境界層の遷移に及ぼす単一粗さの影響の続実験

概要

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As the continuation of the previous work of one of the authors, wind-tunnel experiments were made to investigate the effect of a single roughness element on transition from laminar to turbulent flow in the boundary layer in the presence of favorable pressure gradient and of free-stream turbulence. As pointed out by Dryden, the roughness effect proves to be dependent on the ratio of the height k of the roughness element to the displacement thickness δ^*_k of the boundary layer at the element, provided that the transition occurs at a distance from the element. A good correlation of the available data is obtained by plotting the transition Reynolds number Re^*_t based on the displacement thickness as a function of the ratio k/δ^*_k. The presence of a favorable pressure gradient can scarcely alter the relation between Re^*_t and k/δ^_k in the range of variables covered by the present experiment. The effect of free-stream turbulence is conspicuous only at small values of k/δ^*_k, the relation between Re^*_t and k/δ^*_k tending to become a single curve as k/δ^*_k increases.
宇宙航空研究開発機構の論文
1954-10-21