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Kiichi TSUCHIYA
1990 Volume 10 Issue Supplement2 Pages
1
Published: October 15, 1990
Released on J-STAGE: July 31, 2009
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Kazuyasu MATSUO, Toshiyuki AOKI, Hideo KASHIMURA, Yasutaka OZAKI
1990 Volume 10 Issue Supplement2 Pages
3-6
Published: October 15, 1990
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The new methods of the computer aided visualization of a shock wave which called computer-schlieren and computer-shadowgraph were showed in the previous report. The visualization technique of a propagating shock wave on a round corner using these methods is described. Forthermore, by the pressure distibution on the wall, the time history of the second shock behind the diffracted shock wave is indicated.
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Tateyuki SUZUKI, Takashi ADACHI, Susumu KOBAYASHI
1990 Volume 10 Issue Supplement2 Pages
7-10
Published: October 15, 1990
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The experiment on oblique shock reflection has been carried out by means of a shock tube and a model wedge. The incident shock Mach number M was about 1.42 and the working gas was air. Waves were visualized and analyzed by schlieren photography. Attention was focused on the quantitative analysis of the unsteady behavior of the triple point. The evolution of waves were discussed from the viewpoint of its effect on the behavior of the triple point. The rarefaction wave generated at each corner of bumps pulled the triple point down, and consequently the value of the angle of reflection ?? increased abruptly.
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Toshiaki SETOGUCHI, Toshihiro NAKANO, Nobuyuki KITA, Kenji KANEKO
1990 Volume 10 Issue Supplement2 Pages
11-14
Published: October 15, 1990
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The vapor-screen method, a simple and practical method of flow visualization for high speeds, has been applied to the threedimensional shock waves generated in a supersonic nozzle with the obstacle. The shock wave profiles at each of the cross-sections have been shown clearly. As a result, it has been demonstrated that the vapor-screen method is very useful to visualize the three-dimensional shock wave configuration.
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Shinichiroh KOSUGI, Takashi OHISHI
1990 Volume 10 Issue Supplement2 Pages
15-18
Published: October 15, 1990
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Experimental study on shock waves in a high repitation rate excimer laser has been carried out. In a high repitation rate excimer laser. shock waves in subsonic loop are induced by the active medium excitation by means of pulse discharge. Shock waves in He gas by a pulse discharge are visualized by schlieren method using a scale discharge section model, CCD camera, stroboscope, and digital image memory which used to take photographer. Shock waves from anode surface, cathode surface. discharge region, and pin sparks for preionization are observed. Shock waves reflect at anode and cathode surfaces alternately for several times. Shock waves from dischrage region travel through channel.
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Tadatomo KOJIMA, Yoshihiro MATSUOKA
1990 Volume 10 Issue Supplement2 Pages
19-24
Published: October 15, 1990
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The structure of, pseudo-shock waves generating in underexpanded sonic jet has been investigated. In order to elucidate the structure the flow visualization was conducted by both the schlieren and shadowgraph methods. Further, the pressure and velocity distributions etc. in the flow were measured. The experiments for the five kinds of test pipe of different inner diameter were carried out for mean Mach numbers, ranging from 0.8 to 2. As a result, the fundamental forms of flow, the length of pseudo-shock waves, and the correlation between the static pressure and velocity distributions were clarified.
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Toshio NAKAHIRA, Masanori KOMORI, Kinji TSUJIMURA, Takashi SUZUKI
1990 Volume 10 Issue Supplement2 Pages
25-28
Published: October 15, 1990
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The authors have improved the combustion of DI diesel engine, using high pressure injection equipments which can produce over 150MPa injection pressure, and still been studying the simultaneous reduction of NOx and particulate emissions. In those researches, shock wave was observed around the diesel spray which was injected into a high pressure vessel, at high injection pressure. In this paper, the shock wave was visualized on the schlieren photographs taken by a still camera and an image-converter camera, using rubby or argon laser as a light source.
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Tomohide NI-IMI, Tetsuo FUJIMOTO, Kenichi IJIMA
1990 Volume 10 Issue Supplement2 Pages
29-34
Published: October 15, 1990
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The structures of two opposed supersonic argon free jets with different source pressure are studied by flow visualization using laser-induced fluorescence of iodine molecules seeded in argon. A ratio between source pressures is kept at 2.0. Experiments are carried out for various source pressures and various ratios of the source pressure to the pressure of the expansion chamber. Characteristic structures of the flow field are classified roughly into four types depending on the condition of the source pressures and the pressure of the expansion chamber. Specifically, an unstable flow in the interacting region are found. The condition of pressures is examined for each type of the flow field.
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Tomohide NI-IMI, Tetsuo FUJIMOTO, Norihiro SHIMIZU, Keiji WAKAYAMA
1990 Volume 10 Issue Supplement2 Pages
35-40
Published: October 15, 1990
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A method for measurement of two-dimensional temperature field in rarefied gas flow by two-line laser induced fluorescence is proposed. Temperature is determined from the ratio of the intensities of fluorescence, which are obtained by irradiation of two laser beams of different wave length. Use of a laser sheet and a high-sensitivity vidicon camera allows multiple-point measurements of temperature in the flow field. Effectiveness of this method is verified by its application to the determination of the temperature distribution of a supersonic free jet. It is found that the results obtained by P(16)/R(18) [514.720 nm] and P(26)/R(28) [514.942 nm] absorption lines in the transition of B3∏o+u(v'=43)←X1Σ+ 8(V"=0) can predict temper-ature below 300 K with reasonable accuracy.
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Kazuhiro MURAI, Kawashima YOHSUKE, Shigeyasu NAKANISHI, Masao TAGA
1990 Volume 10 Issue Supplement2 Pages
41-44
Published: October 15, 1990
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A new method based on the Coanda effect for self oscillation of a circular jet bounded by rectangular enclosure is suggested. The flow pattern is observed by an experiment for water flow by using a light sheet and a domestic movie camera. And the experiments in both air and water reveal regions of stable oscillation wherein relationships are obtained between geometrical dimensions of the enclosure.
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Tetsuhiro TSUKIJI, Hiroyuki HORI
1990 Volume 10 Issue Supplement2 Pages
45-48
Published: October 15, 1990
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Impulsively started jet flow issuing from the metering orifice of the spool valves commonly used for hydraulic power applications are investigated by flow visualization test. A two-dimensional model of the spool valve is designed to visualize the jet flow by a hydrogen-bubble method. The images of flow fields taken by a CCD monochrome camera are fed into a microcomputer, and a digital image processing technique is employed to investigate the process of jet formation.
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Yukio ITO, Toshihiko UCHIDA, Risaburo OBA
1990 Volume 10 Issue Supplement2 Pages
49-52
Published: October 15, 1990
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In order to increase the performance and the reliability for several kind of nozzle in jet cutting, fuel injection, atomization and so on, the microscopic internal structures of high-speed water-jets were carefully visualized by using techniques of a laser light sheet and laser holographies. The free jets discharged from a small nozzle, 1.11mm in diameter, were injected into the non-restricted atmosphere. The ruptured processes of water columns, which play an important role in the abilities of jet-cuttings and fuel injections, are clearly shown.
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Toru KOSO, Sei NAGASAWA, Hiroshi HAYAMI
1990 Volume 10 Issue Supplement2 Pages
53-58
Published: October 15, 1990
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A circular turbulent jet issued along a plane wall is visualized by means of laser-induced fluorescence to investigate the large-scale structure in the fully devloped region of jet.The fluorescence dye was premixed to jet fluid, and a cross section normal to jet axis was illuminated by a thin laser sheet. To observe the evolution of jet fluid pattern, the laser sheet was moved to follow the flow strucure. And a surrounding fluid was marked by deeper fluorescence dye and process of the entrainment and the mixing with jet fluid were observed. The results indicate that the structure of the jet is characterized by three-dimensional large-scale vortices and that the flow is filled with numerous streamwise vortices. A pair of large-scale secondary flow which entrain the fluid from upper region and push to lateralward is found to exert an important effect on the entrainment of surrounding fluid and appear to play a dominant role on the greater lateral rate of spread.
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Takahiro KIWATA, Atsushi OKAJIMA, Hisanori UENO
1990 Volume 10 Issue Supplement2 Pages
59-62
Published: October 15, 1990
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Double coaxial pipe jets which consist of a central round air jet (an inner jet) and an annular air jet (an outer jet) were experimentally investigated. Detailed measurements of the mean-velocity, turbulent intensity and Reynolds stress distributions in the double jets were made. Flow visualization is carried out by mists of a liquid-paraffin for the nozzles with different outer pipe length of L=0, 1Do, 2Do at Reynolds number of 1.35×104. Visualized flows suggest possibilities of the self-excitation of flow in the outside pipe with the length, 1Do.
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"(2nd. report, Study for reducing vertical air temperature difference in the room in case of ceiling suspended split type air conditioners)"
Kunihiko MIYAKE, Kanjiro KINOSHITA
1990 Volume 10 Issue Supplement2 Pages
63-66
Published: October 15, 1990
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Experiments were performed to evaluate the air flow and air temperature distributions in a model room heated by both blown hot air from the lower supply air opening and blown room temperature air from the upper one in case of a model of an indoor ceiling-suspended system air conditioner having two supply air openings. Measurements were made of the local air velocities and local air temperatures in the room by varying the supply air temperatures, the supply air velocities and supply air jet angles of two supply air jets from the model indoor unit. The local air velocities in the room were determined by means of a particle image tracing technique. The obtained results indicated that two supply air jets formed a flow that circulated in the large part of the room. It was also found that difference in vertical air temperature became small.
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Fei GAO, Hiroto YAMAJI, Nobuo SHUTO
1990 Volume 10 Issue Supplement2 Pages
67-72
Published: October 15, 1990
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A Thermal Video System is used to measure instantaneous temperature distribution due to the heated water horizontally discharged onto the still water surface. The images are translated into digital data, with which several characteristics of the surface plumes are discussed. Mean temperature distribution deviates from the Gaussian distribution. Coefficients to express the distribution are given in terms of the densimetric Froude number. Contours of the temperature variance and their three-dimensional expression show the generation area of the major eddies, interference and breaking of the eddies, and general paths of broken eddies.
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Motoo FUMIZAWA, Makoto HISHIDA
1990 Volume 10 Issue Supplement2 Pages
73-76
Published: October 15, 1990
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An experimental study has been performed to investigate the behavior of flowand mass transfer in gaseous slow jet in which buoyancy force opposed the flowforming stably stratified field. The study has been performed to understand thebasic features of air ingress phenomena at pipe rupture accident of the hightemperature gas-cooled reactor. A displacement fringe technique was adopted inMach-Zehnder Interferometer to visualize the mole fraction distribution. As theresult, the followings were obtained:
(1) The stably stratified fields were formed in the vicinity of the outlet of theslow bet. The penetration distance of the stably stratified fields increased with Froude number.
(2) Mass fraction distributions in the stably stratified fields were well correlatedwith the present model using the ramp mole velocity profile.
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Tomomasa Uemura, Fujio Yamamoto, Hiroaki Nakajima, Wataru Mizukosi
1990 Volume 10 Issue Supplement2 Pages
77-80
Published: October 15, 1990
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The binary correlation method is revised to measure 3D-velocity field. The revised binary correlation method for 3D measurement is also aimed to work on a personal computer as the 2D version was. Because of that reason, the new version was developed by considering minimizing the memory occupation and shortening calculation time.
By introducing a overlapped volume function and uniform paticle image, cross correlation coefficient between two 3D particle-patterns could be evaluated easily.
The performance of the new method is examined by personal computer simulation, and found to be promizing in the actual measurement.
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Fujio YAMAMOTO, Tomomasa UEMURA, Kazuo OHMI
1990 Volume 10 Issue Supplement2 Pages
81-86
Published: October 15, 1990
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A mixing flow in a cylindrical vessel agitated by a bubbling jet is analyzed quantitatively by using the binary cross correlation method, which is a particle tracking velocimetry (PTV). With this method quantitative results such as instantaneous velocity distributions, velocity fluctuations and particle paths can be obtained easily in a short time. Instantaneous motions of dispersed air bubbles in a water vessel are tracked by establishing correspondence of particle pairs between two sequentially frozen pictures.
As a result, a pair of circulation flow pattern was found in the upper region of the vessel and the mixing flow was regarded as three dimensional turbulent flow with large and impulsive fluctuations superposed frequently on the general velocity variation at low speed, though the image processing technique was of a two dimensional type.
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Kyu TAKADA, Frederick M. LANGDON, Kenjiro SUZUKI, Yoshimichi HAGIWARA
1990 Volume 10 Issue Supplement2 Pages
87-90
Published: October 15, 1990
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To provide insight into the mechanism of heat and momentum transport during nucleate pool boiling of a fluid on a holizontal heating surface, flow visualization experiment was conducted to determine fluid motion around an air bubble. Nuclate boiling was simulated by injecting air through an orifice in the bottom surface of an acrylic tank filled with glycerin. For the visualization of flow, tracer particles were suspended in the fluid. Two images at a constant time interval were digitized and stored in an image memory. Comparison of these images were then made by the cross-correlation method and the velocity vectors were determined. The results show a radial flow during the stage of bubble growth, a radial flow and a fluid motion approaching below the bubble during the stage of bubble detachment, and a suction flow underneath the rising bubble in addition to those types of flow during the stage of bubble rise through the fluid.
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ELIMINATION OF INADEQUATE VECTORS ACCORDING TO FLOW DIVERGENCE
Yukishige KIMURA, Akikazu KAGA, Yoshio INOUE, Katsuhito YAMAGUCHI, Aki ...
1990 Volume 10 Issue Supplement2 Pages
91-94
Published: October 15, 1990
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A three-dimensional velocity measurement with two TV cameras cannot avoid contamination with inadequate vectors. In this paper, a computer algorithm to eliminate inadequate vectors among measured data is proposed. The algorithm was successfully applied to a set of experimental data.
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Atsushi TANAKA, Kiyoshi ISHII, Kazushi YAMAMOTO
1990 Volume 10 Issue Supplement2 Pages
95-98
Published: October 15, 1990
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In order to analyze combustion characteristics of the spark ignition engine, a new photographic system was developed to photograph the high-speed and low-luminescent phenomenon of flame propagation.
This system, comprised of an electronic framing high-speed camera, high-sensitivity SIT (Silicon intensifier Target) camera and digital image processing device, is capable of taking images of flames with a luminescence of 1, 000 cd/m
2 at a speed of 10, 000 frames/second and displaying the images on a screen in real-time.
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Tohru WATANABE, Hideyo SAKURAI, Akira IWASAKI, Shunsuke HOSOKAWA, Isao ...
1990 Volume 10 Issue Supplement2 Pages
99-102
Published: October 15, 1990
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It is possible to obtain the microgravity environm-ent for short time(approx.7min)by launching a small rocket(MASER)into a ballistic flight. This flight is used for microgravity experiment as a simple means of obtaining microgravity.In this report, the devero-pment of IN SITE observation system using sounding rocket is described.
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Masahiro INOUE, Takashi MURAISHI, Mitsuharu MASUDA, Koichi NATSUNARI
1990 Volume 10 Issue Supplement2 Pages
103-106
Published: October 15, 1990
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In the large-scale gas or stream turbine, the flow around the blade tip becomes transonic, and the shock waves are generated in the blade passage. These shock waves induce the boundary layer separation and the vibration of blades, which degrade the efficiency. This unstable flow phenomenon is closely related to the secondary flow associated with the large change in flow direction in the blade passage. To measure the secondary flow, the nonintrusive diagnostic technique is desirable, and the laser-induced fluorescence (LIF) method offers one of the best tools for this purpose. In the present research, the curved nozzle with rectangular cross-section was made to simulate the transonic turbine cascade, and the gas temperature distribution inside the nozzle was obtained by using the LIF method.
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Hideki ONODERA, Kazuyoshi TAKAYAMA, Osamu ONODERA, Hidenori OJIMA, Kik ...
1990 Volume 10 Issue Supplement2 Pages
107-112
Published: October 15, 1990
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It is known that the large scale explosion satisfies the similarity law. But it is not clarified that the microexplosion satisfies the similarity law or not. If the microexplosion induced spherical shock wave satisfy the similarity law, large scale explosion can be simulate by a microexplosion in a laboratory.
To explore the suitable method for measuring the microexplosion phenomena, we've designed and constructed a high speed drum camera combined with a pulsed Argon-ion laser as a light source. In selecting the appropriate laser pulse interval and the mirror rotating speed, framing speed of 4×10
6 fps and 40 numbers of flame can be obtained. And in case of streak recording, streak speed of 100 ns/mm and 500 mm record length can be obtained. Consequently, it is found that the present microexplosion induced spherical shock wave satisfies the similarity law.
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Masahiro OTA
1990 Volume 10 Issue Supplement2 Pages
113-116
Published: October 15, 1990
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Non steady rarefied gas jets emitted from the thruster nozzle for an artificial satellite were numerically simulated by the Direct Simulation of Monte Carlo method.The trajectory of test gas molecules were visulaized at an each time step.The number of an ensemble average affects the macrosccopic velocity distributions at the pressure ratio of 100 and infinite, respectively.
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Hiromasa KAWAI
1990 Volume 10 Issue Supplement2 Pages
117-120
Published: October 15, 1990
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The mechanism of the vortex induced vibration of a circular cylinder was discussed based on numerical simulations of the discrete vortex model. The cylinder vibrates even when the frequecy of the vortex shedding is not locked in that of the vibration. Because the vortex sheds into the wake synchronized with the vibration in a regular interval and encourages the vibration in the interval. The process to the lock-in state is triggered by the prevention of the rolling up of the shear layer by the vibration. Therefore, the lock-in phenomenon can be considered as the transition from the vortex shedding by the interaction of the shear layers to the one controlled by the vibration. When the splitter plate is set in the wake, the interaction of the shear layers is prevented and the lock-in state can be occurred in the wider range of flow velocity. As the result, the cylinder can vibrate even in very high velocity.
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Teruo Matsuzawa
1990 Volume 10 Issue Supplement2 Pages
121-124
Published: October 15, 1990
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It is well known that the abdominal aorta is a site of predilection for the occurrence of atherosclerosis and atherosclerotic aneurysms. In this study three dimensional flow patterns in the lateral saccular aneurysm were investgated by finite element methods. The aneurysm model had dome-shaped diverticulum arising from one side of the straight circular tube and simulated lateral saccular aneurysms. Calculation were performed of steady flow at Reynolds number of 15, 75, 150, 300, 600. The flow was separated from diverging part of expansion. The formation of the vortex was occured in essentially the same manner as those in the axisymmetric models. The downward flows from the ceiling at the diverging part were observed at Reynolds number 300, 600. At the converging part the direction of secondary flow was reversed. The formation of the vortex resulted in complex distributions of shear stress fields. These fluid motions can be important factors in thrombogenesis.
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Takao KAGEI, Nobuyuki TANIGUCHI, Toshio KOBAYASHI
1990 Volume 10 Issue Supplement2 Pages
125-128
Published: October 15, 1990
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In a general flow simulation of the mechanical engineering, it is usually desired that the complicated grid is interactively generated and modified by using computer graphics as to remarkably increase the efficiency of the pre-procedure for the flow simulation.
In this paper, a routine system checking the adaptability of grid is developed to indicate any intersection, concentration, orthogonality, inclination and so on, and visual examples are displayed for the grid around the formula car with wheels.
The procedure is executed efficiently on a graphic computer of TITAN.
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Eiji MUKAI, Yasushi SUGENO, Ryu-ichiro OHYAMA, Kiyoji KANEKO
1990 Volume 10 Issue Supplement2 Pages
129-132
Published: October 15, 1990
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The authors proposed and developed an inversible visual method by using a fluid mapper equipment, which was a very useful method for visualizing the electric field and equi-potential lines of electrostatic fields. The inversible visual method is based on the idea of an inversibility that the equation of pressure and stream function of fluid map-per can be exchanged each other. In this paper, a numerical calculation technique is proposed to calculate the electric field and equipotential lines of two dimensional fields by means of the inversible visual method. The proposed calculation technique is applied to the analysis of electric fields at the straight form boundary of dielectric substances with different dielectric constants put into the parallel plate electrode arrangement in order to check the computerized results. It has been shown that the inversible visual method can be extensively applied to the numerical calculation of electric fields.
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Hidetaka Miyake, Shigeru Murata, Hiroshi Kise
1990 Volume 10 Issue Supplement2 Pages
133-136
Published: October 15, 1990
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This paper proposes a method of line fitting by Fourie descriptor by which overlapped and curved pathlines in separated flow around a circular cylinder are excluded, and line fitting is applied to the remaining pathlines. Further more, this method is applied to the measurement of the length of the formation region, and it is shown that results obtained are in agreement with the other experimental ones.
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Kazuhide DAN, Motoaki YANO
1990 Volume 10 Issue Supplement2 Pages
137-142
Published: October 15, 1990
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Hologram is a record of an intensity of the diffraction wave from the object. Breakwater piles arranged in a straight line in coast are seemed to be the hologram. In order to find the simple calculating method of the diffraction sea wave of these piles, the superposition method is applied in this study. Many discussing points are remained, however the superposition method can be applied to be obtain the diffraction wave from the piles with arbitrary arrangement and diameter.
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Takashi SAITOU, Tsutomu OSATO
1990 Volume 10 Issue Supplement2 Pages
143-146
Published: October 15, 1990
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The motion of asphere falling through still fluid and the vortex shedding were experimentally invesigated. The sphere falls with little spin driven on guid railway or without spin. The motion of sphere was recorded by two cameras set at right angle and the trajectory and the rotation of sphere were analyzed to obtain the velocity and thecirculation. The vortex shedding from falling sphere and fixed sphere in uniform flow may be identical under the fact that the strouhal number were almost same values and the shape of wake were similer. But the shedding point of vortex were under the control of the rotation of falling sphere, as the results of this control, the trajectory of falling sphere was a sine curve in some vertical plane.
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Hiroyuki HIRAHARA, Masaaki KAWAHASHI, Kouju SHIOZAKI
1990 Volume 10 Issue Supplement2 Pages
147-150
Published: October 15, 1990
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Breakup of droplets have been investigated by many researchers. The process of disintegration is influenced on Weber number, Bond number and Laplace number or Reynolds number. We have investigated the deformation and disintegration of small droplets with a large viscosity in a high speed air behind a shock wave. The consequent Weber number is of 20 to 100. Droplets are deformed by the hot air behind a shock wave. For the visualization of droplets, a flash light is used and the photograph are taken by the direct shadowgraph method. The results are analyzed with Weber and Laplace numbers.
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Kesayoshi HADANO, Takashi SAITOU, Nobuyuki MUNENO, Noriyoshi NAKAMURA, ...
1990 Volume 10 Issue Supplement2 Pages
151-154
Published: October 15, 1990
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Flow visualization of the oscillatory flows around a circular cylinder was carried out using tracer particles whose specific gravity was set at about the same as the water's one. The flow field at various phases of the main oscillatory flow was pictured using a motor-driven camera. Velocity vector distribution was obtained from the locuses of the individual particles on a photo-print which indicate the lines on which particles moved during the explosure time. The technique which enables to distinguish the directions of movements of individual particles on a photo-print was employed.
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Shinzaburo UMEDA, Wen-Jei YANG
1990 Volume 10 Issue Supplement2 Pages
155-160
Published: October 15, 1990
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The dynamic characteristics of surface-floating particles in liquids flowing in a two-dimensional, semicircular open channel is studied experimentally. For high visibility in experiments, relatively large particles are employed whose particle-liquid density ratio is either equal to or less than unity. Particles of different size and geometry are tested in a water-glycerin mixture. A modified dynamics(Basset-Boussinesq-Dseen) equation is derived and numerically solved by means of a finite-difference technique. A new dimensionless parameter is disclosed which is pertinent to both particle geometry and fluid flow conditions. It correlates particle trajectory and velocity, trajectory dispersion and fluid-particle velocity ratio.
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Ryozo ISHIWATA, Takashi KAWAGUCHI
1990 Volume 10 Issue Supplement2 Pages
161-164
Published: October 15, 1990
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It is known that manipulators of marine robots are oscillated by Karman-vortex shed from themselves when they move in a water. To analyze fundamentally this, flows around a circular cylinder turned round its end have been visualized by means of hydrogen-bubble method in this study.
The separation vortices generated in the neighborhood of the other end of cylinder were periodically shed from it. The vortex shedding made continuously progress toward the center of rotation, and vortex filaments like ox-horn were formed. They were not continued to the center of rotation but broken off in the middle of the cylinder. The locations of breakaway point were scattered in every vortex shedding. Therefore the shedding frequency was higher in outer region than in inner.
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Kazuo OHMI, Kensaku IMAICHI, Ei-ichi TADA
1990 Volume 10 Issue Supplement2 Pages
165-170
Published: October 15, 1990
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The interaction of vortex streets generated behind two circular cylinders in tandem arrangement is examined and discussed in terms of visualization experiments in a towing tank. The cylinder spacing parameter L/d is varied from 2.0 to 20.0 for the Reynolds numbers ranging between 40 and 300. The main interest of the study consists in the flow characteristics at the critical spacing where, according to many of the former experiments for the Reynolds numbers around 10
3-10
5, the curves of the Strouhal number and of the drag coefficient meet some marked discontinuity or jump. Another point of the paper is the complicated vortex interaction and the subsequent wake transformation observed at the level of the downstream cylinder for spacing ratios greater than the critical one. In order to support the analysis in some aspects, an image processing technique is applied to estimate quantitative distributions of stream function and vorticity within the vortex wake.
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Visualization with Liquid Crystal Particle Suspension Method
Toshiyuki KAMEOKA
1990 Volume 10 Issue Supplement2 Pages
171-174
Published: October 15, 1990
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Natural convective heat transfers on IC package type resistance elements were made clear by the experiments in silicone oil. Temperature distribution and flow pattern of natural convection around resistance elements on the vertical circuit board in silicone oil were made visiable with the liquid crystal particle suspension method. Natural convection around resistance elements were affected by the array of resistance elements on the vertical board. Thermal boundary layer and thermal plume around resistance elements were made clearly observation. The natural convective heat transfer performances were affected both resistance elements with each others.
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Hideo YAMADA, Takashi NAITOH
1990 Volume 10 Issue Supplement2 Pages
175-180
Published: October 15, 1990
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This paper describes a flowfield produced by a circular vortex ring travelling across a thin circular cylinder. The flowfield was investigated by using the smoke visualization method. A pair of vortices was found to be induced by boundary layer separation from the cylinder surface as the vortex ring travelling across the cylinder. These induced vortices were ejected from a circulating region of the main ring. According to pictures taken at various locations. it was conjectured that induced vortices have a kind of horseshoe shape. After travelling across a thin cylinder the main vortex ring underwent distortion, that is. the ring performed such a motion as an elliptical vortex ring. We studied the effect of the diameter of the circular cylinder on the motion of the ring. Some critical values of the diameter to define the mode of vortex motion were suggested to exist.
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Nobuyuki FUJISAWA, Futoshi GOTOH, Hiroyuki SHIRAI
1990 Volume 10 Issue Supplement2 Pages
181-184
Published: October 15, 1990
Released on J-STAGE: July 31, 2009
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Separating region of a flow over Savonius-rotor blades with and without rotation are studied by smoke-wire visualization combined with smoke injection technique and by calculating the separation points with the measured wall-pressure distributions. Both of the results are in agreement and indicate a large reduction of the separating region in the rotating rotor in comparison with the still one. This phenomenon can be explained by the moving wall effect of the rotor blades and by the low-pressure effect produced by central circulation.
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Yutaka MASUYAMA, Takashi MIYAKAWA
1990 Volume 10 Issue Supplement2 Pages
185-188
Published: October 15, 1990
Released on J-STAGE: July 31, 2009
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Some experimental visualizations have been made on the flows past fin keels with or without winglet. Flow patterns on the keels are visualized using a lead white-ammonium sulfide method. A tuft grid is also used to investigate the stream direction in the wake of the fin keel. This results are compared with the velocity vectors measured using a X-probe hot-film velocimeter. Hydrodynamic forces acting on the fin keel are also measured using a load cell.
The experimental results show the winglet expands the area of trailing vortex region in the wake. The winglet also increases lift-curve slope and decreases induced drag of the fin keel.
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Kiyoyuki Minato, Hano Ryu, Toshio Kobayashi
1990 Volume 10 Issue Supplement2 Pages
189-192
Published: October 15, 1990
Released on J-STAGE: July 31, 2009
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Japanese roads and their traffic are characterized by their topographical due to mountainous land. In road vehicle tunnels exhaust pollutations are assumed to be transported convectively with the air flow and to be removed by being extracted via exhaust fans. This paper describes aerodynamics of road vehicles in tunnels, especially the effect of overtaking by used lazer ligth sheet method.
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Ichiro YAMAGUCHI, Kenjo UMEZAKI, Kazuhiro NAKATSURU, Michitoshi TAKAGI
1990 Volume 10 Issue Supplement2 Pages
193-196
Published: October 15, 1990
Released on J-STAGE: July 31, 2009
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The cross flow vector, total pressure loss and microdrag maps around 1/5 scale passenger car models are visualized by flow surveys with 5-hole pitot tubes in a scale wind tunnel with a moving belt. Five passenger car shapes, that is, a notch-back, a sedan, a sedan with under floor cover, a first-back, and a wagon are examined and survey data are obtained in the cross sections in the wake, under the floor, and beside the car. These data are calculated and presented as color contour maps with the car shapes from CAD data. The survey around the car clarifies the effect of the belt movement, and that the microdrag map in the near wake can indicate the part of the body shape which produces the large portion of the drag.
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Hirotoshi FUJIEDA, Hitoshi TAKAHASHI, Toshimi FUJITA, Akihito IWASAKI, ...
1990 Volume 10 Issue Supplement2 Pages
197-200
Published: October 15, 1990
Released on J-STAGE: July 31, 2009
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Aircraft adopting USB(Upper Surface Blowing) concept as a powered lift system achieves powered lift augumentation by deflecting the engine exhaust flow over the wing and the extended USB flap by Coanda principles. To obtain higher powered lift, optimal engine exhaust nozzles design and engine allocation which enhance effectively exhaust flow turning performance are important factors.
This report describes the exhaust flow characteristicsin the case of varying space between two engines installated on the semi-span USB powered lift model. Measurements of Exhaust flows behind two engines were made by a traversing wake rake with 5-holes pitot tube in NAL 2m×2m Gust Wind Tunnel.
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Masao YAMAMOTO, Yoshihiro MATSUOKA, Yuri AOYAMA, Noboru KOIKE, Hiroyuk ...
1990 Volume 10 Issue Supplement2 Pages
201-206
Published: October 15, 1990
Released on J-STAGE: July 31, 2009
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The purpose of this study is to clarify the flow pattern in the curved diffuser and to improve its performance.
In this study, the effects of the variation in interposed position of the guide vane in the curved diffuser and the existence of the straight duct connected at the rear of the curved diffuser on the flow pattern of the logarithmic spiral curved diffuser were clarified by the flow visualization using dye flow method, and their results were compared with the numerical solutions obtained by the finite element method.
As the results, it was found that the flow patterns obtained by the flow visualization almost agreed with numerical results, and especially, the performance of the curved diffuser was affected considerably by the interposed position of the guide vane.
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(EFECT OF EXPANSION RATIO)
Katsumi AOKI, Kenji KATHO, Hiroo OKANAGA, Yasuki NAKAYAMA
1990 Volume 10 Issue Supplement2 Pages
207-210
Published: October 15, 1990
Released on J-STAGE: July 31, 2009
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This paper is described an experimental study on circular duct flow with wirling flow. The swirling flow is very important for gas turbine combustor, fornaces, etc.
In this study, the velocity and flow pattern of the swirl flow in a circular duct is measured using a laser Doppler Velocimeter (LDV) when the expansion ratio(D/d) in circula duct is varied from 1.5 to 3.0.Further, the flow visualization is carried out using a streamer, sparktracting method and alminium powder method.
From these results, the present study clarifies the flow patterns and the size and shape of recirulation, eye of vortex and sub-recirculation zones for the expansion ratio.
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Takamitsu OHSHIMA
1990 Volume 10 Issue Supplement2 Pages
211-214
Published: October 15, 1990
Released on J-STAGE: July 31, 2009
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An experimental investigation of flow unsteadiness occurring in regular pyramidal diffusers has been done using air as the working fluid. This report is shown that the average flow pattern in cross section across outlet flow of the diffuser, in which unsteadily flow is visualized by tuft grid method, and by using the photographic film and video imaging. The diffusers are presented for following condition: length ratio=10 and total divergence angles= 2, 4, 6, 8, 10, 12 degree. The total tuft length is 6.5mm. Visualization results clearly show the change of flow pattern between the different divergence angles. These results were compared to the spectrums of total pressure.
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Masaaki KAWAHASHI, Kenji HOSOI, Masahiro ARAKAWA
1990 Volume 10 Issue Supplement2 Pages
215-218
Published: October 15, 1990
Released on J-STAGE: July 31, 2009
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When a strong sound wave is attenuated by friction in a unsteady boundary layer adjacent to a solid wall, an acoustic streaming is produced. The acoustic streaming is a steady motion defined by the steady part of second-order velocity caused by non-linearity in a wave motion. A creeping motion generated by a standing wave formed in a pipe by intense sound is known as a typical acoustic streaming which forms dust patterns in a Kundt's tube. And also a second-order pressure distribution is generated in a standing wave. The pressure distribution is shown by deformation of a surface of liquid that partially fills a tube. And when the sound pressure exceeds a certain threshold value, a rupture of liquid surface is occur and fountains are present at sound pressure nodes. This report presents visualization of the fountains and critical values of sound pressure for ruptures of liquid surface.
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Kiyohito TANI, Yukio ITO, Risaburo OBA, Masahiro IWASAKI
1990 Volume 10 Issue Supplement2 Pages
219-224
Published: October 15, 1990
Released on J-STAGE: July 31, 2009
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To make clear the flow domain of erosive cavitation arisen in the typical bounded flows though butterfly valves, the spatial distributions of cavitation-induced pressure-pulses, which are directly related to the occurrence of the cav-itation, are precisely studied by using pressure-sensitive-films in the downstream region of a valve, where very erosive vortex cavitation takes place predominantly. It is found that the erosive pressure-pulses are distributed in limited parts of the whole cavitating region, which corresponds the highly shear layers separated from the leading edge of the valve disc on the orifice side.
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