2010 Vol. 24, No. 1

Display Method:
2010, 24(1)
Abstract(44) PDF(1)
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2010, 24(1)
Abstract(33) PDF(2)
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Four sequences laser shadowgraph for the visualization of hypervelocity impact debris cloud
LIU Sen, XIE Ai-min, HUANG Jie, SONG Qiang, LUO Jin-yang
2010, 24(1): 1-5. doi: 10.3969/j.issn.1672-9897.2010.01.001
Abstract(162) PDF(13)
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Four sequences laser shadowgraph system has been set up on the hypervelocity im-pact range of Hypervelocity Aerodynamics Institute, CARDC, to visualize the hypervelocity im-pact debris cloud. The system includes YAG laser source, shadowgrapher and imaging system. Satisfying debris cloud image, with impact velocities up to 4. 6km/s, was obtained with the tech-nique of multi-light source divided in space, polarization decomposition, light angle magnification and compensated filter, etc.. Contents introduced in this paper are the principle, the debug of the system and the result of test. Test results show that: (1) Four images of hypervelocity impact debris cloud are gotten at different time which least interval is 1s and time of exposure is 10ns, which satisfies the need of photo of the debris cloud for the research of hypervelocity impact; (2) Eight sequences laser shadowgraph system could be developed at the base of the four sequences laser shadowgraph system, and the system can be used in the field of other hypervelocity process.
Microchannel mixing by magneto hydrodynamic stirrer
LIU Qing-ming, John Batton, Nadine Aubry, BAI Chun-hua
2010, 24(1): 6-14. doi: 10.3969/j.issn.1672-9897.2010.01.002
Abstract(123) PDF(5)
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Mixing is important and critical for most microfluidics devices. An active mixing method based on magneto hydrodynamic theory is studied for microchannel flow mixing control.A mixing chamber is used for the microchannel flow mixing.The dynamic Lorentz force acted on the fluids causes them to move back and forth periodically in the chamber.The periodically changed velocity causes the interface between fluids folded and the interfacial areas increase.The repeat movement and the folding of the interface make the fluids mixed. Rapidly mixing process is recorded and the mixing performance is evaluated.
Experimental research on flow in jagged channel with flat top of micro-irrigation emitter
ZHANG Hong-yan, HE Wen-bo, JIN Wen
2010, 24(1): 15-19. doi: 10.3969/j.issn.1672-9897.2010.01.003
Abstract(142) PDF(2)
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Using micro-fluidic particle image velocimetry(micro—PIV)technique, the paper investigated measurements for the square micro—channel with side lengths of 800pm. To attain distinct particle image, solve the problems of matching camera with PIV system and improve the image'S signal—to-noise ratio, the research adopted 10x microscope, 14一bit CCD camera system, 3μm fluorescent particles and filter lens that only allow 610nm red light penetration. In the image processing, Brownian motion'S impact on tracing particles was eliminated by the average of images. Using ensemble correlation arithmetic acquired velocity distribution and velocity streamline. The results show that iags'flow structure iS basically consistent inside the micro-channel. The fully developed internal flow in the channel is a cycling movement. There exists low speed vortex area in the micro-channel'S flat top and corner. whose vortex structure and size depend on time and Reynolds number. The particles are vulnerable to deposit in the low—speed vortex area, which proves the main factor for block.
Experimental research of wake electron density of hypersonic sphere models
MA Ping, ZENG Xue-jun, LIU Sen, SHI An-hua, HUANG Jie
2010, 24(1): 20-25. doi: 10.3969/j.issn.1672-9897.2010.01.004
Abstract(118) PDF(4)
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In this paper, wake electron density of hypersonic sphere models has been measured in ballistic range, CARDC.The electron density measurement system is made up of 8mm micro-wave interferometer, open microwave cavity measurement system and closed microwave cavity measurement system.The diameter of the steel sphere models is 10mm.The model velocities are 5.8, 5.5, 5.6 and 5.5km/s. The corresponding flight environmental pressures are 2.79、5 32、 5.85 and10.91kPa.The diameter of copper sphere models is 10mm.The results present the wake electron density of steel sphere models is larger as a result of high environment pressure under the test conditions of the pressure ranged from 5.3kPa to 11kPa, speed 5.5km/s.The composite speed is quick under the conditions.The wake electron density of copper sphere models is larger as a result of high environment pressure under the test conditions of the pressure ranged from 1.3kPa to 6kPa, speed 5.6km/s test conditions. The composite speed is slow under the condi-tions.The composite speed of copper sphere models is slower than that of the steel sphere models under the conditions of the pressure 10.7kPa and speed 5.5km/s.
PIV study of supersonic flow around an optical bow cap
TIAN Li-feng, YI Shi-he, ZHAO Yu-xin, HE Lin, CHENG Zhong-yu
2010, 24(1): 26-29,54. doi: 10.3969/j.issn.1672-9897.2010.01.005
Abstract(130) PDF(6)
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Velocity field of supersonic optical bow cap was studied using PIV (Particle Image Velocimetry) in Ma =3.8 supersonic wind tunnel. The application of PIV to supersonic flow de-mands good performance of PIV hardware, fine flow-following ability of tracer particle and high accuracy of PIV algorithms.Synchronizer with high accuracy and high energy laser were chosen for the PIV system in this paper; tracer particle with diameter at nanometer scale was selected and its performance in supersonic flow was assessed through measurements of particle lag down-stream of a two-dimensional oblique shock wave; several high-accuracy PIV algorithms were used for particle image processing.The results revealed that the tracer particle performed very well in supersonic flow, and the algorithms yielded the velocity field of the supersonic optical bow cap faithfully.
Experimental research of fluctuating pressure on surface for a certain missile configuration
WANG Na, GAO Chao
2010, 24(1): 30-35. doi: 10.3969/j.issn.1672-9897.2010.01.006
Abstract(111) PDF(9)
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The characteristics of fluctuating pressure for a certain missile configuration are studied. The Mach number is M∞=0.8,0.84 , 0.86, 0.96, 1.0,1.15, 2.0, 2.5, and the angle of attack is α=-5°、-3°、0°、3°、5°, there were 14 testing holes on the surface along the axes of this missile configuration.Dtailed information for fluctuating pressure coefficient, power spectrum density and spatial correlation has been acquired.The results of the experiment indicate that the fluctuating pressure coefficient reduced with the Mach number increasing.The fluctuating pres-sure has the similar axial cross correlation for any two of the testing points along the axes of this missile configuration at different Mach number.The aixal cross correlation for different testing points along the axes of this missile configuration at zero angle of attack can be neglected.In the range of angle of attack, different angle of attack has little influence over the fluctuating pressure coefficient in the region of small curvature changes.The fluctuating pressure coefficient varies obviously under different angle of attack in the region of remarkable curvature changes.The pow-er spectrum density shows that the character frequency is obvious low at supersonic, and the character frequency increases with the Mach number increasing, and the maximum power spec-trum density located at the location of character frequency.
Experimental measurement of flow field in 180°curved duct with rectangular cross-section by LDV
XU Jun, DU Cai-hong, WANG Tian, WEI Yao-dong, SHI Ming-xian
2010, 24(1): 36-41. doi: 10.3969/j.issn.1672-9897.2010.01.007
Abstract(127) PDF(8)
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The flow field in the 180° curved duct with the rectangular section was measured by Laser Doppler Velocimetry (LDV).The mean velocity and the turbulent intensity of the flow field were investigated.At the radial location, except for the r~* =0. 1 location, the tangential velocity changed a little along the Z direction, and the tangential velocity decreased gradually until zero near the upper wall.The tangential velocity increased between 0° and 60°, while the tangential velocity decreased between 60° and 180° near the inner wall.On the contrary, the tangential ve-locity decreased between 0° and 60°, but the tangential velocity increased between 60° and 180°near the outer wall.In the 180° curved duct, the tangential velocity near the inner wall was larger than the tangential velocity near the outer wall.At the r~* =0. 1 location of 90°~180° longitudinal section, the tangential velocity had obvious fluctuation due to the boundary layer and secondary flow.The axial velocity was much less than the tangential velocity, and had a little change along the Z direction.The axial velocity showed significant positive and negative values, which indica-ted the existence of the secondary flow, and the center of secondary flow moved from the outer wall to the inner wall.The tangential intensity and axial turbulent intensity were about 0. 1Vi with the same order of magnitude.The tangential turbulent intensity had an obvious fluctuation at the r~* =0. 1 location between 150° and 180°. But the axial turbulent intensity changed a little along the axial and radial direction.
Aerodynamic characterization of an integrated hypersonic vehicle
JIN Liang, LIU Jun, LUO Shi-bin, WANG Zhen-guo
2010, 24(1): 42-45. doi: 10.3969/j.issn.1672-9897.2010.01.008
Abstract(133) PDF(6)
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An analysis was conducted for the aerodynamic characteristic of two hypersonic in-tegrated vehicle configurations (cowl-closed and cowl-opening) with numerical simulations and wind tunnel tests. The color schlieren techniques were used to visualize supersonic flow about the subscale model vehicle, the lift, drag and pitching moment of the vehicle was measured with a 6-component wind tunnel balance, the CFD predicted results were compared against the experimen-tal data and showed good agreement, and the region of center of mass location was calculated for the analysis of the vehicle longitudinal static stability. These results showed that the act of open-ing the inlet door resulted in a loss of the lift, drag and nose-down pitch increment, but the trim angle of attack was still too high with no deflection of control surfaces. These results helped build confidence in the CFD tools and provide reference data for the vehicle configuration design.
Test study of drag reduction technique by hybrid laminar flow control with two-dimension airfoil
GENG Zi-hai, LIU Shuang-ke, WANG Xun-nian, ZHANG Yang
2010, 24(1): 46-50. doi: 10.3969/j.issn.1672-9897.2010.01.009
Abstract(152) PDF(4)
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The main purpose of test study is to find out the effect of drag reduction technique by hybrid laminar flow control Using NACA0006 series laminar airfoil as physical model, using FLUENT CFD software to calculate and analyse pressure grads of airfoil surface. Uniting optimi-zation local figure of airfoil surface to enlarge positive pressure grads region and disposal leading edge suction control unit of airfoil to come into being drag reduction technique by hybrid laminar flow control. Testing laminar flow area with infrared image in low speed wind tunnel contrasting using drag reduction technique by hybrid laminar flow control and without it. The analysis of the results give the conclusion: the laminar flow area of airfoil surface become larger in evidence after using drag reduction technique by hybrid laminar flow control. The results satisfy the goal of the research.
Elementary research on the application of high temperature heat-pipe to the thermal protection
CHEN Lian-zhong, OU Dong-bin
2010, 24(1): 51-54. doi: 10.3969/j.issn.1672-9897.2010.01.010
Abstract(161) PDF(9)
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This experiment study on the application of high temperature heat-pipe to the ther-mal protection was carried out in CAAA. With the arc heated wind tunnel, the high tempera-ture, supersonic flow field was created. A principle thermal protection model with a high temper-ature heat-pipe in it was heated; the surface temperature distribution was measured by an infrared temperature instrument, contrast to general composite material model, and the stagnation point temperature reduced distinctly. We found the high temperature heat-pipe transfer the heat effec-tively from the high temperature field to the lower field, and the thermal protection performance was showed.
Advances in wind-blown sand flow optical measurement and image processing techniques
WANG Yuan, YANG Bin, WANG Da-wei
2010, 24(1): 55-64. doi: 10.3969/j.issn.1672-9897.2010.01.011
Abstract(138) PDF(6)
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Based on the important role of optical measurement in wind-blown sand flow exper-iments, this paper reviews all kinds of optical measurement techniques from the birth of the dy-namics of blown sand. The advantages, disadvantages and application range of these methods were pointed out. Then, the applications and image processing methods of latest optical measure-ment techniques, PIV and high-speed digital measurement. were specially introduced. It is proved that the increasing resolution ability in spatial and temporal of optical measurement will offer plenteous support on sand micro-mechanics analysis and wind-blown sand flow macro data statistic.
Influence of the fluid elasticity on hydraulic systems in the wind tunnel and its measurement methods
WANG Fan, SHEN Hong, LI Shu-cheng
2010, 24(1): 65-67. doi: 10.3969/j.issn.1672-9897.2010.01.012
Abstract(143) PDF(3)
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The electro-hydraulic systems are widely applied in control of many kinds of mecha-nism in wind tunnels. With the development of wind tunnel test technique, and the requirement of miniaturization of the structure, the working pressure and the control precision of the hydrau-lic servo systems need to be improved. Under this condition, the elasticity of the fluid can not be neglected. In this paper, two engineering oriented methods of measurement of the module of elas-ticity are presented, and applied to the experiment in the lab. It shows that the module of elastic-ity of the fluid is in the range of 900MPa to 1000MPa in hydraulic systems in wind tunnels. The results are used in analysis of the problem accounted in a new built model supporting mechanism in a supersonic wind tunnel. The calculation keeps accordance with the phenomenon.
The pressure measurement of millimeter level plane cascade using pressure sensitive paint
CAO Chuan-jun, HUANG Guo-ping, LIANG De-wang
2010, 24(1): 68-73. doi: 10.3969/j.issn.1672-9897.2010.01.013
Abstract(129) PDF(8)
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A novel non-contact pressure measurement system of pressure sensitive paint (PSP) was established. One set of test section of millimeter level plane cascade which can be dis-assembled was designed. The surface pressure of blade suction side with and without tip clearance was measured using PSP technology for the first time. The results show that, because of tip clearance, the blade pressure side gas leaks into the suction side through tip clearance and the surface pressure of the top of blade suction side is bigger than it of the bottom. Contrast with the condition of no tip clearance, leakage has significant impact on the pressure on one third of the blade span of suction side, but little on the bottom of suction side.
Investigation and application of pressure sensitive paint technique in wind tunnel test
ZHANG Yong-cun, CHEN Liu-sheng, YAN Li, DENG Xue-ying, CHENG Hou-mei
2010, 24(1): 74-78,94. doi: 10.3969/j.issn.1672-9897.2010.01.014
Abstract(103) PDF(12)
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The Pressure Sensitive Paint (PSP) technique is one of the important pressure measurement techniques on model surface in wind tunnel test. This report presents that has tried to make the pressure sensitive paint in China, the automatization test data collection technique, the test data disposal technique, the application method of PSP technique, the comparison tests between PSP technique using PSP FOP-1 paint made in China and classic tap measurement tech-nique on the wing, leading-edge flap, trailing-edge flap, aileron of airplane model.
Orthogonal projection method for rotator's spatial sweep angle and rotating speed measurement
WANG Si-guo, TANG Geng-sheng, YANG Hui, ZHANG Long, ZHANG Jun
2010, 24(1): 79-83. doi: 10.3969/j.issn.1672-9897.2010.01.015
Abstract(136) PDF(2)
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Sweeping angle and rotating speed are important parameters of a parachute-ball ro-tator in wind tunnel measurement experiment as well as a necessary quantitative dynamic meas-urement test. The principle of the orthogonal projection method is to use a two-way orthogonal parallel light source of a given cross-section area to project the rotator into two orthogonal screens, two high-speed cameras synchronically record the projecting images. The image process-ing software automatically calculates the angularity of two-way image sequence, sequentially pho-tographs every moment's spatial sweep angle, and according to the sequential angularity, the in-stantaneous rotating speed and average rotating speed of all cycle can be calculated. Applying the orthogonal projection method, we have successfully measured different types of parachute-ball ro-tator in a vertical wind tunnel in Xi'an and obtained good results. The static angle measurement accuracy is 0.18°, the dynamic sweeping angle measurement accuracy is limited in 0.25°. This pa-per describes the principle and structure of the orthogonal projection method as well as the appli-cation of the image processing system, and the wind tunnel measurement results were also given.
Simulative and experimental investigation on effect of upstream pipe elbow on the performance characteristics of cone flowmeters
LI Yan-mei, XU Ying, ZHANG San-gang, GUO Yu, JIANG Shan-he
2010, 24(1): 84-88. doi: 10.3969/j.issn.1672-9897.2010.01.016
Abstract(124) PDF(3)
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In order to acquire the shortest straight pipe length and investigate the performance of cone flowmeter with installed upstream elbow, this study has put forward three different structure prototypes with lOOmm diameters and the p values being 0.45. 0.65. 0.85 respectively. Simulation and experiment investigations have been carried out with the installment of a upstream single 90o elbow, double closed 90o elbows of "S" shape under the same plane and double closed 90oelbows under the vertical plane, with the medium of normal temperature water and Reynolds numbers being 0.498 × 10~5 ~4.98 × 10~5 and 0.14 × 10~5 ~4.5 × 10~5 respectively. The numerical simulation result is consistent with the experimental conclusion. Through both of them, we ob-tain the length of the straight pipe for the cone flowmeter while the effects of the relative error and additive uncertainty of the averaged discharge coefficient on the installation of upstream el-bow have been considered.
The fuzzy control of pressure after the air-driven valve in combustion heater
ZHU Ru-song, TANG Geng-sheng, CHEN Zhi-qiang, ZHANG jun-sheng
2010, 24(1): 89-94. doi: 10.3969/j.issn.1672-9897.2010.01.017
Abstract(165) PDF(3)
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The combustion heater is a key part of the ground testing facility for the research on scram jet.The main test gases ingredients include hydrogen, oxygen, air and nitrogen. The pressure and flow of these test gases ingredients need to be regulated during testing, and the pressure is controlled directly by the air-driven valve. A control system with a industrial control computer as it's central part is designed, and a good balance between the reliability and the prac-ticality of the system can be achieved. According to the characteristics of the air-controlled valve, a kind of adaptive Fuzzy-PI controller is designed to realize the fine pressure control during test. It is realized by connecting the conventional PI controller with a parameter regulator which adjust the integrator and proportion parameter of the PI controller through fuzzy inference during test. It has improved the pressure control precision with some good qualities such as quick response, less over-regulating and less stabilizing time.
Primary investigation of the virtual flight testing techniques in wind tunnel
HU Jing, LI Qian
2010, 24(1): 95-99. doi: 10.3969/j.issn.1672-9897.2010.01.018
Abstract(197) PDF(11)
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lt is introduced that the virtual flight testing system built in the FD-1O wind tun-nel, and the test techniques was investigated for its validation. The purpose for this study is to pursue the principle and key techniques including combined roll bearing, fin actors and cable sup-port systems techniques. Wind tunnel tests are conducted to test the model rolling and yawing re-spond to the fin deflections. Thought wind tunnel tests. it has verified the feasible of virtual flight testing and some experience was accumulated, this, established the fundament for establis-hing test apparatus in the productive wind tunnels.
Vibration of micro cantilever applied in micro scale jet velocity measurement
ZHOU Jun-hu, WANG Yang, YANG Wei-juan, LIU Jian-zhong, WANG Zhi-hua, CEN Ke-fa
2010, 24(1): 100-104. doi: 10.3969/j.issn.1672-9897.2010.01.019
Abstract(101) PDF(2)
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In the experiment, the vibration of a micro cantilever varying with the jet velocity is studied. It is suggested to measure the micro scale jet velocity based on this mechanism. A copper thread with length 56.2mm, diameter 0.07mm is used as the micro cantilever. The jet velocity comes from a micro nozzle with diameter 0.36mm. The vibration of cantilever is investigated with a high-speed camera while the jet velocity varying between 2.7~27.3m/s.The result shows that the vibration amplitude increase with the jet velocity while the nozzle is amied at 3/5 of the canti-lever length.But while the nozzle is aimed at 9/10 or 3/5 of the cantilever length, the amplitude stops increasing at high jet veloicty. A hall sensor and a magnet are used to measure the vibra-tion. The output voltage increases linearly with the jet velocity, while the nozzle is aimed at the 3/4 of the cantilver lenth. But at the other positions, the viburation is not inneratic because the attached magnet change the mass distribuion of the cantilever.