著者

佐野 正利 佐川 貴浩 加藤 琢真

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.855, pp.17-00395-17-00395, 2017 (Released:2017-11-25)

参考文献数

19

被引用文献数

1

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In industrial devices such as heat exchangers, fuel cells, and chemical reactors, the fluid flow enters the inlet manifold and streams into many branch passages. In order to improve the performance of these devices, it is important to obtain a uniform flow rate distribution in each passage. In the present study, an experimental investigation is performed for multiple-passage duct flows. The multiple-passage duct is a reverse flow type and consists of five branch ducts. The duct flows are investigated from the view-point of flow uniformity and pressure loss. Experiments are performed for Reynolds numbers ranging from 6.0 × 102 to 1.5 ×103, based on the bulk velocity and hydraulic diameter at the inlet duct. The aspect ratio (i.e., the ratio between the height and width of the branch duct) is varied as 0.6, 1.0, and 20. The effect of the outlet manifold volume on the flow distribution is investigated. The wall static pressure is measured, and the pressure loss and flow rate are evaluated. The velocity profiles are measured by a PIV system in order to clarify the effect of the increasing the outlet manifold volume. The results reveal that the flow rate changes only slightly with the aspect ratio. As the Reynolds number increases, the uniformity of the flow rate through each branch duct worsens. A uniform flow distribution is realized by increasing the volume of the outlet manifold. The flow uniformity is related to the reduction of the recirculation region at the inlet manifold.

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.