二重円管内ガス流の加熱層流化現象

概要

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This paper describes a study on the laminarization phenomena of annular tube flows that are strongly and uniformly heated from both sides of the annulus. Experimental as well as numerical results exhibited a remarkable reduction in the local heat transfer coefficient of both inner and outer walls, and the local Nusselt numbers were found to finally approach the laminar values. Moreover, the calculated radial profiles of turbulent kinetic energy, time-averaged streamwise velocity, etc., all suggested the transition from turbulent to laminar flows. Hence, it was concluded that the annular flows can actually be laminarized as the circular tube flows. Following this conclusion, a discussion is developed on the occurrence criteria of laminarization of the annular tube flows. It is concluded that if it is heated uniformly from both walls, the annular tube flows are laminarized at the same bulk acceleration level as the circular tube flows. Otherwise, however, the annular flows are less vulnerable to Laminarization.
社団法人日本機械学会の論文
1991-05-25