著者

金子 明成

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.61, no.585, pp.1880-1887, 1995-05-25

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A two-dimensional finite-element model for dye diffusion thermal transfer printing has been developed, in which partition coefficients are included. Experimental data of the partition coefficients and the dye diffusion coefficients are used in the model. Dye concentration after printing is not always continuous at the interface between the dye-coated layer and receiver-coated layer in the model. The stability of the computer calculation has been checked from various points of view. The optical density prediction shows good agreement with the experiments. The model has been applied to the calculation of the amount of transferred dye when the physical parameters of the medium are varied. It is concluded that the most important factors for increasing the amount are the dye diffusion coefficients and the partition coefficients.

著者

多田 茂 大島 修造 山根 隆一郎

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.57, no.536, pp.1257-1264, 1991-04-25

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A numerical method employing physical components of the tensorial quantity as dependent variables on boundary-fitted curvilinear grids is applied to the simulation of flow in arbitrary cross-section curved pipes for an imposed pressure gradient of oscillatory nature. The basic equations are formulated for Stokes fluid. The computation for a Newtonian incompressible fluid in curved concentric annuli and curved eccentric annuli was carried out for the range 10^3 ≤ De ≤ 10^5, 1 ≤ Wo ≤ 10^2, where De is the Dean number and Wo is the Womersley number. It is found that, at very low or very high Womersley number, the amplitude of the wall shear stresses derived numerically is in good agreement with that of the zero-th order of the asymptotic expansions of the solution of concentric annuli as the curvature parameter δ tends to zero, and that 2 pairs of secondary flow appear for even low Womersley number, contrary to the case of the circular coiled tubes.

著者

橋本 知之 渡辺 義明 渡邉 光男 上條 謙二郎

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.63, no.607, pp.765-771, 1997-03-25

被引用文献数

1

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The regions of cavity fluctuations in an inducer were investigated with three different types of housing : modified, original and straight. The region of rotating cavitation with modified or straight housing shifted to a higher flow rate range than that with original housing. Some results of visual observations suggested that the reversed flow aroud the tip of the inducer inlet is related to this phenomenon. The rotating cavitation velocity ratio seemed to approach 1.0 as the magnitude of shaft vibration increased. Another rotating cavitation was identified at a lower cavitation number than that at which attached cavitation occurred.

著者

岸田 耕一 金子 雄大 大島 伸行 永田 晴紀

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.76, no.765, pp.789-794, 2010-05-25

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This paper investigates a thermal-fluid dynamics of CAMUI (Cascaded Multistage Impinging-jet) type hybrid rocket developed in Hokkaido University by using a large eddy simulation of turbulence. The performance of the hybrid rocket is sensitive to the changing shape of its chamber. To clarify this effects, numerical simulations were conducted using measured shapes. The results show the flow structures such as impinging fountain flow depending on the shapes at different burning time. Thease structures generate the particular heat flux distributions on the surface.

著者

奥田 孝造 井小萩 利明

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.62, no.603, pp.3792-3797, 1996-11-25

被引用文献数

10

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In order to investigate the complex behavior of collapsing bubbles in cloud cavitation, numerical simulations have been performed by solving the 2-D governing equations for gas-liquid two-phase media. Here, the equation of state for such media is derived from the locally homogeneous assumption, so that the apparent compressibility can be taken into account. The interface of a bubble or a cloud of bubbles is treated as a contact discontinuity surface, where the values of density and void fraction are allowed to jump. When the void fraction in a bubble cloud is almost 100%, the collapsing behavior agrees well with that of a single bubble. Numerical results of the interaction between some bubbles and an incident shock wave show qualitative agreement with experimental results. Therefore, complex interaction phenomena between multibubbles can be simulated when some small bubbles are arranged in a bubble cloud by distributing the corresponding void fractions nonuniformly.

著者

永井 秀和 趙 黛青 山下 博史

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.71, no.709, pp.2339-2345, 2005-09-25

被引用文献数

3

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In order to clarify the effects of density ratio and laminar burning velocity on the vortex bursting phenomenon, the premixed flame propagation in swirling flow has been examined by the numerical calculation for various preheating temperatures and equivalence ratios. In this calculation, the flame is fixed in the computational domain by adding an axial flow to the unburnt premixed gas so as to obtain the steady state propagation characteristics. The obtained results are as follows: The present flame propagation velocities relatively agree on "the back-pressure drive flame propagation theory (radial expansion)" proposed by Ishizuka et al. The variation of the pressure along the vortex axis occurs between the inflow part and the flame front, and the pressure in the burnt region is almost uniform. Therefore, the propagation speed must be estimated by the Bernoulli's equation by using the density of unburnt mixture. We have proposed a new formula on the basis of the present calculation results, and have confirmed that flame propagation speed accords qualitatively and quantitatively with this formula. Moreover, we have suggested that, considering the application to the combustor with swirling flow, the preheating of premixed gas enhances its performance due to the large burning velocity.

著者

大上 芳文 赤松 映明

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.55, no.510, pp.298-305, 1989-02-25

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A numerical investigation is carried out to examine the validity of the unsteady Kutta condition presented by many authors. Using a vortex method with a diffusion velocity model, the flow under a transient and oscillating motion of a NACA 0012 airfoil at Re=10000 is calculated. It is found that after the airfoil starts impulsively from rest, the rear stagnation point moves to the trailing edge instantly. Then the angle between the stream line from the trailing edge and the edge bisector decreases from 90° to 10° for the nondimensional time 0 to 0.1. After that time, the classical Kutta condition gradually becomes satisfied. In an oscillating motion, the rear stagnation point is always on the trailing edge and the amplitude of the angle of stream line direction from the trailing edge increases with the frequency. This result shows that the classical Kutta condition is always violated in an oscillating motion.

著者

大西 領 松田 景吾 高橋 桂子 黒瀬 良一 小森 悟

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.73, no.734, pp.2062-2069, 2007-10-25

参考文献数

18

被引用文献数

1

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We have developed a new simple inversion scheme for retrieving collision kernels from the change of droplet size distributions due to collision growth. Three-dimensional direct numerical simulations (DNS) of colliding droplets in an isotropic steady turbulence are performed in order to investigate the validity of the developed inversion scheme. In the DNS, air turbulence is calculated using a quasi-spectral method, and droplet motions are tracked by a Lagrange method. The initial droplet size distribution is set to be equivalent to that obtained in a wind tunnel experiment. Comparison between collision kernels retrieved by the developed inversion scheme and those obtained by DNS shows that the collision kernel can be retrieved within 15% error. This verifies the feasibility of retrieving collision kernels by using the present inversion scheme.

著者

井村 英昭 吉田 正道

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.56, no.532, pp.3816-3820, 1990-12-25

被引用文献数

4

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An experimental study on the heat transfer coefficient and critical heat flux in two-phase double-tube thermosyphons was carried out using water, ethanol and R113 as the working liquids. The same experiment for a single-tube thermosyphon was also performed for comparison. The effects of the top-end shape of inner tubes on the heat transfer coefficient and the critical heat flux were investigated in detail. As a result, it was shown that the heat transfer coefficient was not significantly affected by the difference of the top-end shape, but the critical heat flux was very sensitive to the top-end shape of the inner tubes. For R113, the critical heat flux in the thermosyphon with the inner tube having a T- or flange-shape top-end, was about four times as large as that in the single-tube thermosyphon.

著者

三輪 惠 武内 久 江口 知孝 楊 長林

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.65, no.638, pp.3517-3522, 1999-10-25

参考文献数

13

被引用文献数

4

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In order to realize simultaneous reduction of NO_x and Particulate emissions, effects of combustion chamber geometry were investigated in a high speed direct-injection diesel engine. The reentrant combustion chambers with different throat diameter were compared in terms of engine performance, combustion characteristics and emissions such as NO_x, particulate and THC. The phenomena of combustion process were also observed with endoscopic high speed photography. The results showed that when the throat diameter of a reentrant combustion chamber was reduced to an extent, NO_x and particulate decreased simultaneously due to retarded injection timing and the intensified squish.

著者

沢田 正剛

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.57, no.535, pp.1097-1100, 1991-03-25

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Field experiments on utilizing the cold energy obtained during winter by storing it in the ground as artificial permafrost using heat pipes have been carried out over several years. Using the data obtained from the experiments, mumerical simulations were performed for the creation and degradation of a frozen underground zone. For predicting the temperature field, the finite difference method was used, and the latent heat associated with freezing or thawing of the soil water was treated as a heat sink (source). The simulations were performed using three kinds of soil: silt, clay and sand. The following fact became clear as a result of the simulations: if the two-dimensionality of the ground temperature is maintained under suitable soil conditions, it is possible to surround an area of 8m×8m with 4m-thick artificial permafrost using 72 lengths of heat pipe.

著者

土方 邦夫 鈴木 祐二 相澤 芳弘 小澤 由行

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.61, no.587, pp.2757-2763, 1995-07-25

参考文献数

5

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For more effective ventilation from the room floor, where polluted air and dust arise, a new ventilation system located on the ceiling has been developed by using fresh intake air and generating a tornadolike vortex to ventilate the air near the floor both locally and directly. In a water tank, which simulated a room space, the same tornadolike vortices were visualized using ink diffused from the base, and the ventilation efficiency was measured. In order to apply this new ventilation system to local cooling, the heat transfer performance at the floor was also investigated.

著者

平松 道男 石丸 典生 松崎 耕正

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.55, no.519, pp.3457-3461, 1989-11-25

被引用文献数

3

著者

内藤 健 伊東 輝之 高木 靖雄 桑原 邦郎

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.59, no.559, pp.953-959, 1993-03-25

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Large-eddy simulation of a turbulent premixed flame in an engine is performed in a wide range of operating conditions such as engine speed, airfuel ratio, and ignition timing. A numerical method for estimating supergrid fluctuations of physical quantities and the space-averaged quantities accurately is proposed. As the subgrid estimations, the Yakhot-Orszag turbulence model based on the renormalization group theory and a flamesheet model are employed. For some variations of the operating conditions, obtained computational data agree well with experimental data on turbulence intensity and pressure history. It is also shown that the developed numerical model has the potential of calculating the cyclic variations of flow and combustion. An important understanding on the physical situation in conventional 4-valve engines, is obtained from the present study, which is that laminar regions may exist at the low engine speeds.

著者

蒔田 秀治 飯田 明由

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.55, no.515, pp.1847-1854, 1989-07-25

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The local similarity hypothesis was verified in quasi-isotropic turbulent flow fields with turbulence Reynolds numbers of over 3000. The quasi-equilibrium range was known to exist in a turbulence field with turbulence Reynolds numbers of Re_τ >60. The lowest wave number of the quasi-equilibrium range in the energy spectrum was dependent on T_L/T_O : the ratio between the time scale of decay of turbulence energy and the characteristic time scale o an energy-containing eddy. Turbulent eddies with characteristic time scales of less than T_L/4 were statistically stable. The energy dissipation rate was theoretically determined as ε=C_1(q^2/2)^<3/2>/l_O, and the scales of turbulence were estimated from C_1 and Re_λ.

著者

高木 周 松本 洋一郎 黄 華雄

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.61, no.586, pp.1976-1983, 1995-06-25

被引用文献数

10

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A numerical method is developed to simulate the unsteady axisymmetric flow with a free surface. The method is based on a finite-volume solution of the equations on an orthogonal curvilinear oordinate system. A new iteration technique is used for the boundary condition of the free surface to stabilize the solution. The method is applied to simulate an unsteady motion of a single deformed bubble rising through a quiescent liquid. The numerical results show quantitatively good agreement with those of experiments and calculations of others. In the present study, the transitional phenomena of the initially spherical bubble in reaching the steady state are investigated. It is known experimentally that the rising bubble begins to show an unsteady three-dimensional (spiral or zigzag) motion beyond certain critical Reynolds and Weber numbers. Our numerical results of the axisymmetric flow show unsteady shape oscillations in the parameter range of the three-dimensional motions.

著者

藤沢 延行 Adrian Ronald J.

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.63, no.607, pp.818-823, 1997-03-25

被引用文献数

8

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A new calibration technique of liquid crystal thermometry has been introduced to the quantitative measurement of temperature in a thermal fluid and applied to the study of turbulent thermal convection. The present calibration technique improves the accuracy of temperature measurement in comparison with the classical calibration technique with hue. Three-dimensional temperature measurement of turbulent thermal convection over a horizontal smooth surface is carried out at a flux Rayleigh number of 3×10^9 by scanning a light sheet normal to the image plane and capturing a number of sequential visualized images. The spatial temperature distributions of thermal plumes over a horizontal surface are demonstrated by the reconstruction of isothermal contour surfaces and various cross-sectional views of the plumes. These results indicate the presence of a polygonal cell structure close to the surface and the generation of plumes at the intersections of high-temperature lines.

著者

清水 徹 横川 明 鈴木 基光 中村 育雄

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.51, no.469, pp.2908-2915, 1985-09-25

被引用文献数

1

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種種の乱れ発生要素を入り口に設けたく形断面流路における繊維懸濁液流れの濃度むらを比較的高い濃度にわたって測定し,その管軸方向への分布や平均濃度および平均流速に対する依存症について検討した.この結果,流れの乱れによる濃度むらの減少には限界値が存在すること,また十分に発達した流れ場における繊維懸濁液の濃度むらは非ニュートン流体の広義のレイノルズ数で整理できることが明らかになった.

著者

篠山 鋭一 斉藤 敬三

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.47, no.421, pp.1891-1899, 1981-09-25

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比較的光化学スモッグが発生しやすい条件を基本にとり, この条件から各種因子を変えてスモッグチャンバによる光化学エアロゾルの生成実験を行うことによりこの条件における各種因子の影響を調べた. HCはエアロゾル生成に正負両面の影響を持ちその影響は種類により大きく異なること, NO_xは負の影響を持つと考えられること, SO_2は正の影響を持つこと, 湿度は大きな正の影響を持つことなどが解明された.

著者

佐藤 義久 吉田 尚嗣 田辺 幸典 藤田 秀紀

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.72, no.717, pp.1335-1341, 2006-05-25

被引用文献数

2

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It is necessary to use the low temperature thermal energy around 100 degress C from a viewpoint of global warming prevention. Even if a shape memory alloy is bent in normal temperature, when it is heated, it has the character which returns to the original straight form. Using this character of a shape memory alloy, unused thermal energy will be able to transform into rotation energy. A shape memory alloy belt is hung on a high temperature wheel and a low-temperature wheel. On this simple pulley type shape memory alloy engine, a shape memory alloy belt is heated with a high temperature wheel, it occurs a moment when returning to the original straight form, the moment kicks a high temperature wheel by the principle of action reaction, and torque is generated. We solved this torque generating mechanism. We proposed the theory which can design the output power of the simple pulley type shape memory alloy engine. Furthermore, the validity of this theory was verified by experiment.