巻号一覧
35 巻, 2 号
選択された号の論文の6件中1～6を表示しています
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Technical Papers
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(第１報：腐食性物質の濃縮域と腐食疲労に関する考察)秦 聰, 宮脇 俊裕, 長井 直之, 山下 晃生, 塚本 寛2007 年 35 巻 2 号 p. 72-80
発行日: 2007年
公開日: 2008/09/24
ジャーナル フリーCorrosion fatigue phenomena of low-pressure blade on chemical enrichment zone for mechanical-drive steam turbines were studied by FEA vibration response and fracture surface analysis. Effects of Main factors as corrosive chemicals, corrosion pit size and enrichment concentration are quantitatively analyzed according to useful data and actual samples of blades and operation experience. Based on these detailed studies, blades have been improved to have sufficient integrity under practical chemical enrichment zone.抄録全体を表示PDF形式でダウンロード (2389K) -
松尾 繁, 金 義東, 瀬戸口 俊明, 金子 賢二2007 年 35 巻 2 号 p. 81-87
発行日: 2007年
公開日: 2008/09/24
ジャーナル フリーThe present stury describes a new method to improve the performance of the ejector which can be employed for the hydrogen fuel cell system. A cone cylinder is inserted into a conventional ejector-diffuser system. Experiment is carried out to investigate the operation characteristics of the variable sonic and supersonic ejector system. For a wide range of the operation pressure ratios of the ejector system, the mass flow rate of suction flow is measured. The results obtained show that the present variable ejector system can control the suction flow rate at a fixed operation pressure ratio, and that the sonic ejector is considerably different from the spersonic ejector system. As the ejector throat area ration increases, the recirculation ration of suction flow increases for the sonic ejector, but it decreases for the supersonic ejector. The present variable ejector system can effectively control the suction mass flow rate.抄録全体を表示PDF形式でダウンロード (485K) -
鈴木 正己, 荒川 忠一2007 年 35 巻 2 号 p. 88-93
発行日: 2007年
公開日: 2008/09/24
ジャーナル フリーThe Wells turbine rotor consists of several symmetric airfoil balades arranged around a central hub, and the stagger angle is 90 degrees. These characteristics simplify the total construction of OWC type wave energy converters. Although the Wells turbine is simple, the turbine produces a complicated flow field due to the peculiar arrangement of blades, which can rotate in the same direction irrespective of the oscillating airflow. In order to understand these flows, flow visualization is carried out with an oil-film method in the water tunnel. This research aims to analyze the mechanism of the 3-D flows around the turbine with the flow visualization. The flow visualization explained the influence of attack angle, the difference between fan-shaped and rectangular wings, and the sweep angle.抄録全体を表示PDF形式でダウンロード (1135K) -
長谷川 裕晃, 菅原 健2007 年 35 巻 2 号 p. 94-101
発行日: 2007年
公開日: 2008/09/24
ジャーナル フリーJets issuing through small holes in a wall into a freestream have proven effective in the control of flow separation. This technique is known as the vortex generator jet (VGJs) method. If a precursor signal of separation is found, the separation control system using VGJs can be operated just before the onset of separation and the flow field with no separation is always attained. In this study, we measured the flow field and the wall static pressure in a two-dimensional diffuser to find a precursor signal of flow separation. The streamwise velocity measurements were carried out in the separated shear layer and the spectral analysis was applied to the velocity fluctuations at some angles of diffuser. The pattern of peak in the spectral analysis is changed as the divergence angle increases over the angle of which the whole separation occurs. The change of spectral pattern is related to the enhancement of the growth of the shear layer vortices and is appeared just before the onset of separation. Therefore, the growth of the shear layer vortices can be regarded as a precursor signal of flow separation.抄録全体を表示PDF形式でダウンロード (1593K) -
兼森 祐治, 潘 応康2007 年 35 巻 2 号 p. 102-112
発行日: 2007年
公開日: 2008/09/24
ジャーナル フリーThis papaer reports on an innovative method of changing a centrifugal low specific speed pump performance by applying exit blade flaps to impeller outlet. Centrifugal pump is designed to a specification associated with the maximum impeller diameter. Therefore, when higher head is demanded, a large impeller diameter will be required. Another method to modify pump performance is the formation of flaps at impeller blade exits. The exit blade edge section corresponds to the trailing edge of wing on the circular-cascade, which dominates the pump performance and pressure fluctuation. This paper presents an analytical method of predicting the pump performance related to the attachment of a flap at the trailing edge of impeller outlet. The influence of the flaps on the pressure fluctuation is explained by introducing Kurtosis of flow velocity distribution.抄録全体を表示PDF形式でダウンロード (1840K) -
宮部 正洋, 古川 明徳, 前田 英昭, 梅木 勇, 實谷 善則2007 年 35 巻 2 号 p. 113-121
発行日: 2007年
公開日: 2008/09/24
ジャーナル フリーThe flow instability in a low specific speed mixed-flow pump, having a positive slope of head characteristic curve was investigated. After it was found from pressure measurement that a rotating stall in the vaned diffuser caused the instability, dynamic Particle Image Velocimetry (PIV) measurement and numerical simulation of Computational Fluid Dynamics (CFD) were carried out. Then, the rotating stall is simulated even in CFD and calculated patterns of instantaneous velocities agree well with measured ones by dynamic PIV. It is indicated that a periodical large scaled backflow, generated at the leading edge of the suction surface of the diffuser vane, causes the instability. Moreover, the growth of the strong vortex towards the leading edge of diffuser vane induces the strong backflow from the diffuser outlet to the inlet. The scale of one stall cell is covered over four-passages in thirteen vane-passages.抄録全体を表示PDF形式でダウンロード (1648K)
Review
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