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Published: August 22, 2001
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Article type: Appendix
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Published: August 22, 2001
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Article type: Appendix
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Published: August 22, 2001
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Article type: Appendix
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Published: August 22, 2001
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Article type: Index
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Published: August 22, 2001
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Hiroyuki YASUJIMA
Article type: Article
Session ID: K-1030
Published: August 22, 2001
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Two-dimensional simulations of gas flow inside a plasma reactor of parallel-plates RF etcher are performed using the direct simulation Monte Carlo (DSMC) method, In order to couple the outlet gas pressure to the pressure range of the pumping field, the outlet model of gas area filled with virtual gas particles is used. In this model, the virtual particles are set at random points and at random velocity estimated by the Maxwell-Boltzmann distribution for those pressure and temperature. Those are characterized effective only as the target of collision pairs and those tracking is not functional. The number density of gas(BCl3) is calculated on computational conditions of the outlet boundary, which are estimated by the reflectivity depending upon the number of the gas layers.
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Keizo WATANABE, Tsukasa TAKAYAMA, Seiji ISOZAKI, Satoshi OGATA
Article type: Article
Session ID: K-1031
Published: August 22, 2001
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Fluid slip of Newtonian fluids was clarified by measuring the velocity profile close to the highly water-repellent wall in a Couette flow by using a particle tracer method for flow visualization. The maximum slip velocity is less than 20% of the wall velocity of the inner cylinder, which rotate. The values that the drag reduction ratio for the torque was calculated by applying to the values of slip velocity, agree with the experimental result quantitative.
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Keizo WATANABE, Manabu HASEGAWA, Satoshi OGATA
Article type: Article
Session ID: K-1032
Published: August 22, 2001
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Experiments were carried out to make sure that the air exist in the fine many grooves on the highly water repellent-wall when tap water flow on the wall. It was cleared that the air exist in fine grooves when the wall was covered by water. However, the fine grooves were filled with the solution in the case of Ethoquad O/12 solutions that the drag reduction does not occur. It is seen by the flow visualization results that the difference lies between the flows behavior of laminar and turbulent flows near the wall for the shape the interface between the groove edge and liquid.
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Satoshi OGATA, Atsushi HIROSE, Keizo WATANABE
Article type: Article
Session ID: K-1033
Published: August 22, 2001
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In order to clarify the relationship between the drag reduction and the fine grooves on the wall surface, we measured pressure losses of tap water in a pipe with new water-repellent wall. The pipe walls are different in terms of width, length and intensity of development of the grooves on its surfaces each other. The surfaces of those water-repellent walls are excellent in durability comparing to those of highly water-repellent walls, whose endurance is a serious problem of the practical use of this wall. The experimental result shows that the drag reduction does not occur for the test pipes. It can be considered that the size of the grooves is larger than that of the drag reducing highly water-repellent wall.
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Masao ISHIKAWA, Nobuyoshi KAWABATA, Takuji ISHIKAWA, Yuko KUNIKANE
Article type: Article
Session ID: K-1034
Published: August 22, 2001
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It is important to clarify the basic characteristics, such as backlayering distance and velocity of the thermal plume generated by the fire accident in a road tunnel in order to design the ventilation system for securing the evacuate environment. In this research, the backlayering velocity and distance are investigated by the experiments which use a reduced scale model tunnel and by the large eddy simulation. The reliability of numerical code is verified by compareing numerical and experimental results. The results show that the backlayering velocity increases with increasing the heat release rate and that the backlayering velocity and distance decrease with increasing the ventilation velocity.
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Takumi HAYASHI, Noboyoshi KAWABATA, Takkuji ISHIKAWA, Tetsuharu MATSUM ...
Article type: Article
Session ID: K-1035
Published: August 22, 2001
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When a tunnel fire happens, the accident vehicle and other vehicles often exist around the fire source. These obstacles influence are exerted on the critical ventilation velocity of the thermal plume from backlaryering and the characteristics of the backlayering distance etc. Then, we install the obstacle in the 1/15 scale model tunnel, and the influence of the obstacle on the backlayering characteristic of the thermal plume was investigated experimentally and numerically
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Nobuyuki YAMAMOTO, Nobuyoshi KWABATA, Takuji ISHIKAWA, Yuuko KUNIKANE
Article type: Article
Session ID: K-1036
Published: August 22, 2001
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When the tunnel fire occurred, the damage by smoke and thermal plumes is considerable. The temperature of thermal plumes, which is stratified and moves along the ceiling, decreases because the ceiling gradually absorbs the heat from the thermal plume. The decrease of temperature induces the thermal plume and smoke descending towards the ground. Practically, in order to keep the evacuate environment, fire exits are installed with a certain interval. Therefore, in order to set up fire exit of appropriate interval, it is necessary to clarify the distance where smoke descends to the ground. Consequently, in this research, the influences of various parameters on the descent of smoke were examined by the 3D Large Eddy simulation.
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Akinori SANO, Nobuyoshi KAWABATA, Takuji ISIKAWA
Article type: Article
Session ID: K-1037
Published: August 22, 2001
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If fire smoke is generated in the upstream successive tunnel by a traffic accident, the exhausted smoke flows into the downstream tunnel, which may destroy the evacuate environment in the downstream tunnel. It is, therefore, important to discuss the interference rate of successive tunnels. In this paper, the effect of variouse parameters on the interference rate is investigated by large eddy simulation. The reliability of numerical code is verified by comparing with the real scale tunnel experiment. Consequently, the interference rate is expressed by a new equation.
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Tomoki KAWAI, Noboyoshi KAWABATA, Takuji ISHIKAWA
Article type: Article
Session ID: K-1038
Published: August 22, 2001
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Recent year, traffic jam often occurs in the urban area. In the urban area, the highways are expected to be constructed under ground as a solution of the traffic jam. Such tunnels have large curvature in the junction area, however the behavior of thermal plume and critical velocity have not been clarified in case of fire accidents. In this research, a fire in the curvature tunnel was simulated, and the behavior of the thermal plume was discussed.
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Kimihiro ASABATAKE, Nobuyoshi KAWABATA, Takuji ISHIKAWA, Miyoshi SHIMO ...
Article type: Article
Session ID: K-1039
Published: August 22, 2001
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When tunnel fire occurs, pressure drops at the fire source by the expansion of the air. The strict pressure drop has not been estimated in the discussion of the tunnel ventilation in the emergency fires as yet. In this research, tunnel fires are simulated in one and three dimensionaly and the pressure drop is investigated. The effects of the fire scale and the ventilation velocity on the pressure drop by the fire is clarified.
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Kazuhiro HINO, Genshi KAWASHIMA, Hiroshi OHUE
Article type: Article
Session ID: K-1040
Published: August 22, 2001
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In this study, heat transfer enhancement occurred from turbulence of flow by fin was considered. Fins were arranged in in-line form, and longitudinal pitch Sp and lateral pitch Sn were varied. Cool air flows through the slant fin array to take away heat from the heated plane. Visualization of temperature distribution image was processed by color image processing to determine the quantitative temperature distribution by a hue angle-temperature correlation curve. The flow around the fin array was visualized using talc powder. Average Nusselt number on the heated plane was calculated from the quantitative temperature distribution. Coefficient of pressure of flow passage loss was also calculated by pressure loss.
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Akinori FURUKAWA, Yinchun CAO, Kusuo OKUMA, Takahiro CHONO, Satoshi WA ...
Article type: Article
Session ID: K-1101
Published: August 22, 2001
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A contra-rotating axial flow pump has been developed against demands for higher performance. Experiments were conducted to investigate effects of rotational speed control of the rear rotor on pump efficiency. The operating point with the maximum efficiency of the pump is discussed and the guiding principle of a rear rotor speed control is shown in the present paper. In the maximum efficiency point of the rear rotor, the relative flow smoothly enters the rear rotor passage at the inlet. This operating point is different from the maximum efficiency one of the pump and the circumferential velocity at the rear rotor exit, bringing about additional flow loss in downstream section, is still remained. When the zero circumferential velocity condition at the rear rotor exit, or the maximum pump efficiency condition is chosen by the rear rotor speed control, it is possible to improve the pump efficiency at the off-design point from that in the designed rotational speed.
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Sunao Miyauchi, Hironori Horiguchi, Jun-ichirou Fukutomi, Akihiro Taka ...
Article type: Article
Session ID: K-1102
Published: August 22, 2001
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To design a pump, there are so many design parameters. So we propose a new design method, which design a meridional and blade-to-blade shape by the parallel use of the circulation distribution which a designer gives. Thus, we use an optimization method to design an axissymmetrical meridional shape from the circulation distribution. And we use the inverse design method proposed by Zangeneh et al. To design a three-dimensional blade shape from the circulation distribution and the optimized meridional shape.
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Seiji AZUMA, Akira FUJII, Hironori HORIGUCHI, Yoshiki YOSHIDA, Yoshino ...
Article type: Article
Session ID: K-1103
Published: August 22, 2001
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In the present study, a higher order rotating cavitation predicted by the stability analysis was identified thorough the measurements of inlet pressure fluctuation and blade stress fluctuation. The propergation speed ratio of the higher order rotating cavitation is about 5, and the amplitude of the blade stress fluctuation caused by this rotating cavitation is the same as that by the conventional rotating cavitation. In addition, a higher order cavitation surge was observed at the transition point from the conventional to the higher order rotating cavitation.
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Junichiro FUKUTOMI, Hironori HORIGUCHI, Yuichi NAKATANI
Article type: Article
Session ID: K-1104
Published: August 22, 2001
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The region where pressure rises and the rate of the rise were examined in a centrifugal blower casing which has no diffuser and large tongue clearance. At the design point, the pressure recovery in the scroll was about 45 percent. The remaining 55 percent were recovered in the section between the scroll end and exit duct. This section acted as a high-performance diffuser. It was concluded that centrifugal force produced by secondary flow and boundary layer section was the main cause of the high pressure recover. Moreover, it was suggested that the flow conditions from the scroll toward the exit duct were closely related to the low flow rate characteristics of the blower.
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Yuzuru KOBAYASHI, Nobuyuki YAMAGUCHI, Masayuki OGATA
Article type: Article
Session ID: K-1105
Published: August 22, 2001
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For an improvement of aerodynamic performances of axial-flow compressors, effects of tip clearances on the suction-corner flow of the blade cascades were studied by cascade-wind-tunnel tests. The cascade pressure-recovery coefficients were found to improve by about 5 % for an optimum small tip clearance (0.4mm for the chord length of 100 mm). The measured distributions of total pressure and the visualized flow patters on the end-wall evidenced the structure of the improved end-wall flow. The phenomenon is promising for the future improvement of the machine, although the tip clearance is too small for practical application at the present level of technology.
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Kentaro WATANABE, Yoshihiro HARA, Makoto YAMAMOTO, Ikuhisa MIZUTA, Kun ...
Article type: Article
Session ID: K-1106
Published: August 22, 2001
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Electro-Chemical-Machining (ECM) has been used in highly specialized fields such as aerospace, defence and medical industries. In recent years ECM makes use of other industries, because of the advantage. That is, ECM has no tool wear, and it can machine difficult-to-cut-metals and complex geometries with high accuracy. However, ECM has some problems such as the design of the tools, electrolyte processing disposal of metal hydroxide sludge and so on. In the present study, the three-dimensional flow field in ECM process is calculated, changing bow and sweep stacking Visualizing flow field around a jet engine blade the characteristics of the flow are investigated.
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Yasutomo KANEKO, Kazushi MORI, Hiroharu OHYAMA, Toshihiro MIYAWAKI
Article type: Article
Session ID: K-1107
Published: August 22, 2001
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Under the low load and low condenser vacuum operation, the rotating end-blade of the low-pressure steam turbine is vibrated by the random excitation forces due to an inverse flow, a flow separation, and so on. These excitation forces can cause the excessive random vibration and the stall flutter to the blade. In order to research the vibratory characteristics of the integral shroud blade (ISB) structure under the low load and low condenser vacuum operation, the model turbine test is carried out and the vibratory stress of the blade is measured under various operating conditions. From the test results, it is confirmed that the vibratory stress of the ISB structure is much smaller than the conventional grouped blades and shows the excellent stability to the self-excited vibration due to the higher blade damping.
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Yoshiyuki NAKASE, Yasuyuki NISHI, Syunsuke NAKAJIMA, Tetsutaro MATSUMO ...
Article type: Article
Session ID: K-1108
Published: August 22, 2001
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This paper describes a development of three buckets wind turbine with through ways. We used six kinds of wind turbines (three type and two depth). We carried out an examination of a capacity to change wind velocity and a shaft resist. We achieved about 12% of power coefficient and 60% of torque coefficient. This wind turbine can resist over 40m/s wind. Therefore, this wind turbine was expected to be use for an anemometer in an area of strong wind and an elevation of the rate of operation, because usual propeller can be use only above 3.5m/s wind and under 22.5m/s wind and that rate of operation is on more than 20%.
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Nobutaka HAYASHI, Ichiro ARIGA, Masatoshi SANO
Article type: Article
Session ID: K-1109
Published: August 22, 2001
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In centrifugal compressor or blower, operation becomes unstable as flow rate reduces because of self-exciting phenomena like rotating stall or surge. This study describes unsteady phenomena in the static pressure field due to rotating stall observed in a radial vaneless diffuser of a centrifugal blower. In the experiment, static pressure measurement was conducted using pressure transducers attached on the diffuser wall. The data was acquired slowly changing the operation region from stable to unstable by throttling the flow control valve. As result, by means of spectrogram and cross-correlation analyzes, transient process under unsteady condition in the diffuser was made clear.
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Tomoyuki DEGUCHI, Yutaka MIYAKE, Kouhei OKITA
Article type: Article
Session ID: K-1110
Published: August 22, 2001
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Unsteady numerical simulatons are conducted for flows in axial rotors in rotating stall regime. Although numerical viscosity is inevitably introduced to stabilize computation to this highly complicated flow, the obtained flow reasonably explains the observations in experiments. It is confirmed that in some rotor geometry characterized by solidity, aspect ratio of a blade, hub ratio, etc., rotating stall cells never appear but several stall areas of various scales scattered along the casing wall are found, even though head characteristics shows rotating stall regime. In another rotor used in the numerical imulation, stable stall cells appear as observed in the corresponding experiments. However, the nature of the stall such as whether it is of reprsenting light stall or of heavy stall is not identified. It turned out that the rotating stall cell is a strong vortex tube which is generated by a strong jet ejecting toward upstream through a couple of inter-blade flow passages.
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Taufan SURANA, Masahiro ISHIDA, Zixian SUN, Daisaku SAKAGUCHI
Article type: Article
Session ID: K-1111
Published: August 22, 2001
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With respect to the impeller with radial blades and inducer blades revised in the inlet geometry, the flow visualization of the separation ring on the shroud casing wall was conducted as well as a 3-D steady turbulent flow calculation in order to investigate the inducer stall at small flow rates. The numerical analysis shows that the small separation bubble appears at the blade root leading on the blade suction side at small flow rates, then, the reverse flow appears and develops remarkably at the inducer tip portion as the flow rate decreases further. Judging from these results, the initial unstable flow might be caused by the separation at the blade leading, and the strong unstable flow might be due to the large reverse flow at the inducer tip portion.
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Kimihiko MITSUDA, Yusuke KAWAMURA, Kazuhiko YOKOTA, Yoshinobu TSUJIMOT ...
Article type: Article
Session ID: K-1112
Published: August 22, 2001
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This paper describes the model experiment and its numerical simulation for the vortex structure between a main flow and a backflow at the turbomachine inlet at a low flow coefficient. In the model experiments, the vortex structures were visualized by the injected air and recorded by a high speed video for various flow ratios of the axial and tangential speeds of the backflow to the axial speeds of the main flow. The numerical simulations are performed for some experimental conditions and the results agree with the experimental ones qualitatively. All the results show that the ratios of the axial and tangential speeds of the backflow to the axial speeds of the main flow greatly influence on the number of vortices.
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Hiroshi IMAMURA, Junichi KUROKAWA, Jun MATSUI, Osamu TAKAMURA
Article type: Article
Session ID: K-1113
Published: August 22, 2001
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The purpose of this study is to show the applicability of J-Groove for controlling swirl flow in a draft tube of water turbine. J-Groove is very simple device composed of shallow grooves mounted parallel to the pressure gradient on the diffuser wall. Experiment with J-Groove has been performed using the conical diffuser with the divergent angle of 20 degrees. The pressure fluctuation on the wall has been measured to show the effect of J-Groove for the spiral vortex core in the diffuser.
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Tatsuro WAKIMOTO, Tsuneo AZUMA
Article type: Article
Session ID: K-1114
Published: August 22, 2001
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The laminar-turbulent transition process in a liquid sheet is investigated by linear instability analysis and laser measurement. A radial liquid film flow is generated by a water discharge through a small gap formed between the end of a nozzle and the flat surface of a disk. The liquid film flow spreads radially on the disk, flowing from the disk edge into the still air as a liquid sheet. Sudden laminar-turbulent transition occurs in the liquid sheet when the Reynolds number exceeds a critical value, resulting in the perforation and the disintegration of the liquid sheet. In this flow, a disturbance wave(D wave) is appeared before the transition. The frequency of D wave is measured with a laser. The measured frequency agrees with the frequency in which a disturbance grows most rapidly because of an inflectional velocity profile in the sheet. This agreement shows the transition is due to the inflectional instability.
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Takayuki YAMAKAWA, Kenkichi OHBA, Kenji KANAZAWA
Article type: Article
Session ID: K-1115
Published: August 22, 2001
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Wave generated on the liquid column surface is an important origin of the liquid column disintegration. Hence, the wave characteristics on the liquid column injected into an air flow were experimentally and theoretically investigated. Critical wavelength, drop diameter and wave velocity were measured from the images for the varicose mode by high-speed video camera with a speed of 18000 frames per second. For the low relative velocity, good agreements are obtained between the Rayleigh's theoretical critical wavelength and the experimental values. On the other hand, for the high relative velocity, the critical wavelength is decreased with the increase in relative velocity. Therefore, the drop diameter is decreased with the increase in relative velocity for high relative velocity.
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Tomohiko FUJII, Kenkichi OHABA
Article type: Article
Session ID: K-1116
Published: August 22, 2001
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The electo-hydrodynamic (EHD) spraying is an atomization process that involves an instability of liquid interface owing to the electrostatic force. The instability of this type is produced due to an electric charge overcoming the surface tension force of the liquid. The EHD spraying involves various modes, and our attention is focused on a cone-jet mode, in which minute and homogeneous droplets are produced. Our purpose is to produce a model blood cell by using the cone-jet mode EHD spraying. But the mechanism of the cone-jet mode is not understood very well. Therefore, at first, we examined the influence of the electrode polarity on sprayed droplets.
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Toshihiro SAWAMURA, Shinya YAMABE, Kenji KURYU, Yukiya KANAZAWA
Article type: Article
Session ID: K-1117
Published: August 22, 2001
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The cleaning method that the cavitating jet is applied to remove the oil on the surface of the spherical object is suggested in this paper, and the cleaning experiment by cavitating jet are carried out to examine the effects of cleaning on the various conditions. The white aluminum ball is chosen as the specimen to be able to distinguish between the removed region and the remaining region. As the result, it is shown that a peak on the standoff distance and the pressure that the removed angle is constant exist on the cleaning capability.
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Takeshi YAMADA, Jun MIZUSHIMA, Masahiko IIZUKA, Yutaka OHTA
Article type: Article
Session ID: K-1118
Published: August 22, 2001
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Unsteady behavior of Taylor vortex flow between eccentric rotating cylinder was investigated by three-dimensional incompressible N-S simulation. Research attention has been focused on unsteady fluid force acting on the inner rotating cylinder. Fluctuation of resultant force is largely influenced by generation and recession of Taylor vortices formed in the vicinity of the most narrow region of the eccentric clearance. When the number of Taylor vortices are regularly formed, momentum of the inner fast fluid is transported toward the outer region to form the low-pressure field. Then the time history of fluid force shows positive extreme against the most narrow region of the clearance. In the same way, negative extreme of the fluid force happens when vortices are disappeared by merging. Moreover, small perturbations overlaid on the force fluctuation are found to be caused by birth of vortices aligned along the inner cylinder.
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Akira OGAWA
Article type: Article
Session ID: K-1119
Published: August 22, 2001
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The radial distribution of the tangential velocity of turbulent rotational gas flow in the cylindrical vortex chamber is depended on not only the Reynolds number Rec but also the construction of this chamber. When the ratio of the body diameter D1 to the diameter Do of the tangential inlet pipe is larger than 6〜7 , so the distribution of the tangential velocity in the quasi-free vortex region is not always represented by the simple free vortex model. A cause of this effect is mainly depended on the distribution of the radial velocity. In this paper a comparison of the experimental results of the tangential velocity of gas flow in the quasi-free vortex region with the numerical calculation by Runge-Kutta method is discussed.
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Masaru ARAKAWA, So YAMAMOTO, Tsuyoshi IGARI, Akira OGAWA
Article type: Article
Session ID: K-1120
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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An axial flow cyclone dust collector with fixed guide vanes ( called simply as a cyclone) is applied in many industrial fields. Therefore, it is used widely in all over the world. Until now, the various constructions of cyclone is devised. However, the report which described collection performance or flow characteristic depended on shape of exit pipe is very few. In order to explain the separation characteristic depended on the diameters D_2 and D_f, this paper describes the detailed radial distributions of the tangential and axial velocities in the separation chamber. The velocity distributions were meassured with a cylindical Pitot tube with single hole. Here, main sizes of the cyclone are the body diameter D_1 of the cyclone, exit pipe of diameter D_2, the imaginaly cylindical length Hi, a max funnel diameter D_f and as well as the angle of the fixed guide vanes θ _B as D_1=99 (mm), D_2=33 (mm), Hi=134 (mm) and θ _B=45° Funnel ratio D_f/D_1 was changed as 0.5,0.6 and 0.7.
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Katsutoshi Kobayashi, Nobuyuki Taniguchi, Toshio Kobayashi, [in Japane ...
Article type: Article
Session ID: K-1121
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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Some wall stress models have been proposed to reduce the CPU time required in LES and to predict with a good accuracy. We improve the 0 equation model of the turbulent eddy viscosity in the differential equations model using the gradient Richardson number. In this model we calculated the strongly swirling flow inside the cylindrical furnace. There is no difference between the improved model and non-improved model. If the tangential mean velocities are compared between LES and the experiment, that of LES is a free-vortex-type but that of the experiment is a forced-vortex type.
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Takashi Murata, Takanori Ishida, Tsutomu TAKAHASHI, Masataka SHIRAKASH ...
Article type: Article
Session ID: K-1201
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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In this study, a start-up viscoelastic fluid flow in a reservoir upstream a circular pipe entry was visualized by the photochromic method. The photochromic flow visualization technique is based on a photo-chemical reaction where a chemical material, C_<19>H_<18>N_2O_3(SP-1), turns into purple-colored by shining ultra-violet laser light for a few minutes. Among many visualization techniques, the photochromic technique applied in this work has a dominant advantage in that it needs no contaminant such as die or tracer particles which may affect the velocity and stress field. It also allows very free arrangement of initial patterns by designing the fading screen and repetitive use of a same test fluid.
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Atsushi WATANABE, Yosuke ARUGA, Tsutomu TAKAHASHI, Masataka SHIRAKASHI
Article type: Article
Session ID: K-1202
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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A flow near a die entry or in an abruptly contracting pipe flow is one of flows where elasticity of fluid can have dominant effect because a fluid element is elongated unsteadily even when the flow field itself is steady. This investigation is focused on the effect of elasticity on the development process of a capillary entry flow. An aqueous solution of polyacrylamide with a concentration of 0.2wt% was used as the viscoelastic test fluid. The start-up behavior of entry flow to a pipe of 2mm inner diameter attached to the bottom of a large reservoir was investigated by applying flow visualization and LDV. While the developing process of capillary entry flow of a Newtonian fluid is virtually quasi-steady, it takes a considerable time for a viscoelastic fluid to attain its terminal regime. The flow pattern upstream the capillary entry determines the elongation rate, which governs the elongation stress at the entry, and the entry pressure loss in turn. Hence, the transient behavior of the flow rate is attributed to the gradual development process of the flow field upstream the entry.
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Hiroshi YAMAGUCHI, Hiroshi MURAMATSU
Article type: Article
Session ID: K-1203
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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A study is carried out for viscoelasitic fluids in two dimensional two-cycle diverging-converging channels. In order to investigate flow behavior in the channels, experiments are conducted using polyacrylamide water solutions as model viscoelastic fluids with which measurements of pressure and velocity are made together with observation by flow visualization. In visualization results, various modes of complicated flow patterns, which are caused by viscoelastic effect are observed, and the classification of prevailing flow modes is obtained. By measurements of pressure along channel walls, it is found that additional pressure losses exist related with an appearance of the extra normal stress due to the viscoelasticity. Furthermore, by measurements of velocity in the center line of the channels, the symmetry breaking flow deflection is found to occur at the critical Reynolds number.
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Shigeki IMAO, Yasuaki KOZATO, Toshio TANAKA, Hironobu MIZUNO
Article type: Article
Session ID: K-1204
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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Non-Newtonian fluid flow in a channel obstructed by an antisymmetric array of cylinders has been studied by means of pressure loss measurements, flow visualization, and particle image velocimetry. The fluid used here are polyacrylamide 300ppm solution and Xanthan gum 800ppm solution, which show nearly same shear viscosity. In the case of PAM solution, pressure loss becomes very large compared with Xanthan gum solution, and the fluid cannot pass through the smaller gap between the cylinder and the wall. This fact may be due to high extensional viscosity of PAM solution.
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Naoya OHARA, Hiroshi YAMAGUCHI
Article type: Article
Session ID: K-1205
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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Flow of viscoelastic fluid contained between a stationary outer sphere and a rotating inner hemisphere is studied experimentally. In the present investigation, relatively low-concentration polyacrylamide-water solutions are used as viscoelastic fluid, and for sake of comparison glycerin-water solutions are used as the Newtonian fluid. In experiments, measurements of the rotational torque and thrust are carried out. Various transition phenomena of flow modes that are unique to viscoelastic fluids are investigated by flow visualization for a wide range of rotational Reynolds numbers.
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Akinori Kishine, Takashi Koshiba, Noriyasu Mori, Kiyoji Nakamura
Article type: Article
Session ID: K-1206
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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In order to clarify a displacement mechanism of fossil oil in crust by polymer solution, the polymer flow in undulating slit channel filled by a Newtonian fluid was experimentally examined. This study used a machine oil for the displaced fluid. The fluids injected into the channel were aqueous solutions of polyacrylamide (PAA) with two concentration and a solution of PAA(0.01wt%PAA) using an aqueous solution of 88wt% Glycerine as a solvent. In the undulating channel, the immiscible flow of a polymer solution with a Newtonian fluid was observed. The configuration of an interface between both fluids was related to the Theological property of polymer solution. It was found that the efficiency of displacement was affected by the channel geometry.
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Takashi Koshiba, Noriyasu Mori, Kiyoji Nakamura
Article type: Article
Session ID: K-1207
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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The concentric elongational flow known as a bicomponent coextrusion fiber spinning process was experimentally examined. In this study, a Newtonian fluid and aqueous solutions of polyacrylamide(PAA) were used for a skin and core layer, respectively. In the observation of concentric flow, the interface between core and skin layers varied linearly along the flow direction. In the numerical simulation using the Giesekus model, it was shown that the shape of interface was dependent on a ratio of flow rate between two fluids.
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Masashi MORITA, Seiji GOTO
Article type: Article
Session ID: K-1208
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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This report describes Numerical analysis of flow of the viscoelastic fluid in two dimensional channel junction with a dividing angle of 90 degree. The upper convected Maxwell model and the Denn model were used as the constitutive equations of viscoelastic fluid. The vorticity transport equation is solved using the finite difference method with an upwind scheme for it and the viscoelastic stress. The numerical results of flow pattern did not agree with the characteristic flow patterns of polymer solutions in experiment. However the sizes of separation zones of the polymer solutions agreed qualitatively with the numerical results using UCM model, and did not agree with these using Denn model.
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Takehiro YAMAMOTO, Masakazu ISHIYAMA, Kiyoji NAKAMURA
Article type: Article
Session ID: K-1209
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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Three-dimensional viscoelastic flows in a rectangular channel with a cavity were numerically studied. The finite volume method was applied for solving the discretized equation. The simplified Phan-Thien Tanner (PTT) model was applied for a constitutive equation. The simulation was carried out for three Weissenberg numbers We=0.2, 2, 4 and for three values of the model parameter ε=0.001, 0.01, 0.25. In addition, Newtonian flows were also calculated for comparison. In viscoelastic flows, the swell of the main flow was observed near the entrance to the cavity and the vortex inside the cavity was asymmetric. When We was large, three-dimensional flow properties appear obviously.
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Ikuhisa GOTO, Tomomi HAYAKAWA, Hikaru WAKI, Shuichi IWATA, Hideki MORI ...
Article type: Article
Session ID: K-1210
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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In the finite element analysis using biquadratic shape functions, velocity gradients(▽v) are of the discontinuous in nature at the element boundary. To improve this lack of continuity of the velocity gradient, we introduced a smoothing technique of velocity gradient. The terms ▽v used in constitutive equation may be replaced by tensor D which is smoothed velocity gradients evaluating from the velocity field calculated in previous step of iterative method. This technique, associated with the techniques previously reported, improved the convergence behavior of decoupled finite element analysis of die swell flow of viscoelastic fluids.
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Masahito HATTORI, Ikuhisa GOTO, Hikaru WAKI, Shuichi IWATA, Hideki MOR ...
Article type: Article
Session ID: K-1211
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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As far as singularity problems of Newtonian fluid analysis are concerned, Georgiou et al. proposed the singular finite element method (SFEM), which used the singular elements that were taken into account the nature of the singularity. We introduced these singular elements to the stress field as well as the velocity and pressure fields, for solving the die swell flow of viscoelastic (single mode Giesekus model) fluids using decoupled finite element method. Introducing the singular element meshes to the stress fields, associating with the previously reported techniques, enabled the prediction of die swell flow at We=100 successfully, and the results showed that wiggles in variable fields were reduced in the vicinity of die lip, compared with the solution using the standard FEM.
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Takeshi YASUDA, Shuichi TANOUE, Yoshiyuki IEMOTO
Article type: Article
Session ID: K-1212
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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Plastics is one of the most important materials. The flow state and temperature of polymer melts are important on polymer processing. Polymer melts have elasticity as well as viscosity. In addition to this, its zero-shear viscosity and relaxation time depend on temperature. In this study, we investigate effects of Nusselt number by using the streamline-upwinding finite element method. The non-isothermal Phan-Thien, Tanner model proposed by Sugeng and Phan-Thien was used as the constitutive equation. When the Nusselt number increases, the temperature of extrudates decrease and the maximum swelling ratio increases.
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Hiroshi WATANABE, Kazunori SORIMACHI, Tomiichi HASEGAWA, Takatsune NAR ...
Article type: Article
Session ID: K-1213
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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The drag reduction effect was experimented in turbulent flows througu a pipe of the diameter 3.17mm for polymer and surfactant solutions. As water, Newtonian fluids is not shown the drag reduction. But dilute solution of polyacrylamide(Separan) is observed reduction. In surfactant solution, dilute Ethoquad aqueous solution give similar results in the case of Newtonian fluids, and Ethoquad aqueous solution adding NaSal have the tendency of large drag reduction. For the solutions which are shown the drag reduction, in low frequancy region, the power spectrum of these are higher than that of water.
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