回転管内層流の不安定性 : 第1報,速度変動

概要

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An experimental study of the instability of a flow in an axially rotating pipe is performed. It is found that periodic velocity fluctuations occur even in the developing region, when the pipe rotates. Under a certain value of swirl ratio N, the amplitude of the velocity fluctuations amounts to 30% of the axial velocity. This result is related to the occurrence of spiral waves predicted by other investigators by means of linear or nonlinear stability analysis. Velocity fluctuations are measured using the Laser Doppler Velocimeter, and measured azimuthal wavenumber is 1 or 2 and the angular velocity of spiral waves is less than that of the pipe. The rms value of the velocity fluctuation becomes the maximum at N=3, which means that periodic fluctuation is amplified most. As the swirl ratio becomes large (N > 3), the rms value decreases and the periodicity of the fluctuation is weakened.
社団法人日本機械学会の論文
1990-05-25