発達チャンネル乱流における壁面加熱の影響

概要

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The experiment was carried out under conditions that the temperature of the lower wall was kept constant and the range of Reynolds number was lower than 30000 (Re_r=121〜507,T_r<2.0℃). About the fully developed channel flow of velocity and temperature, the authors investigated the effects of Reynolds number and heat flux. As a result, distributions of time mean velocity hold a universal law and distributions of time mean temperature also show universality, that is, they are independent of Reynolds number and heat flux. Particularly, the distribution of universal time mean temperature coincides with the case of pipe flow. And the distributions of velocity turbulence intensity are independent of Reynolds number, but are strongly affected by friction temperature. Therefore we have introduced the factor KY in putting results in order, which means the ratio of the velocity turbulence intensity for the heated steady flow to that for the non-heated in the viscous layer, and investigated relation of friction temperature with this factor. This factor relates only friction temperature and the empirical function is shown by the equation of KY=1+0.0854×T_r+0.1027×T^2_r. In the viscous layer, the skewness and flatness factors of velocity fluctuation are agree with nonheated steady flow and not affected by friction temperature. Those factors of temperature fluctuation have the same feature as the velocity fluctuation.
1998-11-25