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Ryoji KOBAYASHI
1986 Volume 52 Issue 483 Pages
3645-3649
Published: November 25, 1986
Released on J-STAGE: March 28, 2008
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Haruo YOSHIKI, Sadanobu TSUMURA, Toshihiko ENDOH, Nobuyuki TAKAMA
1986 Volume 52 Issue 483 Pages
3650-3654
Published: November 25, 1986
Released on J-STAGE: March 28, 2008
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This paper describes experimental velocity distributions in a circular pipe for some periodically oscillating air flows produced by tow pistons with arbitrary phase differences including 180°. The following facts are found for experimental conditions having a Reynolds number R
e=1.32×10
4-5.94×10
4 and a reduced frequency √(ω')=10.9-18.8. (1) The turbulence appears in velocity waves for all conditions independently of the piston phase difference. (2) The instantaneous velocity distributions become almost uniform in the centre region and look like those for the steady turbulent flow regardless of the piston phase difference. (3) The velocity near the pipe wall is comparatively large in the accelerating period and comparatively small in the decelerating period independently of the piston phase difference. (4) As the piston phase difference becomes smaller from 180°to 90°, the difference of the maximum velocity and the period becomes larger between the right running flow and the left running flow.
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Seiichi SUDO, Hiroyuki HASHlMOTO
1986 Volume 52 Issue 483 Pages
3655-3659
Published: November 25, 1986
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An experimental study is presented for the dynamic behavior of a liquid in a cylindrical container subject to horizontal oscillation with lower frequencies. The nonlinear effects on frequency characteristics of liquid surface response are investigated. It was observed that several nonlinear wave motions occurred in the container when the excitation amplitude exceeded the threshold value. These waves cannot be predicted by linear theory. It was found that the nonlinear surface waves induced by the growth of linear waves responded as 2-superharmonic, harmonic, and 1/2-subharmonic of the excitation. The occurrence of the nonlinear waves increased the elevation of the free surface. It was also observed that the breaking wave and swirl motion of the first antisymmetric slosh mode were formed in the vicinity of the natural frequency of liquid motion.
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Katsumi MIYAKOSHI, Seiichi TANIGUCHI, Seiji DOHDA
1986 Volume 52 Issue 483 Pages
3660-3665
Published: November 25, 1986
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The interference effect on the thickness of the turbulent boundary layer and the gap height between a two-dimensional circular cylinder and a plane wall was experimentally investigated. The increment of the thickness of the turbulent boundary layer reduced the increasing rate of the time-mean drag force with respect to the increasing gap ratio, while being not notable in the time-mean lift force. it was also found that the fluctuating fluid forces became negligibly small in the case of δ/d=0.34, when the gap ratio s/d was 0.3, δ being the thickness of the boundary layer, d the diameter of the cylinder and s the gap height, respectively. This characteristic of the interference flow was induced by the laminarization of the turbulent flow around the cylinder in the above conditions. such a striking feature became, however, obscure as the thickness of the boundary layer increased.
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Seizo TSURUNO, Toshimi YASAKA, Hiromi TAKASAKI
1986 Volume 52 Issue 483 Pages
3666-3672
Published: November 25, 1986
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A method for estimating Reynolds stress -<u'v'>^
- in a turbulent boundary layer was developed. In outline, the estimating equation for -<u'v'>^
- introduced by integrating the momentum equation is solved numerically by applying measured values of velocity, pressure gradient and wall shear stress. for confirming the validity of this method, the experimental results presented by Klebanoff were employed. The results obtained were in good agreement with his measured data on -<u'v'>^
-. also it showed that his method could estimate -<u'v'>^
- in developing a thin boundary layer like the entrance region of a pipe by using our data measured by an I-probe of hot wire.
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Toshio TANAKA, Eiichi TANAKA, Yoshihiro INOUE
1986 Volume 52 Issue 483 Pages
3673-3677
Published: November 25, 1986
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An experimental study is presented on the control of the reattachment of a radial turbulent jet flow (main jet flow) discharged from a cylindrical nozzle onto an adjacent offset disc plate, with the addition of another control flow (suction and blowing). The effects of various step heights and control flow rates on the flow properties were investigated by the velocity and pressure distributions, and by flow visualization. A flow field was divided into four regions: the initial region, the recirculation region, the transitional region and the wall jet flow region. Deflections of jet potential core and jet center axis, changes of jet center velocity and jet half width, and static pressure distributions at the wall surface in each region were examined.
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Nobuyuki SHlMA
1986 Volume 52 Issue 483 Pages
3678-3684
Published: November 25, 1986
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A Reynolds stress model for near-wall regions of low Reynolds numbers proposed by the author in a previous paper is, with some modifications of the model function and model constant, applied to an accelerated turbulent boundary layer. The predicted case is a relaminarizing flow presented at the 1980-81 Stanford conference on Complex Turbulent Flows. Comparison of the numerical results with the experimental data includes profiles of the mean velocity and streamwise turbulence intensity at several stations as well as the streamwise variations of the momentum thickness, the shape factor and the skin-friction coefficient. it is shown that the predictions are generally in close agreement with the experimental data including the profile of streamwise turbulence intensity which is not predicted directly by the two-equation models.
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Hiroshi OHUE, Keiichi MITO, Eiji KASAHARA
1986 Volume 52 Issue 483 Pages
3685-3688
Published: November 25, 1986
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In a CO
2 gasdynamic laser (CO
2 GDL), output laser power is extracted by rapidly cooling preheated gases. There are several methods for getting hot gases. To carry out the present study, a simple shock tube was designed and employed. The shock tube is superior to other methods in the following ways: a molar fraction with high accuracy can be chosen; high purity of the test gas can be achieved; and the required pressure can be obtained rather easily; so the shock tube technique is suitable for obtaining basic experimental data. In this paper, nine types of nozzles are employed and the gasdynamic characteristics on CO
2 GDL are investigated.
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Manabu SANO
1986 Volume 52 Issue 483 Pages
3689-3692
Published: November 25, 1986
Released on J-STAGE: March 28, 2008
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The author found that an internal flow did not necessarily show the bi-stability which is indispensable in fluid logic devices. The existence of bi-stability depended on the splitter arrangement, which, at times, produced an almost periodic oscillation. The author investigated the splitter arrangement systematically and found the oscillating condition. In this paper, velocity fluctuation in the output port is measured by a hot wire anemometer and the output signals are recorded on the floppy discs of a personal computer after analog-to- digital conversion. Power spectrum analyses by FFT are applied to those records, and aspects of oscillating phenomenon are experimentally clarified. In order to load in the output ports, both ports are blocked by throttle plates with knife-edged ends and the extent of the load is estimated by a coefficient of wall static pressure.
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Susumu INAGAKI, Yukio TOMITA, Hisami MURAMATSU, Shoji SUZUKI
1986 Volume 52 Issue 483 Pages
3693-3701
Published: November 25, 1986
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In the turbulent wake behind the upstream cylinder in uniform flow, the downstream cylinder was set in the form of an intersection with the upstream cylinder. It was found that the acoustic radiation from the two circular cylinders forming a cross was far smaller, in comparison with that from one cylinder. Measurements were made on (1) the fluctuating surface pressure distributions on both cylinders, and (2) the mean velocity profiles and fluctuating velocity distributions in the turbulent wake behind the upstream cylinder. Then, the relation between the flow and the noise generation was studied.
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Tosihiko IKEDA, Tyozi HORIKOSI, Xiuren LI, Tosihiro TANAKA
1986 Volume 52 Issue 483 Pages
3702-3705
Published: November 25, 1986
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The influence of the suction flow in an inactive output port on the internal fow of a fluid amplifier has been investigated using the hydrogen bubble method. The ratio of the suction flow rate in an inactive output port to the flow rate of the main jet is a constant regardless of the main jet Reynolds number and the offset distance. On the other hand, the ratio increases with the splitter distance. It was found that the suction flow in an inactive output port reduces the reattachment point of the main jet.
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Tosihiko IKEDA, Tyozi HORIKOSI, Tosihiro TANAKA
1986 Volume 52 Issue 483 Pages
3706-3711
Published: November 25, 1986
Released on J-STAGE: March 28, 2008
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This paper describes the influence of the suction flow in the control port and the inactive output port on the internal flow of a fluid amplifier. The ratio of the suction flow rate in the control port and the inactive output port to the flow rate of the main jet is a constant regardless of the main jet Reynolds number. It was found that suction flow in the inactive output port and in the control port of the inactive output side reduces the distance of the reattachment point. On the other hand, the suction flow in the control port in the active output side enlarges the distance of the reattachment point. In addition, the distance of the reattachment point decreases with the increase of (Q
β/Q)
av defined in equation (1).
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Shigeharu OHYAGI, Teruo YOSHIHASHI, Yasuo HARIGAYA
1986 Volume 52 Issue 483 Pages
3712-3717
Published: November 25, 1986
Released on J-STAGE: March 28, 2008
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A numerical simulation of the initiation processes of gaseous detonation waves was performed by the Random-Choice Method (RCM) developed by Chorin. The initiator was high-pressure and high-temperature gas which was chemically inert. The chemical reaction was assumed to be a one-step irreversible reaction with its rate described the Arrhenius law. It was found that the initiation processes were strongly dependent on the total energy contained in the initiator gas. Local explosions were observed in the initiation processes and were found to be most essential in these processes.
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Terufumi KAWASAKI, Masanori NAITOH, Takeshi TAKAMARU
1986 Volume 52 Issue 483 Pages
3718-3722
Published: November 25, 1986
Released on J-STAGE: March 28, 2008
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A two-dimensional model of gas-liquid tow-phase flow was developed in order to simulate flow in a carburetor. it is assumed that small particles of dispersed fuel are transferred at the same velocity as air flow. The air-fuel mixture, which is assumed to have volume-averaged density, is numerically calculated by the fluid in cell method (a finite difference method) in accordance with conservation laws of mass, momentum and energy. It was confirmed that minimum pressure and maximum velocity were shown at the narrowest point of the top venturi in the air single-phase flow analysis. in the two-phase flow analysis, fuel flow was decelerated in the central region of the carburetor and was accelerated in the periphery.
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Yoshiyuki MATSUNO, Hiroyuki FUNATSU, Tsunetoshi IKEUCHI
1986 Volume 52 Issue 483 Pages
3723-3728
Published: November 25, 1986
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For transportation through a pipeline, COM should be kept at a temperature of 70°C, because its viscosity increases with a decrease in temperature to render its pipeline transportation difficult. This paper reviews a concept with which the authors developed a method of calculation to determine changes in temperature, viscosity, and flow velocity of COM in a pipe that take place with time, when operation of the transfer pump and transportation pipe heating system stops suddenly due to power failure and when this is reversed with the return of electric power. As COM has non-Newtonian properties, the viscosity of which changes with changes in temperature and shear rate, the authors employd new devices for the calculation method.
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Hideo OSAKA, Hideki FUJII, Masahiro SUGIHARA, Yoshiro KAGEYAMA
1986 Volume 52 Issue 483 Pages
3729-3735
Published: November 25, 1986
Released on J-STAGE: March 28, 2008
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Conditional averages of longitudinal, normal velocity and of their products have been obtained in a fully developed plane turbulent wall jet. For detecting the coherent structure, the VITA technique and TD method were utilized in the inner and the outer region of the wall jet respectively. It was inferred from the ensemble averaged patterns of u- and v- fluctuating velocities that the existence of a pair of counter-rotating spanwise vortices was supported through most of the present wall jet. The strong outflow events found near the location of a detective probe correspond to the trunk of a pair of spanwise vortices, where the ensemble averaged Reynolds shear stress takes a peak value. These events were at an oblique angle of about 25 deg. to the wall.
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Kaoru KATAYAMA, Toshio IIJIMA, Tsuyoshi ASANUMA
1986 Volume 52 Issue 483 Pages
3736-3741
Published: November 25, 1986
Released on J-STAGE: March 28, 2008
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The characteristics of an intermittent air jet ejected into a prechamber through a two dimensional torch nozzle during the compression stroke are studied. The effects of prechamber volume and torch nozzle area on the jet velocity, and its fluctuation measured with a Laser Doppler Velocimeter (LDV) are make clear. The temporal variation and spatial distribution of the jet velocity and its fluctuation make clear the jet behavior in the prechamber. The jet flow in the prechamber visualized by using the spark tracing technique verifies clearly the results measured by LDV, that the jet velocity on its center axis is always negative during the initial period of the compression stroke from Bottom Dead Center (BDC) to about 90° in the crank-angle.
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Tateyuki SUZUKI, Takashi ADACHI
1986 Volume 52 Issue 483 Pages
3742-3746
Published: November 25, 1986
Released on J-STAGE: March 28, 2008
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Shock tube experiments were performed to investigate the initial stage of dust dispersion by a shock which propagates over a dust layer deposited on a solid floor. Amberlite was used as a model dust because it promised good reproducibility of experiments. The profiles of the densities and the velocity components of the dispersed dust particles above the dust layer were determined through the trajectories on the visualized photographs, which were taken using double-flashed light sources. It was found that the density near the dust layer is much larger than usually expected, that its profiles for different shock Mach numbers are reduced to a single curve when non-dimensionalized distance is taken, m and that the heights of the dust cloud and the dimensionless velocity profiles for different Mach numbers can be reduced to each single curve where reasonable abscissas are chosen, respectively. The comparison of velocity components for various floor conditions revealed that surface roughness is one of the important factors for the mechanism of dust dispersion by a shock wave.
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Yoshinobu TSUJlMOTO, Allan.J. ACOSTA, Chiristopher.E. BRENNEN
1986 Volume 52 Issue 483 Pages
3747-3754
Published: November 25, 1986
Released on J-STAGE: March 28, 2008
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Fluid forces on a centrifugal impeller rotating and whirling in a vaneless diffuser are analysed on the assumption of a two-dimensional inviscid flow. It is assumed that the number of impeller vanes is infinitely large and that the loss in the impjller can be estimated from the steady hydraulic and incidence losses taking into account the delay time of the loss. Further, the pressure at the outlet of the diffuser is assumed to be constant. On these assumptions impeller and/or diffuser attributed rotating stalls are observed, and the effects of parameters affecting the stalls are discussed. It is found that both stalls may cause the whirling instability of a centrifugal impeller.
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Masahiro TAKEBAYASHI, Hiroshi IWATA, Akio SAKAZUME, Masahiko SUGIYAMA
1986 Volume 52 Issue 483 Pages
3755-3760
Published: November 25, 1986
Released on J-STAGE: March 28, 2008
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This paper concerns the effects of the flow resistance of nozzle type fluidic diodes on the discharge characteristics of an oil feeder pump for a horizontal type compressor. This pump replaces the conventional valves by fluidic diodes. These fluidic diodes have characteristic such that the resistance in the reverse flow direction is greater than that of the forward flow direction. In this study, we investigated experimentally the flow resistance of the nozzle type fluidic diodes and analyzed the resistance of each section of this pump system. We calculated the change of the flow rate per cycle based on their resistance and discussed the relation between the flow resistance of the fluidic diodes and the discharge characteristics of the pump.
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Yoshikata KOMIYAMA, Fusao MIKAMI, Kenichi OKUI
1986 Volume 52 Issue 483 Pages
3761-3768
Published: November 25, 1986
Released on J-STAGE: March 28, 2008
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Fully developed steady laminar flow of viscous incompressible fluid in straight square ducts rotating at a constant angular velocity about an axis perpendicular to its axis under thermal conditions of axially uniform wall heat flux and peripherally uniform wall temperature at any axial position is studied. Numerical solutions were obtained for R
eR
Ω numbers from 10 to 10
5 (for R
e numbers form 1 to 4200). At low to moderate R
eR
Ω numbers, a double
vortex secondary flow appears under the influence of the Coriolis force. For higher R
eR
Ω numbers it is found that an additional counter-rotating pair of vortices appeared and disappeared for the range of R
Ω numbers from 10 to 100. Correlation equations for friction factors and Nusselt numbers are obtained from numerical results. The numerical results in regard to the friction factor and Nusselt number are in good agreement with experimental and analytical results by other reseachers for circular pipe.
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Katsuo NISHIYAMA
1986 Volume 52 Issue 483 Pages
3769-3773
Published: November 25, 1986
Released on J-STAGE: March 28, 2008
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The condensation of R11 vapor on vertical fluted tubes in three modes (heave, sway and roll) of sinusoidal vibration were studied experimentally in order to evalute the effect of motion on the heat transfer performance for a moving ocean platform such as the OTEC plant. The cross-sectional shapes of the groove of the used tubes were the circular arc and triangle respectively. The effects of heave and sway motion on heat transfer performance were not detected at a vibrating force of up to 0.135g. But the roll motion enhanced the heat transfer performance as the amplitude or frequency became larger. This effect was recognized when the vibrating force became 0.11g on larger.
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Ichiro TAKAHASHI, Akira SUGAWARA, Hidenobu MIFUNE
1986 Volume 52 Issue 483 Pages
3774-3781
Published: November 25, 1986
Released on J-STAGE: March 28, 2008
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The purpose of this study is to demonstrate a viable method to measure the thermophysical properties of thin ribbon samples such as amorphous alloys, which cannot be adequately studied by conventional methods. In this paper, the techniques of measuring thermal conductivity and total hemispherical emittance by an improved steady state direct electrical heating method and theoretical evaluation of the accuracy in a thin ribbon sample are described. From the results of the experiments on JIS·SUS304 ribbon samples with 20μm thichines, it becomes clear that the measurement of the above mentioned properties for a thin ribbon sample can be satisfactorily conducted by the use of this method.
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Kazutomo OHTAKE, Tadashi KONISHI, Katsuhiko ARAYA
1986 Volume 52 Issue 483 Pages
3782-3786
Published: November 25, 1986
Released on J-STAGE: March 28, 2008
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The current conducting and the arc discharge characteristics through coal slag layers over the electrodes are experimentally studied. The molten slags of Taiheiyo coal (original), 5% of Fe
2O
3 added to the original in order to change the electron conductiveness, 5 and 10% of K
2SO
4, added simulating the seed materials to be absorbed, are tested. The electlochemical reaction between slag and anode and the segregations of metals in the cathode slag layer, which have large ionization tendencies occur in rather short time form 10 to 30 seconds. These phenomena give the increase of resistivity at the anode, while the decrease at the cathode and the different behaviors to the arcs on the respective electrodes. The current density at the arc spot themselves on the cathode are decided from the synchronized data of current and TV images. The order of 10 to 50 A/cm
2 are obtained depending on the slag materials.
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Toshihisa UEDA, Masahiko MIZOMOTO
1986 Volume 52 Issue 483 Pages
3787-3793
Published: November 25, 1986
Released on J-STAGE: March 28, 2008
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Numerical analysis on a aerodynamic structure of a laminar boundary layer diffusion flame over a horizontal flat plate has been done, taking into account a local pressure gradient in a boundary layer. The calculation were carried out, using a 'Simpler' algorithm. a flame sheet approximation was applied to describe the combustion process. When the flame is formed, the pressure field in the boundary layer is varied locally and the stream wise pressure gradient is formed even if the effects of gravity of of acceleration of the free stream velocity are not taken into account. This streamwise pressure gradient induces the volocity overshoot. This shows that the flame formation plays an important role on the pressure variation in the boundary layer and the velocity overshoot. Furthermore, the numerical calculation, taking into account the effects of gravity and the free stream accerelation in the present equations, shows good agreement with the corresponding experimental results.
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Yasuo KANEKO, Shiroh FUJIMOTO, Setsujiro KOBATAKE, Yukio KANAUCHI, Shi ...
1986 Volume 52 Issue 483 Pages
3794-3802
Published: November 25, 1986
Released on J-STAGE: March 28, 2008
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Methanol has emerged as a near-term alternative to hydro-carbon fuel. On the one hand, in Japan, LPG fuel has been utilized for the Taxi as an alternate to gasoline in respect of economy. This paper reports a comparison of methanol and propane as LPG fuel to base gasoline on S. I. engine performance. The results obtained are as follows: (1) the compression ratio is as high as 12:1; the maximum methanol and propane engine output is higher by approximately 20% and 8% respectively than the base gasoline engine. (2) brake thermal efficiency of the methanol and propane engine is better than the base gasoline engine, but the difference becomes smaller as the engine output becomes lower. (3) engine out emission level of methanol fuel are lower than gasoline, especially for NO
x and THC; but the NO
x level of propane fuel is higher than that for gasoline.
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Shinzo KIKKAWA, Yoshiaki OKUI
1986 Volume 52 Issue 483 Pages
3803-3810
Published: November 25, 1986
Released on J-STAGE: March 28, 2008
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The distributions of film cooling effectiveness on the suction surface of a gas turbine blade were measured by using the analogy of heat and mass transfer. A rectangular injection hole was made on a midspan-line of the blade. As a result, the following were clarified: (1) the optimum blowing rate is about 1.0, (2) the distribution of film cooling effctiveness in the spanwise direction agrees well with Gaussian error function. (3) the effects of the pitch-chord ratio and incidence angle on the film cooling effectiveness are slight, (4) a universal distribution of the film cooling effectiveness on the midspan-line of the blade was introduced, (5) by using the above results and the principle of superposition, one can predict the distribution of film cooling effectiveness on the suction surface of a gas turbine blade on which many injection holes are laid out in an arbitrary position and injection angle.
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Hideaki KOBAYASHI, Michio KITANO, Yoshiro OTSUKA
1986 Volume 52 Issue 483 Pages
3811-3817
Published: November 25, 1986
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For the basic investigation of a premixed flame subjected to the effects of both flame stretch and flame curvature, we took up the stretched cylindrical flame formed inside the porous cylinder when the mixture was ejected uniformly from the inner wall surface of it. With methane/air and propane/air mixtures, flame behavior observations and measurements of extinction limit and flame diameter were made for these flames, and the effects of flame stretch and flame curvature were discussed, including those of heat loss to the burner wall, buoyancy, and Lewis numbers of reactants. Theoretical analysis was also made and extinction limits of the cylindrical flame and counter-flow twin flames, which have no flame curvature effects, were calculated and compared. The results showed that the curvature of the cylindrical flame propagating outward weakness resistibility to the flame extinction due to stretch.
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Kishiro AKIBA, Akira SHlMIZU, Hiroshi SAKAI
1986 Volume 52 Issue 483 Pages
3818-3826
Published: November 25, 1986
Released on J-STAGE: March 28, 2008
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This paper suggests that the shock force working on the valve stem of the internal combustion engine at the valve closing moment has a great influence on the wear of the valve face. The authors have simulated the behavior of valve trains with the new seven mass model. This model gives freedom of motion to the parts so that parts can be separated or made to contact each other while in motion. It is made clear that the predicted data agree fairly well with the experimental data; and it is recognized firstly that the shock force has regular peaks with increasing cam speed. To reduce the shock force, the seven mass model is used thoroughly. The optimum value of the cam ramp velocity and the appropriate range of the stiffness of the valve trains are proposed.
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