实验流体力学

Visualization of the melting process of clathrate in a rectangular cell (part 1)

CHEN　Bin

2001, 15(1): 1-9. doi: 10.3969/j.issn.1672-9897.2001.01.001

Abstract(114) PDF(3)

Abstract:
The refractive-index matching technique was used for visualizing the thermal con~vective flows of a particle suspension in a square cavity which was suddenly heated from the bottom wall. The glass beads with 57.5μm diameter were dispersed in a refractive index matching fluid of tetralin and silicon oil mixture. The inside of the suspension was visualized and transient features of flow pattern was clarified.

Stationary stability of free vortex behind the triangle obstacle

HU Wen-rong, HUANG Ming-ke

2001, 15(1): 10-14. doi: 10.3969/j.issn.1672-9897.2001.01.002

Abstract(113) PDF(2)

Abstract:
The free vortices behind triangle obstacles are investigated based on the potential flow theory in this paper.It is found that the stable free vortex behind a triangle obstacle is neutrally stable.Moreover,the stationary positions of the free vortices behind various triangle obstacles are provided.Under experiment condition,the stable vortex can be captured only when suction is applied on the side walls of the obstacle.

Research for the wind-induced vibration of the overhead power transmission line system

FU Guo-hong, CHENG Zhi-jun, SUN Bing-nan, TANG Jin-chun

2001, 15(1): 15-21. doi: 10.3969/j.issn.1672-9897.2001.01.003

Abstract(97) PDF(3)

Abstract:
Overhead UHV power transmission line system is a combination of high-rise tower and large-span line.It can vibrate violently under wind load for it is sensitive to wind. To offer accurate wind-induced vibration coefficients for design of a power transmission line system and check the influence of conductors on vibration of tower, an aeroelastic model was designed and manufactured according to the law of similarity.Based on the principle of energy balance,the conductors and ground wires which are connected by the tower were simulated;The model was tested to obtain its wind force and wind-induced vibration response in an atmospheric boundary layer wind tunnel.Some important design data such as type coefficients, response of wind-induced vibration were obtained and coefficients of wind-induced vibration was formulated simply according to them.The research indicates that the acceleration responses of the tower increase with wind speed;The acceleration responses of the tower in both the following wind and the cross-wind direction are adjacent to each other, so the wind-induced vibration forces in both direction should be considered in the design and calculation; The influence on the tower's wind-induced vibration provided by conductor varies with wind direction, but it can be ignored on the whole.

A law of similitude for ballistic target ground testing

Chen Wei-fang, SHI Yu-zhong, WU Qi-feng

2001, 15(1): 22-25. doi: 10.3969/j.issn.1672-9897.2001.01.004

Abstract(187) PDF(4)

Abstract:
According to the analyzing method of characteristic quantities for flow's sub-processes,this paper presents a law of similitude for hypersonic chemical reaction flows.Using this law of similitude into ballistic target ground testing,criteria of determining ground test's condition has been obtained,and other basic theory problems to be solved in the future has been analyzed.

Preliminary research on non-linear correction method of sting interference

HE Zhong, FAN Zhao-Lin, WU Jun-qiang, LEI Zhen

2001, 15(1): 26-31. doi: 10.3969/j.issn.1672-9897.2001.01.005

Abstract(154) PDF(2)

Abstract:
A non-linear correction method of sting interference is presented by using CFD and overlap grid.Using this method,the sting effects such as sting length,diameter,conical degree,or model with angle of attack,on aerodynamic characteristics of model are investigated,and corrections of sting interference to drag of GBM-04A are applied.

A method for verifying mechanisms of increased stagnation point heat transfer rate in dusty flow

LIN Jian-min, LI Zhong-fa

2001, 15(1): 32-35. doi: 10.3969/j.issn.1672-9897.2001.01.006

Abstract(137) PDF(3)

Abstract:
A method for verifying mechanisms of increased heat transfer rate at stagnation point in dusty flow was introduced.The experiments with same dusty loading rate and with close particle velocities were performed at both subsonic and supersonic flowfield,respectively.The experimental results indicate that heating augmentations at stagnation point in dusty flow only depends on impact velocity of particles.

Study of the surface wind load and response of carrier rocket

HUANG Han-jie, HE De-xin

2001, 15(1): 36-42. doi: 10.3969/j.issn.1672-9897.2001.01.007

Abstract(112) PDF(2)

Abstract:
This paper describes some wind tunnel experiments of boosted carrier rockets in ground wind surrounding.The changing laws of pressure distributions on the different pressure measuring cross sections of main rocket and boosters are analyzed.The interaction between the main rocket and boosters,and the influence of the launching tower on the rocket are evident.The along-wind and across-wind dynamic responses of aeroelastic model under ground wind load are calculated.The results are in good agreement with the measured responses.

The IR thermography technique for high temperature measurement

DENG Jian-ping, WANG Guo-Lin, HUANG Pei-ran

2001, 15(1): 43-47. doi: 10.3969/j.issn.1672-9897.2001.01.008

Abstract(122) PDF(4)

Abstract:
A CCD IR thermography system can be used to measure the model surface tempe~ratures up to 3500K.In this paper,the system calibration test and dynamical compare test are introduced.The surface temperatures distribution of the hemispherical and small blunt model in high enthalpy facility are measured by the CCD IR thermography system. The results are compared with that obtained by an infrared pyrometer.It indicats that the developed system is successful and it will play an important role in high enthalpy wind tunnel experiment.

The design of balance of H-6 components and external store

PENG Chao, LU Wen-xiang

2001, 15(1): 48-52. doi: 10.3969/j.issn.1672-9897.2001.01.009

Abstract(100) PDF(2)

Abstract:
This paper introduces the force measurement test difficult points of the H-6 components and external store:First,the design loads of balance isn't matched especially;Next,the model's tail likes a stern.If the routine supporting form is used,the string strength will not be enough and the test will not be safe.and the arrangement of balance wire will not be convenient.The structural form that the model's tail and string is an integral combination ensures the test safety as well as the convenience of the balances' wire arrangement in the total test scheme.At first,the balance's design ensures the test safety,then the use of double electric bridges raises the output of balance.The test result shows that the total test scheme is right,the balance's design is reasonable,the supporting stiffness is good and the measure precision is high.

Research on anti-interference technique in strain measurement under intense radiation conditions

ZHANG Cong-he

2001, 15(1): 53-57. doi: 10.3969/j.issn.1672-9897.2001.01.010

Abstract(111) PDF(3)

Abstract:
This paper emphatically describes a series of anti-interference technical measures adopted in the strain measurement under the environment conditions of intense radiation and intense electromagnetic pulse interference,including techniques in the selection of the components and materials,the installation pattern of the sensing strain gauges,bridge combination and wire connection pattern,sealing and shielding etc.In order to realize the strain measurement under such an environment,a number of simulated tests and researches have been made.The paper also gives a brief description of the application of aforesaid technical measures in the strain measurement test on a test site.

LDA full field measurement of swirling flow inside container and the method to keep constant experiment Re number

Liu Ying-zheng, CHEN Han-ping

2001, 15(1): 58-63. doi: 10.3969/j.issn.1672-9897.2001.01.011

Abstract(163) PDF(3)

Abstract:
Rich complicated flow problems present in swirling flow inside container,secondary flows,vortex breakdown,to name a few.However,constant working condition is necessary and important for full field measurements.The popular method to keep working condition constant used in most experimental apparatuses is to place a high-precision constant temperature water tank outside of the flow field.But it makes the measurement system complicated,and the controllable precision is limited.The method of adjusting the rotating rate dependent on measured temperature to keep Reynolds number is presented here.It is experimentally testified that the method is convenient to be used,and can keep the flow pattern at the same Reynolds number with high precision for long time.By means of the method,the full field LDA (Laser Doppler Anemometer) measurements of swirling flow inside cylindrical container are shown here,as well as measurement results of flow field inside vortex breakdown region with large number of measurement points.

Flow field measurement of three-passage combustion facility for cement pit

ZHANG Hong-qiang, HE De-xin, ZHU Ming-hong, YIN Deng-gao

2001, 15(1): 64-69. doi: 10.3969/j.issn.1672-9897.2001.01.012

Abstract(139) PDF(4)

Abstract:
This paper introduces the test that was carried out in CARDC about the flow field measurement of three-passage combustion facility for cement pit.The results show that the attenuation law of the axis direction velocities of jet in the three-passage jetting coal pipe is reasonable,which can be used to analyze the inflow characteristics of combustion facility;The new jetting coal pipe designs reasonably.It is a better parameter that the ANGEL of WHIRL BLADE (AWB) is 45° for the new jetting coal pipe.

The measurement and control of the model attitude angle in airfoil wind tunnel test

YIN Di-yi, ZHU Zhao-xia, HUI Zeng-hong, JIN Cheng-xin

2001, 15(1): 70-74. doi: 10.3969/j.issn.1672-9897.2001.01.013

Abstract(125) PDF(3)

Abstract:
This paper describes the characteristics of model attitude angle measurement and control system for normal and dynamic test,and the effective methods for advancing the precision and accuracy of angle measurement in NF-3 low speed airfoil wind tunnel.Used a DC servo system based-micro computer,we have achieved the precision of the model attitude angle in±3′,by means of motor position and velocity closed loop.For higher performance of the measurement and control to 2-dimensional test,used a round inductive synchronous transducer fixed on airfoil axis measuring model actual angle and acting as feed back signal.This all position closed loop system can arrive at angle precision in ±0.0083°.To 3-dimonsional test,used an accelerometer fixed in model measuring in time the model actual attack angle,and preprocessed to test results,so that diminished those errors as a consequence of the aeroelastic angle.

Research on the control strategies of the 2.4m wind tunnel Mach number and stilling chamber total pressure control systems

ZHOU Ping, DONG Yi-xin, HE Yue, GE Si-hua, HAN Jie, LI Shang-chun, TANG Geng-sheng

2001, 15(1): 75-81. doi: 10.3969/j.issn.1672-9897.2001.01.014

Abstract(137) PDF(7)

Abstract:
Compared with all the other wind tunnels in our country, 2.4m wind tunnel is the first one of running with Mach number and stilling chamber total pressure controlled at the same time for all the tunnel running control. Considering the specific characteristics of the tunnel control systems, the possibility and feasibility of control strategies of neural control, adaptive mode following control, self-adjusting control, intelligent control and intelligent learning control used on wind tunnel are given out, and then, the actual control strategy is proposed. Actual running results are provided to illustrate the feasibility of the proposed control strategy.

Fuzzy control of Mach number of FL-7 wind tunnel

CHEN Wan-chun, LUO Dong-ling

2001, 15(1): 82-87，92. doi: 10.3969/j.issn.1672-9897.2001.01.015

Abstract(172) PDF(5)

Abstract:
FL-7 is a continuous transonic wind tunnel,which is powered by three engines.Mach number is adjusted by the rotating speed of engines,the flexible wall nozzle and the by-pass valve.It is difficult to establish the precise mathematical model,because there are many aspects influencing the Mach number.We use the fuzzy control with function of self-learning for getting better in speed and precision of Mach number control.And then we have got more satisfied results.This paper describes the methods and the rules of control.

The Choke finger control system of 1.2m×1.2m trans-supersonic wind tunnel

LI Shang-chun, LI Ling, LI Rong-yu, QI Gang

2001, 15(1): 88-92. doi: 10.3969/j.issn.1672-9897.2001.01.016

Abstract(150) PDF(12)

Abstract:
This paper gives a detailed introduction for the choke finger control system of 1.2m transonic and supersonic wind tunnel.It includes the system design,device configuration,function choice and programing,as well as the connection between the pressure control system and the Mach number control system.In last,the tuning results have been presented.

2001 No. 1