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Hiroshi TANIGUCHI
1989 Volume 55 Issue 509 Pages
1-7
Published: January 25, 1989
Released on J-STAGE: March 28, 2008
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Hideo KIMOTO, Kazuyuki HANAHARA
1989 Volume 55 Issue 509 Pages
8-12
Published: January 25, 1989
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In the present experiment, a handy apparatus is made to observe the transient cavitation bubble motion. The bubble motion is optically observed by a CCD linear image sensor, which is driven by high sampling frequency of 4 MHz. The output data of the CCD sensor are directly sampled by an A/D converter and buffer memory system and transfered to a microcomputer. The sampling speed of the apparatus for one-dimensional data is about 37 microseconds, which corresponds to a high-speed photograph of about 27000 frames/s. The apparatus is applied to observe the motion of a spark-induced cavitation bubble near solid boundary and it is confirmed that the apparatus is very useful to observe the transient cavitation bubble motion. Moreover, some new facts about the transient cavitation bubble motion near solid boundary are confirmed by the present experiment.
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Shigetoshi KAWAGOE, Shigeru MATSUO, Toshiaki SETOGUCHI, Mitsuhiro FUKU ...
1989 Volume 55 Issue 509 Pages
13-18
Published: January 25, 1989
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When condensation occurs in a blade passage in a steam turbine, a condensation shock wave appears and interacts with a boundary layer on a blade surface or an oblique shock wave which originates from the trailing of the blade. In the present study, a condensing flow with a condensation shock wave was produces by a expansion of moist air in a supersonic circular nozzle, and by inserting a wedge-type shock generator in the supersonic part of the nozzle, the interactions of the condensation shock wave with the oblique shock wave were investigated experimentally. The interaction patterns are discussed ant are explained qualitatively. The change of shape of the oblique shock wave by the interaction is clarified quantitatively.
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Toshiyuki AOKI, WANG Yiping, Mitsuharu MASUDA, Nobuaki KONDOH, Kazuyas ...
1989 Volume 55 Issue 509 Pages
19-24
Published: January 25, 1989
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The purpose of the present paper is to report the results of numerical and experimental studies of supersonic flows in a diagonal type MHD generator. Numerical analysis has been carried out using one-dimensional conservation equations coupled with Maxwell's equation and the generalized Ohm's low. It is shown that when the loading factor increases, m the Mach number in the channel decreases in the case of an absolute value of a diagonal coefficient smaller than a Hall coefficient, and the Mach number increases in the opposite situation cap. The limiting length of the channel for choking decreases with an increase in he interaction parameter and friction coefficient. The experimental results show the validity of the numerical analysis.
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Keizo WATANABE, Yoshiharu ITAGAKI, Hiroshi KATO
1989 Volume 55 Issue 509 Pages
25-29
Published: January 25, 1989
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Experiments for the solid concentration profiles in the cross-sectional flow area and the pressure gradient for gas-solid mixture flow in a spiral tube with three shaped groove tube walls have been carried out using a horizontal pipeline with a 3600-mm test section. Three kinds of particles in the range of 2.52 to 3.50-mm mean diameter were used in the test for pressure gradient. Photographic data for the solid concentration profiles in the spiral tube reflected the symmetric suspension flow patterns in the low air velocity range. It was also cleared so that minimal air velocity was required to keep particles from depositing on the bottom of the pipe decreased compared to the of a circular pipe within a certain range of gas-solid mixture transport in the spiral tube. The empirical formula for the friction factor for gas-solid mixture flow obtained by considering the effect of the spiral pitch was correlated with experimental data.
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Michio SADATOMI, Yoshifusa SATO, Hisaharu TASHlRO
1989 Volume 55 Issue 509 Pages
30-35
Published: January 25, 1989
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Experimental data relating to pressure drop over sharp-edged orifices in two-phase flow conditions are presented. The data were obtained from corner tap orifices of 22.5, 20, 17.5 and 15 mm diameters inserted ina 2 mm bore horizontal tube. The working fluids were air and water at pressures and temperatures close to atmospheric conditions. The volumetric fluxes of air and water ranged over 0<j
G<30m/s and 0.2<j
L<2.0m/s, respectively. A simple model is proposed which is able to predict the pressure drop. The model was tested against the above experimental data, and against Murdock's and James's data on steam-water flows. The result shows that the proposed model correlates the available data to well within ±30%.
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Akihiko ITO, Sirajul Karim CHOUDHURY, Tohru FUKANO
1989 Volume 55 Issue 509 Pages
36-40
Published: January 25, 1989
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The flow characteristic of pure water partly heated on the surface was experimentally investigated by using a holographic interferometer. An extremely low velocity of water surface flow compared with that of any other liquid had been previously observed. In this experiment the water surface was cleaned by sucking out the surface layer before heating. The measured surface velocity is about one order of magnitude higher than that of water without cleaning the surface and is consistent with the velocity expected by Marangoni convection which was calculated by temperature distribution of the water surface. The flow characteristic of pure water is not dependent on the absolute value of surface tension force, as was previously thought, but on the surface condition. If the surface is spoiled by a contaminant such an oil, dust or any other inhibiting elements, Rayleigh convection dominates the flow pattern. The effects of liquid film thickness on flow pattern and on temperature distribution in liquid phase was also discussed in relation to film breakdown.
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Seiichi TANIGUCHI, Masanori MATSUMURA, Tatsuya YAMAUCHI, Seiji DOHDA
1989 Volume 55 Issue 509 Pages
41-48
Published: January 25, 1989
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The wake structure of a spinning cylinder situated in a uniform flow was experimentally investigated by means of the phase averaging technique. The measurements of velocity vectors were carried out at a section 7.5 diameters downstream from the axis of the spinning cylinder. The Strouhal number St of the vortex shedding from the cylinder gradually increases to the spin parameter s≈0.8. Here, the spin parameter s denotes the ratio of the circumferential velocity to that of the uniform flow. Beyond s≈0.8, St rapidly increases with respect to the increasing value of s. Corresponding to the trend of St, the coherent structures of the wake are in almost identical in the range of s=00.8, however, they become obscure ant are embedded in random fluctuating velocities as s increases. Furthermore, no coherent structures are found behind the spinning cylinder when s is over 1.7.
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Seiichi TANIGUCHI, Masanori MATSUMURA, Tatsuya YAMAUCHI, Seiji DOHDA
1989 Volume 55 Issue 509 Pages
49-55
Published: January 25, 1989
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This paper describes the structure of the energy. Reynolds stress and intermittency in the wake of the spinning cylinder. The energy of the fluctuating velocity was decomposed into the regular flactuating component associated with the fundamental vortical structure and random fluctuating one contributed to he random fluctuating velocity. The level of each energy rapidly decreases when the spin parameter s exceeds 0.8 and becomes negligibly small over s≈1.7; the s values are well correlated with the trend of the cortical structure described in the former paper. The difference between the energy levels of the shedding vortices from both sides of the spinning cylinder suggests that the amount of the turbulent production at the saddle points depends on the strength of the rib between two consecutive vortex rolls.
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Tohru FUKANO, Hidechito HAYASHI, Sadayuki KATAOKA, Yoshinori HARA, Min ...
1989 Volume 55 Issue 509 Pages
56-61
Published: January 25, 1989
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The characteristics of the wake of a rotating flat plate with a large attack angle were investigated experimentally with special attention of the flow near the tip of the plate. When the tip clearance is small, the dead air region becomes large towards the tip of the plate and the shear layer of the suction side of the plate curves outward as a result of the accumulation of low-energy fluid. On the other hand, when the tip clearance is large, the leakage flow is so large that the leakage vortex is generated from the trailing edge of the suction side and the shear layer forms by contacting the leakage flow and the dead air region. The variations of the flow rate and the momentum of the wake flow are closely related to those of the leakage flow.
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Seiichi TANIGUCHI, Masanori MATSUMURA, Yoshihiro MORIHlRA, Katsumi MIY ...
1989 Volume 55 Issue 509 Pages
62-66
Published: January 25, 1989
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The wake structures of a circular cylinder having a finite length were experimentally investigated using a hot-wire anemometer and analyzing the data by means of the phase-averaging technique. The cylinder was installed at the centre of the test section of the wind tunnel such as its axis was in the direction of the main flow. It was found that the shedding vortexes consisted of hair-pin type vortex tubes and had the double-sided structures. Furthermore, the presence of such structures was confirmed by the flow visualization using the dye-injection method.
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Hajime YAMAGUCHI
1989 Volume 55 Issue 509 Pages
67-72
Published: January 25, 1989
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Turbulent boundary layer characteristics are studied experimentally under two different conditions: with a rapid pressure decrease at the start of the convex surface curvature (CASE I), and without a pressure decrease (CASE II). It is clear that there are distinct differences in the turbulent boundary layer characteristics between the two conditions. The causes of the marked differences are discussed in detail, evaluating the turbulent stress production terms in turbulent stress transport equations. The effect of the pressure decrease in CASE I makes [∂u/∂y] increase rapidly in the region close to the convex surface, which increases the stress production terms. Furthermore, u'
2^^
- increases. The effect of the convex curvature in CASE II reduces the Reynolds stress in the layer under the influence of the [ku] term in the equation. Then the negative region of the stress appears. There are distinct differences between the two conditions with respect to mean velocity characteristics affected by the turbulent characteristics.
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WATANABETakashi, Yasuhiro BAN, Masafumi MlYATA, lkuo NAKAMURA
1989 Volume 55 Issue 509 Pages
73-79
Published: January 25, 1989
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A high-Reynolds-number k-ε model is used to predict the relaxation process which develops in the channel whose upstream half wall is made rough. Experimental evidence shows that after the step change in wall roughness, the mixing length increases considerable over the value expected in the ordinary boundary layer. It is also shown that the convection term in the turbulence kinetic energy equation is not negligible and the existence of the wall equilibrium layer is not expected. Therefore, two new refinements are applied to the boundary condition adjacent to the wall. One is that the Karman constant in the logarithmic law of the wall is assumed to vary with streamwise distance. The other is that all the terms in the turbulence energy equation are considered. It is found that the prediction of the variation in the mean velocity is improved and the abrupt decrease in the turbulence kinetic energy, which is found in the usual model, disapears.
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Koichi HISHIDA, Kazuhiro KOBASHI, Naritoshi SANAI, Masanobu MAEDA
1989 Volume 55 Issue 509 Pages
80-85
Published: January 25, 1989
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The present processing system was designed to measure size and velocity of particles in dense two-phase flows. A fast Fourier transform method was adopted to detect not only Doppler frequencies but also phase shifts of Doppler signals, where a particle size was proportional to the phase difference of Doppler signals observed by photodetectors at different positions. A fast digital signal processor was employed for the high speed calculation of FFT processing. The transmitting and receiving optical systems of the present LDV was constructed by fiber optics the stabilize and compact it. The present system provided a high accuracy in measurements of particle velocity and size for noisy signals.
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Tetsuo FUJIMOTO, Tomohide NI-IMI, Hiroyuki KUMAZAKI
1989 Volume 55 Issue 509 Pages
86-94
Published: January 25, 1989
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CAFV (Computer Sided Flow Visualization) system for gas dynamics has been developed and is applied to analyze three-dimensional structures of the flow field visualized using laser-induced fluorescence of I
2 seeded in Ar. The flow field is visualized by many laser sheets and photographed two-dimensionally by a highly sensitive vidicon camera. These image data are stored up in a personal computer in order to record three-dimensional information on the entire flow field. For the purpose of suppressing the noise, an image datum is made from the averaging of many frame data. From the image data, the pictures at arbitrary cross sections (CT; Computer Tomography) are reproduced on the monitor by the personal computer. The propriety and effectiveness of this system are verified through the results applied to two flow fields, i. e., the free jet expanding into the vacuum chamber and an interacting flow field between the skimmer and the free jet.
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Manabu SATOH, Katsuhiro ITOH, Osamu ONODERA, Kazuyoshi TAKAYAMA, Makot ...
1989 Volume 55 Issue 509 Pages
95-100
Published: January 25, 1989
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A new concept of a super charger for diesel engines is proposed and its performance is examined by TVD numerical simulation. The structure of the super charger has a simple duct-valve system which allows the feeding of compressed inlet air to the engine cylinder by an exhaust-gas driven chock wave. The two-dimensional unsteady flow of this duct-valve system was simulated by TVD numerical scheme applied to the Euler equations. It was found that the present supercharger has a performance which is preferable to low engine speed. The complicated wave interactions are simulated in detail.
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Shohei YAGISHITA, Yoshinori WAKAMIYA, Goro YAMANAKA
1989 Volume 55 Issue 509 Pages
101-106
Published: January 25, 1989
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In passenger transportation, especially in subways, air-conditioning in stations and passenger cars is indispensable to keep passengers comfortable. In low altitude cities, closed environmental control systems are designed and applied for their low energy consumption. Car air-conditioners release almost the same amount of heat into the tunnels and stations as a total of other car equipment. This additional heat ejection could cause problems for the normal operation of the station and car equipment, and the environment of the subway tunnels. However, they are not studied quantitatively, because actual measurements and model tests are difficult to be carried out. Here, we report the results of studies on the calculation of unsteady flow distribution and temperature distribution in tunnels. The calculation program is applied to actual system check, such as the temperature variation of passenger cars, the operating conditions of car air conditioners, the design of the station air conditioners, and so on, and proved to be effective.
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Toshio KOBAYASHI, Tetsuo SAGA, Shigeki SEGAWA, Hiroshi KANDA
1989 Volume 55 Issue 509 Pages
107-115
Published: January 25, 1989
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A real-time velocity measurement system based on the digital image processing technique has been developed for analyzing two-dimensional flow fields. The system consists of a TV camera with electrical shutter, a digital image processor interfaced with a microcomputer and two high-speed image analysis algorithms. Flow fields are visualized by a large number of tracer particles. Using this system, the velocity vectors are extracted fully automatically from the particle images in consecutive TV frames. This system has been applied successfully to a quantitative analysis of the flows around rotating discs and around a circular cylinder.
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Yasuo MORl, Hideaki OKAHISA
1989 Volume 55 Issue 509 Pages
116-119
Published: January 25, 1989
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A velocimeter consisting of a thin rectangular plate performing revolving vibration caused by Karman vortexes is studied to measure the flow velocity from the vibration frequency of the plate. The revolving plate provided with a splitter-plate behind it with a several mm gap between the vibrating plate and with a stopper which limits the amplitude of the revolving vibration of the plate is found to conduct a satisfactorily sinusoidal vibration with the same frequency as the shedding Karman vortexes. The frequency of the plate vibration is measured by use of LED and a optical sensor of photo-diode. The obtained results are that, first, the frequency of the plate vibration is linearly proportional to the flow velocity and, secondly, this velocimeter measures accurately the gas velocity down to 1 m/s and is also suitable to hot gas velocity measurement.
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Hiroki TANAKA, Zenshi IMAYAMA, Kenichi KOGA, Keiichi KATAYAMA
1989 Volume 55 Issue 509 Pages
120-125
Published: January 25, 1989
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Tube arrays in cross flows sometimes excite the acoustic vibrations of sound fields in ducts. It is very important, for practical applications, to understand the conditions of acoustic resonance in ducts with tube bundles. Exciting forces due to tube arrays of pitch-to-diameter ratio of 1.57 were measured in a water tunnel and characteristics of acoustic resonance in ducts with tube arrays were revealed. The results of experiments correspond to the field test data very well.
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Myeongkwan PARK, Shuzo OSHIMA, Ryurchiro YAMANE
1989 Volume 55 Issue 509 Pages
126-134
Published: January 25, 1989
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Oscillation modes of a circular shock wave in supersonic radial flow were studied both experimentally and theoretically. The pressure fluctuation was measured on concentric positions to investigate modes of a circular shock wave in case of mean radii of 70 and 77 mm, and the A-D converted signals were statistically correlated. A simple model of an oscillating shock wave was proposed. Frequency of the oscillation increased from low to high values with the increase in its radius. The oscillation was mainly consisted of mode 0 superposed by modes of 1, 2 and 4. The mode 1 is considered to be weak. The experimental frequency of each mode agreed well with the theoretical results.
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Takao KOBAYASHI, Hiroyuki TAKATA
1989 Volume 55 Issue 509 Pages
135-140
Published: January 25, 1989
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Unsteady flow calculations for two-dimensional cascades in incompressible flow are performed as a first step toward solving the three-dimensional oscillating cascade problem. A potential flow is assumed and unsteady formulation is based on the small perturbation approach. The governing equations are discretized by FEM. C-type grids are used which are generated numerically. The calculations are performed for isolated blades and cascaded blades as well. The behavior of steady pressure distribution around the leading edge, the treatment of second derivatives of steady velocity potential on blade surface and those effects on unsteady pressure distribution are examined. A parametric study is conducted to find the effects of reduced frequency, interblade phase angle, blade camber angle and blade thickness on unsteady aerodynamic characteristics of translationally oscillating cascades.
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Masanori KIKUCHI, Kimitaka HlRANO, Yasunori OKAMOTO
1989 Volume 55 Issue 509 Pages
141-145
Published: January 25, 1989
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A three-dimensional theory is developed for a supersonic finite pitch cascade between a rigid wall and a sound absorbing liner to estimate the effect of a sound absorbing liner on supersonic cascade flutter. A side wall is the infinite extent of the liner with uniform acoustic admittance. The aerodynamic work of blades for uniform amplitude bending and torsional oscillation shows that there exists a sound absorbing liner which reduces the negative damping forces for torsional oscillation and that effective acoustic admittance magnitude is on the order of a O(0.01)0(10 range.
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Kouji MORITA, Yasutomi MIKl, Youichirou NAKAMURA, Tetsuya KONDOH, Kenj ...
1989 Volume 55 Issue 509 Pages
146-151
Published: January 25, 1989
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The temperature distribution and flow pattern of natural convection in a horizontal cylindrical annulus were made visible using the liquid crystal particle suspension method. Results were obtained using three kinds of silicone oil having different high Prandtl numbers. The Rayleigh number based on the gap width varied from 6.1×10
4 to 3.8×10
5. Resulting flows were observed to be steady in all cases. Numerical investigation was also performed with a transient two-dimensional finite difference scheme which have been reported in the previous paper. Comparison between the experimental and numerical results shows good agreement.
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Norio AKINO, Tomoaki KUNUGI, Yasuaki SHIINA, Masahiro SEKI, Yoshizou O ...
1989 Volume 55 Issue 509 Pages
152-158
Published: January 25, 1989
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The temperature and flow distributions in a horizontal silicone oil layer in a circular cylinder heated from below and cooled from above are visualized by means of liquid crystal particle suspension method. In a Rayleigh number range from 10
6 to 10
8, thermal plumes travel between both upper and lower plates through fluid layer and transport thermal energy directly between the plates. Consequently, cold fluid spots emerge in the vicinity of the hot plate. For the cooled plate, just vice versa. This explains the temperature gradient reversal in the previous studies and others.
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Kiyoshi BANDO, Yutaka MlYAKE, Masayoshi ISHIKAWA
1989 Volume 55 Issue 509 Pages
159-164
Published: January 25, 1989
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A panel method for solving three-dimensional, inviscid, compressible, subsonic flow in a axial-flow rotor is presented. The surface integral equations are often used to solve the Laplace equation with panel methods. The extension to compressible flow is to introduce the volume integral term of Green's third identity. The present method does not require the surface fitted grid. Instead it uses a rectangular grid with embedded surface panels on which boundary conditions are imposed. The Poisson problem is solved using the fast Fourier transform and the panel influence coefficient technique. The volume integral calculation is performed efficiently by using the FFT. The first numerical example is a flow about the NACA 0012 aerofoil. The results show the accuracy of the present method with a somewhat coarse grid. The second numerical example is a flow through an axial-flow rotor. The results show three-dimensional characteristics and compressible effects.
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Masahiro ISHIDA, Hironobu UEKI, Hirotaka EGAMI, Yasutoshi SENOO
1989 Volume 55 Issue 509 Pages
165-170
Published: January 25, 1989
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The velocity distribution is measured at the exit of two different types of unshrouded centrifugal impellers under four different tip clearance conditions each, one with twenty radial blades and inducers and the other with sixteen backward-leaning blades. The secondary flow induced by the tip leakage is similar in both impellers, and the underturning near the blade tip due to the stationary shroud is reduced significantly with the increase of tip clearance. The local change of angular momentum due to the tip clearance is related to the flow rate ratio of leakage-flow and through-flow, and an almost proportional relationship between them is found. Despite a similar secondary flow in both impellers, the input power is hardly changed in the radial blades impeller and is decreased in the backward-leaning blades impeller by the increase of tip clearance.
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Kenji KANEKO, Toshiaki SETOGUCHI, Hiromitsu HAMAKAWA, Masahiro INOUE
1989 Volume 55 Issue 509 Pages
171-175
Published: January 25, 1989
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In the development of an air-turbine with self-pitch-controlled blades for a wave power generator, existence of hysteretic characteristics in a reciprocating flow has been examined, which results in the inaccurate prediction of performance in a quasi-steady analysis. In order to clarify the usefulness of the quasi-steady analysis, a numerical simulation has been made by use of the experimental results obtained from a steady unidirectional flow-condition. The comparison between the analysis and experiment has shown that the quasi-steady analysis is available for this turbine. Furthermore, the running and starting characteristics have been investigated analytically taking into account the blade turning process.
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Shunichi AlYOSIZAWA, Asahiro WAKIGAWA, Daisuke KONNO, Kiyokazu TAKAGI
1989 Volume 55 Issue 509 Pages
176-181
Published: January 25, 1989
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Friction coefficients of various sleeve-type submersible bearings for vertical pumps in air and water were investigated. The tested materials were SiC-sintered ceramics, WC-cemented carbides, self-fluxing alloys, and conventional bearing materials such as rubber, resin, PTFE # and soft sintered alloy. Test equipment simulated the frictional condition of the actual vertical pump shaft, that is, the shaft of the test equipment precessed to the bearing. It was clear that, in water, when silicon carbide was used as a stationary bearing, lower friction coefficients than conventional bearings could be obtained, regardless of rotating sleeve materials. In slurry, the abrasive grains had a bad influence on the friction coefficient of the conventional bearings. But, bearings of ceramics could keep low friction coefficients owing to their hardness. In air, a combination of silicon carbide and tungsten carbide showed low friction coefficient. And it is confirmed that dry start of vertical pumps can be attained with this material combination.
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Hideki NARIAI, Ataru ICHINOSE, Isao KOMORlYA
1989 Volume 55 Issue 509 Pages
182-187
Published: January 25, 1989
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The flow characteristics of single phase natural circulation in parallel channel were investigated. Non-dimensional correlations were derived based on the assumption that the total pressure drop in each channel of parallel flow is completely the same as those of other channels, and diagrams for flow characteristics were proposed both for density governed conditions and for heat-flux governed conditions. The change of a very small flow rate can be explained in the diagram. An d the validity of the diagram was confirmed through an experiment with three-channels apparatus. The existence of hysteresis in the flow characteristics for heat-flux governed condition was made clear. The hysteresis showed by Chato could be explained by using the diagram.
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Tadatomo KOJIMA, Yoshihiro MATSUOKA
1989 Volume 55 Issue 509 Pages
188-193
Published: January 25, 1989
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In this paper, the structure and behavior of the impingement jet issuing from two pipes for various impingement angles and distances were studied mainly by the flow visualization. Impingement angles between two jet axes were varied in 45°, 60° and 90°, and the impingement distance between the pipe exit and impingement point that was intersection of the centerlines of two pipes was varied in 2 ways. The flow visualization of mean and instantaneous flows with time, both in a vertical plane, contained centerlines of two pipes and a horizontal plane contained in the impingement point were conducted by the schlieren and shadowgraph methods, moreover mean total pressures were measured. As a result, the interference characteristics of the impingement jet were clarified for mean Mach numbers, ranging from 1 to 2.5, at the pipe exit. In particular, it was found that the flow could be classified into 2 patterns by the size of impingement angles.
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Yoshihiro IIDA, Kentarou TSUTSUI
1989 Volume 55 Issue 509 Pages
194-199
Published: January 25, 1989
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The effect of ultrasonic wave application on film boiling heat transfer is investigated. A series of heat-transfer experiments are carried out using a fine heater made of a 0.20-mm-dia. horizontal platinum wire, which is immersed in saturated ethyl alcohol and exposed to a 28 kHz ultrasonic wave. The heat-transfer coefficient increases with the increase of power supplied to a ferrite-type vibrator and it is doubled for the maximum in this experimental condition. The minimum heat-flux point is also improved. At a lower degree of superheat than the MHF line, nucleate boiling and film boiling coexist separately along the platinum wire with a high reproducibility. The film boiling configuration is also observed through photograpty. Under a high intensity of ultrasonic wave, many tiny bubbled begin to generate and the shapes of large bubble becomes rather irregular.
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Hideo INABA, Motohiro NAGAYA, Takeyuki FUKUDA, Masahiro SUGAWARA
1989 Volume 55 Issue 509 Pages
200-205
Published: January 25, 1989
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Melting characteristics of a solid phase change material in a inclined rectangular heat storage enclosure heated from one side is investigated experimentally. According to the inclination angle of the enclosure, the natural convection pattern in s liquid phase shifts from three-dimensional flow to two-dimensional one. The interface morphology is found to be dependent on the angle of inclination and heating wall temperature. The time-wise variation of the melt fraction is obtained for various inclination angled. Correlation equations of natural convection in a liquid phase are presented in terms of Rayleigh number, inclination angle and Stefan number.
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Hiroshi NAKAJIMA, Ichiro TANASAWA
1989 Volume 55 Issue 509 Pages
206-209
Published: January 25, 1989
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Direct contact condensation of Freon R 113 vapor at atmospheric pressure on the surface of falling drops of chilled water was investigated experimentally. Water and R 113 were immiscible and insoluble, the condensed phase forming a separate layer on the water droplets. The dependence of the rate of condensation on the initial subcooling (11-38 K) was measured with high accuracy at different falling distances. The results were compared with those obtained form condensation on solid particles, which made clear the importance of the effects of deformation of condensate film and the circulatory flow inside the drops.
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Tetsu FUJII, Shigeru KOYAMA, Youichi SIMIZU, Masaharu WATABE, Yoshiro ...
1989 Volume 55 Issue 509 Pages
210-215
Published: January 25, 1989
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The experimental results for gravity-controlled condensation of ethanol and water vapor mixtures on a horizontal tube are presented. Dropwise, drop and streak, and ring wise condensations are observed for the ranges of ethanol vapor mass fraction W
<1∞>=0.20.5, 0.50.7 and 0.750.8, respectively, while smooth-film condensation takes place for the ranges of W
1∞=00.2 and W
1∞=0.81. Previous theoritical results for the heat transfer coefficent by the present authors based on the two-phase boundary layer theory are valid for the case of smooth-film condensation, while 20 to 60% higher heat transfer coefficient values are obtained for the other cases.
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Itsuki MORIOKA, Masanori KIYOTA
1989 Volume 55 Issue 509 Pages
216-220
Published: January 25, 1989
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The improvement of absorbers is necessary for the LiBr-water absorption chiller; but the fundamental values, such as the mass transfer coefficients and the heat transfer coefficients in the absorber having horizontal tube banks as cooling tubes, are not well known. The aim of this paper is to propose and analytical model of a single-tube case and to compare it with the experiments. The absorbent flow is assumed to have the same velocity profile over the inclined flat plate. The boundary conditions at the film surface are extended from the vertical flat plate case. The conducted experimental range of parameters are Γ=0.005-0.07 kg/(m·s), T
f=26-38°C and p=5-6 Torr. The obtained absorption rates are compared with the theoretical predictions. Mass transfer coefficients and heat transfer coefficients are found to lie in the range of (0.5-1.5)×10
-4m/s and 2.0-2.5kW/(m
2·K), respectively.
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Kazuhiko SUGA, Hiroshi AOKI, Tsutomu SHINAGAWA
1989 Volume 55 Issue 509 Pages
221-226
Published: January 25, 1989
Released on J-STAGE: March 28, 2008
JOURNAL
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Using an overlaid grids method, finite difference analysis have been made on two-dimensional flow and heat transfer characteristics of louvered fins which comprise automotive heat exchangers used in the forced convection regime at low Reynolds number. In this method the physical domain is subdivided into some regions which can adapt easily to Cartesian grids. The maximum total number of the grid points allocated non-uniformly in the respective regions is about 100000. Communication between the grids is accomplished by linear interpolation of the dependent variables at grid boundaries. It took 3060 minutes of the CPU (supercomputer NEC SX-2) for the iterative computation. In the rage of Re=64450, the present numerical scheme was validated through the comparisons between the numerical results and the corresponding experimental data which were also obtained in the present study.
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Toshiharu NOGI, Yoshishige OHYAMA, Teruo YAMAUCHI
1989 Volume 55 Issue 509 Pages
227-231
Published: January 25, 1989
Released on J-STAGE: March 28, 2008
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A study was conducted on hollow cone spray which was injected from a pintle-type and swirl-type injector. The effects of the surrounding pressure and liquid temperature on the spray patterns are discussed experimentally and analytically. The calculated results which are based on the hollow cone spray model including the effects of surface tension, centrifugal force and liquid density almost coincide with the experimental results.
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Takaaki MORIMUNE, Naomichi HlRAYAMA
1989 Volume 55 Issue 509 Pages
232-238
Published: January 25, 1989
Released on J-STAGE: March 28, 2008
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The catalytic reduction process of nitrogen oxide with ammonia was studied using a mixed gas of air, CO
2 and NO at the reaction temperature of 240°C. The catalyst used was V
2O
5-TiO
2 pellets, and the average diameter of the pellets was 5 mm. The volumetric concentrations of inlet gas were O
2 10%, CO
2 79%, NO 100140 ppm and the remainder N
2 gas. The effects of aspect ration of the catalyst packed bed, retention time, reaction temperature and linear velocity through the reactor on the NO
x removal efficiency were studied experimentally, and the change of reaction rate constant and the amount of leaked NH
3 were also investigated.
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Sanyo TAKAHASHI, Iwao YAMASHITA, Kouji KOREMATSU
1989 Volume 55 Issue 509 Pages
239-245
Published: January 25, 1989
Released on J-STAGE: March 28, 2008
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The influences of oxygen, water vapor, ammonia and hydrogen concentration on DeNOx process by ammonia addition were investigated by varying their initial concentration levels and the reaction temperature over wide ranges. The experiments were carried out with use of a flow reactor system and by measuring nitric oxide and ammonia concentration. The experimental results were compared to the computer simulations based on the reaction scheme proposed by Lyon et al. While the Lyon reaction scheme predicts qualitatively the influences on the reaction process due to the initial concentrations, large differences are found between them in lower temperature region, particularly in the case of oxygen and water vapor effect. The prediction for the influence of hydrogen and ammonia was improved by the modification of some reaction rate constants, however, barely improved for that of oxygen and water vapor.
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Yutaro WAKURl, Koji TAKASAKl, Kazunori HAMASAKI, YANG Yanxiang, Seiich ...
1989 Volume 55 Issue 509 Pages
246-252
Published: January 25, 1989
Released on J-STAGE: March 28, 2008
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The authors have examined in the past the influences of air swirl on the combustion performances of D. I. type diesel engines and shown various factors which affect the optimum swirl intensity. In the present studies, the authors have rebuilt the engine used in the above experiment to take high-speed photos from the lower part of the combustion chamber, and examined the correlations between fuel spray dispersion and combustion characteristics with the aid of photographic visualization. Comparing the visualized data with the results of operation tests, it has been verified that the utilization of air by the fuel spray can be evaluated geometrically by the extent to which fuel spray is dispersed by the swirl during the fuel injection in the case of shallow bowl type combustion chamber. The effects of the combustion chamber shape and injection pressure on the formation and oxidization of the soot have been also clarified.
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Shigeru TOSAKA, Yasuhiro FUJIWARA
1989 Volume 55 Issue 509 Pages
253-256
Published: January 25, 1989
Released on J-STAGE: March 28, 2008
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Exhaust particulates in diesel engine are affected by fuel properties, but the reason for this is not clear. Formation of particulates has been reported to stat with thermal cracking of the fuel to lower boiling point hydrocarbons, and the formation of particulates takes place via polycyclic aromatic hydrocarbons. This is and investigation of the thermal cracking process and condensation polymerization process of fuel, also analyzing dehydrogenation with the thermal cracking apparatus. A comparison of n-paraffin fuels and aromatic fuels shows differences between thermal cracking and condensation polymerization.
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Hiroshi NAKAGAMA, Mataji TATEISHI, Masayoshi NAKASHIMA, Satoshi KATO, ...
1989 Volume 55 Issue 509 Pages
257-260
Published: January 25, 1989
Released on J-STAGE: March 28, 2008
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The scavenging process of a 2 stroke cycle engine dominates not only fresh air charging but also the air flow in a cylinder at the compression end. So, the combustion performance of a 2 stroke cycle diesel engine depends on the scavenging efficiency η
s and the scavenging air swirl intensity in the cylinder. In this report the scavenging air flow is investigated by motoring of a 2 cycle engine rig. From the LDV measurement of air velocity in a cylinder at the compression stroke, it is shown that the scavenging port made by the combination of a large angle port and a small angle port has high scavenging ability and sufficient swirl intensity for air-fuel mixing.
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