著者

松岡 常吉 中村 祐二

出版者

日本実験力学会

雑誌

実験力学 (ISSN:13464930)

巻号頁・発行日

vol.20, no.4, pp.229-236, 2021-01-07 (Released:2021-01-14)

参考文献数

12

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Scale modeling based on static and dynamic similarity has been widely used with high-speed photography techniques for motion pictures to reproduce unrealistic world. Focusing on video works created by SFX as examples of scale modeling experiments, this paper attempts to explain the scale modeling theory, so called “Law approach” which is a method to derive the scaling law based on deep physical insights. To accomplish this, the falling motion of an object in fluid is taken up as the simplest but frequent case. The governing equation of the phenomenon is considered, and the magnitude of each term is estimated. A quantitative comparison demonstrates which factor is most significant in that phenomenon. Though it seems a relatively complicated explanation, it is believed that this approach gives a clear insight into how the dominant factor(s) is extracted in the Law approach.

著者

松岡 常吉 中村 祐二

出版者

日本実験力学会

雑誌

実験力学 (ISSN:13464930)

巻号頁・発行日

vol.20, no.4, pp.229-236, 2021

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<p> Scale modeling based on static and dynamic similarity has been widely used with high-speed photography techniques for motion pictures to reproduce unrealistic world. Focusing on video works created by SFX as examples of scale modeling experiments, this paper attempts to explain the scale modeling theory, so called "Law approach" which is a method to derive the scaling law based on deep physical insights. To accomplish this, the falling motion of an object in fluid is taken up as the simplest but frequent case. The governing equation of the phenomenon is considered, and the magnitude of each term is estimated. A quantitative comparison demonstrates which factor is most significant in that phenomenon. Though it seems a relatively complicated explanation, it is believed that this approach gives a clear insight into how the dominant factor(s) is extracted in the Law approach.</p>

著者

中村 祐二 松岡 常吉

出版者

一般社団法人 日本燃焼学会

雑誌

日本燃焼学会誌 (ISSN:13471864)

巻号頁・発行日

vol.60, no.192, pp.75-82, 2018 (Released:2019-02-15)

参考文献数

16

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Resonance behavior of twin flickering (non-premixed) flames at various separation distances horizontally is examined and two oscillation modes (in-phase and anti-phase) are clearly identified depending on the distance. Our ultimate goal is to develop the acceptable mathematical model to explain such resonance behavior. There has been proposed “radiation-basis” mathematical model by physics-oriented researchers, claiming that the radiation is a primary factor to give an anti-phase mode. Our recent experimental and numerical studies, on the other hand, suggest that the radiation may not be the essential factor, rather, fluid dynamical motion shall be a key factor to cause the mode transition. Potential strategy to upgrade the mathematical model are proposed. Taking a “mathematical-scientific” approach to combustion problem is typical inter-disciplinary issue and productive interaction between physicists and combustion researchers is found to be highly recommended to develop further.

著者

山崎 貴史 松岡 常吉 横山 博史 中村 祐二

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 (ISSN:21879761)

巻号頁・発行日

vol.86, no.889, pp.20-00210, 2020 (Released:2020-09-25)

参考文献数

25

被引用文献数

1 1

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The effects of the traveling sound wave generated by the speaker on diffusion flame were investigated experimentally. The sound frequency was varied from 50 to 1000 Hz using two sizes of loudspeakers, whose peak frequency showing the maximum sound pressure amplitude is nearly identical. A spirit lamp was used as the reference (diffusion) flame. Having irradiation of sound, the flame was inclined and stretched toward the traveling direction under specific range of the exposed frequencies and importantly, the effective range of the frequency was found to be quite different in two speakers used in this study. Precisely speaking, the deformed flame length reached its maximum value under the condition of 200 to 400 Hz for small speaker and 50 to 200 Hz for large speaker, respectively. In addition, the velocity distribution around the speaker was measured to reveal that the variation of flame length with respect to frequency, and it was found that the response against the applied frequency was rather close to that of flow velocity, not that of the acoustic pressure amplitude. Further investigation of flow field nearby the speaker clearly showed that the pump-like flow acceleration was induced by the periodic motion of the membrane of the speaker. From the above results obtained, it was confirmed that the effect of acoustic sound on the flame shall be come not only from pure acoustic wave feature but also from the factors depending on the hardware. Without the eliminating the latter effect, nature of acoustic-flame interaction behavior by using acoustic characters (e.g., frequency or acoustic pressure) is not readily available.

著者

松岡 常吉 村上 智志 山崎 拓也 中村 祐二

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 (ISSN:21879761)

巻号頁・発行日

vol.83, no.852, pp.17-00009-17-00009, 2017 (Released:2017-08-25)

参考文献数

29

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This paper numerically investigated the detail process to appear the asymmetrically spreading flames in narrow channel consisted of combustibles. We have successfully reproduced the transient process to form asymmetrically arranged spreading flame first ever in this work. 2-D, time-dependent mass and energy transport process as well as one-step chemical process in gas-phase is considered. Thick solid combustible plates (PMMA) are placed at both sides, then exactly the same ignition operation is made to initiate symmetrical processes. Pure oxygen is fed into the channel at the fixed rate to promote the spreading. Oxidizer velocity and channel height are varied as numerical parameters in this study. After the forced ignition, the combustibles are pyrolized via one-step reaction to evolve the fuel gas into the gas phase to form the opposed-mode flame spreading. Results show the distinctive three spreading modes (two-symmetric flames spreading, two-asymmetric flames spreading and one flame spreading) and transient process from one to the other mode is successfully simulated, which is hardly achieved in experiment. The asymmetric flame spreading mode appears under the limited combination of channel height and velocity. Moreover the distance between two leading edges of the flame varies depending on the imposed condition. Flow patterns are found to be sinus motion, thus the heated and accelerated oxidizer flow may enhance the reaction in the downstream. In this way, it is suggested that the flowing oxygen is effectively used to burn two fuel slabs. It is obvious that the asymmetrical configuration gives temporary stable condition. To study the details further, systematic study is demanded.

著者

松岡 常吉

出版者

豊橋技術科学大学

雑誌

研究活動スタート支援

巻号頁・発行日

2012-08-31

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噴流間の距離が衝突噴流群による固体燃焼の燃焼速度におよぼす影響を明らかにすることを目的として,スリット間隔の異なるノズルを用いて実験を行い,以下のことを明らかにした.・水平方向の燃焼速度分布はスリット間隔によって大きく変化することを示した.間隔が広い場合には燃焼速度が最大となる位置がスリット直下より外側にずれることを示した.・燃焼速度のレイノルズ数依存性を明らかにした.燃焼速度は,非燃焼の場合のよどみ領域と同様,レイノルズ数の0.5乗に比例して大きくなることを示した.一方,スリット間隔が広いときのスリット直下の燃焼速度はレイノルズ数の0.8乗に比例することを示した.