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松尾 一泰, 屋我 実, 望月 博昭, 江藤 敏美
1988 年 54 巻 498 号 p.
225-229
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
Previous investigations show that a shock wave in a transonic diffuser under a constant overall pressure ratio may be either a stable one or an unstable one. However, the behavior of an unstable shock wave is not well understood since the extent of the pressure ratio of an unstable shock wave is very limited. In the present paper, the behavior of an unstable shock wave has been observed by a schlieren optical method, and pressure measurements for a two-dimensional hyperbolic-type diffuser where the unstable shock wave is observed in a wider extent of the downstream section of the throat in comparison with usual diffusers. The effect of diffuser geometries on the unstable shock wave has been discussed in the latter half of this paper.
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山根 隆一郎, 朴 明寛, 大島 修造
1988 年 54 巻 498 号 p.
230-235
発行日: 1988/02/25
公開日: 2008/03/28
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フリー
The mean wall static pressure and the pressure fluctuation were measured near the separation shock wave produced by the turbulent boundary layer separation ahead of the forward-facing steps, and the A-D transformed pressure signals were statistically correlated. The oscillation model was presented. The highest peak of the pressure fluctuation occurred at the foot of the separation shock wave. The oscillation of the separation shock wave was mainly due to the low frequency fluctuation at the separated region and also to the high frequency fluctuation of the upstream turbulent boundary layer. The propagation speed of the low frequeocy component was far lower than the speed of sound and was comparable to the recirculation velocity in the separated region.
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増田 渉, 遠山 茂登伺
1988 年 54 巻 498 号 p.
236-242
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
A numerical analysis is presented with a CO chemical laser, which utilizes the supersonic mixing of the dissociated products of CS
2 diluted in Ar with O
2. It is assumed that the flow is quasi-one-dimensional, and that the nozzle flows undergo instantaneous mixing at the nozzle exits. The constant gain method is applied to estimate the laser power. The present results show that the rate of formation of the CO molecules is scarcely reduced, although the temperature rise in the reacting flow field is suppressed due to the conversion of the chemical energy into the laser energy. It is also shown that about 19.5 KW laser power can be extracted from a supersonic flow CO chemical laser, whose cross sectional area of the flow field is 50 mm ×450 mm.
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今尾 茂樹, 張 棄名, 山田 豊
1988 年 54 巻 498 号 p.
243-248
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
In this paper, velocity profiles of the laminar flow in the developing region of an axially rotating pipe are analyzed numerically and are compared with the experimental results when an uniform axial flow is introduced into it. It is found that the axial velocity in the rotating pipe exceeds the value of the Poiseuille flow at the center, and a backward flow appears near the wall as the swirl ratio becomes large. The greater the swirl ratio N becomes, the more remarkable it tends to become ; but at about N = 3 experiments show that the rotation of the pipe causes the flow to become unstable and the development of the flow is delayed.
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吉野 章男, 林 達夫
1988 年 54 巻 498 号 p.
249-255
発行日: 1988/02/25
公開日: 2008/03/28
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フリー
Aerodynamic forces acting on a circular cylinder rotating about its axis in a uniform shear flow were numerically obtained at a relatively low Reynolds number. The range of the Reynolds number is from 20 to 100 while those of the specific circumferential speeds and the velocity gradients of the shear flow are from 0 to -2 and from -0.2 to 0.2, respectively. The following results were obtained : First, the mean lift coefficient C^
-l is the sum of the lift due to the rotation of the cylinder (Magnus effect) and that due to the velocity gradient. Second, the mean drag coefficient is the sum of the profile drag on a cylinder standing still in a uniform flow and the Magnus drag due to the induced velocity by vorticity originating at the cylinder in rotation and by that of the shear flow in the wake.
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谷口 清一, 出口 晶久, 宮越 勝美, 堂田 誠治
1988 年 54 巻 498 号 p.
256-264
発行日: 1988/02/25
公開日: 2008/03/28
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フリー
The wake structures of two-dimensional rectangular cylinders with length-to-width ratios, l/h, ranging from 0.25 to 4.0 were experimentally investigated by means of the phase averaging technique. The vortex region of the wake remarkably extended at l/h = 2.0. There were two kinds of vortices in the region 2.0≤l/h<3.0. One was formed by the rolling shear layer separated from the leading edges of the cylinder, and the other was the vortex shedding from the rear edges which was also formed by the attached shear layer from the leading edges on the side walls of the cylinder. In case of l/h over 3.0, the vortex region became more narrow and the vortex strength more intense than at the small values of l/h.
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深野 徹, 林 秀千人, 原 義則
1988 年 54 巻 498 号 p.
265-270
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
The characteristics of the wake of a blunt body near its tip were investigated experimentally. When the tip clearance is large, the downwash flow is so large that the radial component of the velocity in the wake promotes mixing and diffusion of the wake. Therefore the velocity recovery is rapid and the width of the wake increases quickly in the wake. The velocity fluctuation in the wake becomes irregular, and vortex shedding disappears near the tip of the body. On the other hand when the tip clearance is small, the downwash flow is weak and near the tip of the body the dead air region becomes large as a result of gathering the low energy fluid. So the mixing and diffusion in the wake are inactive, and the regularity of the velocity fluctuation in the wake is kept up to the tip of the body.
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富田 幸雄, 石橋 幸男, 斉藤 英治, 斉藤 俊郎
1988 年 54 巻 498 号 p.
271-276
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
The flow behavior of water-base ferrofluids in a two-Dimensional channel are experimentally examined under the action of magnetic fields having various strength and directions. Moreover, various factors governing such flow are clarified by using dimensional analysis, and then an empirical formula for pipe friction coefficient is found.
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応和 靖浩, 坂尾 富士彦, 松岡 洋浩
1988 年 54 巻 498 号 p.
277-281
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
Finite-difference analyses of the two-dimensional Navier-Stokes equations were given in stream function-vorticity formulations from the range of the steady state to the range of the unsteady vortex street behind a square cylinder placed in the middle of a flow channel between two parallel walls. For flows in a multiply-connected region, the value of the stream function on the body cannot always be given a priori. A new method to determine this value was proposed for getting the circulation flowing out of a control surface set behind the body. Transitional phenomenon from a steady state of the twin-vortices to an unsteady state of the vortex street was successfully reproduced with good agreement with experimental results.
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加藤 健司, 藤田 秀臣
1988 年 54 巻 498 号 p.
282-289
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
This study concerns surface wave attenuation by viscosity, in particular, the effect of viscosity on the interior motion of the fluid. The standing wave formed near an obstacle in a horizontal channel is chosen as the subject of this analysis because gravitational and surface tension waves appear separately before and behind the obstacle, and, hence, the effect of viscosity on two typical kinds of waves can be analysed. The linearized differential equation for the stream function is solved analytically to obtain the waveform. The calculated attenuation rate of wave amplitude does not agree well with that of Stokes' approximate estimation based on the irrotational solution. This shows that the Stokes' estimation is not sufficient and the exact analysis as presented here is necessary when the Reynolds number is relatively low as Re≤1 000. As an application of this analysis, the wave form is calculated for the standing wave formed by an obstacle in falling liquid film flow.
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荒川 忠一, ベルンハルト シェーヌンク, ウォルフガング ロディ
1988 年 54 巻 498 号 p.
290-296
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
A multigrid method for solving the Navier-Stokes equations is described. It is applied to the entire relaxation process of the momentum equations as well as the pressure correction equation employed in decoupled calculations, such as the SIMPLE algorithms. The Full-Approximation-Storage scheme and the fixed V-cycle are introduced for smoothing the nonlinear equations. Calculation results with various pressure correction schemes were obtained for the cavity and sudden expansion channel flows. The results are compared with results of the non-multigrid code and the coupled calculation method. For laminar 2-D cavity flow at Re =1 000 and a numerical grid of 82×82, the multigrid method was found to have a faster convergence in ten times compared with the non-multigrid method.
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角田 勝, 須藤 浩三, 湯原 章
1988 年 54 巻 498 号 p.
297-301
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
A new visualization method is devised for researching the secondary flow in curved pipes. The secondary flow in a circular curved pipe, having curvature ratio of 7.6, is visualized by this method in the range of Dean numbers from about 30 to about 500, which corresponds to laminar flow. In this method, the nylon particles suspended in water flowing through the pipe are lighted by a stroboscope and pictures of the nylon particles are taken. The experimental results, the flow patterns and the velocity vectors and profiles of the secondary flow, are compared with the results obtained by numerical analysis. The agreement is fairly good, so the present visualization method shows itself to be effective for the velocity measurement of the secondary flow in curved pipes.
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黒川 淳一, 高木 彰
1988 年 54 巻 498 号 p.
302-307
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
In the preceding report, it was made clear that there exists two types of flow transition from laminar to turbulent in an accelerated flow depending on the degree of acceleration. In order to determine the mechanism of these types of transition the present measurements were performed and the change of the velocity profile at each time step was compared at two different stations. The results show that in the case of relatively large acceleration (r
0/u
stT>10
-3), flow transition takes place simultaneously over the whole area in a pipe due to the flow instability. On the contrary, in the case of relatively small acceleration ((r
0/u
stT<10
-3), flow transition takes place near the pipe inlet and forms a discontinuous surface (transition surface) propagating to the downstream with a velocity larger than the mean flow velocity. In this case the velocity profile changes smoothly from laminar to turbulent in the upstream but becomes peculiar in the downstream due to the development of the transition region.
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井口 学, 三浦 博志
1988 年 54 巻 498 号 p.
308-313
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
Turbulence generated near the wall of a pipe propagates both in the radial and the axial directions. Compared to the axial propagation, knowledge of radial propagation is very limited. This investigation is intended to clarify the radial propagation of wall turbulence in pulsatile turbulent pipe flows. It becomes evident that the turbulence is mainly generated around y
+ = 20 and propagates toward the wall as well as the pipe center, where y
+ = yu^
-*, ta/v, y the distance from the wall, u^
-*, ta the time-averaged friction velocity, and ν the kinematic viscosity. The propagation time near the generation region scales well with inner variables, u^
-*, ta and ν, whereas in the central part of the pipe it scales with u^
-*, ta and the pipe radius R. Empirical expressions for the propagation time are derived, and models for Reynolds shear stress and eddy viscosity are proposed.
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坂本 弘志, 羽二生 博之, 小畑 芳弘
1988 年 54 巻 498 号 p.
314-321
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
Fluctuating fluid forces acting on two square prisms in tandem arrangement under free-stream turbulence were studied experimentally. In particular, paying attention to the region of jump phenomenon, the region of the jump occurrence, the switching frequency of the jump and the fraction of the time of the occurrence of one flow pattern were studied in detail. Obtained results are summarized as follows : (i) The location of the region of jump phenomenon shifts toward the upstream prism as the free-stream turbulence increases. (ii) As the free-stream turbulence increases, the flow pattern around the two prisms becomes unstable, and the switching frequency of the jump largely increase. (iii) Fluid forces acting on the upstream prism were found to be strongly subject to the free-stream turbulence. (iv) Free-stream turbulence was found to significantly change the vortex shedding frequency. In particular, at the region of synchronization, the Strouhal numbers of the two prisms were found to increase considerably as the free-stream turbulence increased.
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西山 哲男, 阿部 慎治, 高木 武夫
1988 年 54 巻 498 号 p.
322-329
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
Present paper aims to yield a theoretical basis for the torsional flutter of guide vanes in the pump stage of pump-turbines. The guide vanes are assumed to oscillate torsionally about their axis with arbitrary intervane phase differences in the outward flow of pump stage. A theoretical analysis by the singularity method is developed for steady and unsteady flows of guide vanes under the assumption that the former is of finite order of magnitude compared with the latter of infinitely small order. Torsional flutter of guide vanes is shown to occur at low reduced frequency and for small valve opening for two intervane phase differences of 90° and 270°, and then some theoretical explanations are paid from notable features of unsteady pressure distributions and unsteady moment.
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中村 育雄, 植木 良昇, 山下 新太郎
1988 年 54 巻 498 号 p.
330-336
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
Measurements have been made for space-time correlations of velocity fluctuations in the turbulent shear flow around a circular cylinder spinning in a quiescent fluid. Optimum delay time and the associated motion of lumps of eddies are considered. In order to examine the spatial structure of the turbulent field, Taylor's hypothesis is used to transform the time coordinate to the peripheral one, and various contour maps of spatial iso-correlations are obtained in plane perpendicular to the cylinder axis. The change in the iso-correlation contours for Q
2, 2 in the plane of y
s = 0 with the cut-off frequency of a high-pass filter suggests that the mean shear has only a little effect on large eddies with low frequency. The contours for Q
2, 3 show that the range over which the correlation holds the finite value extends in the axial direction over nearly twice the radius of the cylinder, and that there exists a comlex large-eddy structure.
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奥田 洋司, 江口 譲, 矢川 元基
1988 年 54 巻 498 号 p.
337-344
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
This paper describes the turbulent flow analysis technique that is suitable for three-dimensional large scale problems. The k-ε turbulence model and the finite element method are used with low order elements. The coefficient matrices are evaluated by one-point quadrature with hour-glass control in order to reduce the computaional storage and CPU cost. The pseudo-time integration scheme based on the velocity correction method is utilized to obtain a steady-state solution. For the verification of this FEM program, a two-dimensional plenum flow is simulated and compared with the experiment. As an application to three-dimensional problems, the turbulent flows in the upper plenum of the Fast Breeder Reactor (FBR) are calculated for various boundary conditions.
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中村 育雄, 酒井 康彦, 角田 博之
1988 年 54 巻 498 号 p.
345-353
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
Various conditional statistics have been examined on a turbulent diffusion of dye solution from a continuous point source in uniform mean vertical shear flow. The conditional sampling technique consists of two steps, i.e. the first step A which determines the intermittency factor from the probability density function and the second step B at which is obtained the intermittency function by using a threshold level and a hold time. It is shown that the vertical profiles of the intermittency factor, the zone-averaged mean concentration and the zone-averaged concentration fluctuation r.m.s. value are all asymmetric about the centerline of plume. The new dimensionless diffusion time η is introduced in terms of the r.m.s. value and the integral length scale of longitudinal velocity fluctuation, and the relative decay rates with η of these conditional statistics on center line of plume are estimated and compared with the results in grid-generated turbulent flow.
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飯田 誠一, 松田 寿
1988 年 54 巻 498 号 p.
354-360
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
A circular turbulent wall-jet along a convex wall was measured in comparison with that along a flat plate, and the flow characteristics of the three-dimensional wall-jet under a streamwise curvature effect was examined. By hot-wire anemometry, all velocity components were measured so that the components of turbulent intensity, the Reynolds stresses, and the mean streamwise vorticity were fiqured out. The main conclusions are as follows : 1) there are two pairs of secondary flows in the circular wall-jet along a flat plate, 2) an additional pair of secondary flows appears in the case of the flow along a convex wall 3) as an effect of curvature, the wall static pressure along the centerline decreases considerably, and 4) a significant increase of the vertical jet width compared with that of the spanwise one is observed.
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東 恒雄, 森島 直正
1988 年 54 巻 498 号 p.
361-366
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
The laminar-turbulent transition in the radial flow of a free liquid film is studied. The liquid film flow is generated in the same way as in the previous papers. When the Reynolds number which is based on the liquid surface velocity and the film thickness at the disk edge is high, the transition from laminar to turbulent flow takes place several millimeters downstream of the disk edge. The change of the velocity distribution in the process of the transition is examined by LDV. It is found that the reduction of the radial velocity component due to the occurrence of very small vortices starts at the higher velocity side of the liquid film a few millimeters downstream of the disk edge, and thereafter the velocity distribution becomes uniform immediately.
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田中 敏嗣, 石橋 秀紀, 白鳥 哲也, 辻 裕, 森川 敬信
1988 年 54 巻 498 号 p.
367-373
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
Particle velocities were measured in air-solid two-phase flow through 90° horizontal-to-vertical bends by using an optical fiber probe. Two kinds of polystyrene spherical particles were used, the mean diameters of which were 0.406 and 1.50 mm, respectively, and the pipe diameter was 40 mm. The bend curvature to pipe diameter ratios were 10 and 6. Measured results were compared with calculations based on the conventional one dimensional models developed by Weidner and Kovacs. It was found in the course of the work that differences in the flow patterns of particles should be taken into account in order to obtain a good agreement between measurements and calculations. Thus the patterns were classified into three types according to the loading ratio and superficial air velocity; dispersed flow, dispersed biasing flow and sliding bed flow. It was found that the one dimentional model without fluid drag is applicable to fully developed dispersed biasing flow.
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鮎川 恭三, 越智 順治
1988 年 54 巻 498 号 p.
374-381
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
Single component two phase flow in a state of thermodynamic non-equilibrium has been investigated analytically. It is difficult in general to determine mass and heat transfer through the interface as vaporization and condensation. As the first step to reveal the characteristics of these complicated two phase flows occuring in variable area channels or in high speed flow, the analysis for the process of phase change between the liquid and the vapor is taken by the theoretical method, approximately, without any empirical conditions. The result of numerical calculation for steam-water critical flow in a state of thermodynamic non-equilibrium is shown to be in the range of 0.6 - 8.6 MPa saturated pressure at a nozzle inlet, and is compared with the equilibrium flow and experimental data on the critical flow in the past.
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川橋 正昭, 毛利 菊男, 鈴木 允
1988 年 54 巻 498 号 p.
382-386
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
The thermal effects produced by air column oscillations in resonance tubes driven by a piston, or in Hartmann-Sprenger (H-S) tubes excited by an air jet have interested many researchers. The effects show not only heating of the tube wall near the closed end in both tubes, but also cooling at the section of pressure nodes in the resonance tube. The heating and cooling effect in the resonance tube is explained by energy balance, considering thermoacoustic streaming. The experimental investigations o thermal effects i higher mode oscillations of single-step H-S tubes show that the wall temperature is maximum at the section of velocity nodes and minimum at pressure nodes. It can be explained by the thermoacoustic effect. In the present report, the thermoacoustic effect produced by aircolumn oscillation in a H-S tube separated into two cavities by an orifice is investigated and compared with phenomena in the resonance tube.
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安達 勤, 松内 一雄, 小野 博基
1988 年 54 巻 498 号 p.
387-392
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
A cryogenic wind tunnel, in which liquid nitrogen is sprayed into the closed wind tunnel body to get low temperature and high pressure gas, is used to produce high Reynolds number flow in fluid dynamic measurement. In this case, if we want to use a hot wire anemometer to measure flow velocity, the calibration curve, i.e. the relation of output voltage and wind speed must be obtained. Under these low temperature and high pressure conditions we must use thick tungsten wire. The effect of heat conduction through both ends is also important. Several investigations have been conducted to determine the character of hot wire placed in atmospheric air flow. In this study, an analysis of the relation of output voltage and flow velocity of a constant temperature type cot wire anemometer by changing its length and diameter was made for various values of temperature and pressure of nitrogen gas using a small cryogenic wind tunnel. It was concluded that the nondimensional relation acquired in the atmospheric condition can be extended in the cryogenic condition.
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蔦原 道久, 木村 雄吉
1988 年 54 巻 498 号 p.
393-397
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
An application of the Weis-Fogh mechanism to pumps was studied. A pilot pump was built and the characteristics were investigated experimentally, and it was shown that this mechanism works well for pumps. From the point of of view of the specific speed, the characteristics of this pump are similar to those of diagonal flow pumps. The maximum efficiency was about 24%. A flow visualization about the wing was performed and clusters of vortices were found to be produced periodically in the wake. Some possibilities for raising the efficiency were discussed.
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青山 邑里, 松岡 祥浩, 山本 全男, 小池 昇, 谷奥 基資
1988 年 54 巻 498 号 p.
398-403
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
This paper deals with an experimental study on the unsteady cavitation performance in an oil hydraulic poppet valve. Experiments are carried out under two kinds of flow conditions : one is an unsteady flow in which the valve inlet pressure p
1 takes the form of trapezoid varying with time keeping the outlet pressure p
2 constant ; and the other is the flow in which the former p
1 and p
2 are interchanged, respectively. It is found that as absolute values of the rates of pressure change dp
1/dt and dp
2/dt increase the incipient cavitation number k
ci shows a tendency to decrease, and the desinent one, k
cd, shows a tendency to increase under all geometrical parameters in this test. As the absolute values of dp
1/dt and dp
2/dt further increase, the hysteresis between k
ci becomes larger for each combination of the valve and valve seat.
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呉 平東, 北川 能, 竹中 俊夫
1988 年 54 巻 498 号 p.
404-409
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
New type logic valves can be composed of a poppet valve with series restriction chokes. The advantage of them is their wide applicability ; that is, by changing only the control source and the type of pilot valve, they can be readily used as directional control, flow control and pressure control valve. As an example of the new type logic valve, the static characteristics of the new type relief logic valves are studied analytically and experimentally. It is showed that the effect of main flow variation and flow force are smaller than for the usual relief logic valve.
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森下 悦生, 菅波 拓也, 西田 光博, 木藤良 善久, 山本 作衛, 藤井 好三郎
1988 年 54 巻 498 号 p.
410-413
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
Scroll machines have very good sealing characteristics, and the authors have attempted to develop a scroll vacuum pump. A rotating mechanism was employed instead of an orbiting mechanism from the point of view of load pattern and mechanical simplification. The axial and the radial sealing techniques were utilized. The radial sealing mechanism is particularly easy and effective due to the stationary seal line. A spiral with zero top clearance volume and a compact Oldham coupling were the other key technologies. Vacuums of 1 Pa (10
-2 Torr) for dry operation, and of 10
-2 Pa (10
-4 Torr) for oil flooded operation were achieved at 1 800 rpm.
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速水 洋, 玄 容翊, 妹尾 泰利
1988 年 54 巻 498 号 p.
414-418
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
To investigate the influence of tip clearance of a variable-area nozzle on the performance of a radial turbine, a series of experiments at the rated nozzle angle were pursued with various tip-clearance at various rotor speeds. The theory based on a two-layer flow model for nozzle with tip clearance, proposed in the preceeding paper, is applied to the prediction of turbine performance by combining the conventional prediction method for a turbine rotor. The predicted performances, such as the efficiency, the torque coefficient and the flow coefficient, agree well with the experimental data in practical application.
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井上 雅弘, 金子 賢二, 瀬戸口 俊明, 濱川 津充
1988 年 54 巻 498 号 p.
419-422
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
In order to develop an air-turbine with self-pitch-controlled blades for wave power utility, experimental investigations have been performed by model testing of turbine rotors with fixed staggered blades under steady operating conditions. Twelve kinds of rotors have been manufactured and tested to investigate the effect of setting angle, thickness/chord ratio, aspect ratio and solidity on the turbine performance. The results have shown that the self-pitch-controlled turbine is superior to the wells turbine both in starting and running characteristics. A suitable choice of the design factors has been suggested.
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原田 英臣
1988 年 54 巻 498 号 p.
423-429
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
The flow distortion at the impeller inlet of the multistage centrifugal compressor which employs three-dimensional impellers, and its effect on the overall compressor performance are studied experimentally by using a two-stage test apparatus. The flow distortion caused by the inlet casing which turns the flow from a radial to an axial direction are investigated. this experiment reveals that if the inlet casing of a low loss coefficient is used, the overall performance is almost the same as that obtained from an axial inlet stage. The flow distortion caused by the return channel are also investigated. The experiment shows that even if a flow distortion occurs at the second stage impeller inlet by the effect of the flow passage of the first stage, the overall performance of the whole stage can be predicted based on the single stage performance data obtained from the axial inlet test apparatus.
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井上 雅弘, 福原 稔, 九郎丸 元雄
1988 年 54 巻 498 号 p.
430-434
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
In order to allow an exact prediction of end wall blockage and losses of an axial flow compressor, the blade force-defect terms contained in pitch-averaged boundary layer equations are investigated on the basis of the data obtained from internal flow measurements. It is found that the existing models for the defect force are not in conformity with the actual flow phenomena near the blade tip region. Empirical formulae for simple modeling are presented to estimate the boundary layer development through a rotor with various tip clearances. The calculated results are satisfactory both in the displacement thickness and the tangential momentum thickness at the rotor exit.
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井上 雅弘, 九郎丸 元雄, 若原 啓司, 岩元 崇人
1988 年 54 巻 498 号 p.
435-441
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
Detailed measurements of tip clearance flow were made in an isolated axial flow compressor rotor with various tip clearances. The structure of the clearance flow was clarified by a phase-locked multi-sampling technique with a slanted hotwire in the clearance and with a high response pressure sensor on the casing wall. In the case of small clearance, leakage jet flow interacts violently with through flow near the leading edge and a rolling-up leakage vortex decays downwards. As the clearance increase, a stronger leakage vortex appears at a more downward location and a reverse flow appears due to the leakage vortex. A scraping vortex is observed at the downstream pressure side of the blade only for small tip clearance, and a horse-shoe vortex comes into existence at upstream part inside the rotor for every tip clearance.
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森下 悦生, 角田 昌之
1988 年 54 巻 498 号 p.
442-445
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
Scroll machines are being used for air conditioning application. The machines operate under heavy duty conditions. The scroll supercharger which has a rather light application, has also been studied. The authors have found that traction drive with the scroll wrap is possible by rotating the balanced scroll pairs. The machines may be employed for fans and blowers without oil. This type of machine does not require any balance weight, coupling or crank mechanism. Therefore extreme simplification has been achieved. This report presents the concept of the simplified scroll machine and the test results of the prototype.
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大八木 重治, 吉橋 照夫, 針谷 安男
1988 年 54 巻 498 号 p.
446-451
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
A 3m detonation tube with 25 mm ×30 mm rectangular cross-section instrumented to monitor a shock front (pressure transducers) was used to study the detonation of kerosene film attached to the tube walls. The effects of oxidizer dilution and initiation energy were investigated. The initiation was performed by oxyhydrogen detonation produced in a driver tube attached to the tube being tested. Shock waves whose propagating Mach number was as large as 5 were observed, which can be considered as detonation waves. The critical initiation energy above which the detonation waves could be initiated in this tube was obtained as a function of the oxidizer dilution ratio.
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林 勇二郎, 國峰 寛司, 山口 邦彦
1988 年 54 巻 498 号 p.
452-458
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
The freezing of an aqueous solution, occurs over a range of temperatures, and is composed of the solid, solid-liquid and liquid states. In this paper, latent heat thermal energy storage using aqueous solution as PCM is proposed, to pursue the high performance of a storage unit. Heat transfer characteristics were clarified by the experimental and theoretical studies, and the efficient and optimum configurations of the unit were determined.
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渡部 安雄, 南部 健一
1988 年 54 巻 498 号 p.
459-465
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
The angular distributions of molecular beam flux evaporated from a two-dimensional crucible partially filled with liquid are studied by use of the direct simulation Monte Carlo method. As the Knudsen number increases, the molecular flux is collimated near the center-line of the crucible. The collimation also increases as the liquid level in the crucible lowers. The thickness distributions of the film deposited on the holder surface perpendicular to the center-line of the crucible are calculated by assuming that every molecule incident on the holder is deposited on it. When the distance between the crucible exit and the holder is 50 times the crucible width, the thickness distribution can accurately be estimated by regarding the crucible as a point evaporation source.
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柏木 孝夫, 岡島 次郎
1988 年 54 巻 498 号 p.
466-471
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
This paper is concerned with the mass diffusion in the processes of NH
3 vapor absorption into the pure water and the aqueous solution of LiBr with 60% by mass. A holographic interferometer was employed to observe the sequence of the absorption phenomena and also to measure the unsteady concentration distributions in this absorption process. The results are compared with the theoretical ones, and it is determined that the mass diffusivities are 3-4.5×10
-9(m
2/s) for a binary system in the NH
3 concentration range of 35-70% by mass and 0.7-1.5×10
-9(m
2/s) for a ternary one in the NH
3 concentration range of 55-80% by mass. As seen in these results, since the mass diffusivity of the ternary system decreases considerably compared with the binary one, it is clear that the enhancement of mass transport is highly essential to increase the performance of the ternary absorption heat pump system.
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妹尾 泰利, 中村 克孝
1988 年 54 巻 498 号 p.
472-477
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
A liquid-fillet is formed in front of the rotor blades in thin-film evaporators. The shape of the fillet varies along the axis so that an axial flow is induced in the fillet. Furthermore, the shape of the fillet varies periodically as the blades rotate due to the circumferential variation of the gravitational effect. However, these secondary effects are disregarded and steady two-dimensional flow in the circumferential direction is theoretically examined. The influences of the viscosity and the amount of fluid in the casing as well as the tip clearance effect of blades on the thickness of the liquid-fillet are predicted, and good agreement with experimental data is demonstrated. The secondary effects disregarded in the present analysis will be presented in following papers.
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宋 載翼, 小栗 康文, 吉田 正武, 本望 行雄, 五味 努
1988 年 54 巻 498 号 p.
478-483
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
The Humidity in a mixture make delay times (Flame propagation delay : τ
dp, Total ignition delay : τ
t = τ
dfτ
dp) and total combustion period (τ
pmax) long. τ
df was determined by the record of the ion current, τ
dp and τ
pmax were determined by the indicated pressure diagram in the constant volume combustion chamber. the results are as follows : 1) The ignition delay time takes the minimum value around φ =1.15. 2) τ
df andτ
t time increased according to the increases of the concentration of dilution gases, because the adiabatic flmae temperature decreased due to the increases of the heat capacity. But dilution gases have little effect on flame nucleus formation delay. 3) The relation between τ
t time and the reciprocal of the laminer burning velocity is almost linear. 4) The larger the propagation length, the more was rate of changeτ
df, τ
dp, τ
t, τ
pmax by dilution gases addition ratio.
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宮本 登, 侯 志新, 原田 明, 小川 英之, 村山 正
1988 年 54 巻 498 号 p.
484-491
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
This research analyzes the nature of diesel soot suppression with soluble additives, aiming at efficient and sootless diesel combustion. A large number of additives were systematically examined for soot reduction and it was found that Ca and Ba were the most effective. The soot reduction ratio is expressed by an exponential function of the metal mol-content in the fuel, depending on the metal but independent of the metal compound. A rise in the excess air factor or gas turbulence in the combustion chamber increases the weight of a coefficient in the function, resulting in a larger reduction in soot with a fuel additive. In-cylinder soot sampling showed that the additive acted as a catalyst not only to improve soot oxidation but also to suppress soot formation.
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角田 敏一, 佐藤 豊水, / 角田 長三多, Osata SUMIDA
1988 年 54 巻 498 号 p.
492-498
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
The laser Rayleigh scattering technique was applied for the space resolved measurements of vapor concentration in the concentration in the combustion chamber of a multipoint injection spark ignition engine for automotive use. The mixture formation during the intake stroke was simulated by the timed or continuous injection of freon 113 (liquid) or freon 12 (gas) into the steady flow of dust-free dry air through an intake port. The vapor concentration in the transparent combustion cylinder was determined from the intensity of scattered light which had been calibrated beforehand. The results showed that the present optical system was found to be successful in determining the local vapor concentrations for both liquid and gaseous fuel injections. It was also evident that the highly heterogeneous field of vapor concentration was established in the combustion cylinder. The vapor concentration profile was largely affected by the place for fuel injection and the intake valve lift.
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吉川 滋, 西田 恵哉, 新井 雅隆, 廣安 博之
1988 年 54 巻 498 号 p.
499-505
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
Visualization by the liquid injection technique, in which liquid fuel is injected into another liquid, was applied to an investigation of the spray developing processes in a small direct injection diesel engine. The injector was newly designed to obtain spray characteristics similar to a diesel spray in a high-pressure atmosphere. The spray injected into water by this injector has a penetration and break-up length similar to the diesel spray. The behavior of the spray in a swirling water flow was investigated. Sprays with different break-up lengths show different behavior in the same swirling water flow. The spray with a higher injection pressure shows a larger spray angle, a lower dispersion by the swirling flow before impingement with the combustion chamber wall, but wider distribution along the wall after the impingement.
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石田 正弘, 泉 修平, 吉村 良孫, 末次 秀雄, 植木 弘信
1988 年 54 巻 498 号 p.
506-512
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
The authors have been conducting studies on the reduction of exhaust emissions using a high speed diesel engine with a bore of 110 mm and a maximum speed of 2 500 rpm. By applying composite countermeasures consisting of five items ; 1) timing retard, 2) optimization of fuel injection system, 3) water-in-oil type emulsified duel, 4) application of ignition improver and 5) an increase in air flow quantity, an exhaust NO
x level about a half of the original was attained while retaining the original low levels of fuel consumption, smoke density and engine noise. Especially, in combustion tests on water-in-oil type emulsified fuel, it is clearly demonstrated that not only exhaust NO
x but also smoke density are significantly reduced due to an increase in the excess air ratio of the fuel spray.
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石田 正弘, 泉 修平, 吉村 良孫, 末次 秀雄, 植木 弘信
1988 年 54 巻 498 号 p.
513-517
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
This paper deals with quantitatively the influence of water emulsified fuel on combustion, engine vibration and noise, and the effect of ignition improver on the reduction of vibration and noise. The main conclusions obtained are as follows : (1) With an increase in the water addition rate, ignition delays and the maximum pressure rise rate increases. As a result, engine vibration and noise increase, in proportion to the pressure rise rate. (2) An increase in ignition delay with the addition of water is closely related to the heat quantity required to evaporate water in the fuel spray under a high temperature and high pressure condition. (3) Increases in engine vibration and noise due to the addition of water can be reduced by adding a small amount of ignition improver without aggravating engine performance.
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山根 浩二, 近久 武美, 宮本 登, 村山 正
1988 年 54 巻 498 号 p.
518-526
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
This paper describes the factors affecting measurements of particulate and unburnt hydrocarbon emissions from diesel engines. A dilution mini-tunnel was used to characterize the effects of the dilution ratio and the sample temperature on the total particulate mass concentration and the soluble organic fraction (SOF) constituents. Increasing the sample temperature resulted in changes in the polynuclear aromatic hydrocarbon (PAH) constituents in SOF. The SOF components were separated by the column chromatographic technique, and the PAH fraction was determined by high performance liquid chromatography (HPLC). The analytical efficiency was improved by the use of silicagel for column chromatography, and octadecylsilan-bonded column for HPLC by keeping the column at high temperature. The gaseous hydrocarbon in the raw exhaust was analysed by GC with FID. The heated temperature of a sample glass syringe affected measurements of high boiling point hydrocarbon constitunts.
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関根 紀朗, 松村 修二, 高山 和喜, 小野寺 収, 伊藤 勝宏
1988 年 54 巻 498 号 p.
527-531
発行日: 1988/02/25
公開日: 2008/03/28
ジャーナル
フリー
In connection with the reduction of the exhaust noise of an internal combustion engine an experimental investigation was carried out with initiation and propagation of shock waves in the exhaust pipe in an internal combustion engine. The pressure measurements along the exhaust pipe clearly show that shock waves exsit in the exhaust pipe when the engine is running at high speed. In order to obtain a direct evidence of the existene of shock waves in the exhaust pipe, a flow visualization Study was conducted by using holographic interferometry, and shock waves were found. This indicat that, the non-linear effect should be taken into account at the design stage of engine muffler.
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