著者
小原 哲郎 大八木 重治 高藤 亮一 蔡 品
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.67, no.659, pp.1680-1686, 2001-07-25 (Released:2008-03-28)
参考文献数
14

Experiments are carried out to investigate behavior of shock wave diffraction from a safety-engineering point of view. Because, once the shock wave is released into an ambience, high pressure and negative pressure lasting for relatively long period have possibility to cause serious damages against human bodies as well as general buildings. Therefore, it should be one of the most significant subjects to attenuate the shock wave efficiently within a short distance from the source. In this report, a cavity is installed at an open end of a shock tube and flow-fields behind diffracted shock wave are visualized using schlieren photography. In addition, piezo-electric pressure transducer is flush mounted on the surface of reflector, which is installed at test section, and pressure histories are recorded with wide frequency response. Lastly, numerical simulation using the TVD finite difference scheme is performed to compare with the experimental results. As a result, (i) the pressure histories on the reflector coincides well between the numerical and experimental results, (ii) flow-fields behind the shock wave are clarified, (iii) maximum pressure behind reflected shock wave can be attenuated by installing several cavities inside the open end of the shock tube.
著者
高藤 亮一 山中 昭央 小原 哲郎 蔡 品 大八木 重治
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:03875016)
巻号頁・発行日
vol.65, no.639, pp.3602-3607, 1999-11-25 (Released:2008-03-28)
参考文献数
12
被引用文献数
2 2

As is well known when a shock wave is emitted from an open end of a tube, an expansion wave and a vortex ring are generated behind the shock wave. Furthermore, a contact surface, slip line and these wave interactions may cause considerably complicate flow-fields. In this study, shock waves of Mach number 1.3, 1.6 and 2.2 are produced utilizing diaphragm-less shock tube of 50 mm diameter and c. a. 10 m total length, and the flow-fields are visualized with an aid of schlieren optical techniques. A cylindrical reflector is installed at test section and stagnation pressure behind reflected shock wave is measured with wide frequency response. A numerical analysis is also carried out to investigate these flow-fields using Predictor-Corrector TVD finite difference scheme. As a result, (i) the contour of diffracted shock wave is well coincided between experimental and numerical results, (ii) pressure histories behind reflected shock wave are clarified, (iii) an empirical formula is obtained between Mach number, non-dimensional distance from the open end of the tube and non-dimensional pressure just behind reflected shock wave.
著者
田中 忠良 山田 幸生 石黒 博 竹内 正顕 山下 衛 小竹 進
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.55, no.515, pp.p2018-2023, 1989-07

The body temperatures of anesthetized patients under going operations decrease gradually because control of the body temperature is suppressed and the temperature of the operating room is kept lower than the body temperature. In order to prevent a patient's body temperature from lowering during an operation, a mat with hot-water circulation is often used. However, it has been reported that burn injuries occasionally occur in such cases, even when no defect in temperature setting and control of the mat is found. The mechanism causing this burn injury has not been determined. This report analyzes the heat transfer of a body-mat system simulated by a simplified model to examine the possibility and mechanism of such burn injuries. The analysis discusses the effects of hot-water flow rates, hot-water temperature and metabolic heat generation on body temperature. It is found that burn injury can occur, particularly in the high metabolic state, when heat transfer by the blood flow is negligible and the rate of water flowing into the mat is reduced considerably.
著者
山田 敏郎 可児 弘毅 生田 耕治
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.47, no.415, pp.450-460, 1981

衝撃超高圧力研究用に超高速飛しょう体発射装置(二段式軽ガス銃)が試作され, その性能の数値解析が試みられた. 試作装置により16.4gの飛しょう体が3.57km/sまで加速・発射された. 発射実験結果と性能解析の予想値との良い一致により, 解析法の妥当性が確かめられた. 性能解析により, 試作装置は9.5gの飛しょう体が5km/sまで加速できることおよび発射速度支配因子のうち, 特に装薬量と飛しょう体質量の影響が大であることなどが明らかにされた.
著者
古谷 正広 太田 安彦 北口 佳範 大崎 守 村井 美樹 磯貝 鉄也
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.67, no.662, pp.2625-2631, 2001-10-25

Compression ignition of a stoichiometric iso octane/oxygen/argon mixture was observed using a shock tube and a rapid compression machine. Reducing the compression temperature, the activation energy for the shock compression ignition fell suddenly at the critical temperature the ignition delay exceeded around 1 ms. This peculiarity could be seen in the shock compression stoichiometric methane ignition with which mixture absolutely no cool flame low-temperature reactions accompanied. Shock wave diagrams indicated that the ignition was originated not at the end of the tube but to the inside of the tube. It resulted in the smaller activation energies in the lower temperature regions. This phenomenon was not due to the difference of chemical reaction mechanisms. IIigh-speed schlieren observations using another shock tube with visualization windows have allowed us to confirm the peculiarity that the earliest ignition sites were located apart from the tube end and the ignition initiation structure would change depending on the compression temperature.
著者
田中 耕太郎 根岸 明 増田 俊久
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:03875016)
巻号頁・発行日
vol.58, no.553, pp.2857-2862, 1992-09-25 (Released:2008-03-28)
参考文献数
13

The replacement of working fluid of the alkali metal themoelectric converter (AMTEC) is eminently suitable for achieving higher performance under lower operating temperatures. Potassium is a reasonable condidate because it has lower latent heat of vaporization and higher vapor pressure than sodium over the AMTEC operating conditions. The performance of the AMTEC cycle with potassium as the working fluid has been evaluated and discussed based on the recently reported ionic conductivity data of potassium-β"-alumina solid electrolyte. The calculated results show that the replacement of working fluid increases the peak efficiency from 28% to 31% at 1100K with 1mm thick β"-alumina solid electrolyte. If the thinner solid electrolyte is practically developed, the improvement of the performance can obviously be recognized because of the decrease of ionic conductivity.
著者
佐藤 明
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.583, pp.933-938, 1995-03-25 (Released:2008-03-28)
参考文献数
15

The object of the present study is to evaluate the performances of various microcanonical molecular dynamics algorithms. To do so, the divergence times and energy fluctuations are discussed for a model system, i. e. a three-dimensional Lennard-Jones system under various conditions of number densities and temperatures. The results of the evaluations of superiority or inferiority of algorithms are as follows. The velocity Verlet, leapfrog, and Beeman algorithms are significantly superior to the other algorithms such as the 4-value Gear algorithm since a system does not diverge and the energy conservation law is reasonably satisfied for much larger time intervals. Although these three algorithms show approximately the same performance concerning the properties of divergence times and energy fluctuations, we can conclude that the velocity Verlet algorithm is the most suitable for molecular dynamics simulations of flow problems, since this algorithm is easy to use, requires less computer memory, and evaluates molecular positions and velocities at the same time steps.
著者
上宇都 幸一 越後 亮三 長谷川 修
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.45, no.390, pp.261-269, 1979-03-01

繊維媒体領域に外部から一様な平行光が入射する場合の媒体中でのふく射輸送を積分方程式法によって解析し、入射ふく射束分布、ふく射熱流束分布を明らかにしたが、とくに入射ふく射束分布については、散乱のアルベドが大きい領域で、ピークが形成されることを示した。また精度のよい指数積分核近似法を提示した。さらに本体系のふく射減衰関数はBickley-Naylor関数で表示できることを示し、二、三の積分公式を導いた。
著者
岡西 直樹 福谷 格 渡部 英一
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:03875016)
巻号頁・発行日
vol.56, no.525, pp.1558-1564, 1990-05-25 (Released:2008-03-28)
参考文献数
4

To improve the volumetric efficiency of a crankcase-supercharged 4-stroke cycle engine in the high speed range, rotary disc valves were used at both the inlet and the outlet sides of the crankcase in an investigation of the effects of opening angle and timing of disc valves on the volumetric efficiency. As a result it was found that a volumetric efficiency of 120% was possible over a wide engine speed range of 3000-6000 rpm, which was not poss ble by using the reed valve system.
著者
染矢 聡 吉田 智 李 艶栄 岡本 孝司
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:03875016)
巻号頁・発行日
vol.75, no.758, pp.1983-1988, 2009-10-25 (Released:2017-06-09)
参考文献数
7

It is known that flying fish perform long-range flight in the air in order to escape from predators such as tuna and swordfish. During the unsteady flight, ground effect enables the flying fish execute to flight for the maximum range and longest time. In this study, it was investigated a basic characteristic of the flow around the flying fish fin in ground effect, in order to understand the flying fish gliding performance quantitatively. The streamwise velocity profiles around the airfoil model were measured by a high time-resolved PIV (particle image velocimetry) in an open loop wind tunnel. A moving ground essential to generate the ground effect was supplied using a rotating disk. Two plates were put in tandem as the test wing model of a pectoral fin and a ventral fin of the flying fish. It was found that decreasing the height of the airfoil model caused a larger difference between the velocity in the suction surface side and that in the pressure surface side of the pectoral fin model.
著者
宗像 鉄雄 永田 眞一
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:03875016)
巻号頁・発行日
vol.74, no.747, pp.2365-2371, 2008-11-25 (Released:2011-03-03)
参考文献数
6
被引用文献数
4 7

Sodium acetate trihydrate is considered as the promising thermal energy storage material due to its high melting enthalpy at the melting temperature of 58°C. However, incongruent melting (phase separation) and remarkable supercooling are made difficult to use. In this study, solidification process of the sodium acetate trihydrate from supercooled state was both experimentally and numerically investigated. On the experiment, effects of supercooling and sodium acetate concentration on the crystal growth rate were measured by varying the supercooling temperature (-48K) and the sodium acetate concentration (40-55wt%) and obtained an empirical equation. Further, simplified crystal growth model, which is based on the experimentally obtained crystal growth rate, was also proposed and the heat release process, which is important for the thermal energy storage equipments, was investigated.
著者
段 智久 大石 直己 千田 二郎 藤本 元
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.60, no.577, pp.3192-3197, 1994-09-25 (Released:2008-03-28)
参考文献数
4
被引用文献数
1 4

In the experiments presented, a single diesel spray of n-tridecane was injected for a certain duration through a hole-type nozzle into a quiescent atmosphere at room temperature at high pressure. The experimental variables were nozzle hole dimensions such as the hole diameter dn, the hole length ln and the hole offset between the nozzle axis and the hole axis, and the nozzle needle lift, in order to assess the turbulent flow field inside the nozzle, and the other was the back pressure, in order to examine the effect of the ambient gas properties, especially its kinematic viscosity. The macroscopic spray structures were observed by using instantaneous photography and a high-speed video camera system. Furthermore, the microscopic structure was observed by meant of scattering photography of fuel droplets taken by the laser light sheet of a pulsed ruby laser, and the quantitative 2-D image of fuel concentration in the cross section of the spray containing its central axis was obtained by the image processing. From the experiments, the variation in the spray cone angle with the needle lift is promoted by the turbulence in the sac volume, and spray angle is closely related to the ambient kinematic vincosity.
著者
伊藤 慎一郎
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.73, no.734, pp.1975-1980, 2007-10-25 (Released:2011-03-03)
参考文献数
7
被引用文献数
2 2

A slipstream is a region of reduced pressure or even suction (negative pressure) formed behind an object in downstream. Even in a marathon event, it is possible to use preceding runners as a shield to reduce aerodynamic drag and to carry out physical strength presservation. These preceding runners are called pacemakers, who maintain a lap time of an main runner. In this research, to confirm the effect of pacemakers' slipstream and to find a suitable arrangement of pacemakers, drag of the main runner was measured using 3 component load cells in a wind tunnel. And the factor of drag reduction was studied by grasping the flow field using a smoke tunnel. Numerical calculations were also carried out in a real Reynolds number and compared with experiments concerning drag and flow field.
著者
新井 雅隆 天谷 賢児 長倉 邦仁
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.64, no.622, pp.1925-1931, 1998-06-25
被引用文献数
2

Laser induced fluorescence method was applied for the measurement of NO concentration in the propane and methane diffusion flames. A tunable, narrow band ArF excimer laser was used to excite the D (υ′=0) ←X (υ″=1) band of NO molecule. Emission spectrum of the induced light by a laser beam was measured by a spectroscope. Spectrum of the induced light from the diffusion flame was compared with that of the premixed flame. Although the spectrum had only NO fluorescence components on premixed flame, a lot of strong spectrum components related to the laser induced incandescence of the soot and laser induced breakdown appeared in the spectrum from the diffusion flame. NO fluorescence component was picked out from the emission spectrum with traversing the irradiate position of laser beam in order to obtain the accurate distribution of NO fluorescence on the flame axis. In this paper this method was named as S-LIF method. A planer laser induced fluorescence (P-LIF) method was tried to measure the distribution of NO fluorescence on the flame axis. In the P-LIF method, an interference filter was used to remove the obstructive light component from the LIF image. NO fluorescence distribution measured by P-LIF method was compared with that of S-LIF method. As the result, the P-LIF image qualitatively agreed with the data of S-LIF. It was confirmed that the interference filter did not remove completely the obstructive light components.
著者
畠沢 政保 杉田 洋 小川 孝廣 瀬尾 宜時
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.70, no.689, pp.292-299, 2004-01-25 (Released:2011-03-03)
参考文献数
9
被引用文献数
15 30

A new type of thermoacoustic sound wave generator driven with the waste heat of a 4 cycle automobile gasoline engine is described. The exhaust-pipe connected sound wave generator, in which the hot heat exchanger is set in the exhaust pipe in order to recover the waste heat of exhaust gas, is proposed. A temperature of 780°C of exhaust gas in the exhaust is observed. In a conventional thermoacoustic sound wave generator, sound waves originate at a temperature of the hot heat exchanger, TH, of 200-300°C and become sufficient at 700°C. It is confirmed that the new generator generates sufficient sound waves and its performance is almost equal to that of the electric heater driven generator at a thermal input of 300 W, which corresponds to slightly more than 1% of the heat quantity of exhaust gas provided under the condition that the number of engine revolutions is 2 600 r.p.m. and that the throttle opening is 35%.
著者
平石 雅之 蔦原 道久
出版者
一般社団法人日本機械学会
雑誌
日本機械学會論文集. B編 (ISSN:03875016)
巻号頁・発行日
vol.74, no.746, pp.2132-2137, 2008-10-25

We propose the Spectral Lattice Boltzmann Method (SLBM) that is the numerical calculation method of fluids based on the lattice BGK (Bathnagar Gross Krook) model discretized with spectral method. Two dimensional homogeneous isotropic turbulence are simulated by the SLBM. Numerical results agree with another calculation results i.e. the energy spectra proportional to the wave number to -4 and backward cascade of energy is observed. As a result, we obtain the conclusion that homogeneous isotropic turbulence can be simulated by the SLBM, and it is confirmed that this method is useful for numerical simulations of turbulent flows.
著者
奥 知久 笠木 伸英 鈴木 雄二
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.69, no.686, pp.2313-2320, 2003-10-25 (Released:2008-03-28)
参考文献数
9
被引用文献数
2

Micro bare-tube heat exchangers can accomplish high performance and compactness with their simple structure. In general, decreasing characteristic length leads to higher heat transfer area density at the expense of larger pressure drop. The trade-off has been so far optimized by trial and error. In the present study, simulated annealing (SA) is employed to optimize various design parameters of heat exchangers, which composes a multiple-variable highly nonlinear system. Although the heat transfer coefficient and the pressure drop on the air-side make major contribution to the total heat resistence and pumping power, empirical correlations of flow around tube bank can not predict them accurately in the low Reynolds number range, which is characteristic of compact heat exchangers. Hence, we make a series of numerical simulation for heat transfer and pressure drop of flow in the tube bank at various tube spacings and Reynolds numbers, and correlation functions are developed using an artificial neural network. Finally, optimum design is made for three types of micro bare-tube heat exchangers, i. e., heater core and radiator for automobiles, electronic equipement cooling system, and recuperator for micro gas turbine.
著者
田中 道雄 河嶋 敬 磯崎 俊明 竹平 昭暢
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.1681-1690, 1981-09-25

超音速衝動タービン翼列の設計方法は, 既に, いくつか公表されており, 中でもBoxerらが最初提唱した超音速自由うず流式のものが著名である. しかし, その性能については系統的資料が乏しく, 不明な点が多い. 本研究は, 設計転向角・マッハ数を違えた四種の自由うず流式翼列の二次元翼列実験を行い, 流入マッハ数と背圧による翼列特性の変化, 設計転向角・マッハ数と性能の関係など翼列性能の全般を明らかにした.