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Volume 51, Issue 472
Displaying 51-67 of 67 articles from this issue
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Tomofumi YAMAMOTO, Kimitaka HIRANO, Masanori KIKUCHI1985 Volume 51 Issue 472 Pages 4218-4222
Published: December 25, 1985
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSThe fluctuating pressures on two circular cylinders arranged side-by-side to the approaching flow is experimentally investigated at a Reynolds number of 1.87×104. The transverse spacing G between the circular cylinders is 0.5D to 3.25D, where D is the cylinder diameter. Strouhal numbers and dominant components-magnitude and phase-of fluctuating pressures on the cylinders are measured, and the fluctuating drag and lift forces acting on the cylinder are calculated by integrating pressure distributions. The results indicate that the fluctuating forces are very sensitive to spacing, but Strouhal numbers are nearly constant. At the nondimensional spacing G/D=1.25, the amplitude of the fluctuating resultant force is 40 percent greater than that on a isolated cylinder.View full abstractDownload PDF (618K) -
Kouichi NAKABAYASHI, Osami KITOH1985 Volume 51 Issue 472 Pages 4223-4229
Published: December 25, 1985
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSFlow in a channel rotating about an axis perpendicular to its axis receives Coriolis force, which gives rise to secondary flow and flow-stability-instability on it. These phenomena affect the flow pattern in the cross section, the degree of which largely depends on the channel shape, rotation rate and Reynolds number. In the present paper, the effects of Coriolis force on friction factors and velocity distributions are studied as a function of these parameters experimentally and numerically and discussed in relation to the phenomena described above.View full abstractDownload PDF (773K) -
Kiyoshi UZAWA, Shigeru IKEO1985 Volume 51 Issue 472 Pages 4230-4238
Published: December 25, 1985
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSThis paper deals with the laminar oscillatory flow of an incompressible fluid through a slightly convergent tube. The velocity distributions in the convergent tubes, whose convergent angles are in the range of 24°, are measured by a Laser Doppler Velocimeter. The flow in the convergent tube is numerically analysed by a finite difference method (SOR), without neglecting the convective terms in the Navier-Stokes equation. Experimental results agreed well with the numerical ones. The velocity profile of a laminar oscillatory flow in the convergent tube is quite different from the velocity profile in a straight tube of circular cross-section, even if the convergent angle is very small. The instantaneous pressure distribution in the convergent tube is uniform at each cross section as in a straight circular tube.View full abstractDownload PDF (928K) -
Masahiko KOYA, Susumu KOTAKE1985 Volume 51 Issue 472 Pages 4239-4247
Published: December 25, 1985
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSFully three-dimensional transonic periodic flows through turbine stages are studied numerically by solving time-dependent, three-dimensional Euler equations with the finite volume method. The phase relation of stator and rotor flows and the related blade row interaction are accounted for in the time-space domain. The established method of numerical calculation makes a practical contribution in predicting turbine flows through turbine stages, both stator and rotor, which have an arbitrary number of blades.View full abstractDownload PDF (803K) -
Makoto SUZUKI, Masaaki KAWAHASHI, Atutomo YOSHIZAWA1985 Volume 51 Issue 472 Pages 4248-4256
Published: December 25, 1985
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSThe total temperature separation of gas is produced by a swirling flow-field in a circular tube. This device is called the vortex-tube or the Ranque-Hilsch tube. When whistling is produced within the swirling flow in the vortex-tube, the tangential velocity distribution in the radial direction is deformed toward the forced vortex type in the whole region. This is caused by the acoustic streaming induced by the whistling. The whistling in the vortex-tube of a counter-flow type is produced by the area contraction having a rectifier effect on the hot-gas flow near the tube wall. As a result, the efficiency of temperature separation by the vortex-tube improves. However, the complex flow configuration induced by the contraction also affects the temperature separation.View full abstractDownload PDF (808K) -
Toshihiko SHAKOUCHI1985 Volume 51 Issue 472 Pages 4257-4264
Published: December 25, 1985
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSRegular oscillation of a three-dimensional, rectangular jet occurs depending on the condition such as the shapes of a nozzle or flow passage and the jet velocity, when the jet squirts in the suddenly enlarged two-dimensional flow passage from the rectangular nozzle with smaller height (height; a) than the flow passage (height; H). In order to obtain some basic knowledge on the flow characteristics of this oscillatory phenomenon, reattachment of a three-dimensional, rectangular jet flow from the nozzle (a/H<1) to an adjacent side wall is examined. Approximate theory using momentum principle is developed for the reattachment distance, the mean pressure within a separation bubble and etc. The agreement with experiment is fairly well. And also, these results are compared with the two-dimensional reattaching jet's ones.View full abstractDownload PDF (777K) -
Hirohiko OGINO, Yasuki NAKAYAMA1985 Volume 51 Issue 472 Pages 4265-4272
Published: December 25, 1985
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSThe numerical calculation and the experiment of a wall attachment device have been performed in a turbulent flow field. In this calculation method, the flow field was divided according to the local Reynolds number into turbulent, transition and laminar flow regions, and a calculation method suitable for each region was applied. Then, the k-ε turbulent flow model was used for turbulent calculation. The experiments comprised velocity measurement using a 3-port Pitot tube and flow visualization by the tuft method. The calculation and experiment were carried out under the condition that the ratio of the control flow rate to the supply flow rate was 0 and 20%. These calculated results agreed well with the experimental results. The effects of the control flow exerted on the flow pattern, and the characteristics of the turbulent flow field in a wall attachment device were clarified.View full abstractDownload PDF (767K) -
Yukimaru SHIMIZU, Shunsuke NAKAMURA, Hideo OHIRA1985 Volume 51 Issue 472 Pages 4273-4279
Published: December 25, 1985
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSThe report represents the relations among the plane shape of horizontal shaft wind turbine blade, the characteristics of wind turbine and the velocity distributions around the wind turbine. The power coefficient, torque coefficient and rotation of the wind turbine rotor are measured in the wind tunnel test. Also, the velocity distributions around the turbine are measured by means of three hot wires. The flow visualization of boundary layer on the rotating blade is carried out by the surface tuft method. Three kinds of blades used in the experiment correspond to taper, equi-chord and reversed-taper blades. All the blades are twisted under almost optimum condition. From the above results, many interesting facts are solved.View full abstractDownload PDF (830K) -
Masahiro INOUE, K-Chi WU1985 Volume 51 Issue 472 Pages 4280-4285
Published: December 25, 1985
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSAn expedient method is presented for the determination of a blade element of a diagonal flow impeller of a high specific speed. Firstly, a flow on an averaged stream surface is transformed into a plane where the blade element is selected from the cascade data. Two kinds of velocity diagrams can be defined on the transformed plane: the directly transformed diagram and the virtual diagram. A linear combination of these diagrams enables use of the cascade data for any design specification. Then, the blade geometry is corrected taking account of the change in circulation due to inclination and thickness of the stream surface. The validity of the method has been examined by perfomance tests using nine diagonal fans.View full abstractDownload PDF (673K) -
Koji KIKUYAMA, Mitsukiyo MURAKAMI, Eiji ASAKURA, Yutaka HASEGAWA1985 Volume 51 Issue 472 Pages 4286-4294
Published: December 25, 1985
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSFlow patterns near the inlet portion of an impeller and cavitation inception were examined experimentally using centrifugal pumps with 3, 7 and 9-bladed impellers, respectively. In low flow rates velocities at the inlet of the seven and nine-bladed impellers have uneven distributions between the hub and shroud. This causes a large drop in pressure on the suction surface of the blades near the shroud. In the three-bladed impeller passage, a large vortex was created near the suction side of the inlet, and this prevents a severe drop in the pressure, as seen in the seven-bladed impeller. Three kinds of cavitation according to the pressure distribution on the blade surface were observed in the impeller passages.View full abstractDownload PDF (956K) -
Hiroaki OHTA, Katsumi AOKI, Yasuki NAKAYAMA1985 Volume 51 Issue 472 Pages 4295-4300
Published: December 25, 1985
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSWhen centrifugal pumps are used for pumping high viscosity liquids, a problem exists where the pump performance decreases as the viscosity of pumped liquid gets higher. The cause of this, i.e., the change of influence on the efficiency of various losses (for example, disc friction loss, the loss owing to the channel from the inside impellers leak loss, and collision loss), accompanying the change of flow within the pumps, will be considered. In this study, the effect of the clearance ratio on the pump performance, when high viscosity liquid is pumped up, was investigated. It was clarified that the pumping performance was affected by the clearance ratio and Reynolds number.View full abstractDownload PDF (574K) -
Tadashi YANAGISAWA, Takashi SHIMIZU, Mitsuhiro FUKUTA1985 Volume 51 Issue 472 Pages 4301-4305
Published: December 25, 1985
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSThis paper is concerned with a sliding vane type rotary compressor for an automotive air conditioner. The load when the compressor starts depends on the presence of liquid refrigerant. The fundamental characteristics of the liquid compression at the starting were examined experimentally. The pressures in a cylinder and the torque of the shaft of a compressor were measured by changing the speed of the compressor and the amount of liquid refrigerant stored in the reservoir between the evaporator and the compressor. Liquid compression occurred frequently as both the compressor speed and the amount of liquid refrigerant increased. The period of liquid compression was almost in proportion to the amount of liquid refrigerant, not depending on the compressor speed. As the compressor speed increased, the value of the pressure peak increased noticeably, but the value of the torque peak didn't increase so much.View full abstractDownload PDF (641K) -
Naohiro IBOSHI, Atsushi YAMAGUCHI1985 Volume 51 Issue 472 Pages 4306-4312
Published: December 25, 1985
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSA theoretical analysis is carried out to study the effects of surface roughness on the characteristics of a slipper bearing in a mixed lubrication regime. The slipper tilting angle is assumed to be zero. Forces due to hydrodynamic pressure and asperity contact are based on the Patir and Cheng's average flow model and the Green wood and Williamson's theory of random rough surfaces in contact, respectively. The effects of the roughness on the behaviour of the slipper and the power loss are presented as parameters of the standard deviation of roughness, the balance ratio of forces acting on the slipper and the operating conditions. As a result, it is shown that the slipper bearing in the fluid film lubrication gives smaller power loss at high rotational speeds, and in the mixed lubrication at low ones.View full abstractDownload PDF (663K) -
Kyung-kun KIM, Jun INUMARU, Tatsuhiro UEDA1985 Volume 51 Issue 472 Pages 4313-4321
Published: December 25, 1985
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSWall temperature fluctuations at the CHF condition are measured for subcooled flow boiling. From the measured inner wall temperature history, the surface heat flux and the outer wall temperature are computed by a numerical method for one-dimensional inverse heat conduction problem. Heat transfer characteristics during overheating and quenching periods at the CHF condition and the wall superheats at rewetting point and minimum heat flux point are presented. The results show that the wall temperature rise at the CHF condition consists of the temperature fluctuations accompanied with passage of large coalescent bubbles and a subsequent sharp increase under film boiling condition.View full abstractDownload PDF (928K) -
Kohshi MITACHI, Hisanori TACHIBANA1985 Volume 51 Issue 472 Pages 4322-4326
Published: December 25, 1985
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSAn analytical study was performed to design an Accelerator Molten Salt Breeder (AMSB). The core of a vortex flow was adopted as a target of AMSB. In addition to heat deposition due to a proton beam, the influence of heat generation by the nuclear fission reaction was considered to evaluate the maximum temperature of a target region. The Rankine's vortex motion was assumed to calculate the velocity distribution in the target region. The rate of heat generation by the fission reaction was assumed to be constant and uniform within a proper cylindrical region. The temperature distributions were obtained by a finite difference method. The results indicated that heat generation by fission reaction played a dominant role on the temperature distribution and also on the maximum temperature of the target fluid, even in the case of the standard from AMSB, in which the target fluid contained few fissile components.View full abstractDownload PDF (511K) -
Yoshiaki ONUMA, Naohiro MURATA, Koji SHIBATA1985 Volume 51 Issue 472 Pages 4327-4333
Published: December 25, 1985
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSIn order to elucidate the basic ignition characteristics of mixed fuel sprays, ignition delay was measured on sprays injected perpendicularly to hot air flow under atmospheric pressure. The solution fuels of ethanol/Diesel-oil, ethanol/gasoline and methanol/gasoline, and the emulsion fuel of Diesel-oil/water, were used as fuel. The following results were obtained: (1) In all the fuels examined in this experiment, the temperature dependence of ignition delay was of the Arrhenius type with constant activation energy. (2) When Diesel-oil or gasoline is mixed with ethanol or methanol, and increase in the ignition delay is small with an alcohol content of less than 50% in weight. Ignition delay increases considerably with a content of 75%, but a 1015°C rise in air temperature shortens the lag by the same amount as the increase. (3) Ignition delay of Diesel-oil/water emulsion fuel sprays τ can be related to Diesel-oil content Cf as τCf-a, where a is a positive constant.View full abstractDownload PDF (768K) -
Akira NAKAYAMA, Hitoshi KOYAMA1985 Volume 51 Issue 472 Pages 4334-4336
Published: December 25, 1985
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSAn integral procedure based on the two-phase boundary layer theory is proposed for the analysis of forced convection film boiling on a wedge. The effects of pressure gradient, superheating, subcooling and liquid Prandtl number on the flow and heat transfer characteristics are investigated in detail. Asymptotic expressions are reduced under various limiting conditions. It was found that, when subcooling is low, the friction coefficient grouping Cfx R1/2ex initially decreases, and then increases as superheating becomes significant.View full abstractDownload PDF (360K)