著者

赤塚 純一 永井 伸治 本阿弥 眞治

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B編 (ISSN:18848346)

巻号頁・発行日

vol.77, no.784, pp.2391-2400, 2011 (Released:2011-12-25)

参考文献数

18

被引用文献数

3 5

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This paper propose two new flow visualization methods based on the Background-Oriented Schlieren (BOS) technique for compressible flow. One is “Simplified background-oriented schlieren (S-BOS) ”. This technique does not require a cross-correlation algorithm, which is typically used in BOS. The data processing is much simpler than that of the original BOS, since image displacement associated with density gradient is algebraically calculated from intensities of the images with the periodic background pattern. Moreover, it easily allows us to automate the data processing, because it is neither necessary to remove incorrect vectors nor to optimize parameters such as the interrogation window and search window. The other is referred to “Wavelet-based background-oriented schlieren (W-BOS)”. This technique provides a schlieren image using continuous wavelet transformation for the periodic background pattern. By transforming the periodic intensity pattern into the phase, a schlieren image can be obtained easily. Since the optical setup in both techniques is simpler than that of a conventional schlieren imaging, they could be used in various situations including field tests. A wind tunnel test was conducted in a 1 m × 1 m supersonic wind tunnel. Their usefulness was demonstrated by comparing with the conventional schlieren images.

著者

野木 優佑 佐野 正利 豊田 国昭 本阿弥 眞治

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.849, pp.17-00031-17-00031, 2017 (Released:2017-05-25)

参考文献数

28

被引用文献数

1

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This study is concerned with the active flow control of a two-dimensional offset jet using a dielectric barrier discharge plasma actuator (PA). The offset jet is produced by the flow of air that issues from the end of a long parallel channel, and the offset ratio H/h (H: step height, h: channel height) is 1.0. The PA is operated by a continuous sinusoidal waveform with a voltage of 6 kV and frequency of 2.0 kHz applied to the actuator electrode. The PA is installed on the lower wall of the jet exit. The exit Reynolds number Re is changed from 1.5 × 103 to 6.0 × 103. The flow at the channel exit is laminar. The wall static pressure and heat transfer coefficient on the offset plate are measured. The flow field is examined by flow visualization using a CCD high-speed camera, and the velocity profiles are measured using a particle image velocimetry system. In flow without control, clockwise and counter-clockwise vortices appear downstream of the reattachment point. When the PA is applied, these vortices disappear at a short distance from the reattachment point and a transition from laminar flow to turbulent flow occurs immediately. The reattachment length is reduced and the pressure loss is decreased. Nusselt number in the recirculating region increases with the induced flow due to the PA. These effects are remarkable at low Reynolds number flow. Downstream of the reattachment point, Nusselt number is smaller than that without the PA because turbulent diffusion is promoted.

著者

伊藤 智仁 志澤 高朗 本阿弥 眞治

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.66, no.644, pp.985-989, 2000-04-25

被引用文献数

1

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The phase-averaged characteristic of a single pulsed vortex generator jet which is injected periodically into a turbulent boundary layer is described. Detailed measurements of the three components of the velocity in the jet made by a hot-wire anemometer with the X-type probe show evolution of the longitudinal vortex in the jet. The pulsed vortex generator jet in the stable period has a similar longitudinal vortex structure to that in the steady one. Down-wash motion of the longitudinal vortex in the jet introduces high wall shear stress.