D109 レーザー光の屈折を用いた高速水噴流自由界面波の二次元波形測定(OS9 混相流動),動力エネルギーシステム部門20周年,次の20年への新展開)

概要

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Free surface fluctuation on a high speed water jet has been measured employing a laser beam refraction technique. The obtained free-surface slope angle data were divided into each wave period using the zero-up-crossing method and wave speed was estimated from the cross-correlation between fluctuations at two measuring locations. Two-dimensional waveform was calculated as a time integration of slope angle data. For jet average velocity U=6 to 10 m/s, the streamwise variation of ensemble averaged wave steepness takes a maximum at a certain distance from nozzle exit. Some samples of waves indicate the waveform similar to the Stokes wave at the location downstream of maximum wave steepness. On the contrary, the probability density function of non-dimensional wave height records the different profile with the Rayleigh distribution.
2010-06-20