Faculty of Agriculture, Shimane University

ISSN:0370-940X

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Use this link to cite this item : https://ir.lib.shimane-u.ac.jp/1722

Bulletin of the Faculty of Agriculture, Shimane University 15

1981-12-15 発行

Study on the Unsteady Flow in Open Channels under Gates Operation : Transients in Series Channel with Automatic Gate and some Effects of its Control-Elements

Takeyama, Kouichi

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This study was the mathematical simulation and the experimental results on the time series of the water depth of hydrauric transient phenomenon.

The phenomenon was caused by the series of automatic gates, though those should be operated their upstream water depth in constant. And the synthesized components were existed in high depth. For such a time series, the statistical analyses like auto and cross correlation and coefficient were very useful for analyzing the amplitude, the damping ratio, the phase and the cycle of them, respectively.

Next, it was successful with sufficient accuracy to simulate such transients by digital computer with mathematical models. When the undulations were vrey small(max.0.8cm/10sec, when mean depth was 7～8cm), it could be simulated by simple tidal river model or small surge one. But when the undulations were moderate(max. 0.8cm/sec, when mean depth was 25～30cm), the F.D.M. model(the Two Steps Lax Wendroff model) had to be used.

Then, as one of the control elements of the automatic gate system, some roles of the neutral time-zone of its depth-detector were examined besides its neutral depth-zone the ascending or descending speed of the gate, and the time lag between the depth detector and gate-motion.

Consequently, it became clear qualitatively that the neutral time-zone as a control element was very effective against meaning less motions of gate which might amplify the undulations.

The phenomenon was caused by the series of automatic gates, though those should be operated their upstream water depth in constant. And the synthesized components were existed in high depth. For such a time series, the statistical analyses like auto and cross correlation and coefficient were very useful for analyzing the amplitude, the damping ratio, the phase and the cycle of them, respectively.

Next, it was successful with sufficient accuracy to simulate such transients by digital computer with mathematical models. When the undulations were vrey small(max.0.8cm/10sec, when mean depth was 7～8cm), it could be simulated by simple tidal river model or small surge one. But when the undulations were moderate(max. 0.8cm/sec, when mean depth was 25～30cm), the F.D.M. model(the Two Steps Lax Wendroff model) had to be used.

Then, as one of the control elements of the automatic gate system, some roles of the neutral time-zone of its depth-detector were examined besides its neutral depth-zone the ascending or descending speed of the gate, and the time lag between the depth detector and gate-motion.

Consequently, it became clear qualitatively that the neutral time-zone as a control element was very effective against meaning less motions of gate which might amplify the undulations.

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