor liner
HONG Jie, GAO Jin-hai, MA Yan-hong, WANG Jian-jun
2010, 25(2): 388-395.
Abstract PDF(2613KB) icon1605 icon407
Abstract:
In consideration of the "local" feature of combustor liner temperature field and stress field,a concept of "local creep buckling" was presented in this paper along with an engineering analysis method.Firstly,the theoretical model of creep buckling was established based on Hoff theory.Secondly,the feasibility of using finite element method(FEM) to analyze creep buckling was validated by theoretical and test data.Thirdly,a statics analysis with thermal-mechanical loads was performed,and then the dangerous place of combustor liner local creep buckling was captured considering creep buckling instability factors.Finally,sub-model technique was used in nonlinear thermal elastic-plastic/creep finite element analysis to capture the critical time of local creep buckling with "curvature local maximum point" criterion.It could be concluded that,as compared with traditional method,the hypothesis of average temperature,average compressive stress and plane strain could be improved in this paper,thus the computational accuracy was enhanced greatly.The work of this paper is significant on the application of structure design of combustor liner.
Optimization design of a fan casing for reducing vibration
CAI Xian-xin, XIAO Xin-hong, WANG Tao, WU Zhi-qing
2010, 25(2): 396-401.
Abstract PDF(1297KB) icon1659 icon493
Abstract:
High frequency traveling vibration of a fan casing may be excited by the wake of rotating fan blades.High vibration level of a fan casing was observed during the test of a turbofan engine,the causes were analyzed,and the vibration-absorbing measures were investigated.Then,a casing structural optimization method for reducing vibration was proposed.Vibration experiments for casings before and after optimization were carried out.The results indicate that the optimization method is very efficient.
Corrosion impairment experimental study of aluminum alloy LY11 propellers in a certain airplane
GU Yuan, SHI Duo-qi, YANG Xiao-guang, ZHANG Fu-gang, FU Cheng, WANG Fu-qiang
2010, 25(2): 402-406.
Abstract PDF(921KB) icon1597 icon461
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The test of simulation part of a propeller of airplane at different rust corrosion impairment conditions on the experiment machine and electromagnetic table was conducted,whilst the rule of impairment surface ratio A changes with low-cycle loading N,and the change rule of vibration frequency in line with the ratio of corrosion impairment depth,corrosion length and corrosion impairment area were given.The experiment shows that,when the loads and the temperature are the same,the property of material,shot-peen process and the operating environment are impartment factors for corrosion impairment of propellers;and the damnification area A and damnification depth H have more influence on the vibration frequency of propellers of airplane.The most limit depth ratio is 0.14,and the most limit damnification depth of simulation part is 0.7mm.The ratio of damnification area is 0.015,and the most limit damnification area of simulation part is 3.006mm2.
Effects of profile of contact surfaces on the stress distribution for tenon jointing in blade disk assemblies
WEI Da-sheng, WANG Yan-rong
2010, 25(2): 407-411.
Abstract PDF(943KB) icon1983 icon410
Abstract:
To investigate and improve the high stress gradient near the edges of contact zone in conventional tenon jointing,several typical profiles of contact surface were analyzed by means of finite element method(FEM),indicating that different contact profiles would lead to different stress distributions.Then,a set of finite element models with different grids for dovetail attachment were established to analyze stress concentration effects,and improve the solving accuracy of contact stress.Different profiles of contact surface were chosen.The numerical solutions show that arc/line contact profile for two-dimensional(2-D) will remove the high stress concentration,and arc/arc one will further depress the contact stress.
Influence of interblade phase angle on the flutter of rotor blades
ZHANG Xiao-wei, WANG Yan-rong
2010, 25(2): 412-416.
Abstract PDF(1003KB) icon2018 icon471
Abstract:
A numerical simulation method for turbomachinery bladings basing on energy method with interblade phase angle(IBPA) has been developed.The whole annular oscillating cascades have been modeled with each blade channel divided into the moveable region near the blade surface and the outer fixed region.The node displacements of finite element model,on the basis of computational structural dynamics(CSD),have been transferred to fluid interface grids with finite element interpolation algorithm.Reynolds-averaged Navier-Stokes(RANS)equations with k-ε turbulent model for closure have been solved for the whole annular oscillating cascades.At the design speed of NASA Rotor 67,the aerodynamic work in one oscillating period and the corresponding aerodynamic modal damping ratios of the whole annular cascades in different IBPA have been obtained.The effects of IBPA on the flutter of cascades have been determined on the basis of energy method.The results show that IBPA has significant influence on the flutter of rotor blades.
Five-hole probe and its neural network algorithm
WANG Hong-wei, CHEN Xiao-long
2010, 25(2): 417-423.
Abstract PDF(1615KB) icon1717 icon469
Abstract:
Data reduction methods for five-hole probe are investigated and a new method based on artificial neural network is developed.The developed method is then compared with a three-dimensional linear interpolation one.Conclusion is drawn that the neural network method is superior to the interpolation one in accuracy and robustness.The new developed method is also applicable to multi-hole probe through minor modifications.
Research on three-dimensional aerodynamic design of transonic fan and loss analysis
JIANG Bin, WANG Song-tao, FENG Guo-tai, WANG Zhong-qi
2010, 25(2): 424-433.
Abstract PDF(1688KB) icon1603 icon449
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This paper presented the aerodynamic design process for a low pressure transonic fan stage.The solver based on three-dimensional(3-D) viscous Navier-Stokes equations has been adopted as a main design tool with coarse and thick mesh,although the initial blade was sourced from the solution of S2 inverse solver.This design method eliminated the reliance on loss models in quasi 3-D design for the designer.Based on the design result,the flow field structure in the fan stage was also studied in this paper.The main flow loss of the rotor was originated from the shock and the interaction among shock,leakage flow and boundary layer.The 3-D stator design has achieved successfully the high subsonic airflow with high turning angle.
Analysis of aerodynamic design characteristics of core driven fan stage
ZHANG Xin, LIU Bao-jie
2010, 25(2): 434-442.
Abstract PDF(1744KB) icon2539 icon503
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The flow field and aerodynamic design characteristics of core driven fan stage(CDFS) were simulated and analyzed with modified Denton code.The results show that: 1)adjustable inlet guide vane(IGV) is needed to achieve the switch of different working modes;2) the conflict between high tip speed and low aerodynamic loading restrains the efficiency of CDFS;3) IGV outlet swirl distribution and switch mode have remarkable effects on CDFS performance;4) the challenge in the aerodynamic design of CDFS rotor is the shock loss in single bypass mode;5) the change in distribution and magnitude of CDFS stator inlet flow angle is the main challenge in CDFS stator design.
Integrative design method of fan and axial-centrifugal compressor
YANG Xiao-he, SHAN Peng
2010, 25(2): 443-450.
Abstract PDF(2869KB) icon1814 icon442
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Firstly,for the S2,m streamline-curvature approach,the blade force decomposition method using two stream surface angles in the cylinder coordinates was associated with that using one stream surface angle of the computing station quasi-orthogonal to the streamline;then a control momentum equation suitable for axial-,radial-and mixed-flow type compressors was derived.Secondly,an integrative bypass-turbomachine through-flow inverse design method was proposed,which employs either the convergence strategy of automatically re-positioning the splitter or that of re-calculating the bypass ratio.So an integrative design method for the compression system of fan added by an axial-centrifugal compressor was presented.This method has been applied to a two-channel two-shaft system consisting of a two-stage fan,two-stage booster and a centrifugal compressor.The flow fields of first fan stage and the centrifugal impeller were checked by computational fluid dynamics(CFD),demonstrating the operational feasibility and flexibility of this method.Thirdly,the physical significance of the axial velocity ratio and its application in an axial-flowpath self-adjusting inverse problem were discussed.The simpleness and convenience of the axial velocity ratio as a design parameter are showed by another example.
Application of non-uniform rational B-spline curve and knot insertion algorithm to turbine blade optimization
LIU Run-ze, ZHANG Xiao-dong, AN Bai-tao, LIU Jian-jun
2010, 25(2): 451-458.
Abstract PDF(2520KB) icon1448 icon541
Abstract:
Non-uniform rational B-spline(NURBS) curve and knot insertion algorithm were used for parametric modeling of turbine blade profiles,in which actual physical meaning of the parameters and flexibility of profile regulation can be taken into account.Bended,twisted and swept blades were successfully constructed by applying NURBS with adjustable number of control points to stacking line modeling.An aerodynamic optimization platform for three-dimensional turbine blade has been developed,in which the parametric modeling,grid generation,computational fluid dynamics analysis and multi-objective optimization based on design of expert(DOE) and response surface method(RSM) method were integrated.After optimization,the total pressure loss of a single-row turbine cascade was reduced by 0.57% and the adiabatic efficiency of a singe-stage turbine was increased by 0.8%.
Key factors influencing the stability of a two-stage transonic fan
SU Zhong-liang, WU Yan-hui, CHU Wu-li, ZHANG Hao-guang, LU Jia-ling
2010, 25(2): 459-465.
Abstract PDF(2488KB) icon1485 icon456
Abstract:
Three-dimensional flow field simulation was conducted on a two-stage transonic fan stage.The simulated fan stage performance was greatly matched with the experimental performance.Blade tip separation,blade tip leakage blocking effect and the stator corner separation were checked for filtering out the possible cause of incepting fan stage stall.Based on this study,the root cause for the stall was finally concluded as the stator corner separation,along with the mid-span boundary separation on the second stage.
Coordinates calculation method for kinematics parameter of aero-engine fuel piston pump
CHEN Yong-qin, SU San-mai, CHANG Bo-bo
2010, 25(2): 466-470.
Abstract PDF(397KB) icon1812 icon417
Abstract:
A set of new formula to calculate spherical swashplate axial piston pump kinematics parameters,such as: displacement,velocity and acceleration,was deduced from coordinates method.The analysis method and deduction procedure ensure the preciseness of the formula in theory.Applying above new formula and current calculation method to the same aero-engine fuel piston pump,the results show that owing to the use of linearization,the currently calculated displacement and velocity errors are less than 0.4 percent,but the maximum acceleration error reaches 3.34 percent.Compared with current calculation method,the new formula is precise and simple,providing a theoretical basis for calculation of kinematics parameters of this type of piston pump.
Augmented linear quadratic regulator controller design based on non-linear integrated helicopter/engine model
SUN Li-guo, SUN Jian-guo, ZHANG Hai-bo, WANG Jian-kang
2010, 25(2): 471-476.
Abstract PDF(807KB) icon1688 icon512
Abstract:
The unsteady and non-linear helicopter model of UH-60A was established,while the non-linear integrated helicopter/engine model was also constructed.Then,an augmented linear quadratic regulator(ALQR) method for the flight controller was designed.Simulative experiments on the integrated helicopter/engine model were conducted.Numerical simulation results and the comparison with H∞ controller demonstrate that the ALQR flight controller had its superiority of decoupling,command tracking and robustness.In addition,it was also found that the closed-loop system of engine could satisfy the need of power required by the helicopter in usual task,and the power turbine speed could meet the requirement of ADS-33E.
Effect of configurative parameter on the performance of clustered plug nozzles
REN Jun-xue, LIU Yu, XIE Kan
2010, 25(2): 477-482.
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Abstract:
In order to investigate the effect of uncertain design parameters on the performance of cluster plug nozzles in design method,two types of 8-module and one type of 16-module clustered plug nozzles were designed with the same total area ratio and shape size.Their thrust efficiencies were calculated numerically,and also compared respectively under the condition of same module gap and diameter ratio,module number and module area ratio.The 8-touched-module clustered plug nozzle with module area ratio of 30.2 had the highest efficiency in high attitude and the 8-separated-module clustered plug nozzle with module area ratio of 20.7 had the highest efficiency in low attitude.In the design procedure,a bigger module area ratio can be selected to enhance its performance when the clustered nozzle works in medium and low attitude,otherwise a smaller one can be selected.

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