Institute of Space and Aeronautical Science,University of Tokyo
雑誌名
ISAS report/Institute of Space and Aeronautical Science,University of Tokyo
巻
35
号
11
ページ
317 - 377
発行年
1970-08
抄録（英）
Detailed measurements were made on the laminar-turbulent transition of a two-dimensional wake with three kinds of imposed disturbances, the natural disturbance in a wind tunnel, a sound of single frequency, and a sound of two frequencies from outside. In all cases the transition to turbulence is gradual. The production of the fluctuation energy from the mean motion can be negative in a certain stage of the transition. When a sound of single frequency is introduced into the wake, the induced velocity fluctuation is regular and periodic and it persists, resulting in a transition delay. When a sound of two frequencies (f_1 and f_2) is introduced, two velocity fluctuations are induced. They grow independently while amplitudes are small. When amplitudes exceed certain values, two fluctuatoins interact and both amplitudes are reduced. Another result is the generation of velocity fluctuations of frequencies of f_1-f_2,2(f_1-f_2), ..., and f_1+f_2,2(f_1+f_2), ... The behavior of a slow, irregular fluctuation found in the natural transition resembles that of f_1-f_2 component in many respects. Both fluctuations must be generated by the same process. The amplification of randomness in the transition process may be accomplished by the mutual suppression of amplitudes and by the generation of low-frequency components from high-frequency components.
Detailed Measurements in the Transition Region of a Two-Dimensional Wake
SA2400769.pdf
(16.99MB)
