Laminarization of Strongly Heated Gas Flows in a Circular Tube : Numerical Analysis by Means of a Modified k-ε Model

概要

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This paper aims to clarify the laminarization phenomena of strongly heated gas flows in a circular tube through numerical simulation. For this purpose, a k-ε turbulence model, which was originally proposed by Nagano et al., was modified so as to improve its prediction accuracy, particularly in the turbulent-to-laminar transition region. After that, this modified model was applied to the strongly heated gas flows. According to the numerical results, the streamwise variation of the heat transfer coefficient of the laminarizing flows can be predicted more accurately by the modified version than by either the original model or Jones and Launder's model, and its accuracy level can be favorably compared with that of the k-kL model by Kawamura. Moreover, it was concluded that the streamwise variation of the turbulent energy of the laminarizing flows can be clearly distinguished from those of the flows in which the Nusselt number decreases simply as a result of the local change in gas viscosity. Calculated criteria for the occurrence of the laminarization were in good agreement with the experimental results by Ogawa.
一般社団法人日本機械学会の論文
1990-08-15