2000 Vol. 15, No. 2

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Display Method:
Development of Three-Dimensional Turbulent Flow Field at Exit of an Axial Compressor Rotor Passage
Ma Hongwei, Jiang Haokang
2000, 15(2): 113-118.
Abstract PDF(661KB) icon1605 icon409
Abstract:
Detailed measurements of three dimensional turbulent flow field at exit of an axial flow single stage compressor and downstream were made in different mass flow conditions.The flow structure was surveyed with both hot wire probe and high frequency pressure probe.The results show that in design condition,substantial blockage,loss and turbulence mainly exist in the tip mid passage,wake and the corner between the suction surface and the hub as the mass flow reduces,the high turbulence areas enlarge with the flow structure changing,and the flow becomes more turbulent.Distributions of three turbulence intensity components are almost similar,and the radial component is found to be the highest,while the axial radial component of Reynolds stresses is the largest.In the downstream flow the decayed tip leakage vortex moves toward the pressure surface and the low radial location and leads to more flow mixing,blockage and turbulence in the tip region.The rotor wake becomes wider while the flow loss increases.Both radial velocity and radial turbulence intensity decay obviously,and the axial tangential component of Reynolds stresses is the largest.Vortex is one of the most important factors which cause the pressure fluctuation and airflow noise.
Three-Dimensional Mean Flow Field at Both Inlet and Exit of an Isolated Axial Compressor Rotor Passage in Different Conditions
Ma Hongwei, Jiang Haokang, Dong Yuxi
2000, 15(2): 119-123.
Abstract PDF(450KB) icon2034 icon473
Abstract:
Detailed measurements of three dimensional mean flow field at both inlet and exit of an isolated axial flow compressor rotor passage were made in different mass flow conditions.The flow structure was surveyed with a conical four hole high frequency response pressure probe.Strong periodic circumferential distributions of flow parameters were found at inlet of the rotor passage,especially in near stall condition.Both total pressure and static pressure are higher near the blade pressure surface,but lower near the suction surface.Lower axial velocity and larger relative flow angle appeared near the leading edge.The investigation shows that in design condition,mixing between the tip leakage vortex and the endwall boundary layer are main factors of the substantial blockage and loss in the tip mid passage;as the mass flow reduces,the enhanced leakage vortex produces more flow blockage and loss,and a vortex appears at the corner between the suction surface and the casing wall;while the intensified tangential migration in the hub wall boundary layer enlarges flow blockage and loss.In near stall condition,interaction among the tip corner vortex,the leakage vortex and the endwall boundary layer deteriorates the flow and leads to larger blockage and loss,and flow separation of the boundary layer on the suction surface occurs at 0.2 span and 0.8 span respectively.
Numerical Analysis of Compressible Inviscid and Viscous Flows Using LU AUSMPW Schemes
Zhao Xingyan, Su Moming, Miao Yongmiao
2000, 15(2): 124-128.
Abstract PDF(487KB) icon1743 icon469
Abstract:
An AUSMPW scheme in conjunction with the third order MUSCL scheme is developed for the multidimensional hyperbolic conservation laws in curvilinear coordinates.The present scheme is combined with the LU SGS Scheme for compressible Euler and Navier Stokes equations solution.A new MUSCL limiter is proposed.The effects of the present limiter are analyzed in the aspects of efficiency,accuracy and robustness of LU AUSMPW schemes.In order to identify the performance of LU AUSMPW schemes,a two dimensional transonic and supersonic inviscid flow in the cascade of two circular arc blades and a two dimensional supersonic viscous flow in convergent divergent nozzle are chosen as numerical examples.The accuracy of the scheme has been assessed by comparing the results with experimental data or other numerical results available in literature.It is shown that the LU AUSMPW schemes in conjunction with present limiter possess obvious superiority in aspects of convergence rate,accuracy and robustness for calculating compressible flow fields,and there is no any spurious oscillation near the shock wave.
Improvement of Compressor Blade Leading Edge Design
Lu Hongzhi, Xu Liping, Fang Ren
2000, 15(2): 129-132.
Abstract PDF(479KB) icon1993 icon550
Abstract:
The effect of compressor blade leading edge shape on the blade performance was investigated numerically.It is found that the flow experiences rapid expansion around the traditional circular leading edge right downstream of the stagnation point,and causes overexpanding at the leading edge suction surface.An adverse pressure gradient emerges at the blending point of the leading edge with the main blade surface due to the curvature discontinuity.The adverse pressure gradient often causes a laminar separation,if the Reynolds number and turbulence levels of inlet flow are low.The elliptical leading edge has a smooth curvature distribution,which suppresses the overexpansion and causes a weak adverse pressure gradient,so that the blade with elliptical leading edge has a better performance.But the elliptical leading edge is difficult and expensive to manufacture.The circular leading edges with flats are suggested,which have typical Cp structure of multiple weak suction peaks at the edges of the flats instead of a single strong suction peak in the case of the conventional circular leading edge.For most cases,the leading edge with one flat can improve the blade performance no less than the more complicated elliptic (a/b =2) one,and can be manufactured easily.
Numerical Simulation Research on Mechanism of Stability Enhancement by a Dovel Hub Treatment
Li Ling, Yu Qing, Lu Yajun
2000, 15(2): 133-136,141.
Abstract PDF(341KB) icon1581 icon449
Abstract:
WT5BZ]The three dimensional viscous turbulent Reynolds averaged equations of motion and turbulent models based on RNG method are used to simulate the flow field in a blade row with axial skewed slot hub treatment and a blade row with curve skewed slot hub treatment.The difficulty in grid system establishment due to the complex structure in treatment slots is surmounted by using zonal grids technology.By analyzing the mutual interaction between flows in the hub treatment slots and the endwall flows in blade row,the mechanism of the compressor stability enhancement is revealed both for traditional axial skewed slot hub treatment and novel curve skewed slot hub treatment.
Experimental Investigation on Influence of Incidence on Performance of Turbine Stator Cascade
Gu Zhonghua, Han Wanjin, Zhou Xun, Lu Wencai, Wang Zhongqi
2000, 15(2): 137-141.
Abstract PDF(314KB) icon1692 icon454
Abstract:
An experimental investigation was carried out to examine the influence of incidence angle on the performance of an annular turbine stator cascade with controlled outlet angle guide vanes.The tests were made at seven incidence angles from +25° to -28°.The five hole probe measurements were performed at two planes,one was located at the stator cascade exit and another at the guide vane exit.The static pressure distribution on the stator blade surface was also measured.The distributions of local energy loss coefficients with local static pressure coefficients,as well as the secondary flow velocity vector plots show in detail,how much the losses and the secondary flow are influenced by incidence angles.At positive incidence,the losses rise mainly due to the development of passage vortex.At negative incidence,the losses rise due to the separation of pressure surface boundary layer.
The Effect of Inducer Shape on the Alternate Blade Cavitation
Huang Jiande, Gu Chuangang
2000, 15(2): 142-146.
Abstract PDF(367KB) icon1601 icon439
Abstract:
Measurement and visualization of suction performance and cavitation development have been performed on a flat helical inducer with two blades.As the suction pressure is reduced,the balance of the cavity development on both blades may be destroyed.Alternate blade cavitation can occur,in which the cavity development evolves on one blade but weakens on the other.This makes the pump lift decrease quickly.Thus,the same investigation on four types of inducer impellers with different blade numbers and blade lengths have also been performed.The effects of the impeller geometrical parameters on the cavitation performance and occurrence of the alternate blade cavitation are found out and the mechanism is explored.
A Modified Estimation Method for off-Design Performance Prediction of Forward Skewed Rotor Blades
Liu Fubin, Zhong Fangyuan, Du Zhaohui
2000, 15(2): 147-150.
Abstract PDF(280KB) icon1587 icon410
Abstract:
The forward skewed rotor blade of low speed axial flow fan can increase the efficiency by 4～5%,expand the range of off design condition by 15～20% in the comparison with the typical blade straight blade.In this paper,the “di actuator disc”theory model is applied to calculating the flow field of forward skewed rotor blade;the modified loss model in design condition is adapted to the lift/draft model of attack angle and is used to estimate the off design condition flow field,the efficiency of the blade,etc.The estimated results at the design condition are in good agreement with the experimental results [1] .The maximum error of the efficiency along the blade height is 1.5% and that of the total pressure is 1.8%.The mass average errors are 1% and 1.5%.At off design condition,the mass average errors of the efficiency and the total pressure are all less than 2%.It is proved that this method is applicable and can meet the need of the engineering design.
An Experimental Research on the Exhaust Ejector-Mixer System with Tabs on a Rectangular Primary Nozzle
Wang Guangzhen, Wu Shousheng, Wang Zhishan, Wei Fuqing
2000, 15(2): 151-154.
Abstract PDF(304KB) icon1604 icon470
Abstract:
Four triangle mechanical tabs with different area and vertex angle,fixed on the exit of primary nozzle,have been tested comparatively to investigate the effect of number,area(or blockage ratio),shape and fixed angle of the tabs on the aerodynamic characteristics of the exhaust ejector mixer system.The results show that the application of the mechanical tabs increases the system pressure loss coefficient,but it can improve system pumping coefficient and mixing uniformity,and meliorate the synthetic aerodynamic characteristics of the exhaust ejector mixer system.
Experimental Investigation of Flow and Heat Transfer in Straight Labyrinth Seal
Shao Wanren, Wu Shousheng
2000, 15(2): 155-158,163.
Abstract PDF(351KB) icon1822 icon457
Abstract:
A conventional annular exhaust ejection mixer and three lobed exhaust ejection mixers were tested at atmospheric pressure and low exhaust velocity conditions to study the effects of three structure parameters lobe exit angles α/β ,relative mixing length L/D and lobe penetration H/Ho on the aerodynamic characteristics of the lobed exhaust ejection mixers.The results show that the aerodynamic characteristics of the lobed exhaust ejection mixer are obviously better than those of an annular exhaust ejection mixer.The effect of the lobe exit angle α/β on the performance of the mixer is not so distinct if no separation occurs inside the lobes,but the increase of α/β is advantageous to the compromise between aerodynamic performance and weight.The increase of relative mixing length L/D can improve the aerodynamic performance.An optimum L/D exists for the compromise between aerodynamic performance and weight.The effect of the lobe penetration H/Ho on the aerodynamic performance of the lobed exhaust ejection mixer is significant.The enhancement of the lobe penetration H/Ho is advantageous to the flow mixing,but disadvantageous to the pumping ability.
Experimental Research on Lobed Exhaust Ejection Mixer
Huang Xiaoguang, Wu Dingyi, Wang Yonghong, Weng Shilie
2000, 15(2): 159-163.
Abstract PDF(343KB) icon1774 icon482
Abstract:
We built a big scale inhale labyrinth heat transfer wind tunnel.Detailed experimental investigation on the flow field in the labyrinth cavity reveals the two dimensional velocity and pressure fields as well as vortix distribution in the flow field and local heat transfer coefficient distribution on the roof of labyrinths.Therefrom the influences of different Reynolds number and T/C on the velocity and pressure distributions in the cavity of the labyrinth and on the heat transfer coefficient of the labyrinth roof seal are found out.
Experimental Investigation on Flow and Heat Transfer in Shrouded Rotating Disk with High-Positioned Air Inflow
Xu Guoqing, Tao Zhi, Ding Shuiding, Zhu Gujun
2000, 15(2): 164-168.
Abstract PDF(336KB) icon1551 icon453
Abstract:
The flow and heat transfer characteristics of the rotor stator disk system were investigated experimentally.The distributions of the pressure on the stator surface,temperature on the rotating disc surface,local and averaged Nusselt number of the rotating disk were obtained from the tests.Conclusions are drawn as follows:the temperature gradient near disk center is insignificant.The effects of rotating Reynolds number Re ω on the Nusselt number is complex and is related to inlet mass flow coefficient Cw and the clearance gap ratio G s .The averaged Nusselt number is dramatically increased with the increase of inlet mass flow coefficient.It was also found that the pressure on the stator increased with increasing rotation speed or mass flow rate.
Numerical Study on Flow and Heat Tranfer in Shrouded Rotating Disk System with Central Air Inflow
Xu Guoqing, Tao Zhi, Ding Shuiding, Luo Xiang
2000, 15(2): 169-173.
Abstract PDF(362KB) icon1444 icon455
Abstract:
The mixing length model and conjugation calculation were applied to the numerical simulation for the fluid flow and heat transfer process in a rotating shrouded disk with central coolant inlet.Comparison the simulation results with experiments indicates that the mixing length model gives quite reasonable prediction.Numerical simulation shows that:(1)the location of the maximum Nusselt number was offset from the stagnation point at a certain distance;(2)the heat transfer was enhanced with the increase of rotating speed and coolant flow rate.
Performance of Ferrofluid Lubricated Journal Bearing
Chi Changqing
2000, 15(2): 174-178.
Abstract PDF(304KB) icon1485 icon504
Abstract:
The load carrying capacity of the ferrofluid lubricating films can be increased directly by means of the applied magnetic field.The ferrofluid behaves simultaneously as a Binghamoplastic and as a pseudoplastic.The constitutive equations of the ferrofluid can be expressed as τ(H,D)=τ s(H)+η 1(H)D+η 2(H)D 2 .When the uniform applied magnetic field intensity increases from zero to 0.12 MA/m,the load carrying capacity of ferrofluid lubricating film is enhanced by 25 per cent under the condition of high shear rate and by 35 per cent under the condition of low shear rate.So for practical purpose,the ferrofluid lubrication is used to control load carrying capacity by applied magnetic field,but not to obtain high load carrying capacity.It is necessary to make the ferrofluid seal separate from lubricating film in order to avoid restrictions on the load carrying capacity of journal bearing.The calculated results show that the uniform applied magnetic field intensity and the shear rate have little effect on the attitude angle.
Analysis of Work Clearance for High-Speed Rolling Bearing in the Condition of Loss-of-Lubrication
Su Hua, Liu Zhiquan
2000, 15(2): 179-182.
Abstract PDF(416KB) icon1577 icon405
Abstract:
The work clearance of the rolling bearing affects its lifetime and survivability of the transmission system greatly.In the condition of loss of lubrication,the variation of work clearance in the high speed rolling bearing of helicopter transmission system is analyzed,and the factors such as the rolling bearing's installing,turning,difference in temperature and load are researched.The formulas for work clearance variation are derived with considering the elasticity,and the numerical example is presented.They provide the bases for choosing rolling bearing parameters reasonably,improving the lifetime of bearing system and the survivability of armed helicopter transmission system.
Method for Traveling Wave Vibration Analysis of Fan Casing in Aeroengine
Wang Guihua, Li Lin
2000, 15(2): 183-186.
Abstract PDF(298KB) icon2170 icon539
Abstract:
The traveling wave vibration of the fan casing is researched on the basis of analyzing its structure and load characteristics.According to the response line,the natural frequencies with high response are avoided.The method for simplifying the structure into cyclic symmetrical one and the loading method of rotating pulse incitement are given in this paper.An engineering example is calculated with this method,the result shows both time saving and a good agreement with the testing data.
Dynamic Model of Dual-Rotor System with Rub-Impact Fault Between Rotor and Stator and its Feature of Wavelet Transform
Liu Xiandong, Li Qihan, Wang Deyou
2000, 15(2): 187-190.
Abstract PDF(285KB) icon2030 icon427
Abstract:
Using Lagrange′s equation,the dynamic equation of dual rotor system with rub impact fault of some type of aeroengine is established,and emulations of this fault is completed through numerical calculation.The spectral analysis and wavelet transform are also made,and the conclusions are drawn that the dynamic model of dual rotor system with rub impact fault is valid and the wavelet transform is a very effective tool to diagnose this fault.
Non-Stationary Analysis of Rotor/Casing Rubbing
Ding Qian, Chen Yushu
2000, 15(2): 191-195.
Abstract PDF(343KB) icon1824 icon449
Abstract:
A flexible Jeffcott rotor supported at the ends by identical squeeze film dampers is investigated to study the non stationary vibration due to rubbing with casings during passing through the critical speed.The rotational speed of the rotor is supposed increasing at a constant angular acceleration.The contact force theory is used to calculate the impacting forces and friction forces.The numerical ealculation reveals the effects of the rotational acceleration on the occurrence of diverging backward whirl,so as to determine whether the rotor can pass through the critical speed or not.The influence of some system parameters on the critical acceleration is also discussed.
A Study on Fuzzy Neural Network Diagnosis Modelling
Zhang Xiaodong, Miao Xiaoyan, Zhu Jun
2000, 15(2): 196-200.
Abstract PDF(319KB) icon1729 icon425
Abstract:
A fuzzy neural network diagnosis model is established,based on adaptive dynamic performance of the generalized neural network and methods of diagnosis modelling.Its intelligent diagnosis mechanism and outstanding characteristics are elaborated.In the end,this model has been applied to the fault diagnosis of a large turbine generator set,the results show that it features a high diagnostic precision.
Theoretical Analysis and Numerical Simulation of Regression Rate in SFRJ
Tan Jianguo, Chen Xiaoqian, Yang Tao, Zhang Weihua
2000, 15(2): 201-204.
Abstract PDF(280KB) icon1575 icon402
Abstract:
Factors which affect regression rate in solid fuel ramjet (SFRJ) are explored through theoretical analysis.The exponent relationship of the mean regression rate with combustor pressure,inlet air mass flux and air temperature is derived.SFRJ model based on combustion and flow is established.Then the regression rate is simulated numerically by using PHOENICS software.Comparison between the calculated results and the experimental data confirms the eorrectness and reliability of the presented simulation method.
An Identification Model of Aeroengine Based on the RBF Network
Ding Kaifeng, Fan Siqi
2000, 15(2): 205-208.
Abstract PDF(411KB) icon1638 icon489
Abstract:
The identification model of aeroengine based on the Radial Basis Function network is set up by using the measured flight tests data as learning stylebook.The parameters of engine are identified at different flight heights by this method.The network is also compared with several Back Propagation networks.The results show that this method has the advantage of faster learning rate,higher identifying precision and better real time ability.It can be used on the engine on line identification.
Tip Aerodynamic Instability of High Load Rotor with Preswirl and Excess Meridional Backswept
Shan Peng
2000, 15(2): 209-211.
Abstract PDF(353KB) icon1642 icon404
Abstract:
An unusual aerodynamic phenomenon is encountered in designing a high through flow,high load single stage backswept fan.The fan is one of the two base schemes of the model fan ATS 2 with preswirl incoming flow and stage pressure ratio 2.33,tip radius 0.4414 m,tip velocity 490 m/s.In the flow calculation of S2m stream surface streamline curvature,the flow near the rotor tip stagnates unavoidably and the iteration does not converge or converges irregularly.It is found out from the analysis that the phenomenon is mainly associated with the excess backswept of the rotor leading edge.
The Effect of Coupling on Distortion Transfer in Fan and Compressor
Wang Zhanxue, Tang Diyi, Wang Jianfeng
2000, 15(2): 212-214,218.
Abstract PDF(264KB) icon1552 icon428
Abstract:
The mechanism of spool coupling effect on distortion transfer in fan and compressor is analyzed.A quick convergent method is selected to calculate amplitude of the total pressure distortion at exit of low pressure spool in cases of no coupling,complete coupling,and real coupling respectively,then the correcting coefficient of the distortion transfer is obtained.The results show that the distortion transfer characteristics of no coupling differ from those of actual coupling.
Numerical Simulation of 3-D Two Phase Flowfield in Inlet Particle Separator for Helicopter
Hou Lingyun, Yan Chuanjun
2000, 15(2): 215-218.
Abstract PDF(485KB) icon1809 icon403
Abstract:
An inlet particle separator with vanes in helicopter is investigated.Turbulent bifurcated flowfield and particle motion are simulated in the three dimensional non orthogonal curvilinear coordinate system,boundary condition is treated specially and the effect of vanes on flowfield is considered by the use of zonal method.Predicted results and experimental data are in good agreement.
Shape Optimization of Integrated Impeller
Cai Xianxin, Yin Zeyong, Gao Deping
2000, 15(2): 219-221.
Abstract PDF(356KB) icon2270 icon479
Abstract:
A shape optimization procedure for integrated impellers is considered.An efficient approach for the structural analysis of integrated impellers is proposed.The mathematical model of the optimization is discussed,including the definition of objective functions,selection of design variables and specification of the optimization restraints.Behavioural constraints comprise stresses,displacements and vibration frequencies.A numerical example is presented in which an impeller is optimized,and in result its weight is reduced efficiently.
Fault Detection of Microprcessor System in Aeroengine FADEC
Wang Yonggen, Tian Lin, Gou Linfeng
2000, 15(2): 222-224.
Abstract PDF(218KB) icon1735 icon486
Abstract:
A POST(Power-on Self Test)method of microprocessor system is developed in aeroengine FADEC(Full Authority Digital Electronic Control).The methods of fault detection for RAM memory are investigated and the experiment shows that the methods can detect accurately faults of RAM memory.The fault detection and correction method of Hamming coding in the aeroengine FADEC system is researched.The experiments show that one-fold error of information transference can be detected and corrected accurately by Hamming coding,but two-fold error only can be detected

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