To detect stress corrosion cracking (SCC) and evaluate its depth on the surface of Ni-base alloys, a microwave microscope was employed. An open-ended coaxial line sensor was used to increase the spatial resolution. The working frequency was 110 GHz and the standoff distance between the sensor and the sample was 60 μm. The shape of SCC was obtained by microwave imaging. By measuring the amplitude of reflection coefficient, detection of SCC was achieved. To evaluate SCC depth, the attenuation constant of microwave in the crack was decided by comparing the measured microwave signal with the depth of a reference SCC obtained by destructive testing. Finally, the distribution of the depth of another SCC was evaluated by the proposed equation with the obtained attenuation constant.
{"title":"Nondestructive evaluation of SCC on the surface of Ni-base alloy by microwaves","authors":"T. Amano, Y. Ju, A. Hosoi","doi":"10.1299/KIKAIB.77.959","DOIUrl":"https://doi.org/10.1299/KIKAIB.77.959","url":null,"abstract":"To detect stress corrosion cracking (SCC) and evaluate its depth on the surface of Ni-base alloys, a microwave microscope was employed. An open-ended coaxial line sensor was used to increase the spatial resolution. The working frequency was 110 GHz and the standoff distance between the sensor and the sample was 60 μm. The shape of SCC was obtained by microwave imaging. By measuring the amplitude of reflection coefficient, detection of SCC was achieved. To evaluate SCC depth, the attenuation constant of microwave in the crack was decided by comparing the measured microwave signal with the depth of a reference SCC obtained by destructive testing. Finally, the distribution of the depth of another SCC was evaluated by the proposed equation with the obtained attenuation constant.","PeriodicalId":331123,"journal":{"name":"Transactions of the Japan Society of Mechanical Engineers. B","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126079666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fujio Akagi, Yuuki Okuzono, Youichi Ando, Sumio Yamaguchi, M. Furukawa
The formation process of a vortex ring generated by a pulsating jet flow, which is called the cyclic vortex ring, is investigated experimentally with PIV measurement. The waveform of the jet flow is conducted using sine curves by changing the amplitude of Reynolds' numbers Re0 of 1200-5040 and Womersley numbers α of 12.5-24.4. The results indicate that the formation process of the cyclic vortex ring is different from the laminar vortex ring. Another vortex ring which is formed from separated wall boundary layers in the nozzle during the suction period, which is called the separation vortex ring, is transported toward the nozzle exit during the discharge period. This separation vortex ring interferes with the formation process of the cyclic vortex ring at the nozzle exit plane. The circulation of the separation vortex ring depends on the pulsating conditions of the jet flow. Distribution of the vorticity around the core center of the cyclic vortex ring is in good agreement with the Oseen vortex model. The formation process of the cyclic vortex ring is classified into three categories, depending on Strouhal number.
{"title":"Formation process of vortex ring generated by a pulsating jet flow","authors":"Fujio Akagi, Yuuki Okuzono, Youichi Ando, Sumio Yamaguchi, M. Furukawa","doi":"10.1299/KIKAIB.77.546","DOIUrl":"https://doi.org/10.1299/KIKAIB.77.546","url":null,"abstract":"The formation process of a vortex ring generated by a pulsating jet flow, which is called the cyclic vortex ring, is investigated experimentally with PIV measurement. The waveform of the jet flow is conducted using sine curves by changing the amplitude of Reynolds' numbers Re0 of 1200-5040 and Womersley numbers α of 12.5-24.4. The results indicate that the formation process of the cyclic vortex ring is different from the laminar vortex ring. Another vortex ring which is formed from separated wall boundary layers in the nozzle during the suction period, which is called the separation vortex ring, is transported toward the nozzle exit during the discharge period. This separation vortex ring interferes with the formation process of the cyclic vortex ring at the nozzle exit plane. The circulation of the separation vortex ring depends on the pulsating conditions of the jet flow. Distribution of the vorticity around the core center of the cyclic vortex ring is in good agreement with the Oseen vortex model. The formation process of the cyclic vortex ring is classified into three categories, depending on Strouhal number.","PeriodicalId":331123,"journal":{"name":"Transactions of the Japan Society of Mechanical Engineers. B","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130015836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Swirling flow behavior between two parallel disk shape plates was experimentally investigated with the aid of a particle image velocimetry (PIV). The experiment was performed at low Reynolds numbers (Re < 100) to simulate the practical operation in a disk shape planar-type solid oxide fuel cell (SOFC). In the channel installed radial-type current collectors, unfavorable flow deceleration occurred toward downstream direction. Since this result suggested the necessity of improvement of flow uniformity, we designed a new channel with circle involute shape current collectors. In the new involute-type channel, a swirling flow was generated and its velocity was kept at nearly constant value toward the channel exit. This trend was observed regardless of flow rates, and hence flow uniformity was achieved over the wide range of Reynolds numbers. This is because a flow passage consisting of two adjacent involute shape current collectors functions as a constat-area channel due to the geometrical property of the circle involute. Furthermore, an estimation of a fluid motion in the involute-type channel was carried out by using steady state Euler's equation of motion. We confirmed that the velocity component in the flow direction was dominant compared with that in the other direction and played primary role to maintain a swirling motion through the centripetal acceleration term.
{"title":"Swirling flow behavior in a disk channel for planar-type SOFC","authors":"K. Tsunoda, T. Kouda","doi":"10.1299/KIKAIB.77.76","DOIUrl":"https://doi.org/10.1299/KIKAIB.77.76","url":null,"abstract":"Swirling flow behavior between two parallel disk shape plates was experimentally investigated with the aid of a particle image velocimetry (PIV). The experiment was performed at low Reynolds numbers (Re < 100) to simulate the practical operation in a disk shape planar-type solid oxide fuel cell (SOFC). In the channel installed radial-type current collectors, unfavorable flow deceleration occurred toward downstream direction. Since this result suggested the necessity of improvement of flow uniformity, we designed a new channel with circle involute shape current collectors. In the new involute-type channel, a swirling flow was generated and its velocity was kept at nearly constant value toward the channel exit. This trend was observed regardless of flow rates, and hence flow uniformity was achieved over the wide range of Reynolds numbers. This is because a flow passage consisting of two adjacent involute shape current collectors functions as a constat-area channel due to the geometrical property of the circle involute. Furthermore, an estimation of a fluid motion in the involute-type channel was carried out by using steady state Euler's equation of motion. We confirmed that the velocity component in the flow direction was dominant compared with that in the other direction and played primary role to maintain a swirling motion through the centripetal acceleration term.","PeriodicalId":331123,"journal":{"name":"Transactions of the Japan Society of Mechanical Engineers. B","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133872523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"低レイノルズ数域における後方ステップ流れの制御に関する研究（安定性解析を利用したSynthetic jetによる再付着流れの制御）","authors":"Shunsuke Yamada, Shinji Honami, Keita Okamoto, Takashi Nitta, Masahiro Motosuke, Hitoshi Ishikawa","doi":"10.1299/KIKAIB.77.680","DOIUrl":"https://doi.org/10.1299/KIKAIB.77.680","url":null,"abstract":"","PeriodicalId":331123,"journal":{"name":"Transactions of the Japan Society of Mechanical Engineers. B","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124893014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. Yamaguchi, T. Moriyama, K. Ide, J. Ito, Y. Matsuda, T. Niimi
Rotational energy distribution in a nitrogen molecular beam was experimentally studied by (2+2) N2-REMPI(Resonantly Enhanced Multiphoton Ionization). REMPI is known to have high detection sensitivity, which allows obtaining the signal under the very low number density condition like a molecular beam, successfully. Obtained REMPI spectrum was fitted by a theoretical spectrum to determine rotational temperature. The spectrum was well fitted, showing the rotational energy distribution obeyed the equilibrium Boltzmann distribution. The rotational temperature in a molecular beam must be similar to the frozen rotational temperature in a free jet, since a free jet is used as a beam source in the Kantrowitz-Grey type. The parameter p0d, which is a product of the source pressure p0 and the orifice diameter d, is known to characterize a free jet. Therefore, the rotational temperature in a molecular beam was analyzed in terms of the parameter p0d. The rotational temperature was able to be described by the power of the parameter p0d. The rotational temperature and the obtained function were compared with the value in literatures, which showed good agreement.
{"title":"Experimental study on rotational temperatures in nitrogen molecular beam","authors":"H. Yamaguchi, T. Moriyama, K. Ide, J. Ito, Y. Matsuda, T. Niimi","doi":"10.1299/KIKAIB.77.282","DOIUrl":"https://doi.org/10.1299/KIKAIB.77.282","url":null,"abstract":"Rotational energy distribution in a nitrogen molecular beam was experimentally studied by (2+2) N2-REMPI(Resonantly Enhanced Multiphoton Ionization). REMPI is known to have high detection sensitivity, which allows obtaining the signal under the very low number density condition like a molecular beam, successfully. Obtained REMPI spectrum was fitted by a theoretical spectrum to determine rotational temperature. The spectrum was well fitted, showing the rotational energy distribution obeyed the equilibrium Boltzmann distribution. The rotational temperature in a molecular beam must be similar to the frozen rotational temperature in a free jet, since a free jet is used as a beam source in the Kantrowitz-Grey type. The parameter p0d, which is a product of the source pressure p0 and the orifice diameter d, is known to characterize a free jet. Therefore, the rotational temperature in a molecular beam was analyzed in terms of the parameter p0d. The rotational temperature was able to be described by the power of the parameter p0d. The rotational temperature and the obtained function were compared with the value in literatures, which showed good agreement.","PeriodicalId":331123,"journal":{"name":"Transactions of the Japan Society of Mechanical Engineers. B","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126594668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The mass transfer characteristics of gas diffusion layer (GDL) are closely related to cell performance in polymer electrolyte fuel cell (PEFC). It is necessary to characterize the liquid water distribution, the microscopic conformation, and the oxygen diffusion coefficient in a GDL containing moisture. The configurations of a novel hybrid type GDL, in which two porous media with different wettabilities are arranged alternately (1),(2) and two porous media with different pore size distributions were alternately arranged (3), have been proposed with the aim of improving the oxygen diffusivity by controlling the moisture distribution in GDL porous media. However, the basic principles of hybrid type GDLs were examined in the former reports as a pilot study by using thicker media than those used in practice. It is thus necessary to elucidate the performance of the hybrid type GDLs with thinner sizes for the practical use. The present study examined a hybrid type GDL to control the liquid water behavior in the porous media. A carbon paper GDL used in practice for PEFCs with a wettability distribution due to adjacent hydrophilic and hydrophobic region was used as a test material. The measurement of oxygen diffusivity and visualization of liquid water in the GDL with wettability distribution were performed simultaneously using a galvanic battery type oxygen absorber and X-ray radiography, respectively.
{"title":"Simultaneous measurement of oxygen diffusivity and visualization of moisture distribution in gas diffusion layer with wettability distribution for improvement of polymer electrolyte fuel cell performance","authors":"Ryo Koresawa, T. Daitoku, Y. Utaka, K. Uesugi","doi":"10.1299/KIKAIB.77.2019","DOIUrl":"https://doi.org/10.1299/KIKAIB.77.2019","url":null,"abstract":"The mass transfer characteristics of gas diffusion layer (GDL) are closely related to cell performance in polymer electrolyte fuel cell (PEFC). It is necessary to characterize the liquid water distribution, the microscopic conformation, and the oxygen diffusion coefficient in a GDL containing moisture. The configurations of a novel hybrid type GDL, in which two porous media with different wettabilities are arranged alternately (1),(2) and two porous media with different pore size distributions were alternately arranged (3), have been proposed with the aim of improving the oxygen diffusivity by controlling the moisture distribution in GDL porous media. However, the basic principles of hybrid type GDLs were examined in the former reports as a pilot study by using thicker media than those used in practice. It is thus necessary to elucidate the performance of the hybrid type GDLs with thinner sizes for the practical use. The present study examined a hybrid type GDL to control the liquid water behavior in the porous media. A carbon paper GDL used in practice for PEFCs with a wettability distribution due to adjacent hydrophilic and hydrophobic region was used as a test material. The measurement of oxygen diffusivity and visualization of liquid water in the GDL with wettability distribution were performed simultaneously using a galvanic battery type oxygen absorber and X-ray radiography, respectively.","PeriodicalId":331123,"journal":{"name":"Transactions of the Japan Society of Mechanical Engineers. B","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134283372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-12-25DOI: 10.1299/KIKAIB.76.772_2105
宣治 森井, 努 大塚, 明彦 水島, 邦宣 宇波
{"title":"地下鉄系内気流の動的解析 : 実測とシミュレーション(流体工学,流体機械)","authors":"宣治 森井, 努 大塚, 明彦 水島, 邦宣 宇波","doi":"10.1299/KIKAIB.76.772_2105","DOIUrl":"https://doi.org/10.1299/KIKAIB.76.772_2105","url":null,"abstract":"","PeriodicalId":331123,"journal":{"name":"Transactions of the Japan Society of Mechanical Engineers. B","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123244869","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-12-25DOI: 10.1299/KIKAIB.76.772_2018
昌俊 渡邉, 和博 中橋
{"title":"修正Building-Cube法による非圧縮性流体解析(流体工学,流体機械)","authors":"昌俊 渡邉, 和博 中橋","doi":"10.1299/KIKAIB.76.772_2018","DOIUrl":"https://doi.org/10.1299/KIKAIB.76.772_2018","url":null,"abstract":"","PeriodicalId":331123,"journal":{"name":"Transactions of the Japan Society of Mechanical Engineers. B","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129594564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-12-25DOI: 10.1299/KIKAIB.76.772_2002
幸廣 服部, 功一 中林, 修己 鬼頭, 基之 伊藤
{"title":"プッシュプル完全局排方式に関する基礎研究 : 第2報,プッシュプル流れの乱れ特性(流体工学,流体機械)","authors":"幸廣 服部, 功一 中林, 修己 鬼頭, 基之 伊藤","doi":"10.1299/KIKAIB.76.772_2002","DOIUrl":"https://doi.org/10.1299/KIKAIB.76.772_2002","url":null,"abstract":"","PeriodicalId":331123,"journal":{"name":"Transactions of the Japan Society of Mechanical Engineers. B","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116499447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-12-25DOI: 10.1299/KIKAIB.76.772_2118
貞雄 別所, 匡徳 中村, 成生 和田
{"title":"非定常高せん断流れ場における変形挙動を再現する赤血球モデルの構築(流体工学,流体機械)","authors":"貞雄 別所, 匡徳 中村, 成生 和田","doi":"10.1299/KIKAIB.76.772_2118","DOIUrl":"https://doi.org/10.1299/KIKAIB.76.772_2118","url":null,"abstract":"","PeriodicalId":331123,"journal":{"name":"Transactions of the Japan Society of Mechanical Engineers. B","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130772210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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