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41 巻, 4 号
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論文
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阿川 琢哉, 福富 純一郎, 重光 亨, 井内 一博原稿種別: 論文
2013 年 41 巻 4 号 p. 201-208
発行日: 2013年
公開日: 2015/06/13
ジャーナル フリーData center has been built with spread of cloud computing. Further, electric power consumption of it is growing rapidly. High power cooling fans are used for servers in the data center and there is a strong demand to increase power of it because of increase of quantity of heat from the servers. Contra-rotating rotors have been adopted for some of the high power cooling fans. It is important to clarify complicated internal flow condition and influence of a geometric shape of the cooling fans on performance and internal flow condition to achieve the high performance cooling fans. The performance characteristics of the front and rear rotor of high power contra-rotating small-sized cooling fan is clarified by numerical analysis and design guideline to improve the performance is discussed.抄録全体を表示PDF形式でダウンロード (161K) -
原 豊, 鈴木 貴博, 掃部 裕文原稿種別: 論文
2013 年 41 巻 4 号 p. 209-215
発行日: 2013年
公開日: 2015/06/13
ジャーナル フリーIn order to grasp the three-dimensional flow field around Vertical Axis Wind Turbines(VAWTs), measurements of three components of flow velocity had been conducted in the wake of a small VAWT(4-blade rotor, airfoil:NACA 0012, rotor diameter:0.6 m, blade length：0.47 m, chord length:0.075 m)by using an ultrasonic anemometer. Counterflow in the direction of the mainstream was observed even in the averaged wake-flow-field. For a more detail investigation on the counterflow regions, the three-dimensional flow field was reconstructed in a computer from the velocity data obtained at each measuring point and was analyzed by velocity vector maps, vorticity distributions, and path lines. An obvious swirl pattern in two-dimensional path lines was observed near the counterflow region on the equatorial plane in the wake; however, the vorticity of the swirl pattern part was not so strong.抄録全体を表示PDF形式でダウンロード (181K) -
大江 健司, 川口 清司原稿種別: 論文
2013 年 41 巻 4 号 p. 216-225
発行日: 2013年
公開日: 2015/06/13
ジャーナル フリーMultiblade fan noise is large and has various frequencies. The purpose of this study is to clarify the relationship between the internal flow and fan noise using a numerical analysis. In particular、frequency analysis of the pressure fluctuation on blade surface was performed in order to clarify the source of noise. By frequency analysis result、high pressure fluctuation occurred at the impeller side of leading edge in the pressure and suction side. In addition、broadband pressure fluctuation occurred at the shroud side of the leading edge in the pressure side and at the impeller side of the leading edge in the suction side. This broadband pressure fluctuation is caused by reverse flow and stagnation between the blades、and circulation flow in the casing. These are the cause of the broadband noise of 100∼250 Hz.抄録全体を表示PDF形式でダウンロード (277K) -
山田 雅之, 大豆生田 祐介, 渡邉 聡原稿種別: 論文
2013 年 41 巻 4 号 p. 226-232
発行日: 2013年
公開日: 2015/06/13
ジャーナル フリーFor a bearing of the vertical pump, a rubber bearing is generally adopted. However, if there was no lubricating water, the rubber bearing might be damaged in a short time. The installation of the lubricating water unit was necessary. In this case there were problems that operation and maintenance were complicated. From the viewpoint of improving reliability of the system, a ceramic bearing became positively adopted for a bearing of the vertical pump. As for the ceramic bearing, dry operation is possible for a short time. And the ceramic bearing can expect longer life by lubricating of the water, even including the sand. However, the problem also exists that the damage mode of the ceramic bearing is catastrophic in a short period which results in an unexpected shutdown of the pump.
Thus, its close evaluation in design is mandatory. Therefore, in the present paper, a point to keep in mind on designing the ceramic bearing is described based on analysis and experimental data and the mechanism to lead to break of the ceramic bearing, which was not made clear so far is discussed.抄録全体を表示PDF形式でダウンロード (176K) -
西 泰行, 稲垣 照美, 大久保 薫, 菊池 伯夫原稿種別: 論文
2013 年 41 巻 4 号 p. 233-241
発行日: 2013年
公開日: 2015/06/13
ジャーナル フリーA hydraulic turbine for open channels does not have the incidental facilities for conducting water. Moreover, even if an effective head is comparatively low, it can generate electricity. However, because its rotational speed is low, it has the tendency to enlarge. Therefore, because of its sheer enormity, the setting position of the power generation equipment is limited, giving it restricted mobility. In this study, a new portable hydraulic turbine that utilizes the kinetic energy of an open-channel flow instead of its effective head is proposed. This hydraulic turbine is a structure which added collection device to the axial flow runner, and improvement in an output is aimed at by making a flow collect and accelerate. The performance and flow field of the runner simple substance, the collection device simple substance, and the complex of the runner and collection device were clarified by numerical analysis for developing the axial flow hydraulic turbine equipped with this collection device. Furthermore, the validity of this hydraulic turbine was proven by testing it in a real time environment.抄録全体を表示PDF形式でダウンロード (185K) -
藤井 直樹, 天久 和正, 鈴木 正己, 二見 昌寛原稿種別: 論文
2013 年 41 巻 4 号 p. 242-247
発行日: 2013年
公開日: 2015/06/13
ジャーナル フリーA wind turbine generator(WTG)with a power rating of 100 kW and a variable pitch control system was developed for isolated islands. The WTG was designed according to the international standard(IEC 61400-1)with survival wind speed of 80 m/s and built on Kume-Island, Okinawa, in 2009. The Kume-Island have abundant wind energy resources because of annual average wind speed of 6.2 m/s, furthermore there is a strong likelihood of typhoon hits once every year or more. The WTG controlled an AC-DC-AC power converter system interconnects an end of small utility grid with diesel-engine generators of 18,500 kW. In field testing, several typhoons hit the Kume-Islands, however, the WTG didn't have serious damage. The development targets which are low acoustic noise, high strength, good quality electric power etc. have been demonstrated successfully. This paper shows typical examples of field test data in summer season and winter season.抄録全体を表示PDF形式でダウンロード (141K)
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