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Taketoshi OKUNO, Hiroshi HORIUCHI, Akihiro DESHIMARU
1993 Volume 13 Issue Supplement1 Pages
183-186
Published: July 01, 1993
Released on J-STAGE: July 31, 2009
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Observation of a flow around the juncture between flat plate and airfoil was made. The influence of the nose curvature on the separation region was examined using the series models which have different nose curvature. The wake flow behind the airfoil is also visualized. The streakline of milk, injected from the junction point on the plate, shows clearly the unsteady vortex like flow.
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Adjacent region of L/W=1.0 in the diffuser with 2Θ=10°
Takamitsu Ohshima
1993 Volume 13 Issue Supplement1 Pages
187-190
Published: July 01, 1993
Released on J-STAGE: July 31, 2009
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With the divergence angle increasing, flow begins to be turbulent immediately after passing the inlet of a regular pyramidal diffuser.
In the diffuser having an angle of 2Θ=10°, the increase of turbulence on the dif-fuser axis begins to be suddenly great between L/W=0.5 and 1.0.
The cross section of the diffuser has been visualized usimg the taft method at the position of L/W=1.0 where this turbulence begins to be suddenly great.
On the other hand, measurements have been carried out at the visualized point using hot wire anemometer having I-and conical type probes, and mean velocity and velocity fluctuation distributions have been obtained from it.
From these results, the early stage of occurring turbulence has been investigated and concluded.
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(The effect of mutual position between inlet and outlet on the flow pattern)
Mitunobu AKIYAMA, Hitoshi SUGIYAMA, Shiro IKUTA
1993 Volume 13 Issue Supplement1 Pages
191-194
Published: July 01, 1993
Released on J-STAGE: July 31, 2009
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This study aims to obtain uniform flow rates in the tubes of the tube arrays in a heat exchanger, so as to expect the improvement on the heat transfer efficiency. As the first step, the effects of branches and confluents through the passages of the individual tubes are examined.
Flow visualization by nylon particle tracer method is applied for the water flow through the two-dimensional tube array model.A numerical simulation is also carried out on the same model for comparison. The results show that the flow rates and patterns in the tubes are greatly dependent on the mutual position among the tube array in conjunction with the flow inlet and outlet of the model.
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In the Case of Stepwise Arrangement
K. MINAKAMI, S. MOCHIZUKI, A. MURATA, Y. YAGI, H. IWASAKI
1993 Volume 13 Issue Supplement1 Pages
195-198
Published: July 01, 1993
Released on J-STAGE: July 31, 2009
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Using a wind tunnel, systematic measurements were conducted on heat transfer and pressure loss characteristics of pin-fin arrays having stepwise arrangement, by varying the offset pitch as a parameter. The pin-fin arrays used in the present study were made of square shaped thin (0.2 mm) pins. The measurements were carried out on the basis of modified single blow transient testing method. Additionally, the flow visualization tests were carried out utilizing fifteen times enlarged pin-array models with dye injection technique. Water was used as the test fluid. The test results clarified the effects of the pin pitch on the heat transfer performance. It is found that there is a optimum value of offset pitch.
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Effect of Fin Pattern
Dong CAI, Sadanari MOCHIZUKI, Akira MURATA, Yoshinao YAGI
1993 Volume 13 Issue Supplement1 Pages
199-202
Published: July 01, 1993
Released on J-STAGE: July 31, 2009
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Recently, louvered fin heat exchanger geometry is widely used in automotive radiators and air conditioners. However, the optimum combination of geometrical parameters, such as louver pitch, louver angle, and fin pitch, has not been clari-fied yet because of the complicated flow structure in fin arrays. In this study, flow visualization using the smoke wire method and measurement of pressure loss in the fin array were performed. Test section was a 5:1 scale model of an automotive radiator. Various patterns of fin array are examined by varying the Reyn-olds number from 390 to 1116. The results showed the possibility of higher heat transfer for a few patterns of fin array as com-pared with the conventional louvered fin array by causing the transition to turbulent flow at more upstream location in the fin array.
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Masatomi NISHIO, Mutsuo KOTAKE
1993 Volume 13 Issue Supplement1 Pages
203-206
Published: July 01, 1993
Released on J-STAGE: July 31, 2009
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The shock shape around a slender diamond cone traveling at hypersonic speed was visualized by using the first electric discharge method. The visualized shock shape was compaired with the result obtained theoretically. Both the results agreed comparatively well. From this comparison, it was comformed that the first electric discharge method is useful for visualizing three dimensional shock shapes around hypersonic vehicles.
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Toshiaki SETOGUCHI, Takashi TOMINAGA, Toshihiro NAKANO, Kenji KANEKO
1993 Volume 13 Issue Supplement1 Pages
207-210
Published: July 01, 1993
Released on J-STAGE: July 31, 2009
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Since the concept of passive control of shock-boundary layer interaction was published in 1983, many papers have been reported on the application of this technique to transonic airfoil flows. In the present paper, this technique is applied to condensation shock wave which is caused by rapid expansion of moist air in a supersonic nozzle. The effects of passive control on condensation shock wave have been experimentally investigated by a schlieren optical method and by pressure measurements. As a result, it is found that passive control is the useful technique to suppress the periodic oscillation of condensation shock wave.
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Taro Amemiya, Yutaka Yamaguchi, Kiyohide Sekimoto, Shigeru Yamaguchi
1993 Volume 13 Issue Supplement1 Pages
211-214
Published: July 01, 1993
Released on J-STAGE: July 31, 2009
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Transonic flows around an airfoil with the trip strip in a shock tube were visualized to study applicability of the fixed transition technique to the shock tube airfoil experiment by the Schlieren method. The test Mach number and Reynolds number were 0.84 and 0.39 million, respectively. Schlieren photograghs showed that the fixed transition was realized at the transonic flow condition of the shock tube flows by the trip strip of small strips of plastics tape, distributed along the span of the model. Weak, but distingushable compression waves were also observed at the trip strip of some distribution pattern. The disturbance produced by the strips on the airfoil surface is three dinentional. So, further experimental work should be performed to evaluate the influence of such a disturbance on the present results by other quantitative methods.
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Tosiyuki AOKI, Tetuya UKON, Mituharu MASUDA, Kazuyasy MATSUO
1993 Volume 13 Issue Supplement1 Pages
215-218
Published: July 01, 1993
Released on J-STAGE: July 31, 2009
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The purpose of this paper is to report the experimental studies of the gas dynamic characteristics, especially those such as supersonic plasma flow with MHD interaction in the constant area channel. The plasma for exeperiment is produced by a shock tube. In order to obtain a clear and sharp image of the supersonic plasma flow with MHD interaction, the color schlieren photographic method has been employed. The schlieren photographs show clealy the image of the shock-boundary layer interaction in the MHD channel. The experimental results show that the flow Mach number decreases and velocity of propagating shock wave increases in the channel, with an increase in the Lorentz force for the supersonic plasma flow with MHD interaction.
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Hiroshi NAKAMURA, Terumi INAGAKI, Yoshizo OKAMOTO, Yoshiaki SATO, Osam ...
1993 Volume 13 Issue Supplement1 Pages
219-222
Published: July 01, 1993
Released on J-STAGE: July 31, 2009
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In the constructional and mechanical fields, the detection of a leak on a surface is important to maintain and manage various structures, which are a bank, a dam, a tunnel and so on. When fluid is leaking out a surface of the structure, its temperature is not generally consistent with the environmental temperature. Furthermore, expansion of high-pressure gas jetted from a nozzle lessens its temperature and cools a surface around a nozzle. With the aid of the thermograph based on infrared rays, we can detect the leak where the temperature difference between the solid surface and the leaking fluid is remarkable. In this paper, the availability of the infrared radiometer is experimentally investigated to establish the effective detection method of a leak.
Key Words: Thermal Visualization, Infrared radiometer, Leak, Detection Method
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Kenji KANEKO, Akio MURAOKA, Toshiaki SETOGUCHI
1993 Volume 13 Issue Supplement1 Pages
223-226
Published: July 01, 1993
Released on J-STAGE: July 31, 2009
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In order to clarify the mechanism of unstable characteristics of a high specific speed diagonal-flow fan, flow visualization of the internal flow fields ahead and after the rotor was performed with tuft method. Behavior of the flow fields in a low flow range including rotating stall, and the relation to the characteristics of the fan were investigated. The effects of tip clearance on the unstable characteristics and internal flow fields were also discussed.
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Hideki ONODERA, Katsumasa OKUDA, Kohji SAGARA, Naotake FUJITA, Shoichi ...
1993 Volume 13 Issue Supplement1 Pages
227-230
Published: July 01, 1993
Released on J-STAGE: July 31, 2009
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Thermocouple is usefull tool in order to measure the flame temperature. However, the errors by heat convection and radiation can't be avoided and must be climinated by one of the correction method. These method only concern with heat loss to thermocouple. In this report, the infuence of inserted probe for quasi-two-dimensional flame arc visualized by means of infrared radiation thermometer. As the result, existence of higher temperature region at upstream and both sides of the inserted probe are found. In this area the temperature increases 100°C at maximum from normal value. This means that a probe in a flame must be influenced not only heat convection itself but also radiation from the high temperature region.
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Teruo YOSHIHASHI, Shigeharu OHYAGI, Pin CAI
1993 Volume 13 Issue Supplement1 Pages
231-232
Published: July 01, 1993
Released on J-STAGE: July 31, 2009
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The present study aims to obtain a fundamental understanding of the mechanism of instabilities arising on a flame front propagating in a disk-shaped constant-volume chamber by visualizing the flame front with direct and Schlieren photography. For direct photography, a new operating system was used to get a instantaneous photograph with the shortest shutter speed 1/8000 sec. The ignition was performed at the center or at the point on the periphery of the chamber to see the effects of the wall configuration. The mixtures selected were methane-air and propane-air with various equivalence ratios. As a result, it is found that the photographs with a speed 1/4000 were satisfactory for visualizing flame shapes when the instabilities occurs on the flame front. Comparing with the Schlieren photograph, it is revealed that the flame itself wrinkles where the Schlieren image shows an anomalous shape.
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Kazuhide Dan, Noriaki Yagi, Motoaki Yano
1993 Volume 13 Issue Supplement1 Pages
233-236
Published: July 01, 1993
Released on J-STAGE: July 31, 2009
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We estimate the wave height in regular waves by measuring the brightness at the glass plate which is set horizontally at the bottom of the water.
We visualize the diffracted region in two cylinders when the incident wave travels to these cylinders and we compare this visualized diffracted region with the analytical result.
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Futoshi Nakanishi, Kazunari Katoh, Motoaki Yano
1993 Volume 13 Issue Supplement1 Pages
237-240
Published: July 01, 1993
Released on J-STAGE: July 31, 2009
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The wide range of the gradient of water surface can be measured by using three different light sources in this experimental study. These three lights are distinguished by using the different colour filters.
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Toshio SUZUKI, Kazuya SUMINO
1993 Volume 13 Issue Supplement1 Pages
241-244
Published: July 01, 1993
Released on J-STAGE: July 31, 2009
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It is generally known that the light from the bottom of tank is refracted when it passes through water surface. So the light distribution projected on a screen near the wave surface has strong relationship with the wave height and pattern.
Authers clarified the relationship between them before when parallel light passes through the water surface perpendicularly.
In this paper, the theorem is applied to a case of a point light source. Two-dimensional wave pattern and wave height are reproduced from the light distribution using the Fourier Transform method. Results are compared with the parallel light case and good coincidence are obtained when the screen is arrenged near the water surface.
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Katsutoshi Watanabe, Hirofumi Ohnari, Takanori Saga, Takashi Saitou
1993 Volume 13 Issue Supplement1 Pages
245-248
Published: July 01, 1993
Released on J-STAGE: July 31, 2009
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Coherent structure of straight-meandering channel flow is investigated using DPIV technique. DPIV technique enable to consider correlation between coherent structure and instantaneous velocity field. The results indicate that large-scale vortical structure formed near side wall at meanderig portion correspond to many area of concentrating vorticity.
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Hirohumi OHNARI, Katsutoshi WATANABE, Takanori SAGA, Kunio MAEDA
1993 Volume 13 Issue Supplement1 Pages
249-252
Published: July 01, 1993
Released on J-STAGE: July 31, 2009
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Relationship between simultaneous visual pattern of coherent motion and fluctuating components of u and v in the near-wall turbulent flow is investigated using Dye-Particle-Image VeIocimetry(DPIV)' technique. The results indicate that dye-streak patterns of coherent vortical motions associate with the vorticity of ωz and uv structures. DPIV technique plays an important role to understand the physics of coherent motion in the near-wall turbulence.
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Motoo FUMIZAWA
1993 Volume 13 Issue Supplement1 Pages
253-256
Published: July 01, 1993
Released on J-STAGE: July 31, 2009
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An experimental investigation was carried out for the buoyancy-driven exchange flow in a narrow vertical pipe concerning with air ingress process during a stand pipe rupture in high temperature gas-cooled reactor. In the present study, the evaluation method of exchange flow was developed by measuring the velocity distribution In the pipe using laser Doppler velocimeter (LDV) and the flow pattern was visualized by smoke tracer method. It was found that the exchange flow fluctuated irregularly with time and space in the pipe. The velocities of the plumes obtained from visualization were almost the same as the maximum ones measured by LDV.
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Sadao FUJII, Mikio AKAMATSU, Motoo FUMIZAWA, Tomoaki KUNUGI, Makoto HI ...
1993 Volume 13 Issue Supplement1 Pages
257-260
Published: July 01, 1993
Released on J-STAGE: July 31, 2009
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The purpose of this paper is to investigate the phenomena buoyancy-driven exchange flow in an enclosure. A three-dimensional computer code using the Boundary-Fitted Coordinates method was applied to realistic simulation of curved boundary shape. The computed results were visualized by a graphic work station. Unsteady and asymmetric flow patterns such as observed in the experiments were obtained.
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2nd Report; Visualization of 3-D structure of exchange flow
Masaaki KAWAHASHI, Kenji HOSOI, Hiroyuki HIRAHARA, Motoo FUMIZAWA
1993 Volume 13 Issue Supplement1 Pages
261-264
Published: July 01, 1993
Released on J-STAGE: July 31, 2009
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This paper presents the experimental results of visualization into the buoyancy-driven exchange flows between helium and air through a vertical pipe. This type flow might be caused by a pipe rupture accident in a high temperature gas cooled reactor. The exchange flows induced by density difference are complicated by Kelvin-Helm-holtz instability arising on internal contact surface.
The exchange flows formed in the vertical pipe connecting between the helium vessel and ambient air are visualized by means of the laaer-light-sheet illumination technique. The results obtained show the transient process of flow development in the pipe, and unsteady, three dimensional structure of the flows.
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Masao CHAKI, Motoo FUMIZAWA
1993 Volume 13 Issue Supplement1 Pages
265-268
Published: July 01, 1993
Released on J-STAGE: July 31, 2009
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In a High Temperature Gas-Cooled Reactor(HTGR), air ingress after pipe rupture accidents causes corrosion of the graphite structures in a pressure vessel. To prevent this phenomenon, injection of inert gas might be very effective. We have done the transient and steady numerical analyses on the code based on the SIM-PLEST algorithm to study the flow behavior and mass transfer. Experimentally we have measured the velocity fields by LDV and we have suceeded the flow visualization by using the smoke tracer of the joss sticks and a slit light.
As the result, the followings were obtained. The jet is accelerated by the gravity force. The velocity fields by the LDV experiments agree with those by the numerical calculations. And it becomes evidence by the flow visualization that the width of the jet decreases due to the acceleration of the jet and the jet entrains ambient air near the jet outlet.
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