1104 半開放形プロペラファンの空力騒音を支配する非定常流動現象(OS11-1 流体機械の諸問題,オーガナイズドセッション)

概要

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Three-dimensional structure and unsteady nature of vortical flow fields in a half-ducted propeller fan have been investigated by a detached eddy simulation (DES) based on k-ω two-equation turbulence model. To elucidate the complex vortical flow phenomenon, vortex structures were identified by the critical point theory, and limiting streamlines visualized by a line integral convolution (LIC). Furthermore, sound pressure level prediction is implemented by Lighthill's acoustic analogy using the pressure data on the solid surfaces. High pressure fluctuation on the solid surfaces is generated by unsteady flow phenomena, such as interaction with unsteady vortex structures and rotating tip blade loading near the shroud. Unsteady flow phenomena on the walls play a major role in characteristics of the half-ducted propeller fan noise.
2009-11-06