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Article type: Cover
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Published: August 02, 2008
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Article type: Appendix
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Article type: Appendix
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Article type: Index
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A1-A5
Published: August 02, 2008
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Yoichi YAMAGISHI, Shigeo KIMURA, Makoto OKI
Article type: Article
Session ID: 1601
Published: August 02, 2008
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It is known that in a square cylinder with uniform flow, the drag force changes with angle of attack. To clarify the flow characteristics around a square cylinder with corner cutoffs we analyzed the drag coefficient, and the Strouhal number were measured. Moreover, the flow around the square cylinder with corner cutoffs was analyzed by applying the RNG k-ε turbulent model, and the surface flow pattern was investigated using visualization by the oil-film method and mist flow. From these results, the sudden decrease of drag coefficient occurs at an angle of attack about α=0〜10℃ in the case of the square cylinder with corner cutoffs compared with the square cylinder. The minimum value of drag coefficient for the square cylinder with corner cutoffs decreases about 30%, since the wake area of the square cylinder with corner cutoffs becomes smaller compared with that of the square cylinder.
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Kazuki TANAKA, Hiroaki HASEGAWA, [in Japanese]
Article type: Article
Session ID: 1602
Published: August 02, 2008
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Unsteady fluid forces acting on a discoid airfoil in the upward motion with a constant velocity were measured by using the ring structure 2 elements balance. Furthermore, the vorticity field around the airfoil was also described with the flow visualization technique. Dynamic lift/drag coefficients were compared to the steady ones. It is confirmed that the upward motion with a constant velocity is available for keeping lift higher after the separation occurs. The delay of stall for the airfoil is observed and also the value of maximum lift coefficient is greater than the maximum lift coefficient under stationary condition. Furthermore, the value of maximum lift coefficient and the dynamic stall angle are improved as increasing the non-dimensional frequency. The dynamic lift is affected by vortex behavior around the airfoil.
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Yoshiya ITAKURA
Article type: Article
Session ID: 1603
Published: August 02, 2008
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Apex fences are applied to improve low-speed aerodynamic characteristics of 60 deg. delta wing model. The longitudinal forces and moment acting on the thin delta wing with apex fences (Apex fences are used hinged to the delta wing upper surfaces along the leading edges at angles of 45,90 and 135 degrees.) are measured by using universal multi-component sensor and static pressure distribution on the upper surface is also measured by using pressure transducer with pressure scanner. Combination of total-pressure distribution maps and longitudinal force and moment measurements provide information on the three-dimensional nature of the vortex structure induced by apex fences.
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Yuki KASHIWAGI, Yasuyuki YAMAGUCHI, Shigehira OZONO
Article type: Article
Session ID: 1604
Published: August 02, 2008
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Non-stationary responses of the models subjected to accelerated flow was investigated with increasing yaw angle, as well as stationary responses. The accelerated flow was realized by using a multi-fan wind tunnel with 99 small fans. The models used were rectangular prisms and a scale model of similar shape to a real truck. In the non-stationary measurements, a basic case with a small initial velocity near zero is compared with other cases with some considerable initial velocity.
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Ryo YAMASAKI, Takahiro YASUDA
Article type: Article
Session ID: 1605
Published: August 02, 2008
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In the present study, the wobbling motion of a single-flagellated bacterium was analyzed assuming that the bacterium consists of a cell body of prolate spheroid and flagellar helix, the axis of which is inclined to the major axis of the ellipsoid. The results were compared with those obtained by using dark field microscope. We investigated the relationship between the cell body shape of bacterium, inclined angle of flagellum, the angle of the wobbling motion to the promotion direction,the promotion distance during one cycle of wobbling motion and resistive coefficient. It was found that the promotion distance changes sensitively for the inclined angle of the axis of the flagellar helix as minur axis becomes small and the wobbling angle increses as the cell body shape approach from spheroid to the sphere. The variation of resitive coefficient gives qualitatively little effect on the promotion distance
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Yoichi MITO, Keisuke TANIGAWA
Article type: Article
Session ID: 1606
Published: August 02, 2008
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An idealized gas-liquid annular flow in a vertical rectangular channel is considered. Point sources of solid spheres are located on the walls to represent atomizing wall films. Feedback and inter-particle collisions are not considered. Statistics for fluid turbulent flow seen by particles were determined in the calculations in which a direct numerical simulation was used to calculate the fluid turbulence. The influence of a very wide range of particle sizes on the statistics is shown. The momentum balance between the mean value of the wall-normal fluid velocities that are seen by particles and the turbophoresis, in the fully-developed concentration field, demonstrates defects of the models for these effects.
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Takanori YUMURA, Rongyuan SA, Minoru TAKAHASHI, Isao YODA
Article type: Article
Session ID: 1607
Published: August 02, 2008
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As a fundamental study for safety evaluation of water leak accident from steam generators of lead alloy-cooled fast reactors (LFR) and evaluation of gas lift bubbles in a direct contact type LFR (PBWFR), behavior of nitrogen bubble flow in a molten lead-bismuth pool in a rectangular vessel has been visualized by gamma-ray radiography.
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Yasuhiro HIRAI, Kenji KOFU, Mitsuaki OCHI, Masahiro TAKEI
Article type: Article
Session ID: 1608
Published: August 02, 2008
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The difference between rotary feeder system and the vessel system on transportation efficiency could not be made sure. But the air velocity in the rotary feeder system was slightly faster than that in vessel system under the same air mass flow rate. This means that pressure drop in the rotary feeder system is smaller than that in vessel. The cause is the number of incorporated plugs in the vessel is lager than that in the rotary feeder system, because deviation of plug velocity and plug length in the vessel is far larger than that in the rotary feeder system. Additionally, the rotary feeder system could take the transportation limit of air mass flow rate down. This is also caused from small pressure drop in the rotary feeder system.
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Gota WAKABAYASHI, Osamu MOCHIZUKI
Article type: Article
Session ID: 1610
Published: August 02, 2008
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The purpose of this study is to verify the possibility of friction-drag reduction of a flow along a polymer substance. The velocity profiles of a flow along an inclined polymer wall were measured by a PTV method. These are compared with the exact solution of the thin flow driven by the gravity along an inclined wall. The velocity profile obtained the flow along the acrylic resin coincided with the exact solution, namely, parabolic profile. Small discrepancy between the profile of the flow along the polymer wall and the exact one was observed in this study. However, since it is too small, it is hard to determine whether there is a slip flow on polymer wall.
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Hiroto KONISHI, Naoki TAKAHASHI, Jim FUKUSHIMA
Article type: Article
Session ID: 1611
Published: August 02, 2008
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This paper describes influence of gap and equivalent mass upon characteristic of jet in Needle-free injection. For the needle-free injection used for the diabetic treatment to have the problem such as fill the drug to the syringe at each use though it injected two or more times a day, and to solve this, how the jet condition such as the impact gap influenced with the injection force at the rise time was examined. The discharge characteristics of the liquid jet were measured using a test instrument. The experiments reveal that an injection force depends on gap and spring force, and rise time depends on gap.
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Hiroaki Niihata, Kenichiro KOSHIYAMA, Takeru YANO, Shigeo FUJIKAWA
Article type: Article
Session ID: 1612
Published: August 02, 2008
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We investigate the effect of shock wave parameters on characteristic changes of a lipid bilayer by using molecular dynamics simulations. The action of shock wave is modeled by a shock wave impulse that is implemented by adding a momentum to water molecules in a region of the system calculated. The various waveforms are generated by changing the size of the region. From the results of velocity and density profiles across the system, it is found that the waveform becomes steep when the small sized region is used in an impulse condition. The shock wave induces water penetration into the hydrophobic region of the bilayer as in our previous study. The number of water molecules penetrated becomes small with increasing the size of the region; this implies that using steep waveform shock wave is favorable to the water penetration for the shock wave impulse conditions studied here.
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Yukiko WATANABE, Sachiko HORIE, Noriko TOMITA, Fuki OOSAWA, Rui CHEN, ...
Article type: Article
Session ID: 1613
Published: August 02, 2008
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A non-invasive molecular delivery method using nano/microbubbles (NB) and ultrasound (US) is an attractive technique for gene therapy. This method is able to deliver macromolecules such as plasmid DNA to a tissue specific site non-invasively. In addition, a non-invasive quantification method of gene expression has been studied by monitoring ^<124> accumulation caused by the of Na/I symporter (NIS) gene expression with positron emission tomography (PET). In the present study, we delivered NIS gene into the skeletal muscle of vasculitis and muscular dystrophy mice by using the US/NB method, and succeed in visualizing the ^<124>I accumulation caused by NIS gene expression in the muscle with PET. The combination of the US/NB delivery with NIS/PET visualization will be a valuable methodology in gene therapy.
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Kosuke MATSUMURA, Masaaki TAMAGAWA, Yuuta KUBOMOTO
Article type: Article
Session ID: 1614
Published: August 02, 2008
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This paper describes the development of microcapsules for shock wave drug delivery systems (DDS). Especially capsule structure and driving force is investigated. In the first step, the neutrophil based capsule is made for DDS instead of polymer membrane capsule. When some part in our body inflames, materials, whose name is cytokine, are released. These materials pull neutrophil, one of white blood cell, toward inflamed part. It is said that neutrophils are moved to inflamed part by gradient of cytokine concentration that is called chemotoxis. This mechanism is immune mechanism. If we can control chemotasis of neutrophil, it follows the development of application in the fields of immunity and drug delivery system. In the second step, the motion of neutrophil by gradient of cytokine is investigated and it was found that the driving force of neutrophile is caused by the gap of diffusion coefficient at the interface.
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Yu NAKAMICHI, Souichi SAEKI, Takashi SAITO, Takafumi HIRO, Masunori MA ...
Article type: Article
Session ID: 1615
Published: August 02, 2008
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Recently, clinical treatments applying drug delivery system (DDS), e.g. Drug Eluting Stent, have been being developed. However, it is quite difficult to in vivo diagnose spatiotemporal distribution of drug infiltration, so the validation study should be too insufficient to progress the DDS development. In this study, we proposed a quantitatively visualizing assay of DDS, namely 2-Color Optical Coherence Dosigraphy (2C-OCD), which was based on optical coherence tomography using two waveband light sources having different optical absorbance of drug. This can simultaneously provide microscale tomographic images of scatterer density and drug concentration. In this paper, 2C-OCD was applied to biomedical tissue administered DDS drug (AlPcS). The aortic vessel of rabbit, which had highcholesterol diet, was used, and absorption distribution was calculated at the area of arterial plaque. Consequently, tissue characterization and drug distribution in biomedical tissue could be detected by 2C-OCD.
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Sei SYU, Takahiro MATSUNO, Kazumichi KOBAYASHI, Hiroyuki TAKAHIRA
Article type: Article
Session ID: 1616
Published: August 02, 2008
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In the present study, numerical simulations are conducted for the collapse of an air bubble near a tissue surface by using an improved ghost fluid method. A tissue is modeled with a gelatin that was used in the experiment by Kodama and Takayama. The bubble collapse is induced by the interaction between a bubble and an incident shock wave. A flat shock wave profile and an exponential one based on the experimemt by Kodama and Takayama are utilized, and the influence of the shock wave profile on the dynamical motion of the bubble and gelatin is investigated. It is shown that the gelatin surface is depressed by the shock waves generated from the bubble. The penetration of the bubble into the depression of the gelatin, which was demonstrated in the experiment by Kodama and Takayama, is simulated successfully. The results also show that the collapse time of a bubble is longer and the width of the depression is thinner when the shcok wave with the exponential profile interacts with the bubble.
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Shohei YAMASHITA, Kazuhiko YOKOTA, Kotaro SATO, Shinji TAMANO, Motoyuk ...
Article type: Article
Session ID: 1617
Published: August 02, 2008
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Yoko HANEDA, Hirohisa WAKISAKA, Jiro FUNAKI, Katsuya HIRATA
Article type: Article
Session ID: 1618
Published: August 02, 2008
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In the present study, the authors investigate an oscillatory phenomenon of a two-dimensional confined jet with a downstream target, by experiments and computations. By experiments in air and water, jet's frequencies are measured near the target by a hot-wire anemometer and an ultrasonic velocity profiler with a particle-image velocimetry, respectively, at the Reynolds number Re<5000. In computations, the present numerical method is a finite difference method formulated in terms of vorticity and stream function. As a result, we can see the Re effect, the target-distance effect and the target-size effect upon the Strouhal number St. Regarding the Re effect, it is found that there is less influence, which guarantees wide-range workability as a flowmeter or a mixer. All the results can be summarised in empirical formulae describing the relation between St and geometrical parameters.
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Xuezheng ZHAO, Hiroaki HASEGAWA
Article type: Article
Session ID: 1619
Published: August 02, 2008
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Vortex Generator Jets (VGJs) have significant effects on separation control. The longitudinal vortices generated by VGJs embedded in the boundary layer ware investigated experimentally. In this study, to understand the reasons why the vortices for T-shaped jet orifice case behave in a manner different from those for the circular jet orifice case, velocity measurements were carried out in various phases of issuing jets discretely (pulsed jets).The pulsed VGJs with T-shaped orifices make the separation control effective in contrast to the circular jet orifice case. The pulsed VGJs with T-shaped orifices promote the interaction between adjacent vortices, and the strong longitudinal vortices were generated in the region close to the lower wall. The different feature of longitudinal vortices between the T-shaped jets and the circular jets can be explained by considering the vortex behavior in each phase of pulsed jets.
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Masahiko SAKAMOTO, Tsuyoshi YAMAMOTO, Toshio MATSUBAYASHI
Article type: Article
Session ID: 1620
Published: August 02, 2008
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The purpose of this study is to examine the pressure pulsation in a centrifugal blower piping system with the discharge opening below the water surface. The effect of the piping shape on the pressure pulsation was studied experimentally. The pressure and the flow rate in the pipe line were measured for various parameters such as the depth of the discharge opening, the number of revolution for the blower, and the valve opening of the throttle valve. It was clarified that the behavior of the air-liquid interface affects the pressure pulsation in the pipe line. The pressure fluctuating ratio increases with increasing the depth of the discharge opening, and it has the maximum value at the specific depth. The dominant frequency in the pressure pulsation is influenced by the shape in the discharge opening.
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Mitsuhiro Masuda
Article type: Article
Session ID: 1621
Published: August 02, 2008
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By installing a reed valve on a tube with air column oscillations produced within, an acoustic compressor can be built and its volume-flow-rate can exceed the piston's swept-volume, i.e., the limit of reciprocating-compressor's volume-flow-rate. This study had proved that connecting an array of resonators to a tube annihilates shocks and nonlinearity effects in the tube. In this paper the model for this kind of compressors is simplified by considering a valve as an orifice with its opening being changing and the linear formulation for the model is introduced. The effects of the positions of the valve on the characteristics, the relationship between a mass-flow-rate and a load of an acoustic compressor, has been estimated and has been shown to be in good agreement with experimental one in the case of a small load.
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Katsuhisa OHBA, Tokinao OTAKA, Kiyotaka SUGIYAMA, Hideharu MAKITA
Article type: Article
Session ID: 1622
Published: August 02, 2008
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Spatial structure of internal gravity waves was experimentally investigated in a strongly stably-stratified mixing layer with a stepwise mean temperature distribution. Multi-point simultaneous measurement was made on the temperature field by using a rake of 13 cold-wires system. Spatial structure and heat transfer mechanism in the transition process of the internal gravity waves were evaluated through coherence and joint probability density analyses. As the internal gravity waves developed downstream, the time-averaged heat flux was apparently suppressed despite of the positive temperature gradient. The random components produced by the destruction of the wave-front were dominated by the cold descending cells. Turbulence generation through the collapse of the internal gravity waves induced the negative heat flux in the stably-stratified mixing layer.
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[in Japanese], [in Japanese], [in Japanese], [in Japanese]
Article type: Article
Session ID: 1701
Published: August 02, 2008
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This paper describes the inlet prerotation flow of a cross-flow fan and the control. To begin with, the cause of generation of inlet prerotation flow of the cross-flow fan is investigated. Next, it is examined that the prerotation is controlled by the inlet guide vane. As the result, following fact became clear. (1)The prerotation is being generated by drawing in the inlet flow for eccentric vortex of the rotor inside, and therefore, the inlet velocity becomes non-uniform in the circumferential direction. (2)The cross-flow fan becomes a high-efficient and high pressure by controlling the prerotation using the inlet guide vane.
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Yutaro SHIRAI, Tomohiro YASUNOBU, Junichiro FUKUTOMI, Toru SHIGEMITSU
Article type: Article
Session ID: 1702
Published: August 02, 2008
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A sirocco fan using contra-rotating rotors was proposed for the purpose of higher pressure and more compact structure of sirocco fan. If the high discharge pressure is obtained with the adoption of the contra-rotating rotors, it could be used for various purposes. Pressure coefficient of a sirocco fan with contra-rotating rotors is higher than that of conventional sirocco fan which is 2.5 times of conventional one.
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Tadahiro YANO, Tsukasa MATSUOKA, Junichiro FUKUTOMI, Toru SHIGEMITSU
Article type: Article
Session ID: 1703
Published: August 02, 2008
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Small-sized axial fan is used as air cooler for electric equipments. But there is demand for higher power of fan according to the increase of quantity of heat from electric device. Therefore, higher rotational speed design is necessary but it causes the deterioration of efficiency and increases the noise. Then the adoption of contra-rotating rotor for small-sized fan was proposed for the improvement of performance. In the present paper, experiment and numerical flow simulation was conducted to investigate the performance of conventional small-sized axial fan and contra-rotating small-sized axial fan. And internal flow field and pressure distribution were clarified from the numerical results then the effect of contra-rotating type on the performance and the similarity law of small-sized axial fan would be discussed.
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Ken-ichi FUNAZAKI, Takashi SHIMADA, Kazutoyo YAMADA, Hideo TANIGUCHI, ...
Article type: Article
Session ID: 1704
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Flow fields around a PC cooling fan in a narrow space are studied with the experimental measurements using a hot-wire of 45-slanting sensor type and the unsteady Reynolds-averaged Navier-Stokes computations. Effects of the distance between the fan and the cooling target object downstream of it on the fan performances are focused. The numerical results agree with the experimental data. The fan characteristics between the static pressure and the volume flow rate changes greatly as the gap between the fan and the target become below a certain value. It is shown that reversed flow penetrates into the hub region of the fan casing and the effect of tip leakage vortex becomes remarkable as the gap decreases.
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Jae-ho Jeong, Masato FURUKAWA, Zhiming ZHENG
Article type: Article
Session ID: 1705
Published: August 02, 2008
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Three-dimensional structure of unsteady vortical flow field has been investigated by numerical analysis on a half-ducted propeller fan. Complicated and unsteady flow phenomena in the fan were captured by Detached Eddy Simulation (DES) based on k-ω two-equation turbulence model. To elucidate the complex vortical flow phenomena, vortex structures were identified by the critical point theory, and limiting streamlines visualized by LIC. Three-dimensional unsteady vortex behaviors correspond to high pressure loss region after blade passage.
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Soichiro TABATA, Masato FURUKAWA
Article type: Article
Session ID: 1706
Published: August 02, 2008
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A three-dimensional aerodynamic design method for half-ducted propeller fan has been presented. The half-ducted propeller fan has internal and external flow feature. It is important to take into account non-uniform meridional flow distributions around it. The present design method consists of two parts: a three-dimensional inverse design of fan rotor blade and an axisymmetric viscous flow calculation on the meridional plane. Continuing the process between the blade design using the three-dimensional inverse design method and the evaluation of the viscous flow fields around the rotor using the axisymmetric viscous flow calculation, the blade shape matching the flow fields around the rotor is converged. It is found that the present design method is useful to the half-ducted propeller fan design tool.
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Naoto Hagino, Yasushige Kashiwabara
Article type: Article
Session ID: 1707
Published: August 02, 2008
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Surge and rotating stall often damage a compression system. Ishii et al showed the possibility of these unsteady phenomena occurring simultaneously in an axial compressor. The authors examined relationship between surge and rotating stall occurring in small centrifugal compressor. In this paper, we examined relation between surge and rotating stall in a small centrifugal compressor. Our experimental results showed that both surge and rotating stall occurred simultaneously in the test centrifugal compressor. Further, it was recognized that fluctuations occurred just before these unsteady flow phenomena.
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Daisaku SAKAGUCHI, Tengen MURAKAMI, Yu KOBA, Masahiro ISHIDA, Hironobu ...
Article type: Article
Session ID: 1708
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In a turbocharger for diesel engines, a high pressure ratio and a wide operation range are required to achieve extemely low exhaust emissions. In the present study, the ring groove arrangement was adopted to enhance a flow range in a centrifugal compressor of automobile turbocharger. The upstream groove was located at the casing wall of the suction pipe and the downstream groove was located at the shroud casing wall near the leading edge of the splitter blades, where both grooves were connected by an annular bypass. According to the numerical results calculated by using ANSYS-CFX code, it becomes clear that the ring groove arrangement is effective for supression of separation at the leading-edge of main blade even in small flow rates. The reverse flow appeared on the shroud casing is sucked out from the downstream groove, and the recirculation flow was formed in the groove arrangement. The flow incidence at the main blade leading edge is reduced surccessfully by about 5〜7 degrees due to the increased incoming flow rate.
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Yuki FUJIOKA, Nobuyuki YAMAGUCHI, Masayuki OGATA
Article type: Article
Session ID: 1709
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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An air separator employing radial scooping vanes applied on an axial flow fan has demonstrated a significant stall improvement effect in the former report. Changes in the internal flow patterns in the fan in the presence of the air separator device were experimentally investigated. The air separator-applied condition tended to create tip-peaky distributions of axial velocity distributions, compared with those for the solid-wall conditions. It suggests a resulting inclination of meridional streamlines through the rotor blades toward the blade tip region. The change in the behavior was continuous and consistent over the whole flow range. The effects have been achieved only by a very small amount of recirculation flow, as small as 0.4 % of the main flow, within the air separator passage for the practically important working flow range of the fan including the zone originally stalled for the solid wall condition.
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Takahiro NISHIOKA, Toshio KANNO, Hiroshi HAYAMI
Article type: Article
Session ID: 1710
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Numerical and experimental studies were carried out to clarify the flow mechanism behind stall inception at three stagger-angle settings for the rotor blades of a variable-pitch axial-flow fan. When a short length-scale stall cell was observed, tip-leakage vortex breakdown occurred, and a three-dimensional separation vortex developed When a long length-scale stall cell was observed without the short length-scale stall cell, this breakdown also occurred, but the separation vortex did not develop. When a modal disturbance was observed, a separation vortex developed, but the tip-leakage vortex breakdown did not occur. The numerical and experimental results show that the diffusion factor and attack angle at the rotor tip were the aerodynamic parameters that influenced the change in the tip-leakage vortex and the development of the tree-dimensional separation vortex.
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Kazutoyo YAMADA, Ken-ichi FUNAZAKI, Hirokazu SASAKI
Article type: Article
Session ID: 1711
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The purpose of this study is to better understand the unsteady behavior of tip leakage flow in axial compressor rotors at near-stall condition, which leads to the rotating disturbance in stall inception. DES (Detached Eddy Simulation), which has a potential to accurately predict the unsteadiness of separation and vortices to be appeared in compressors at near-stall, was applied to this simulation in a transonic axial compressor rotor (NASA Rotor 37). The result was compared with that of RANS simulation. DES showed that the tip leakage vortex fluctuated with time due to the vortex breakdown, but it happened at a little higher mass flow rate than the near-stall condition of the experiment.
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Mamoru KIKUCHI, Ken-ichi FUNAZAKI, Hidekatsu ATSUMI
Article type: Article
Session ID: 1712
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This paper provides experimental investigations of unsteady flow behaviors in a single axial flow turbine stage with two axial gaps. The aim of this study is to clarify the effect of the axial gap on the unsteady flow field, where the 3-D unsteady flow field downstream of rotor blades is measured using a slant-type hot wire probe. Since the flow field is likely to be affected by the disk and tip cavity flow when the stator-rotor axial gap increased, the cavities on both hub side and casing side were kept constant (about 1 mm) by attaching several rings to openings of the cavities. In addition, we have compared time-averaged flow fields measured by a five-hole probe with unsteady experimental results.
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Yusuke TSUNENARI, Akinori FURUKAWA, Satoshi WATANABE, Kusuo OKUMA, Sat ...
Article type: Article
Session ID: 1713
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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An application of contra-rotating rotors has been proposed in response to a demand for the higher specific speed of axial flow pump. The internal flow field and blade rows interactions between the front and rear rotors should be considered in the design for higher performance and more stable operation. In our previous study, at the partial flow rates, we have observed the positive slope of H-Q curve in the rear rotor, while we expect the negative slope because of the lower blade loading of the rotors compared with the usual axial flow pump rotor. Then, in the present study, for more understanding of the internal flow at the partial flow rate, we investigate the internal flow fields by Laser Doppler Velocimetry measurement and the limiting streamline observation with the Oil-film method.
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Naoki MATSUSHITA, Tomomichi HASUI, Akinori FURUKAWA, Satoshi WATANABE, ...
Article type: Article
Session ID: 1714
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Centrifugal pumps are utilized in various industrial fields, and there is a strong demand to develop a usable one even under the air-water two-phase flow condition with the high inlet void fraction. Authors have investigated air-water two-phase flow performance of centrifugal pump. As the results, we have developed a centrifugal pump for air-water two-phase flow operation. The impeller, having double rotating cascades of the inner and outer with higher outlet blade angle and the installation of diffuser cascade downstream of impeller outlet yields the further improvement of air-water two-phase flow performances. In the present paper, under the case of water single-phase flow condition, we examine the flow distribution in the impeller by EFD (LDV measurement) and CFD (CFX-code simulation) analysis. By comparing the results between the test impellers with no diffuser cascade and with diffuser cascade, we discuss the relation between the impeller performances and flow distribution in the impeller.
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Jun MATSUI
Article type: Article
Session ID: 1716
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In order to balance the axial thrust of turbo machines, devices such as balancing disk, balancing hole and sealing system are used. However many of these devices become complicated and make problems such as the vibration by balancing disk. In order to control and balance the axial thrust, a very simple device of using shallow grooves mounted on a casing wall, known as the "J-Groove", is proposed and studied experimentally and theoretically. This study shows the effect of the J-Groove is estimated by putting a term in the equation of angular momentum on the gap flow, and it is possible to estimate the effect to the various parameters of grooves.
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Yuka IGA, Kei HASHIZUME, Yoshiki YOSHIDA, Toshiaki IKOHAGI
Article type: Article
Session ID: 1717
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Unsteady cavitation occurring in turbopump sometimes yields unstable oscillation in the pump which is called as cavitation instabilities. In this study, cavitation surge accompanied by pulsation phenomenon which is classified into axial directional instability is numerically analyzed in cascade by using a numerical method based on our original gas-liquid two-phase model. As a result, three kinds of surging oscillation having different characteristics are reproduced in the present cascade, and the mechanism is analyzed.
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Yoshiki YOSHIDA, Masato EGUCHI
Article type: Article
Session ID: 1718
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Rotordynamic fluid forces coupled with flow instabilities (i.e., impeller/diffuser rotating stall and rotating cavitation) in turbomachines were examined. Variations of fluid forces arisen from the rotating instabilities have the similar characteristics in rotating stall and cavitation. The phase of the fluid force vector changes by π around the natural frequency of flow instabilities.
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Tomoyuki HASHIMOTO, Yoshiki YOSHIDA, Mitsuru SHIMAGAKI, Toshiya KIMURA ...
Article type: Article
Session ID: 1719
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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An inducer is usually utilized in a rocket turbopump system to increase pump suction performance. According to this point, high suction performance is the principal function for an inducer. However, in high performance rocket turbopump system for recent rocket engines, high pressure rise is required for an impeller. The purpose of this article is to clarify the advantages of a tandem bladed inducer which is recommended for high head rise inducer by NASA criteria for a design of a rocket turbopump system.
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Nobuyuki YAMAGISHI, Masaharu UCHIUMI, Naoki NAGAO, Hitoshi YAMADA
Article type: Article
Session ID: 1720
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The pressure oscillations around a hydrogen inducer under the condition of real flight were measured. Unstable cavitation phenomena were observed by using flush-mounted pressure sensors under the control of the flow rate and cavitation number during tests.
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Kazuki NIIYAMA, Satoshi HASEGAWA, Yoshiki YOSHIDA, Yuka IGA, Katsuhide ...
Article type: Article
Session ID: 1721
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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New cryogenic cavitation tunnel was constructed in the JAXA Kakuda Space Center in March 2008. The tunnel will be used for an elucidation on thermodynamic effect which affects on the growth of cavitation. Liquid nitrogen is used as the working fluid, and the temperature of the working fluid can be varied in order to change the degree of thermodynamic effect on cavitation. The obtained results will contribute to the improvement of the performance of rocket turbopumps.
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Katsuji NAGAURA, Yuusuke KAZAMI, Tomoyuki HASHIMOTO, Tsutomu TAMURA, Y ...
Article type: Article
Session ID: 1722
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Uneven cavitation is known as one type of cavitation instability. On the other hand, cavitation in cryogenic fluids has a thermodynamic effect on cavitating inducers because of thermal imbalance around the cavity. To investigate the influence of the thermodynamic effct on uneven cavitation in a four bladed inducer, we conducted experiments in liquid nitrogen (78K) and water (279K).
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Mitsuo WATANABE, Katsuji NAGAURA, Satoshi HASEGAWA, Tomoyuki HASHIMOTO ...
Article type: Article
Session ID: 1723
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Direct flow visualization under the cavitation using cryogenic fluid have a beneficial effect on in order to examine the thermal dynamically effect. The authors focus a polycarbonate resin as test casing. Direct flow visualization will make advance in the cavitation phenomenon study if demonstration test is conducted in cryogenic test facility at Kakuda space center (CITF).
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Mitsuru Shimagaki, Tomoyuki Hashimoto, Mitsuo Watanabe, Satoshi Hasega ...
Article type: Article
Session ID: 1724
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The inducer inlet flow of rocket engine turbopump was observed by two-dimensional PIV method. It was found that the inlet flow was complicated by the backflow and prewirl flow. The prewirl flow which occurred at close the blade tip showed the strong steady vorticity, and the strong Reynolds stress does not found at the tip leakage vortex area. However, the strong unsteadiness was found in the prewirl flow caused by the backflow vortex.
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Masanori ISAKA, Takashi KUBO, Takahide ITOH, Yasuhiko SAKAI, Kouji NAG ...
Article type: Article
Session ID: 1725
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In order to clarify an internal flow of regenerative pump, velocity measurements have been conducted by PIV (Particle Image Velocimetry) for the pump with casing and impeller made of acrylic resin. Spiral flows that come and go between the flow passage and impeller are confirmed. On the cross section parallel to the rotating plate of impeller, when the flow rate is small (i.e., the pump head is large), the magnitude of radial velocity becomes larger and the circumferential velocity smaller than the case of large flow rate. It is, therefore, considered that the number of turns of spiral flow between the flow passage and the impeller increase, and so the pump head also increase when the flow rate is small.
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Keisuke MORITA, Shigeru MURATA
Article type: Article
Session ID: 1726
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This paper presents a three-dimensional PTV technique for the flow around a rotating object. The present technique is based on a defocusing method of integral photography for three-dimensional measurement and a derotating observation with an image-rotation prism for measuring the flow relative to a rotating object. In the former method, particle images are captured using a multi-pinhole aperture set in front of a camera lens, and then the images are numerically reconstructed with a virtual pinhole aperture. Experimental results show that the particle images on a rotating disk are successfully derotated using the present technique and the correlation between true particle depth and the image location detected in integral photography can be calibrated with small deviation.
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