著者

円山 重直

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:18848346)

巻号頁・発行日

vol.78, no.796, pp.2127-2141, 2012 (Released:2012-12-25)

参考文献数

13

被引用文献数

2 4 1

---

An accident scenario of Fukushima Daiichi Nuclear Power Plant, Unit 2 is analyzed from the data open to the public. Phase equilibrium process model was introduced that the vapor and water are at saturation point in the vessels. Proposed accident scenario agrees very well with the data of the plant parameters obtained just after the accident. The estimation describes that the rupture time of the reactor pressure vessel (RPV) was at 22:50 14/3/2011. The estimation shows that the rupture time of the pressure containment vessel (RCP) was at 7:40 15/3/2011. These estimations are different from the ones by TEPCO, however; many measured evidences show good accordance with the present scenario.

著者

江波戸 明彦 蛭間 貴博

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:18848346)

巻号頁・発行日

vol.78, no.789, pp.979-983, 2012 (Released:2012-05-25)

参考文献数

3

被引用文献数

1 1

---

This paper attempts to improve the performance of ear-plug type earphones. The transmission characteristics of the ear canal with/without earphones are different. Therefore, the sound quality of the earphone is a little poor compared with audio speaker. In addition, it is well-known that the acoustical characteristics of ear canal vary among individuals. Therefore, we are studying to predict the acoustical characteristics of ear canal with ear-plug type earphones by using transfer matrix method and are studying how to improve the transmission characteristics of the ear canal. In this paper, a method for adjusting the resonance characteristic of the ear canal with earphones to the characteristic of the ear canal of AV speakers without earphones using digital filtering technique is proposed. With this method, the improvement of the sound reproduction performance was verified on the basis of experiments.

著者

宇田川 洋一 鈴木 実

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:18848346)

巻号頁・発行日

vol.79, no.808, pp.2818-2825, 2013 (Released:2013-12-25)

参考文献数

22

被引用文献数

1 3

---

Ballast water is used to stabilize an empty ship on the open sea. It often contains various microorganisms such as plankton and bacteria, and causes serious damage to aquatic ecosystems when it is discharged. Ultra-high pressure underwater shock waves were applied to treat those microorganisms. The imploding detonation of propane-oxygen mixture was used to generate the underwater shock waves in a sample holder having an inner diameter of 10.9 mm. We investigated the imploding detonation wave in approximately hemisphere-shaped combustion chamber having maximum inner diameter of 60 mm and generated underwater shock waves of 100 MPa. As microorganisms of the high pressure treatment experiments Artemia salina, Heterosigma akashiwo and Coliform group were used. We could completely treat Artemia salina and Coliform group by 5 shots and Heterosigma akashiwo by 1 shot of the underwater shock wave that maximum pressure was about 100 MPa.

著者

高見 創

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:18848346)

巻号頁・発行日

vol.79, no.803, pp.1254-1263, 2013 (Released:2013-07-25)

参考文献数

8

被引用文献数

1 18

---

There is a strong demand for improving brake system performance of Japanese Shinkansen which is a high speed railway to shorten the stopping distance at the time of an emergency such as a huge earthquake. An emergency brake for conventional train is a wheel disk brake system that is affected by rail tread surface condition (dry or wet condition), because of using friction (adhesion) between a wheel and rail. In order to achieve a high deceleration at the time of over 300 km/h, another complementary brake system guaranteed a stable braking force without the friction is required. In addition, it has to be a lightweight and small equipment space so that a passenger cabin capacity may not be affected. In this study, we discussed a small-sized aerodynamic brake system using an air drag panel. From the computational fluid dynamics using turbulent flow model and the wind tunnel experiment, the suitable shape of air drag panel, arrangement and an opening-and-closing mechanism of the panel were developed. In addition, a full-scale prototype aerodynamic brake device was designed and manufactured. Its aerodynamic characteristics were examined on a large wind tunnel with high Reynolds number. It was proven that the target braking force can be obtained with the small-sized aerodynamic brake placed into a thick turbulent boundary layer around the train at a running speed of 300 km/h.

著者

石野 洋二郎 手嶋 啓介 藤井 博之 山本 優作 齋木 悠

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:18848346)

巻号頁・発行日

vol.79, no.805, pp.1805-1815, 2013 (Released:2013-09-25)

参考文献数

13

---

A novel rotational internal combustion engine has been investigated in this study. No eccentric rotational component is used in this engine, resulting in vibration-free operation. The engine consists of rotor casing and two types of rotor; cycloid rotor and trochoid rotor. The shape of the cycloid rotor is characterized by epicycloid surface, and the trochoid rotor also superior-epitrochoid surface. In this paper, first, the typical configuration was shown. Next, a procedure for designing the rotors were described in detail. Furthermore the design drawing and appearance of the prototype engine were given. Its cyclic behavior, the time variations of the chamber volume and the estimated pressure were also indicated. Additionally the flame behavior in the working volume of the prototype engine driven in motoring condition, was presented. Finally the compactness and S/V ratio of the engine was investigated.

著者

和田 誠 小川 隆申 田村 浩章 山下 公明 大日方 昭善

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:18848346)

巻号頁・発行日

vol.79, no.806, pp.1963-1972, 2013 (Released:2013-10-25)

参考文献数

13

被引用文献数

2 2

---

The motion of a liquid pouring from a beverage can is experimentally and numerically studied. First, we measure pouring motion for sixteen examinees and find that the can motion in pouring consists of three stages; tipping stage, filling stage, and returning stage. In each stage, the angular velocity of a can is nearly constant, and its average velocity is obtained. A liquid flow from a can rotating at the average angular velocity is visualized with high-speed cameras and is also numerically simulated with the Volume of Fluid (VOF) method. At the beginning of pouring, the liquid from a can opening is once blocked by the rim of a upper lid and then flows over the rim. It falls from the can forming a V-shaped surface, which converges few centimeters below the rim expanding the liquid surface in the direction perpendicular to the V-shaped surface. This results in a wavy pattern of the liquid surface. The computational result agrees with the experiment.

著者

中根 一朗

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:18848346)

巻号頁・発行日

vol.78, no.790, pp.1220-1234, 2012 (Released:2012-06-25)

参考文献数

24

被引用文献数

1 2

---

Japanese cedar (Cryptomeria japonica) pollinosis is the most common allergic diseases in Japan, and some researchers show about 26.5% of population being affected. Japanese cedar pollen is carried by the wind, but the pollen suspension transport behavior must be different from the wind (carrier air flow) behavior because the aerodynamic diameter of this pollen is relatively large. I estimate the mean aerodynamic diameter of Japanese cedar pollen as about 35μm in this study. The pollen falls when the wind is weak, and it is blown up and carried (saltation and resuspension) by the strong wind. If the pollen flow behavior was completely corresponding to the wind, the range of Japanese cedar growth would be very broad and the peculiar distribution of Japanese cedar might be confused. This study aims to clarify the cedar pollen suspension transport behavior and saltation transport mechanism, and to confirm the prediction method of this behavior and mechanism. Accordingly, the followings were done : (1) The aerodynamic diameter of Japanese cedar pollen was measured and the test particle was selected. (2) The suspension and saltation behavior of the test particle was observed and measured by the optical measurement methods. (3) The suspension and saltation behavior was also numerically calculated. These measured and calculated results are shown and evaluated by each other result in this paper. The knowledge about the relation between air and particle velocities is acquired. The saltation mechanism is cleared. The suspension and saltation transport behavior can be predicted by this study method.

著者

土田 昭司

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:18848346)

巻号頁・発行日

vol.78, no.787, pp.374-383, 2012 (Released:2012-03-25)

参考文献数

16

著者

田中 光太郎 高橋 けんし 戸野倉 賢一

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:18848346)

巻号頁・発行日

vol.78, no.789, pp.1003-1007, 2012 (Released:2012-05-25)

参考文献数

7

---

A near-IR laser based spectrometer for continuous measurement of stable carbon isotopes in CO2 has been developed. 12CO2 and 13CO2 are detected with wavelength modulation spectroscopy and a Herriott-type multi-pass cell with a optical path length of 29.9 m using a distributed feedback laser diode in the 2-μm wavelength region. To measure the isotope ratio precisely, the influence of pressure and temperature variation in δ13C was evaluated. The limit of detection for 12CO2 in our system was 16 ± 1 ppbv. The precision in the determination of δ13C was 0.1‰ for 120 seconds signal integration time at ambient concentration levels. We demonstrate that our system enables automated continuous measurements of δ13C of CO2 in ambient air without any complex operation by users.

著者

鈴木 実 安西 竜也

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:18848346)

巻号頁・発行日

vol.79, no.801, pp.799-803, 2013 (Released:2013-05-25)

参考文献数

11

被引用文献数

1 1

---

Underwater shock wave, generated by the imploding detonation of propane-oxygen mixture, was applied for extinction processing of microbes. We filled the water containing microbe into a stainless steel pipe having inner diameter of 10.9 mm, and transmitted the underwater shock waves which have the maximum pressure of about 100MPa. As microbe of the treatment experiments, Microcystis species were used. We found that the mortarity rate of Microcystis species increases gradually with the increase in the number of times of shock processing. Although the maximum mortality rate of Microcystis species was 99.9% in one day after processing, it turned out that it becomes 100% in one week after processing. The mortality rate became small when the value of the consistency of Microcystis species was large.

著者

蔦原 道久

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:18848346)

巻号頁・発行日

vol.77, no.784, pp.2367-2378, 2011 (Released:2011-12-25)

参考文献数

78

---

The lattice Boltzmann method is briefly described from its basic theory to some applications. The basic equations, the discrete BGK equations, are introduced, and the concept of this method is explained Two types of models, that are non-thermal and thermal models exist, and some thermal flows are simulated by two-particle models. Examples of the aero-acoustics and the multi-phase flows are shown. Some new topics are also briefly described, and the references are presented.

著者

江端 重葉 安田 孝宏 南川 久人 宮本 悠治 里深 信行

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:18848346)

巻号頁・発行日

vol.79, no.806, pp.1886-1899, 2013 (Released:2013-10-25)

参考文献数

8

被引用文献数

1 3

---

Underwater glider is the glider to use for environmental researches in lake and sea. The Reynolds number of flow around underwater glider is between about 104 ~ 105 and the research for the aerodynamic characteristics of such low Reynolds number region is not so much. So in this study, we investigate the aerodynamic characteristics for various airfoils of under-water glider at low Reynolds number by the towing water tank experiment and 3-dimensional numerical analysis using STAR-CCM+ by IDAJ co. ltd. As results of experiment, the lift-drag ratio of airfoils with camber become larger than those of flat plate. As results of numerical analysis, the effect of maximum camber ratio and maximum camber position and thickness ratio on aerodynamic characteristics and optimum cross-sectional shape of wing for underwater glider are found.

著者

青木 克巳 武藤 浩司 岡永 博夫

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:18848346)

巻号頁・発行日

vol.77, no.775, pp.793-802, 2011 (Released:2011-03-25)

参考文献数

15

被引用文献数

1

---

The present study clarifies the effects of dimples for drag and lift on a sphere with rotation. The sphere with dimples has 328 arc type dimples on its surface uniformly. The present study measures velocity distribution in wake and pressure distribution on a sphere surface, and visualizes flow around a sphere by the spark tracing method for the case in which Reynolds number Re=0.4×105-1.3×105. For the case of a smooth sphere, separation point on deceleration side shifts downstream remarkably as spin rate ratio (circumferential velocity of a sphere / free stream velocity) increases. The pressure distribution on deceleration side decreases compared to that on acceleration side. The wake becomes small and shifts opposite direction of rotation. Therefore, the drag reduces, and the lift becomes negative. For the case of a sphere with dimples, this phenomenon occurs for the case in which critical Reynolds number Re=0.5×105. The separation point on acceleration side shifts downstream, and the separation point on deceleration side shifts upstream as spin rate ratio increases for the case in which super critical Reynolds number Re=1.3×105. The pressure distribution on acceleration side decreases compared to that on deceleration side. In addition, the pressure distribution on outside dimple decreases compared to that on inside dimple. The wake becomes large and shifts direction of rotation. Therefore, the drag and positive lift increase.

著者

篠木 俊雄 前田 毅 舟木 治郎 平田 勝哉

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:18848346)

巻号頁・発行日

vol.78, no.787, pp.415-419, 2012 (Released:2012-03-25)

参考文献数

8

被引用文献数

3 3

---

Supposing the design of ethanol steam-reforming reactors, the authors conduct experiments for Cu/ZnO/Al2O3 catalyst. Using a household-use-scale reactor with well-controlled temperature distributions, the authors compare experimental results with chemical-equilibrium theories. It has revealed by Shinoki et al. (2011) that Cu/ZnO/Al2O3 catalyst shows rather high performance with high hydrogen concentration CH2 at low values of reaction temperature TR. So, in the present study, the authors reveal the influences of liquid-hourly space velocity LHSV upon concentrations such as CH2, CCO2, CCO and CCH4 and the influence of LHSV upon the ethanol conversion XC2H5OH, in a range of LHSV from 0.05 h-1 to 0.8 h-1, at S/C = 3.0 and TR = 520 K. And, the authors reveal the influences of the thermal profile upon CH2, CCO2, CCO, CCH4 and XC2H5OH, for several LHSV's. To conclude, with well-controlled temperatures, the reformed gas can be close to the theory.

著者

横井 嘉文 平尾 恵子

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:18848346)

巻号頁・発行日

vol.77, no.775, pp.590-601, 2011 (Released:2011-03-25)

参考文献数

10

被引用文献数

2 2

---

In this study, the flow features of vortex shedding from a pair of parallel arranged circular cylinders (same diameters and unequal diameters) oscillating along the direction of the flow were observed by visualizing water flow experiment at the ranges of the frequency ratio f/fK=0-7, amplitude ratio 2a/d=0.125, 0.25, 0.5 and 0.75, gap ratio G/d=0.25, 0.75 and 1.75, and Reynolds numbers Re=470-670. The variations of mean vortex shedding frequency from each oscillating cylinder were investigated. As a result of the experiments, typical flow patterns of lock-in or un-lock-in state were shown every gap ratio G/d. It was found that the stage number of flow pattern was depended on the gap ratio G/d. In the cases of gap ratio G/d=0.25, there were four states, in the case of gap ratio G/d=0.75, there were six states, and in the case of gap ratio G/d=1.75, there were seven states. It was found that the measurement result of vortex shedding frequency depended on the observation point because the rearrangement of vortex formation had changed the characteristics of the flow. When the cylinders were oscillated to the direction of flow, the flow pattern of bias gap flow became not seen. The map of lock-in state in the lock-in range was obtained. It was found that the lock-in range and the lock-in form were more different from the case of single oscillating cylinder.

著者

菊地 謙次 今野 友博 市川 誠司 窪田 佳寛 望月 修

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:18848346)

巻号頁・発行日

vol.79, no.798, pp.151-163, 2013 (Released:2013-02-25)

参考文献数

29

被引用文献数

2

---

The purpose of this study is to know differences between steady and unsteady drag coefficients of a sphere. Though we often have to estimate unsteady drag-forces acting on a moving obstacle, we are obliged to use the well-known steady drag coefficient for the first estimation because of lack of information about effects of unsteadiness on the drag coefficient. The usual way to take account of unsteadiness is an added mass. However, its application is restricted within the simple shape of an obstacle. We propose a way based on the equation of motion to obtain the unsteady drag coefficient. To confirm validity of the way, we measured and analyzed the motion of the falling sphere in water by using a high-speed camera and a motion capture method. The drag coefficients as a function of time were obtained by substituting measured values of velocity and acceleration into the equation of motion. The drag coefficient was 0.52 when the sphere attains the terminal velocity, being quite large at the beginning of motion. Comparing with the values obtained by the other previous studies, our result is reasonable.

著者

秋山 修 加藤 千幸 河手 大輔

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:18848346)

巻号頁・発行日

vol.78, no.795, pp.1903-1918, 2012 (Released:2012-11-25)

参考文献数

21

被引用文献数

3 4

---

Mechanism of particle separation in a cylindrical cyclone separator has been fully clarified by a combined numerical method of large eddy simulation and a particle tracking method. The former resolves all the important vortical structures in the separator while the latter inputs the instantaneous flow fields computed by the LES and computes trajectory of each particle by considering Stokes drag as well as gravity force. Particle collection efficiency predicted by the proposed method has been compared with the experimental data measured for two cylindrical cyclone separators with several sets of particle diameters. The results showed that the collection efficiency has been quantitatively predicted by the proposed method, which confirms that the method can be used for the engineering design of such a cyclone separator. Detailed investigation of the particle trajectories predicted by the present method has clarified the mechanism of particle separation of a cylindrical cyclone separator. Those particles that are successfully collected by the separator move outward in the swirl flow and are collected when the swirl flow changes its direction at the bottom of the separator. The essential mechanism of this particle separation is due to the centrifugal forces acting on the particles. Three types of particle trajectories have been identified for those particles that are exhausted from the cyclone separator together with the swirl flow. More than half of the uncollected particles are trapped by longitudinal vortexes. The unsteady longitudinal vortexes and vortex rope drastically decrease collection efficiency.

著者

赤塚 純一 永井 伸治 本阿弥 眞治

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:18848346)

巻号頁・発行日

vol.77, no.784, pp.2391-2400, 2011 (Released:2011-12-25)

参考文献数

18

被引用文献数

3 5

---

This paper propose two new flow visualization methods based on the Background-Oriented Schlieren (BOS) technique for compressible flow. One is “Simplified background-oriented schlieren (S-BOS) ”. This technique does not require a cross-correlation algorithm, which is typically used in BOS. The data processing is much simpler than that of the original BOS, since image displacement associated with density gradient is algebraically calculated from intensities of the images with the periodic background pattern. Moreover, it easily allows us to automate the data processing, because it is neither necessary to remove incorrect vectors nor to optimize parameters such as the interrogation window and search window. The other is referred to “Wavelet-based background-oriented schlieren (W-BOS)”. This technique provides a schlieren image using continuous wavelet transformation for the periodic background pattern. By transforming the periodic intensity pattern into the phase, a schlieren image can be obtained easily. Since the optical setup in both techniques is simpler than that of a conventional schlieren imaging, they could be used in various situations including field tests. A wind tunnel test was conducted in a 1 m × 1 m supersonic wind tunnel. Their usefulness was demonstrated by comparing with the conventional schlieren images.

著者

奥村 幸彦 渡部 弘達 岡崎 健

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:18848346)

巻号頁・発行日

vol.79, no.799, pp.465-476, 2013 (Released:2013-03-25)

参考文献数

31

被引用文献数

1 1

---

The purpose of this study is to clarify the fundamental and general features of N2O formation during the combustion of pulverized biomass under low temperature. First, the effect of various important factors, i.e., combustion temperature, volatilization process (i.e., either slow or rapid dispersion), and nitrogen content in biomass on N2O formation were investigated by numerical analysis. The analysis of the effect of combustion temperature on the formation of nitrous oxide showed that N2O emission level increases with the decrease in combustion temperature, and both N2O and NO levels are strongly dependent on the combustion temperature. In other words, there is a trade-off relationship between the formation of NO and that of N2O. The analysis of the effect of the slow/rapid volatilization process on the formation of nitrous oxide showed that the conversion ratio of biomass-N to N2O increases with the decrease in the dispersion of volatile matter per unit time; it means that biomass-N is effectively converted to N2O during slow volatilization. Further, the gasification reactions among CO2, O2, and C occur simultaneously on the surface of biomass particles during combustion. With respect to the effect of nitrogen content in biomass, the N2O emission level increases with the increase in N-content of the biomass, while the NO emission level remains constant during low-temperature combustion.

著者

一宮 昌司 中村 育雄

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集B編 (ISSN:18848346)

巻号頁・発行日

vol.78, no.788, pp.794-810, 2012 (Released:2012-04-25)

参考文献数

62

被引用文献数

4 4

---

Investigations on the definition and randomness of turbulence was reviewed at first. Then, the Kolmogorov complexity which measures the randomness were introduced. Numerical and graphic data in the mixing layer which was formed downstream of two-dimensional nozzle exit were compressed with the aid of a compression program. Approximated Kolmogorov complexity, AK, and normalized compression distance, NCD, were obtained. The AK indicated the regularity of the laminar flow and the randomness of the turbulent flow quantitatively. The NCD of the numerical value varied with data length. Between the same data, it approached zero, yet, on the other hand, between different data, it approached unity as the data length increased. The NCD of the numerical value in the natural transition process in the mixing layer increased monotonically downstream. Thus the NCD appears to be the measure of the transition process. In the natural transition process in the mixing layer, the AK of the numerical value and the NCD of the graphic data did not change monotonously in the downstream direction. Thus they contain some uncertainty for the measure of the transition process.