实验流体力学

LI Xiao-feng, ZHENG Long-xi, QIU Hua, ZHENG Hua-lei

2013, (6): 1-5. doi: 10.3969/j.issn.1672-9897.2013.06.001

Abstract(91) PDF(4)

Abstract:

In order to study the detailed matching mechanism among the pulse detonation combustor,the turbine and the compressor,the pulse detonation turbine engine test system, which is mainly composed of the pulse detonation combustor,the turbocharger,the lubrication system,the engine monitoring and control system and so on,is established.The pulse detona-tion turbine engine principle experiment is carried out,and it is firstly succeed that the turbine is driven by the pulse detonation combustor and the compressor compresses air supplying for the pulse detonation combustor.The test results show that the pulse detonation turbine engine can stably work at self-suction mode durably,and the pulse detonation chamber,the turbine and the compressor match well,which verifies that using the pulse detonation combustor to alter the con-ventional isobaric combustion chamber is feasible.

HE Zhong, WU Jun-qiang, JIANG Wei-min, WU Ji-fei

2013, (6): 6-13. doi: 10.3969/j.issn.1672-9897.2013.06.002

Abstract(82) PDF(4)

Abstract:
Using pointed tangent-ogive slender body,under the Mach number ranged from 0.4 to 1.2,and angle of attack ranged from 0°to 50°,the pressure measure tests and PIV tests were completed in high speed wind tunnel to investigate the response between model tip perturba-tion and asymmetric vortex flow at high angles of attack.The results show that asymmetric multi-vortex flow structures still exist in high speed case.It was observed that there was a distinct relation between tip perturbation and response of asymmetric vortex flow,but a feeble relation between tip perturbation and response of asymmetric aerodynamic force.

YUAN Ming-chuan, SHI Zhi-wei, CHENG Ke-ming

2013, (6): 14-18. doi: 10.3969/j.issn.1672-9897.2013.06.003

Abstract(98) PDF(8)

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The folding wing aircraft is a new type of aircraft that can change its aerodynamic shape in flight.A model of the folding wing aircraft with active morphing control is manufac-tured.The aerodynamic characteristics of the aircraft in different aerodynamic configuration un-der static conditions and the morphing process are obtained in the NUAA unsteady wind tunnel, and the flow field distribution is got through the PIV testing.The results show that,the folding wing aircraft model have obvious unsteady aerodynamic characteristics in the morphing,and the hysteresis loop is increased with the frequency of the folding motion.The reason for the unsteady characteristics is that the leading-edge vortex structure is changed with the wing morphing.

LU Yu-zhou, XU Shu-min, ZHONG Wei, YANG Jian-zhi, LIU Ming-hou

2013, (6): 19-25. doi: 10.3969/j.issn.1672-9897.2013.06.004

Abstract(54) PDF(3)

Abstract:
Using smoke wires and PIV technique,the near wake(X/D<5 )of circular disk with an aspect of D/H =5 at Re=22400 was experimentally studied.Flow visualization using smoke wires showed that there was a stable recirculation zone and stochastic,distorted and tilted three-dimensional vortices behind the disk.By statistic average analysis of a series of cartogra-phies obtained by PIV technique,it was found that the mean flow field was symmetric with a re-circulation zone in length of 2.1D.POD analysis was applied to the PIV data,reconstruction of the first pair of eigenmodes manifested that the peaks of u2 and uv located in the shear layer be-tween the free stream and the recirculation zone,and the peak of V2 appeared near the stagnation point of the recirculation zone,where vortices were shedding displayed by smoke wires.As a conclusion,vortices generation and shedding in the wake originated from shear layer instability and its interaction with the recirculation zone.The first and second POD modes represent only 10.9% and 10.2% of total turbulent kinetic energy,which means that turbulence structures is relatively stochastic.The first ten modes represent 45.9% of total energy,therefore,the mean Reynolds shear stress can be well described.

LIU Sen, WANG Zong-hao, XIE Ai-min, CHEN Xu-ming, HUANG Jie

2013, (6): 26-31. doi: 10.3969/j.issn.1672-9897.2013.06.005

Abstract(70) PDF(15)

Abstract:
To investigate hypersonic boundary transition phenomena and provide reliable experimental data for CFD code validation,boundary layer transition experiments have been con-ducted at the hypervelocity ballistic range of China Aerodynamics Research and Development Center.The cone-cylinder-flare models are 105mm in length,flying at speed of 1.94km/s(Ma 5. 65),with unit Reynolds numbers of 4.32 ×10 7 ~1.20 ×10 8 m-1 .Images of transition and turbu-lent boundary layer are obtained with laser shadowgraph technique,resulting in measured turbu-lent boundary layer thickness of 0.6 ~2.2mm,and the dimension ratio of 0.3 to 0.8 between turbulent eddy and boundary layer thickness,which reduced along the flow direction.It is shown that,images of Ma 5.65 hypersonic boundary layer transition could be obtained by ballistic range experiments at given flight environment,in which the transition location,boundary layer thick-ness and turbulent eddy scale could be determined.

WU Jun, WANG Jin-jun, LI Tian

2013, (6): 32-38. doi: 10.3969/j.issn.1672-9897.2013.06.006

Abstract(172) PDF(28)

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An experimental study on the boundary layer flow and near wake behavior of a NA-CA0012 airfoil was conducted in the water tunnel,with the primary interest in the evolution of coherent structures at different angles-of-attack up to 15°and Reynolds number of 8200.It is found that the separation point,as well as the location of vortex roll-up,moves toward the lead-ing-edge of the airfoil as the angle-of-attack increases,and the size of reserve flow region also in-creases as the angle-of-attack increased.When a laminar separation bubble is formed at some an-gles-of-attack,the three-dimensional deformation of the roll-up-vortices,as well as vortex par-ing,is observed around the reattachment point.

YANG Ying-kai

2013, (6): 39-42. doi: 10.3969/j.issn.1672-9897.2013.06.007

Abstract(67) PDF(6)

Abstract:
The Bump inlet dynamic characteristics wind tunnel test is introduced.When air-craft pitching maneuver ,the bump inlet performance parameters show periodic change with time, atα>10°,under up pitching,inlet total pressure recovery coefficientσ,integrated total pressure distortion of inlet W ,inlet total pressure circumferential distortion Δσ0 reduce,under down pitch-ing,the above parameters increase,which are less than those under up pitching,and for a pitch period to form a close loop.The inlet total pressure pulsation average turbulence Tu change little in the process.

TAO Yang, ZHAO Zhong-liang, LI Hao, YANG Hai-yong, LI Yu-ping

2013, (6): 43-46. doi: 10.3969/j.issn.1672-9897.2013.06.008

Abstract(86) PDF(2)

Abstract:
The free to roll test,static force balance test and dynamic derivative test of 80°/65° double delta wing at high angle of attack are conducted in FL-23 high speed wind tunnel,which dynamic behaviors are forecast based on the static roll moment coefficients and dynamic deriva-tive.The results show that dynamic motions obtained on a double delta wing was free to rotate a-bout its longitudinal axis at different angles of attack.Different dynamic rolling motions inclu-ding the static stability,double periodic oscillation,quasi-limit-cycle rock motion were observed. The forecast results meet the free to roll result well.

XU Ling-jun, XUE Yang, ZHANG Song

2013, (6): 47-52. doi: 10.3969/j.issn.1672-9897.2013.06.009

Abstract(84) PDF(3)

Abstract:
The process of bubble formation is involved in a lot of gas-liquid reactors and process equipment.It is therefore important to understand bubble formation process and to develop computational models for the accurate prediction of the bubble formation characteristics in different bubbling regimes.Numerical simulation of bubble formation cycle on orifice were carried out using the combined level set and volume-of-fluid method and the predictions were experimentally validated,Effects of gas flow rate and orifice diameter on the bubbling regimes were discussed.Based on the simulation data and experimental data on the transition of bubble formation regimes,Froude and Bond numbers,the inlet gas velocity at orifice decreases with increase in the orifice diameter is presented.

XU Kao, CHEN Lian-zhong, LIU Yang

2013, (6): 53-57. doi: 10.3969/j.issn.1672-9897.2013.06.010

Abstract(62) PDF(2)

Abstract:
For the wing with some deflection angle,the windward angle and the deflection an-gle will directly influence the position where heat flux is the highest on the arc surface of the lead-ing edge.In this paper,based on the triangle theory of the ball surface and the calculation formu-la of heat flux about the cylinder with some sweepback angle,the function equation about the windward angle and the deflection angle and the deviation angle (Deviate the center line on the lending)was derived.When the any two angles were determined among the three angles dis-cussed above,another angle was also obtained according to the function,which was the place where the heat flux was the highest.Those results are basically the same with the experimental results and the empirical results,which almost satisfies engineering requirements.In the end, the variation for heat flux on the leading edge were analyzed when the windward angle and the de-flection angle.

CAO Hong-cai, SHI Sheng-xian, LIU Ying-zheng

2013, (6): 58-63. doi: 10.3969/j.issn.1672-9897.2013.06.011

Abstract(73) PDF(9)

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A state-of-the-art algorithm of the Particle Image Velocimetry (PIV)was proposed to accurately determine the flow field near arbitrarily moving and deforming boundary,which is usually associated with strong nonlinear coupling of fluid-structure interaction.This smart algo-rithm was employed to faithfully track the fluid-structure interface with large deformation;sub-sequently,a body-fitted arrangement of interrogation windows was made and the standard cross-correlation PIV algorithm was applied to get reliable flow field information near the boundary, providing a solid basis for fluid-structure interaction mechanism analysis and validation of numeri-cal calculations.The proposed algorithm went through bench-mark tests by using synthetically generated image pairs,showing the great potential for measuring the fluid flow around arbitrarily moving and deforming interface.Finally,the fluid flow of fluid-structure interaction associated with a flexible membrane,which was placed behind a square cylinder,was measured by PIV;the instantaneous flow fields near the violently moving and deforming membrane were determined.

WANG Qiu, ZHAO Wei, YU Xi-long, JIANG Zong-lin

2013, (6): 64-69,85. doi: 10.3969/j.issn.1672-9897.2013.06.012

Abstract(70) PDF(3)

Abstract:
A laboratory measurements program has been performed in the JF-10 high enthalpy shock tunnel,which provides the aerodynamic and aerothermal conditions wherein plasma envi-ronment issues can be quantitatively examined.Electron number density is measured by a swept-voltage electrostatic probe placed on a 10 degree wedge model.Dual-cable method is explored in order to reduce the induced noise due to the RC characteristic of coaxial cables when a high fre-quency swept voltage is applied to the probe.Results show that electron density in the boundary layer of the model can be effectively acquired and the dual-cable method turns out to be an effec-tive way for electron density measurement in the short duration test facilities.

ZHANG Ya, CHEN Fang, LIU Hong, WANG Xin-yuan

2013, (6): 70-75. doi: 10.3969/j.issn.1672-9897.2013.06.013

Abstract(72) PDF(7)

Abstract:
The tracking capability of tracer particles is one of the key points to the applications of PIV technique in supersonic flow.In this paper,the experiment research of PIV technique was developed in Multi-Mach number High-speed Wind Tunnel of SJTU,and an analytical model of relaxation characteristics was specially proposed,which used to evaluate the tracking capability of tracer particles.In the supersonic flow of Ma4,the results of the PIV experiments on typical models,including a sharp cone and two wedges with different semiapex angles,agree well with the analytical results of the particle diameters,and demonstrate the measurement accuracy and the seeding efficiency of PIV in the supersonic flow.It indicates that the proposed model is prac-tically credible to analyze the relaxation characteristics of tracer particles.

ZHU Bo, LIU Qin, QU Xiao-li, NIE Xu-tao

2013, (6): 76-80. doi: 10.3969/j.issn.1672-9897.2013.06.014

Abstract(49) PDF(4)

Abstract:
A pilot gust generator is as experiment object,by measuring the flow field of the gust generator in different situations with two dimension hot wire anemometer,the measurement scheme and online measuring angle correction,and the calculation of the gust amplitude and flow fluctuation are proposed.Experiment results show that online angle correction used can improve the accuracy and efficiency of two dimension hot wire in Y direction,phase analysis used can sat-isfy the calculate the amplitude and fluctuation of periodic gust.Gust amplitude is in direct ratio with the vane oscillation frequency of 4 ~ 15Hz,oscillation angle of 8°~ 30°,and vane chord length of 50~100mm.Unstability (velocity fluctuation at same phase)of the gust flow has a cer-tain linear relationship with the vane oscillation angle and wind speed,which increases while the vane oscillation angle and wind speed increase in the test range,at the same time,proper vane os-cillation frequency can decrease unstability.The conclusion is helpful for the gust generator de-velopment and flow field measurement in wind tunnel.

L Zhi-guo, LI Guo-jun, ZHAO Rong-juan, JIANG Hua, LIU Ji-chun, WANG Gang

2013, (6): 81-85. doi: 10.3969/j.issn.1672-9897.2013.06.015

Abstract(77) PDF(14)

Abstract:
The research of direct measurement of skin friction in hypersonic shock tunnel is in-troduced in this paper.In the study,the piezoelectric skin friction balance was developed to test the skin friction of the model of engine inlet with compressed corner.In order to improve the pre-cision of calibration and experiment result,and easy to change between the calibration and wind tunnel experiment,a new skin friction balance structure was used.In this new structure,the skin friction balance has a separated measurement head with balance main body,which will en-sure the measurement head and calibration head could be changed in different situations.The measurements were conducted in the flow field with the nominal mach number of 8 and 10,Reyn-olds number of 2.85×10 7/m and 1.58×10 7/m in0.6m shock tunnel of CARDC.The heat flux near the skin friction test location was tested using platinum thin film sensors,the results are co-incided with the Reynolds analogy.

YANG Hong-sheng, MI Peng, LIU Wei, XIE Bin

2013, (6): 86-90,98. doi: 10.3969/j.issn.1672-9897.2013.06.016

Abstract(49) PDF(3)

Abstract:
The vane cable suspension support balance is important component of the vane cable suspension support system in 1.2m × 1.2m wind tunnel,in order to ensure successful development of balance,a new balance structure as the shape of word “E”is presented by finite element analysis(FEA)simulation.Results of balance FEA simulation,static calibration,dy-namics calibration and wind tunnel test show the balance have reasonable structure and excellent performance.

LIU Xiao-bo, ZHANG Wei-wei, ZHAI Jian, YE Zheng-yin

2013, (6): 91-98. doi: 10.3969/j.issn.1672-9897.2013.06.017

Abstract(44) PDF(3)

Abstract:
In order to study the characteristics of the synthetic jet near the trailing edge of an airfoil,an experimental project in wind tunnel is designed for a NACA0015 airfoil.It contains the design of the experimental model,the design of low frequency high power synthetic jet actuator and the method of measurement.The experimental results show that when the speed of the ser-vo-motor runs up to an appropriate rotational speed,the synthetic jet works well.By adjusting the ground cylinder stroke and the operating frequency of the motor,the effect of the spout speed,frequency and other parameters on the aerodynamic loads can be studied.For the two-di-mensional test section,a two-dimensional strain balance is designed to measure the dynamic lift and moment.The present experimental project operates successfully in the wind tunnel.It shows that when the frequency of synthetic jet is 3 Hz,the amplitude of lift coefficient is approximate 0.16 which is equal to the value of the experimental airfoil at 1.5 deg angle of attack.So,a synthetic jet actuator of low frequency and high power can supply a large force to control the aeroelastic problem.The new action provides a new way for future aircraft aeroelastic stability control.

WANG Yu-hua, LIU Wei, WANG Chao, ZHANG Yue

2013, (6): 99-102. doi: 10.3969/j.issn.1672-9897.2013.06.018

Abstract(76) PDF(4)

Abstract:
It is a key to study calibration technique of twin balances used for force-measure-ment test on supporting wingtips in wind tunnel,in which twin balances are used simultaneously to measure aerodynamic loads of the model.Based on measure principle of twin balances,a new complex formula for twin balances is determined,it’s depending on the both calibration formulas for two balances according to spatial force system synthesis principle and interference correction technology among balance components,which is carried out by calibrating the special twin bal-ances separately and synthetically,and is validated with wind tunnel tests.The results show that the calibration technique of twin balances is reasonable and credible,while the maneuverability is well.This technology can serve as the essential theoretical and test basic for the wing-tip support force-measurement test technology wing-tip support.

2013, (6): 103-105.

Abstract(34) PDF(4)

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2013 CONTENTS

2013, (6): 106-110.

Abstract(34) PDF(3)

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2013 Vol. 27, No. 6