振動流中における壁面摩擦と局所的熱伝達に及ぼす圧力勾配の影響

概要

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In this paper, the behavior of oscillating laminar boundary layer over a flat plate with an unheated starting length is analysed theoretically, and the influence of pressure gradient on the frequency characteristics of wall friction and heat transfer is clarified in the case of Howarth type main flow. In addition,b y applying the theory obtained in the case of unsteady laminar boundary layer to the viscous sublayer in an turbulent boundary layer, the phasic relation between wall friction and heat transfer in a turbulent flow is made clear. As ar esult, the following conclusions are obtained; (1) The influence of pressure gradient on frequency characteristics of wall friction and heat transfer is significant in low and intermediate frequency regions, but it is little in high frequency region. (2) The influence of pressure gradient is more significant in a decelerating flow than in an accelerating flow. (3) The phase lag between wall friction and heat transfer becomes zero as the unheated starting length parameter K becomes smaller than 0.02.
長崎大学工学部の論文