著者

荒木 幹也 嶋津 有宏 小保方 富夫 石間 経章 志賀 聖一 増渕 匡彦 杉本 知士郎

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.73, no.726, pp.622-630, 2007-02-25

被引用文献数

9

---

Atomization characteristics of an ultrasonic fuel injector using a micro nozzle array were investigated experimentally. Micro nozzles whose exit diameter is d=3, 6 and 9μm are mounted on a thin metal film. The number of the micro nozzle is 2.0×10^4. Using an ultrasonic oscillator, gasoline is periodically pushed out from the micro nozzles at the frequency of 63.6 kHz. A disk-type PZT is used as an ultrasonic oscillator, and the oscillation is amplified using a step-type horn. The input voltage is varied from 0 to 200 V. At the natural frequency, the oscillation amplitude of the horn is about 10μm. The droplet diameter and velocity are measured with a phase Doppler analyzer at 15 mm downstream from the micro nozzle array. For d =3μm, the Sauter mean diameter (SMD) is about 10μm, and the fuel flow rate is 0.023 cc/s. The SMD is much smaller when compared to conventional port fuel injectors. For d=6μm, the SMD is about 10 to 18μm, and the fuel flow rate is 0.055 cc/s. For d=9μm, the SMD is about 16 to 28μm, and the fuel flow rate is 0.41 cc/s. It is shown that, using the micro nozzle array, a uniform-diameter steady spray can be obtained without high-pressure fuel pump and nozzle type injectors.

著者

阿部 豊 新井 崇洋

出版者

日本機械学会

雑誌

日本機械学會論文集. B編 = Transactions of the Japan Society of Mechanical Engineers. B (ISSN:03875016)

巻号頁・発行日

vol.71, no.702, pp.658-665, 2005-02-25

---

Spontaneous vapor explosion can occur when a layer of the high temperature molten material lies on the water pool or on the moisture floor. This is so-called base-triggered vapor explosion. The base-triggered vapor explosion is supposed to occur in the case of a severe accident in various industrial facilities. It is very important to clarify the occurrence condition and possibility of the base-triggered vapor explosion from the viewpoints of the prediction and the prevention of the vapor explosion. In order to evaluate the occurrence conditions and to clarify the micro-mechanism of the base-triggered vapor explosion, the experimental apparatus to observe the base-triggered vapor explosion from the bottom of the floor to above is designed and constructed. The experiments using U-Alloy95 as a simulant material are conducted. Consequently, the microscopic behavior at the interface between the molten material and water can be observed in detail with this experimental apparatus. The interfacial behavior of the molten material is quantitatively evaluated by the PIV analysis and the digital auto-colrrelation method with the experimental results. The blowout velocity of the molten material at vapor explosion is evaluated from the visual data obtained on the experiment. The generated pressure at the vapor explosion is estimated by using the blowout velocity. In addition, occurrence condition of the base-triggered vapor explosion is evaluated with the thermal interaction zone (TIZ) theory.

著者

石川 拓司 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.63, no.607, pp.789-797, 1997-03-25

被引用文献数

13

---

It is well known that the fluid dynamics of arterial blood flow play an important role in arterial disease. The periodic blood flow through a stenosed tube with a moving wall is analyzed numerically. The Windkessel model is used to express arterial wall movement. A revised Casson model which is appropriate for numerical simulation is proposed as a constitutive equation of blood. The flow is assumed to be periodic, incompressible and axisymmetric. The influence of wall movement on flow through a stenosed tube is investigated. The flow pattern, separated region and the distributions of pressure and shear stress at the wall are obtained. The results show that the wall movement reduces the strength of vortex downstream of the stenosis and has considerable influence on the physical quantity of flow at the wall in one period. Therefore, it is concluded that the influence of wall movement should be taken into consideration for blood flow through a stenosed tube.

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

---

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

---

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

---

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

---

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

---

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

---

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

---

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

太田 有 大田 英輔 斎藤 純夫

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 = Transactions of the Japan Society of Mechanical Engineers. B (ISSN:03875016)

巻号頁・発行日

vol.68, no.671, pp.2056-2063, 2002-07-25

参考文献数

14

被引用文献数

1

---

Active cancellation of noise source of higher-order blade-passing frequency noise, abbreviated to BPF noise, radiated from a centrifugal blower is conducted. The extents of noise sources of 2nd-and 3rd-order BPF components were determined by measuring a cross-correlation function between the data of the acoustic pressure measured at blower inlet and the pressure fluctuation on the scroll surface. The effective noise sources of these higher-order BPF components exist on the volute side surface of scroll relatively apart from the cut off apex, and vary irregularly with operating conditions of the blower. While the noise source of fundamental BPF lies on the vicinity of the cut off apex as usually expected. Oscillating the volute side surface of the cut off, i.e. the effective noise source of higher-order BPF components, directly by piezoelectric actuators, sound pressure level of higher-order BPF components can be reduced more than 15 decibels, and discrete tone disappears completely from power spectra of the blower radiated noise.

著者

藤田 恭伸 アレクサンダー ロペス

出版者

一般社団法人日本機械学会

雑誌

日本機械学会論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.61, no.588, pp.3044-3051, 1995-08-25

被引用文献数

3

---

Experimental data of liquid and vapor flows of R 113 for Re=5000〜400000 were obtained for both a plain tube and snugly fitted twisted tape insert tubes. No evidence of tape fin effects was found in the heat transfer characteristics of a stainless steel tape insert when compared to a Teflon tape insert. For twist ratios γ = 5.9, 10.0 and 16.0, improvements in heat transfer of up to 35% were observed. Based on a simple consideration of the heat transfer enhancement mechanisms of twisted tape inserts, a Dittus and Boelter-type correlation for a plain tube was modified to include twisted tape effects. For such a case, use of available plain-tube data was recommended to maximize the accuracy of the proposed correlation. The trade-off between pressure loss and heat transfer enhancement was considered before determining the overall desirability of twisted tape inserts.

著者

大橋 博志 門脇 敏

出版者

The Japan Society of Mechanical Engineers

雑誌

日本機械学会論文集 B編 (ISSN:03875016)

巻号頁・発行日

vol.79, no.802, pp.1185-1185, 2013

---

3件の誤植がありましたので訂正いたします.

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

---

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

---

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

西村 正治 糟谷 秀太郎 後藤 知伸

出版者

The Japan Society of Mechanical Engineers

雑誌

日本機械学会論文集 B編 (ISSN:03875016)

巻号頁・発行日

vol.78, no.789, pp.949-953, 2012

被引用文献数

1

---

Light wall structures with high sound insulation performance are desired to be developed for houses and fuselage of vehicles. In this paper, a new light sound insulation structure is proposed. It is constructed with light inflated membrane bound by hard wire nets. By impedance tube tests, the proposed structures were proved to have not only high but also adjustable sound insulation performance by tuning the inside air pressure, which means stiffening the membranes. This structure can also construct a light sound insulation panel with high sound insulation performance by being inserted between light double walls.

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

---

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

---

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

---

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

大西 領 高橋 桂子 小森 悟

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 B編 (ISSN:03875016)

巻号頁・発行日

vol.72, no.722, pp.2441-2448, 2006-10-25 (Released:2011-08-16)

参考文献数

21

被引用文献数

1 1

---

The collision frequency of inertia particles in turbulent flows is governed by a wide range of scales of flow motion. Recent studies have shown that large-scale energetic eddies dominate the relative velocity between two colliding particles (the turbulent transport effect), whereas small-scale dissipative eddies can enhance the collision frequency significantly by inducing local non-uniform particle distribution (the accumulation effect). In this study, we have developed an integrated collision kernel model, which takes into account both the turbulence effects and can predict collision frequencies at arbitrary Reynolds numbers and particle inertia. In addition, we have implemented the developed collision kernel model into a large-eddy simulation (LES). We have performed our developed LES for particle collision growth in an isotropic evolving turbulence. A direct numerical simulation (DNS) for the same system has also been done. Comparison between our LES and DNS predictions has confirmed that our LES can predict the particle collision growth in the turbulent flow.