著者
永田 晴紀
出版者
日本混相流学会
雑誌
混相流 (ISSN:09142843)
巻号頁・発行日
vol.27, no.4, pp.393-400, 2013-12-15 (Released:2014-01-17)
参考文献数
9
被引用文献数
1

A liquid oxygen supply system for a small-scale sounding rockets was developed. The sounding rokets are hybrid type employing a combination of plastics (PMMA or high density polyethylene) and liquid oxygen as propellants. Key points for the miniaturization were using no valve in the liquid oxygen feeding line and omitting precooling treatment of the line. Without precooling treatment, the liquid oxygen in the feeding line becomes multiphase flow until the temperature of the feeding line falls below the boiling temperature of the liquid oxygen. A characteristic time of multiphase flow duration was proposed to evaluate the duration a multiphase flow holds in the feeding line. Static firing tests showed that the multiphase flow ends within the half the characteristic time, showing that the liquid oxygen flow rate history without a precooling treatment is acceptable for an actual operation of the rocket motor. Finally, an impinging type injector was developed to remove a combustion instability, caused by a coupling of the combustion chamber pressure and the propellant (liquid oxygen) feed system.
著者
川崎 浩司
出版者
日本混相流学会
雑誌
混相流 (ISSN:09142843)
巻号頁・発行日
vol.26, no.1, pp.11-18, 2012-03-15 (Released:2012-06-20)
被引用文献数
4 7

A undersea earthquake with a magnitude of 9.0 "The 2011 off the Pacific Coast of Tohoku earthquake" took place off the Pacific coast of Japan at 14:46 JST (5:46 UTC) on March 11, 2011. A massive tsunami caused by the earthquake struck the Pacific side of Japan, especially the coasts of Aomori, Iwate and Miyagi prefectures, resulting in a cataclysmic disaster "East Japan Great Earthquake Disaster (Higashi Nihon Daishinsai in Japanese)". This paper describes the fundamental characteristics of Tsunami and the brief overview of the past huge tsunami disasters in Sanriku area. The tsunami damages of the East Japan Great Earthquake Disaster are, furthermore, reported on the base of the field survey, which was conducted from April 4 to 9, 2011 as a group of the 2011 Tohoku Earthquake Tsunami Joint Survey Group of Japan.

4 0 0 0 OA パンと軽石

著者
寅丸 敦志 小川 裕江 大橋 正俊 増山 孝行
出版者
日本混相流学会
雑誌
混相流 (ISSN:09142843)
巻号頁・発行日
vol.34, no.3, pp.403-410, 2020-09-15 (Released:2020-10-09)
参考文献数
11

Explosive volcanic eruptions produce pumice including bubbles (mainly H2O gas) which form by the vesiculation process under decompression during the magma ascent in the volcanic conduit. Shape of bubbles varies from spherical to tubular or irregular depending on the eruption style, intensity and magnitude. Interestingly, huge eruptions such as caldera-forming eruptions characteristically include elongated bubbles. We conduct the bread baking experiments to examine what controls the shape of bubbles by using the vesiculation process due to the fermentation of yeast. We use two experimental setups, baking within and without a glass conduit, to evaluate the effect of 1 dimensional expansion flow on the bubble shape. Results show that breads baked within the glass conduit typically include the elongated bubbles. We make the textural analysis for the cross section of bread after fermentation and baking with a time interval of 5 min to understand the evolution of bubble texture and with variable concentrations of yeast to evaluate the effect of amount of yeast on fermentation, consequent expansion of dough and bubble texture. By experiments with the variable concentration of yeast, it is found that the maximum expansion occurs at the certain concentration of yeast approximately 0.5 g per 50 g dough, and that the number of bubbles monotonically decreases with increasing the concentration of yeast. Time series experiments show that the number of bubbles decreases and average size of bubble increases with time for both within and without conduit. Aspect ratios of bubbles within a glass conduit are larger in smaller size of bubbles and smaller (i.e., elongated) in larger size. Numerical model simulating the evolution of bubble shape under 1 D expansion demonstrates that smaller bubbles relax to the spherical shape by surface tension effect and larger bubbles maintain the elongated shape formed by 1 D expansion.
著者
岩崎 良之
出版者
THE JAPANESE SOCIETY FOR MULTIPHASE FLOW
雑誌
混相流 (ISSN:09142843)
巻号頁・発行日
vol.27, no.2, pp.126-132, 2013-06-15 (Released:2013-07-11)
参考文献数
10

From ancient times fire has been extinguished mainly by using water. But there may be some problems in large amount of water discharge against fire, such as enough water volume for fire extinguishing may not be secured in case of large-scale natural disasters, and also secondary damage may be caused by discharged water. CAFS, one of fire extinguishing method by using air foam, is the solution because it utilizes small amount of water very efficiently. This report presents an overview of fire extinguishing with air foam, how to generate it and verification experiments of fire extinguishing effect with CAFS foam in MORITA Corporation.
著者
香西 みどり
出版者
日本混相流学会
雑誌
混相流 (ISSN:09142843)
巻号頁・発行日
vol.34, no.3, pp.419-426, 2020-09-15 (Released:2020-10-09)
参考文献数
13

Expantion of foods during cooking sometimes causes crack and burst. Burst is undesirable, while crack is desirable in some cases. Karinto with no sugar occasionally causes burst involving danger and cracks in doughnuts are generally favorable. Crack during deep frying is caused when the internal pressure of sample exceeds the cracking pressure of outer layer. Factors of internal pressure of samples are temperature increase and expanding ratio, and those of cracking pressure are thickness, tensile strength, and size and shape of the sample. The value of both internal pressure and cracking pressure can be calculated by using these data. The predicted timing of cracks in doughnut were confirmed in the experiment under various conditions. Mechanism of burst and crack during deep frying was proposed and it was expected to be applicable to the prediction and control of crack in food processing.
著者
岩坪 史弥 渡村 友昭 杉山 和靖 山本 研一朗 四元 祐子 塩野 貴史
出版者
日本混相流学会
雑誌
混相流 (ISSN:09142843)
巻号頁・発行日
vol.32, no.1, pp.124-131, 2018-03-15 (Released:2018-05-03)
参考文献数
20

To clarify the spatial structure of number density distribution of bubbles in stout beer poured into a container, we investigated local time development of the void fraction and velocity of bubbles. The propagation velocity of the texture, i.e. the number density distribution, appearing near the inclined wall of the container is measured by the images analysis. We measured the local void fraction using brightness of images while the velocity of bubbles by means of Particle Tracking Velocimetry. As the result of measurements, we found the local void fraction and the bubbles advection velocity increase and decrease repeatedly with a time delay. We conclude the pattern of the number density distribution of bubbles is composed of fluid blobs which contain less bubbles; extruding and suction flows respectively toward and from the interior of the container form respectively in front and back of the blobs.
著者
太田 光浩
出版者
日本混相流学会
雑誌
混相流 (ISSN:09142843)
巻号頁・発行日
vol.31, no.3, pp.267-275, 2017-09-15 (Released:2017-10-24)
参考文献数
24

The understanding of non-Newtonian two-phase flows is a far from easy issue because two-phase flows dynamically and intricately behave through boundary interfaces with the local variation in rheological properties. A key factor to explore structures and mechanisms of non-Newtonian two-phase flows is to perceive a local profile of non-Newtonian properties corresponding to the shear-rate. In this article, I review current situation and challenges about the study of non-Newtonian two-phase flows through the author' s studies on the dynamic motion of bubbles and drops in non-Newtonian fluids.
著者
大田 治彦
出版者
日本混相流学会
雑誌
混相流 (ISSN:09142843)
巻号頁・発行日
vol.31, no.4, pp.382-391, 2017-12-15 (Released:2018-01-20)
参考文献数
29

Increase in the consumption of electricity and in the heat dissipation density from semiconductors will become a serious problem also in space. To develop thermal management systems for space platforms, fundamental data for their design is to be obtained through boiling and Two-Phase Flow (TPF) experiments onboard international space station (ISS). In addition to the acquisition of data for heat transfer, the clarification of flow and heating conditions, where gravity effects disappear, become an important objective of the experiment. An experimental setup was developed thorough the long-term discussion and design among JAXA, researchers and manufactures supporting the project, and was already transported to ISS. Objectives and situation of the present research and a desired direction of future experiments are described with reference to the existing data obtained from short-term microgravity experiments for flow boiling.
著者
深野 徹
出版者
日本混相流学会
雑誌
混相流 (ISSN:09142843)
巻号頁・発行日
vol.5, no.4, pp.343-347, 1991-12-15 (Released:2011-02-22)
参考文献数
9
著者
松井 剛一
出版者
日本混相流学会
雑誌
混相流 (ISSN:09142843)
巻号頁・発行日
vol.14, no.1, pp.24-38, 2000-03-15 (Released:2011-02-22)
参考文献数
34

Because “flow pattern” relates closely to design parameters of plant such as pressure drop and heat transfer coefficient, better knowledge of the flow pattern leads not only to deep understanding of the flow but also to accurate prediction of the parameters or to safe operation of plant. Therefore, “flow pattern” is an important and fundamental parameter as well as void fraction. Nevertheless the flow pattern has been judged mostly on a basis of visual observation. Therefore, it is desired to identify the flow pattern objectively and quantitatively.Here, identification of flow pattern using differential pressure fluctuations is described. Behaviors of statistical parameters are discussed in the statistical parameter spaces. And also recent flow visualization methods using fast X-ray CT and HPIV are described.
著者
遠田 晋次
出版者
日本混相流学会
雑誌
混相流 (ISSN:09142843)
巻号頁・発行日
vol.26, no.1, pp.4-10, 2012-03-15 (Released:2012-06-20)
参考文献数
30

The 2011 M9.0 off the Pacific Coast of Tohoku Earthquake (Tohoku-oki earthquake) brought a great impact on the long-term forecasting of subduction earthquakes around the Japanese islands. Short historic data together with dogmas of modern seismology, such as conventional asperity model, characteristic earthquake model, and earthquake scaling law prevented us to have anticipated the size of M9 earthquake offshore Pacific coast of Tohoku. It may suggest that longer than 1000-year earthquake occurrence history is required to properly evaluate the size and frequency of mega-thrust events, same as the M~7 destructive earthquakes associated with inland active faults. The Tohoku-oki earthquake has significantly changed the state of crustal stress in northeast Honshu island from EW compression to EW extension, in which numerous widespread triggered earthquakes have been occurring. Here I introduce the coseismic stress transfer due to the Tohoku-oki earthquake onto the major active faults, and then demonstrate the importance of the transient changes of state of stress on the faults for long-term earthquake forecasting during the next few decades.
著者
中島 幸雄
出版者
日本混相流学会
雑誌
混相流 (ISSN:09142843)
巻号頁・発行日
vol.27, no.2, pp.102-109, 2013-06-15 (Released:2013-07-11)
参考文献数
25

The numerical procedure for hydroplaning was developed by considering the following three important factors; fluid/structure interaction, tire rolling, and practical tread pattern. The tire is analyzed by FEM with Lagrangian formulation and the fluid is analyzed by FVM with Eulerian formulation. Since the tire and the fluid are modeled separately and their coupling is automatically computed by the coupling element, the fluid/structure interaction of the complex geometry such as the tire with the tread pattern can be analyzed practically. The predictability was validated by comparing the hydroplaning simulation with the experiment on the subjects such as the water flow, the velocity dependence of hydroplaning, and the effect of the tread pattern on hydroplaning. In order to predict the streamline in the contact patch, the procedure of the global-local analysis was developed. The predicted streamline enabled us to develop the new tire pattern in a short period based on the principle; “make the stream line smooth”.
著者
村井 祐一
出版者
日本混相流学会
雑誌
混相流 (ISSN:09142843)
巻号頁・発行日
vol.31, no.4, pp.369-374, 2017-12-15 (Released:2018-01-20)
参考文献数
17

Drag reduction using bubbles are now in operation for marine vessels, and recorded significant fuel saving. Beside it, fluid mechanics inside high-speed bubbly turbulent boundary layer is highly complex. Efforts by scientists and engineers in Japan straggled in the last 30 years and recently reached the goal. They found further potential of technical improvement with recent experimental discovery on bubbles’ organizing behaviors.
著者
榎木 光治 清 雄一 大川 富雄 齋藤 潔
出版者
日本混相流学会
雑誌
混相流 (ISSN:09142843)
巻号頁・発行日
vol.31, no.4, pp.412-421, 2017-12-15 (Released:2018-01-20)
参考文献数
27
被引用文献数
1

The applications of Artificial Intelligence ie AI show diversity in any fields. On the other hand, research of the predicting heat transfer regardless of single-phase or two-phase flow is still untouched. Therefore, we have confirmed usefulness using AI’s deep learning function on horizontal flow boiling heat transfer in flowing mini-channel that is actively researched. The effect of the surface tension in the mini-channel is large compared with conventional large tubes, and then the heat transfer mechanism is very complicated. For this reason, the numerical correlations of many existing researchers the prediction result is not good. However, the mechanistic correlation based on the visualization experiment, which the authors' research group published several years ago has very high precision. Therefore, in this research paper, we confirmed the effectiveness of using deep learning for predicting of the boiling heat transfer in mini-channel while comparing our correlation.
著者
山内 豊
出版者
日本混相流学会
雑誌
混相流 (ISSN:09142843)
巻号頁・発行日
vol.27, no.1, pp.11-17, 2013-03-15 (Released:2013-06-05)
参考文献数
11

Developments of natural resources in the Arctic region are becoming active in the recent years. Commercial use of the northern sea route is taking on realness with a decrease of sea ice area along the Arctic coast. Also Arctic and Antarctic observation is important to clarify a global climatic change. Icebreakers are indispensable to the support for the development, the escort for cargo ships and the polar observation in ice-covered waters. The technology on icebreaker's performance is improving steadily, responding to those missions. This paper shows the typical characteristics of icebreaker and introduces several technologies to improve the performance.
著者
佐野 寛
出版者
日本混相流学会
雑誌
混相流 (ISSN:09142843)
巻号頁・発行日
vol.25, no.1, pp.4-11, 2011-03-15 (Released:2011-06-15)
参考文献数
10

A lot of forest-biomass exists on the steep mountain in Japan. However, it is very difficult to obtain the forest-biomass like brushwood, from the deep mountain to human habitation. Using by chute, brushwood can be transported automatically if we can keep an appropriate slope gradient. The most important point is a repose angle of chip on the slope. These angles are strongly depending on the figure of chip, the aspect ratio, and the surface roughness of the chute bed.
著者
前田 泰希 金川 哲也
出版者
日本混相流学会
雑誌
混相流 (ISSN:09142843)
巻号頁・発行日
vol.34, no.1, pp.140-147, 2020-03-15 (Released:2020-04-02)
参考文献数
20
被引用文献数
1

Weakly nonlinear propagation of plane pressure waves in a flowing water uniformlycontaining many spherical microbubbles is theoretically investigated. At the initial state, the gas and liquid phases have different flow velocity distributions as a small nonuniform effect in bubbly flows. The basic equations based on a two-fluid model are utilized to describe velocity distributions of gas and liquid phases. By using the method of multiple scales and the determination of size of three nondimensional ratios, we can systematically derive two types of nonlinear wave equations describing long-range propagation of waves. i.e., the Korteweg-de Vries-Burgers (KdVB) equation and the nonlinear Schrödinger (NLS) equation with variable coefficients. As a result, initial velocity distributions affect an advection effect of waves induced by a relative velocity between gas and liquid phases and a moving bubble.
著者
圷 亮輔 慶本 天謹 金川 哲也 内山 祐介
出版者
日本混相流学会
雑誌
混相流 (ISSN:09142843)
巻号頁・発行日
vol.34, no.1, pp.166-179, 2020-03-15 (Released:2020-04-02)
参考文献数
28

Two types of weakly nonlinear propagations of plane progressive pressure waves in an initially quiescent compressible liquid uniformly containing many spherical gas bubbles are theoretically investigated. The treatment of two types of propagations corresponds to an extension of our previous result (Yoshimoto & Kanagawa, Jpn. J. Multiphase Flow, 33 (2019), 77) to a generic form. The main assumptions are as follows: (i) The incident wave frequency is much larger than an eigenfrequency of single bubble oscillations; (ii) The compressibility of the liquid phase, which has long been neglected and induces the high speed propagation mode, is considered; (iii) The wave propagates with a large phase velocity exceeding the speed of sound in pure water. From the method of multiple scales with two types of appropriate choices of three nondimensional parameters, we can systematically derive two types of nonlinear Schrödinger (NLS) equations with some correction terms in a unified way. These two equations can describe high-speed propagation of pressure waves in compressible bubbly liquids.
著者
鮎貝 崇広 金川 哲也
出版者
日本混相流学会
雑誌
混相流 (ISSN:09142843)
巻号頁・発行日
vol.34, no.1, pp.158-165, 2020-03-15 (Released:2020-04-02)
参考文献数
13
被引用文献数
1

Oscillation of gas bubbles in a bubbly liquid induces dissipation and dispersion effectsof waves into a nonlinear evolution of pressure waves. Long-range propagation of pressure waves with a moderately small amplitude is described by the KdV-Burgers (KdVB) equation. This paper numerically solves the KdVB equation via a spectral method to predict the nonlinear evolution of waves in bubbly liquids. Focusing on the waveform, and the nonlinear, dissipation and dispersion terms, the following results are obtained: (i) An initially sinusoidal waveform satisfying a periodic boundary condition is firstly distorted due to the nonlinear effect; (ii) Wave distortion is suppressed by increasing the dissipation and dispersion effects; (iii) A break-up due to the dispersion effect appears; (iv) A balance between the nonlinear and dispersion effects is accomplished and then a pulse wave satisfying a feature of soliton is formed. As a result, the initial bubble radius and the initial void fraction strongly contribute the dissipation and dispersion effects, respectively.
著者
亀井 陸史 金川 哲也
出版者
日本混相流学会
雑誌
混相流 (ISSN:09142843)
巻号頁・発行日
vol.34, no.1, pp.148-157, 2020-03-15 (Released:2020-04-02)
参考文献数
20

This study theoretically clarifies an effect of the liquid viscosity and the thermal conductivity on weakly nonlinear propagation of pressure waves in a liquid containing many spherical microbubbles. As in our preceding paper (Kamei et al., J. JSCE, Ser. A2, 75 (2019), 499) focusing on a long wave, by the use of the method of multiple scales, a nonlinear Schrödinger equation describing the long-range propagation of an envelope wave of short carrier wave is derived from the basic equations incorporating the liquid viscosity and the thermal conductivity. As a result, as in our preceding long wave case, the liquid viscosity and the thermal conductivity affect the dissipation effect, and a nonlinear effect in the adiabatic process decreases in comparison with the previous study (Kanagawa et al., J. Fluid Sci. Technol., 6 (2011), 838). On the other hand, unlike in our preceding long wave case, a dispersion effect in the adiabatic process decreases in comparison with the previous study.