实验流体力学

Computational interferometry for three-dimensional flow

LE Jia-ling, WU Ying-chuan, NI Hong-li, WANG Hui-ling

2001, 15(2): 1-9. doi: 10.3969/j.issn.1672-9897.2001.02.001

Abstract(119) PDF(4)

Abstract:
In present paper,a technology (including a computed optical device and digital image process) of computational interferometry for complicated 3-D steady and unsteady flow is described.A good agreement between computational holographic interferogram for 3-D shockwave flow and experimental ones shows that this technology is a powerful tool for CFD and experimental research in complicated 3-D flows.

Research on blast wave interaction with body traveling supersonically

NI Hong-li, LE Jia-ling

2001, 15(2): 10-15. doi: 10.3969/j.issn.1672-9897.2001.02.002

Abstract(123) PDF(3)

Abstract:
In present paper,the unsteady flow field of a blast wave interaction with a sphere traveling in supersonic speed is determined using a shock-capturing,finite difference approach and hybrid scheme.The presented numerical results compare favorably with the available experimental data,and the weak contact surface of bow shock interaction with the reflected blast wave obtained is shown to agree better with that of experiment.The flow of a blast wave encountered a sphere traveling supersonically at -5° angel of attack is studied further.

Research on side-wall boundary layer three dimensional effect in airfoil testing with adaptive wall wind tunnel

HE Jia-ju, ZUO Pei-chu, A·海德格特, E·司丹纽斯基

2001, 15(2): 16-27. doi: 10.3969/j.issn.1672-9897.2001.02.003

Abstract(149) PDF(6)

Abstract:
In two dimensional airfoil tests for models mounted on the side wall turn table may introduce three dimensional side wall boundary layer effects.CAE and DLR had done a cooperative research on this topic by calculating and measuring method to research the condition of three dimensional boundary layer effects on side wall.This paper describes the work that had been carried out since 1995~1998,including the research object and strategy,calculating method,tests in KRG for verifying and the analysis of the results as well as the primary conclusion.

A method for shortening ignition delay of hydrocarbon fuel-air mixture

SUN Ying-ying, HAN Zhao-yuan, SITU Ming, Xu Sheng-li

2001, 15(2): 28-33. doi: 10.3969/j.issn.1672-9897.2001.02.004

Abstract(96) PDF(3)

Abstract:
A combination facility,which consists of a shock tunnel and a shock tube,was used for studying ignition and supersonic combustion of premixed hydrocarbon fuel-air mixture.In order to shorten the ignition delay time of hydrocarbon fuel-air mixture,an atomized and vaporized hydrocarbon fuel (gasoline) was preheated by shock reflections between the entrance of nozzle and contact surface,which was located between working gas and driver gas,in the shock tunnel.In addition, a hot, burned gas generated from the shock tube was used as pilot flame for igniting the premixed and preheated supersonic hydrocarbon-air mixture generated in the shock tunnel.A schlieren system was used for flow visualization of the flame propagating in a supersonic,combustible flow.By means of these methods mentioned above, the ignition delay time of the supersonic hydrocarbon-air mixture can be shortened to less than 0.2 ms, and the speed of flame propagation relative to the supersonic,combustible gas was obtained.

Performance of the detonation driven shock tube with a converging throat

ZHAO Wei, JIANG Zong-lin, WANG Chao

2001, 15(2): 34-40. doi: 10.3969/j.issn.1672-9897.2001.02.005

Abstract(138) PDF(6)

Abstract:
In order to increase the performance of the detonation driven shock tunnel, some converging throats are added in driver section near the main diaphragm.Experimental results indicate that this way can availably weaken the effect of Taylor rarefaction waves.

Experimental investigation on the aero-elastic behavior of Haicang suspension bridge

LI Ming-shui, CHEN Xin, ZHANG Da-kang, WANG Wei-hua

2001, 15(2): 41-46. doi: 10.3969/j.issn.1672-9897.2001.02.006

Abstract(126) PDF(2)

Abstract:
Haicang Bridge,a tri-span suspension bridge with a main span of 648m and a streamlined steel box girder,is located in Xiamen,Fujian province,one of typhoon-prone areas in southeastern China.This paper investigates the flutter instability and buffeting responses of the bridge at operation and five erection stages through wind tunnel tests of full aeroelastic models.

A numerical test on the accuracy of particle image velocimetry

WEI Qing-ding, YAN Bin, CHEN Jun

2001, 15(2): 47-52. doi: 10.3969/j.issn.1672-9897.2001.02.007

Abstract(117) PDF(3)

Abstract:
A numerical test on the accuracy of the particle image velocimetry is conducted.It is assumed that the information of the particle image photographed by double-exposure with a light sheet is processed by correlation method.In order to study the effect of non-uniformity of fluid motion on determination of the velocity vector at an interrogation spot,five typical non-uniform factors are discussed.A statistical method is used to get quantitative estimation.The results suggest that the accuracy of this PIV method is significantly affected by some factors of non-uniform flow.

Measurement of concentration distributions for the dispersed-phase flow in a mixing reactor with the laser light scattering by particles

SHEN Xiong, PENG Tao, YUAN Hui-jing

2001, 15(2): 53-58. doi: 10.3969/j.issn.1672-9897.2001.02.008

Abstract(111) PDF(3)

Abstract:
A tube reactor mixed by an axial continuous flow and four side jets as the dispersed flow is studied.The concentration distribution of the dispers~ed flow was measured by means of the laser light scattering.The different flow patterns revealed the special construction of concentration distributions in relation with the velocity ratio of side flow and axial flow.

Unsteady liquid jet flowing through a rectangular nozzle

SHI Hong-hui, WANG Xiao-liang, ITOH Motoyuki, KOSHIYAMA Kazuki, HUANG Zhen

2001, 15(2): 59-70. doi: 10.3969/j.issn.1672-9897.2001.02.009

Abstract(158) PDF(5)

Abstract:
An experimental study on the liquid generation using a rectangular nozzle was carried out with the aims of understanding the influence of the nozzle inner structure on the characteristics of the pulsed jet as well as examining the atomization process of the spray.Water jets were injected into ambient air by the impact of a projectile driven by a gas gun operated with high-pressure helium gas.The velocity of the jet from the nozzles with different inner structure was measured using the method of cutting laser beams.The pressure wave fluctuation in the nozzle at two different positions along the flow direction was also measured.The shape of jets at different injection stage was visualized by anano pulse light.Meanwhile,the jet velocity at the nozzle exit was calculated by newly derived formula,which was the extended Ryhming’s incompressible flow theory.This study emphasizes the impor-tance of using unsteady fluid mechanics to deal with the process of the jet generation in the nozzle as well as the atomization,mechanism of the spray in injection.

An experimental study on turbulent scaling law

BI Wei-tao, CHEN Kai, WEI Qing-ding

2001, 15(2): 71-77. doi: 10.3969/j.issn.1672-9897.2001.02.010

Abstract(122) PDF(3)

Abstract:
The scaling of the longitudinal and transverse velocity structure functions is studied experimentally for turbulent jet and cylindrical wake flow.The results support some previous researches and show that the transversal velocity fluctuations are more intermittent than the longitudinal ones.Also,the hierarchical relation in the S-L model of turbulent scaling law is ana~lyzed for the longitudinal structure functions as well as the transverse structure functions.

Measurement of the underwater acoustic field in water entry of blunt body

2001, 15(2): 78-84. doi: 10.3969/j.issn.1672-9897.2001.02.011

Abstract(130) PDF(2)

Abstract:
The acoustic field in water entry of blunt body was studied exten~sively.The pressures of the underwater shock wave (acoustic wave) generated by water entry were measured at about 30 different positions in water.The spatial energy distribution and the propagation velocity of the shock wave were obtained.

Turbulence in super-high intensity standing wave field

WU Jia, XI Bao-Shu, XU Hong-qing

2001, 15(2): 85-91. doi: 10.3969/j.issn.1672-9897.2001.02.012

Abstract(151) PDF(5)

Abstract:
Acoustic streaming in a standing wave field has been measured using Laser Doppler Velocimeter (LDV).If sound pressure level (SPL) of the standing wave tube is larger than 140dB,the stable and regular structure of acoustic streaming will distort apparently.As SPL improved on,vortex combining and breaking can be observed through flow visualization.Under super-high intensity of more than 160dB,it clearly changes to acoustic turbulence.The results of LDV show,following with the improvement of intensity,velocity spectra of some points broaden apparently,while others keep their original status.Results of turbulence intensity across the pressure node plane also show,the regular and symmetrical flow structures in the tube have been turned to turbulence.

2001 No. 2