水平線熱源からの乱流プルームのスペクトルおよび乱流遷移グラスホフ数

概要

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The turbulent transition and turbulence characteristics of the plume above a line heat source in unstratified air are established by the statistical analysis of measured temperature. Spectra in the inertia-convective subrange and the inertia-diffusive subrange are expressed by S[s]=0.130f[Hz]^<-5/3> and S[s]=0.275f[Hz]^<-3.0>, respectively. The laminar spectrum changes gradually to the turbulent spectrum in the transitional region. The plume spectrum enables us to exactly determine the flow state, i. e., laminar, transitional, or turbulent. The Grashof numbers for the beginning and the ending of the turbulent transition are Gr_s=2.0×10^8 and Gr_e=2.0×10^9, respectively. The frequency of the large-scale vortex in the turbulent region agrees well with the dominant frequency of the spectrum and the swaying frequency.
一般社団法人日本機械学会の論文
1992-11-25