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Effects of Aspect Ratio in a Transonic Shock Tube Airfoil Flow

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Journal of Thermal Science 2012年第5期21卷 435-440页

作者： Masashi KASHITANI Keita MIURA Shinichiro NAKAO yutaka yamaguchi Department of Aerospace Engineering National Defense Academy1-10-20 Hashirimizu Yokosuka 239-8686 JAPAN Department of Mechanical Engineering Nagasaki Institute of Applied Science 536 Aba-MachiNagasaki 851-0193 JAPAN

In the present study, the flow visualizations were performed around the NACA 0012 models which differ in aspect ratios. We discussed the effects of the aspect ratio in the test models. Additionally the unsteady, two-dimensional, compressible Euler equations were solved for the NACA 0012 airfoil. Experiments were performed utilizing the conventional gas driven shock tube as the intermittent transonic wind tunnel. The aspect ratios of the models are about 0.86 and 1.5, respectively. The Mach numbers M 2 are about 0.84. The Reynolds numbers of the present experimental conditions were constant that Re based on chord length is about 4.0×10 5 . The results are as follows: in different aspect ratios, the difference of the shock wave location is confirmed though the Mach number and Reynolds number are same. It indicates the different correction Mach number by the effects of the side wall boundary layer though the nominal Mach number measured the same value. Also, on the difference of shock wave location for the effects of the aspect ratio, the tend of CFD shows the qualitative agreement with the result of an experiment.

关键词：跨声速风洞纵横比激波翼型可压缩欧拉方程管流实验条件马赫数

A Study on High Subsonic Airfoil Flows in Relatively High Reynolds Number by Using OpenFOAM

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Journal of Thermal Science 2014年第2期23卷 133-137页

作者： Shinichiro NAKAO Masashi KASHITANI Takeshi Miyaguni yutaka yamaguchi Department of Mechanical Engineering Nagasaki Institute of Applied Science536 Aba-MachiNagasaki851-0193JAPAN Department of Aerospace Engineering National Defense Academy1-10-20 HashirimizuYokosuka239-8686JAPAN

In the present study,numerical calculations of the flow-field around the airfoil model are performed by using the OpenFOAM in high subsonic *** airfoil model is NACA *** maximum thickness is 10 % of the chord *** SonicFOAM and the RhoCentralFOAM are selected as the solver in high subsonic *** grid point is 158,000 and the Mach numbers are 0.277 and 0.569 *** CFD data are compared with the experimental data performed by the cryogenic wind tunnel in the *** results are as *** numerical results of the pressure coefficient distribution on the model surface calculated by the SonicFOAM solver showed good agreement with the experimental data measured by the cryogenic wind *** the data calculated by the SonicFOAM have the capability for the quantitative comparison of the experimental data at low angle of attack.

关键词：翼型模型高亚声速高雷诺数流量实验数据亚音速流低温风洞数值计算

Configuration of Shock Waves in Two-Dimensional Overexpanded Jets

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Journal of Thermal Science 2003年第4期12卷 294-298页

作者： Masashi Kashitani yutaka yamaguchi Yoshiaki Miyazato Mitsuharu Masuda Kazuyasu Matsuo Department of Aerospace Engineering National Defense Academy 1-10-20 Hashirimizu Yokosuka Kanagawa 239-8686 JapanDepartment of Aerospace Engineering National Defense Academy 1-10-20 Hashirimizu Yokosuka Kanagawa 239-8686 JapanDepartment of Energy and Environmental Engineering Kyushu University 6-1 Kasuga-Kouen Kasuga Fukuoka 816-8580 JapanDepartment of Energy and Environmental Engineering Kyushu University 6-1 Kasuga-Kouen Kasuga Fukuoka 816-8580 JapanDepartment of Mechanical Systems and Environmental Engineering The University of Kitakyushu 1-1 Hibikino Wakamatsu-ku Kitakyushu Fukuoka 808-0315 Japan

An experimental and analytical study has been carried out to obtain the clear understanding of a shock wave transition associated with a steady two-dimensional overexpanded flow. Two-dimensional inviscid theory with respect to a shock wave reflection is used in the present study on the characteristic of shock waves. The results obtained from the flow analysis are compared with those obtained from flow visualizations. It is shown that in the region of regular reflection, the angle of an incident shock wave becomes lower than that calculated by two shock theory with an increment in the ratio PJPb of the nozzle exit pressure Pc to the back pressure Pb. It is indicated that the configuration of shock waves in overexpanded jets is influenced by the divergent angle at the nozzle exit. Also it is shown from the flow visualization that a series of shock waves move into the nozzle inside with a decrease in pressure ratio Pc/Pb, even if the Pc/Pb is under overexpanded conditions.

关键词：振动波超声喷管可压缩流体膨胀喷射空气动力学

Study of the Effect of Acetic Acid and Phosphate on Copper Corrosion by Immersion Tests

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Materials Sciences and Applications 2024年第1期15卷 15-23页

作者： Yuna yamaguchi Kaho Sugiura Toyohiro Arima Fuka Takahashi Itaru Ikeda yutaka Yamada Osamu Sakurada Department of Chemistry and Biomolecular Science Faculty of Engineering Gifu University Gifu Japan Dai-Dan Co. Ltd. Saitama Japan Daiwa Techno Co. Ltd. Gifu Japan

It was reported that hemispheric corrosion occurred in copper tubes in an acetic acid environment. When hemispheric corrosion occurred, corrosion could easily progress if water then flowed into the copper pipe, and countermeasures were needed. Therefore, we studied the copper corrosion caused by acetic acid. The present work investigated the relationship between the corrosion form of copper and acetic acid concentration using phosphorous-deoxidized copper, and reported that hemispherical corrosion was observed at acetic acid concentrations of 0.01 to 1 vol.% (0.002 to 0.2 mol·L-1) in the immersion test. In this study, the effects of acetic acid and phosphate on copper corrosion were examined using oxygen-free copper in immersion tests. The results suggested that different concentrations of phosphate in acetic acid solutions and the presence or absence of acetic acid and phosphate affected the corrosion of copper, resulting in different corrosion forms and corrosion progress.

关键词： Acetic Acid Phosphate Oxygen-Free Copper Hemispherical Corrosion Ant-Nest Corrosion

One-Dimensional Analysis of Thermal Choking in Case of Heat Addition in Ducts

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Journal of Thermal Science 2000年第3期9卷 224-229页

作者： Yoshiaki Miyazato Mitsuharu Masuda Kazuyasu Matsuo (Department of Energy and Environmental Engineering, Graduate School of Engineering Science, Kyushu University, 6-1 Kasuga-Kouen, Kasuga, Fukuoka, 816-8580, Japan) Masashi Kashitani yutaka yamaguchi (D Department of Energy and Environmental Engineering Graduate School of Engineering Science Kyushu University Fukuoka Japan Department of Aerospace Engineeirng National Defense Academy Yokosuka Kanagawa Japan

The thermal choking phenomenon is of great importance in an inlet isolator in dual-mode ram jet/scramjet combustor. In some cases the choked flow creates a pseudo-shock wave including a shock train in it at the engine inlet and causes large amounts of drag and radically reduces the performance of the engine at high flight Mach numbers. The present paper describes a one-dimensional flow model taking account of the upstream boundary-layer as well as heat addition by using a mass-weighted av- eraging technique. The simple relationships for the flow field in a constant area duct in which the effect of the upstream boundary-layer is considered but the effect of the wall friction in the duct can be neglected are presented. The results of the calculation such as the maximum heat addition when the thermal choking occurs, the downstream Mach number and the static pressure ratio are presented and examined in detail.

关键词：燃烧室边界层热阻塞热喷管

Evaluation of Expansion Process to Improve Corrosion Resistance of Copper Tubes with High Residual Carbon on the Inner Surface

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Materials Sciences and Applications 2023年第2期14卷 45-52页

作者： Yuma Kano Itaru Ikeda Takashi Iyasu Yuna yamaguchi yutaka Yamada Osamu Sakurada Department of Chemistry and Biomolecular Science Faculty of Engineering Gifu University Gifu Japan Dai-Dan Co. Ltd. Saitama Japan Kurita Water Industries Ltd. Tokyo Japan Daiwa Techno Co. Ltd. Gifu Japan

Residual carbon on the inner surface of copper tubes is known to be a cause of pitting corrosion. We showed previously that the rapid filling test was useful to evaluate the pitting corrosion resistance of copper tubes. Immersion tests using the rapid evaluation test solution showed that corrosion occurs on the entire surface of copper tubes with low residual carbon amounts, while those with high residual carbon amounts show pitting corrosion. Therefore, it is necessary to improve the corrosion resistance of copper tubes with high residual carbon amount, which are expected to undergo pitting corrosion. As pitting corrosion occurs when anodes are locally concentrated on part of the metal surface, it has been suggested that anodes be dispersed over the entire surface by the processing of the metal surface. Metal processing methods have various purposes, including changing the shape and properties of metals, and in this case, leading to desirable surface properties (such as expansion and drawing processes). Here, we focused on the expansion process and its effects on corrosion resistance of copper tubes. The results showed that hydraulic expansion has a significant effect on the inner copper surface by improving corrosion resistance as the anode area increases.

关键词： Expansion Process Carbon Film Pitting Corrosion Corrosive Anion the Pitting Corrosion Resistance Test

Relationship between Corrosion Form and Elution Behavior of Copper Tubes Surfaces with Different Residual Carbon Amounts

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Materials Sciences and Applications 2022年第12期13卷 595-602页

It was well known that residual carbon on the inner surface of copper tubes was a cause of pitting corrosion, and copper tube surfaces with different residual carbon amount were different corrosion forms. In this study, the relation between corrosion form and elution of copper in immersion tests by accelerated corrosion test solutions was examined. Generally, pitting corrosion that occurs in actual machines was reported to observe chloride ion at the bottom of the pitting corrosion of copper tubes. Energy dispersive X-ray (EDX) mapping analysis indicated that chlorine was concentrated in the upper layer of the samples where copper was not detected under conditions of low residual carbon amount, while chlorine was concentrated under part of the micromounds (including the bottom of the pits) under conditions of high residual carbon amount. It was also suggested that the amount of copper eluted was related to the amount of residual carbon.

关键词： Carbon Film Residual Carbon Amount Pitting Corrosion Corrosive Anion The Pitting Corrosion Resistance Test

Design and Prototyping of Micro Centrifugal Compressor

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Journal of Thermal Science 2003年第1期12卷 33-37页

作者： Shimpei Mizuki Gaku Minorikawa Toshiyuki Hirano Yuichiro Asaga Naoki yamaguchi yutaka Ohta Eisuke Outa 1. Department of Mechanical Engineering Hosei University 7-2Department of Mechanical Engineering Hosei University 7-2Department of Mechanical Engineering Hosei University 7-2Department of Mechanical Engineering Hosei University 7-2Department of Mechanical Engineering Waseda University 4-1Department of Mechanical Engineering Waseda University 4-1 Department of Mechanical Engineering Hosei University 7-2 Kajinocho 3 chome Koganei-shi Tokyo 184-8584JapanKajinocho 3 chome Koganei-shi Tokyo 184-8584JapanKajinocho 3 chome Koganei-shi Tokyo 184-8584Japan Kajinocho 3 chome Koganei-shi Tokyo 184-8584JapanKajinocho 3 chome Koganei-shi Tokyo 184-8584Japan Ohkubo 3 chome Shinjuku-ku Tokyo 169-8555JapanOhkubo 3 chome Shinjuku-ku Tokyo 169-8555Japan

In order to establish the design methodology of ultra micro centrifugal compressor,wich is the most important component of ultra micro gas turbine unit,a 10 times of the final target size model was designed,prototyped and *** problems to be solved for downsizing were examined and 2-dimensional impeller was chosen as the first model due to its *** conventional 1D prediction *** and the inverse design were *** prototyped compressor was driven by using a turbocharger and the performance characteristics were measured.

关键词：离心式压缩机设计性能

LUCC （Land Use and Cover Change） and the Environmental-Economic Accounts System in Brazil

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Journal of Earth Science and Engineering 2013年第12期3卷 840-844页

作者： Rodrigo de Campos Macedo Mauricio Zacharias Moreira Eloisa Domingues Angela Maria Resende Couto Gama Fabio Eduardo de Giusti Sanson Felipe Wolk Teixeira Fernando Peres Dias Femando yutaka yamaguchi Luiz Roberto de Campos Jacintho National Institute of Spatial Research Seo Jose dos Campos-SP 12227-010 Brazil Brazilian Institute of Geography and Statistics Florianepolis-SC 88015-600 Brazil

The objective of this work is to produce statistics that are going to show changes occurred in Brazil"s ecosystems and these statistics are going to join the SEEA (Environmental-Economic Accounts System). It is based by a SEEA"s methodology, diffused by UN (United Nations), which aims an approach between economic and environmental statistics, producing international comparability and conceptual uniformity to evaluate change process in land cover and land use that occurs in several countries. It is necessary to verifying the suitability of methodological procedures to Brazilian reality and the access to all information and files needed. The first step was analysing MODIS (Moderate Resolution Imaging Spectroradiometer) as orbital instrument on the purposed classification method. The choice of this sensor was made because of the product"s quality and its capacity to generate images of a large area, though the challenge is to identify accurate Land usage"s categories in images with a spatial resolution of approximately 250 m. After the final classification, the next step is to make a quantification and comparison of data from these different years using a 1 km2 grids, as proposed in an already used methodology by the European Environment Agency. This procedure will allow evaluate and identify the process of changing in each grid of the land cover and land use, and provide historical series of the chosen years.

关键词：经济核算体系土地利用环境统计巴西覆被变化 LUCC 中分辨率成像光谱仪 SEEA