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

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

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.

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

渡邊 裕章 廣瀬 智陽子 青山 千春

出版者

日本混相流学会

雑誌

混相流 (ISSN:09142843)

巻号頁・発行日

vol.36, no.4, pp.407-414, 2022-12-15 (Released:2023-01-13)

参考文献数

15

---

Methane hydrate is expected as domestic energy resources in near future in Japan. Especially the shallow-type methane hydrate and the associated methane plume are regarded as sustainable energy resources. In this paper, the investigation of the methane hydrate particle motion in the methane is presented. A quantitative analysis of the motions of the ascending methane hydrate particles seeping from the seafloor and reproduced by the numerical simulation is performed by the two-dimensional motion analysis technique and the behavior is discussed in detail.

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

松隈 洋介 濱口 涼吉 峯元 雅樹

出版者

日本混相流学会

雑誌

混相流 (ISSN:09142843)

巻号頁・発行日

vol.36, no.4, pp.398-406, 2022-12-15 (Released:2023-01-13)

参考文献数

4

---

A system for recovery of methane hydrate from the deep ocean floor has not been established. As one possible recovery system, a gas-lift system was investigated. Experiments were performed with a gas-lift system of 5 m height and 100 mm in diameter to determine the relationship between injected gas quantity and pumped water quantity. Vertical flow in the gas-lift pipe was calculated with a compressible one-dimensional two-fluid model to analyze flow in the recovery pipe of methane hydrate from the deep ocean floor. Basic equations were mass conservation equations and momentum conservation equations of each phase, the relation of volume fractions and the state equation of the gas phase. The calculation showed that optimal gas injection depths exist. Thus, the gas-lift system can be economically effective the recovery of methane hydrate from the deep ocean floor.

著者

瀬戸 亮平 ローマン マリ モリス ジェフリー・F デン モートン・M

出版者

日本混相流学会

雑誌

混相流 (ISSN:09142843)

巻号頁・発行日

vol.28, no.3, pp.296-303, 2014-09-15 (Released:2014-11-01)

参考文献数

22

---

In a recent article (R. Seto, R. Mari, J. F. Morris, and M. M. Denn, Phys. Rev. Lett., 111:218301, 2013) we found frictional contact forces to be essential for reproducing the shear thickening behavior of non-Brownian suspensions. Although the introduction of frictional contact to a Stokesian Dynamics simulation is speculative and requires the existence of particle-particle contact despite fluid lubrication, the simulation results are in good agreement with experimental data. The model also provides physical insight into the relation between shear thickening and a jamming transition. This article describes the transition from a fluid mechanics perspective to a granular physics perspective.

著者

谷田部 貴大 金川 哲也 鮎貝 崇広

出版者

日本混相流学会

雑誌

混相流 (ISSN:09142843)

巻号頁・発行日

vol.35, no.2, pp.356-364, 2021-06-15 (Released:2021-07-08)

参考文献数

33

被引用文献数

4

---

Weakly nonlinear (i.e., finite but small amplitude) propagation of plane progressive pressure waves in compressible water flow uniformly containing many spherical gas bubbles is numerically investigated with a special attention to a drag force acting bubbles and translation of bubbles. The gas and liquid phases are flowing with initially independent velocities. Drag force and virtual mass force are introduced as interfacial momentum transports. Translation and spherically symmetric oscillations are considered as bubble dynamics. In this paper, under these assumptions, we numerically solve the KdVB (Korteweg-de Vries-Burgers) equation previously derived by ourselves (Yatabe et al., Phys. Fluids, 33 (2021), 033315) from basic equations based on a two-fluid model. The main results are summarized as follows: (i) The drag force acting on bubbles increases a dissipation effect of waves and drastically changes the phase and amplitude of waves. (ii) Although the translation of bubbles increases the nonlinear effect of waves, its contribution to waveform is quantitatively small. (iii) The effect of the drag force decreases with decreasing the initial void fraction and with increasing the initial bubble radius. That of the translation decreases with decreasing the initial void fraction, and is almost independent of the initial bubble radius. (iv) The spatiotemporal evolution of two type of dissipation effects (i.e., dissipation terms) due to the acoustic radiation and to the drag force is different tendency.

著者

加賀見 俊介 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.35, no.2, pp.346-355, 2021-06-15 (Released:2021-07-08)

参考文献数

48

被引用文献数

4

---

Weakly nonlinear focusing of quasi-planar ultrasound in a liquid nonuniformly containing many spherical microbubbles is theoretically investigated with a special focus on a thermal conduction at the bubble-liquid interface toward medical applications such as tumor coagulation by HIFU. Based on the previously derived Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation by our group (Kanagawa, J. Acoust. Soc. Am., 137 (2015), 2642), we derived a KZK equation newly incorporating the viscosity of bubbly liquids and the thermal conduction at the bubble-liquid interface by utilizing the energy equation inside bubble. As a result, two types of dissipation term were discovered in the resultant KZK equation: one is the second-order partial derivative term owing to the viscosity of bubbly liquids and the liquid compressibility and the other is a term without differentiation owing to the thermal conductivity. We found that the thermal conduction strongly contributes the dissipation effect.

著者

桂木 洋光

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.395-402, 2020-09-15 (Released:2020-10-09)

参考文献数

26

---

Dense suspension of non-Brownian particles such as potato starch often shows counter-intuitive behaviors due to its discontinuous rheological property. Using this particular rheological property, people can run on a dense suspension. However, once the motion of leg becomes too slow, the leg is arrested, namely, it is difficult to walk on the surface. To explain this peculiar behavior, propagation of jamming front caused by an impact onto a dense suspension has been considered recently. The effectively solidified zone is developed by the jamming-front propagation. This solidified zone effectively increases viscosity of the suspension. In addition, when the jamming front reaches the bottom of the container, a solidified pillar which causes effective elasticity is developed. Because the lifetime of the solidified zone is short, the suspension recovers usual viscosity after a while. To characterize the viscoelastic properties of the impacted dense suspension, a set of simple impact experiments was performed. A solid sphere was dropped from a certain height onto a suspension. The impact and rebound dynamics were recorded by a high-speed camera. Using the kinematic data, viscoelasticity of the impacted suspension was measured. The obtained data are consistent with the idea of jamming-front propagation. In addition to the impact onto a static target, impact experiments onto a dense suspension under the influence of mechanical vibration were also performed. Although the mechanical vibration can significantly deform the free surface of suspension, the impact response was hardly affected. In this article, a brief review of the impact-induced jamming-front propagation and the resultant effective viscoelasticity is presented.

著者

久保 雄一郎 奥井 翔大 笹川 達也 水谷 義隆 河野 智美 片岡 勲

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.100-110, 2020-03-15 (Released:2020-04-02)

参考文献数

10

被引用文献数

1

---

Thermohydraulic behavior in spent fuel pool is quite important in evaluating safety of a nuclear reactor under accidental conditions. Particularly, accurate prediction of void fraction in spent fuel pool is indispensable for evaluating cooling characteristics of spent fuel. In view of these, experimental and analytical studies were carried out for void fraction in spent fuel pool. The experiment was performed to measure the heat-up and void fraction transient during the postulated SFP accident. In this experiment, a simulated 7x7 BWR rod bundle that consists of 49 heater rods, 7 spacer grids and upper tie-plate was used. The measured data was compared with the some drift-flux correlations under the low pressure and the low flow rate condition related to SFP accident.

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

被引用文献数

1

---

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

被引用文献数

2

---

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

被引用文献数

1

---

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

3

---

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.