Annular Layer is a Generalised One-Dimensional Channel

Abstract

In this paper, we introduce the concept of a new generalized one-dimensional channel – the ring layer. It includes a solid cylindrical wall and a liquid or gas layer adjacent to the wall, on the outer surface of which there is no pulse flow and a maximum speed is achieved. By definition, there are two ring layers: outer and inner. For each of them the article presents the calculation formulas of their geometric characteristics: area, wetted perimeter, hydraulic diameter, curvature of the layer. Depending on the curvature parameter of the annular layer β the channel can pass into a flat, round tube or an equivalent cell of rod bundles of different relative pitch. The velocity distribution in the turbulent flow of the coolant in annular channel is described by the universal velocity profile. Relations are obtained for determining the ratio of the maximum speed to the average, the deviation of the maximum speed from the average, the coefficient of hydraulic resistance of the channel depending on its curvature. Depending on the value of the curvature parameter β, they generalize data on the turbulent flow regime of a liquid or gas in a flat channel, a round pipe, an annular channel and bundles of rods with a smooth and rough channel surface. It is indicated that for a given shape and roughness geometry, it is necessary to know the dependence of the second constant of the logarithmic profile on the dimensionless height. Resulting calculation formulas can be used in engineering calculations of the hydraulics of heat exchange equipment.