Annular Layer as a Generalized One-Dimensional Channel

• Published in: Physics of atomic nuclei 2021-12, Vol.84 (9), p.1572-1576
• Main Authors: Korsun, A. S., Fedoseev, V. N., Pisarevskiy, M. I., Pisarevskaya, Y. N., Medgedem, S.
• Format: Article
• Language: English
• Subjects: Curvature; Diameters; Fluid dynamics; Fluid flow; Heat exchange; Hydraulics; Mathematical analysis; Mathematical Modeling in Nuclear Technologies; Nuclear energy; Particle and Nuclear Physics; Physics; Physics and Astronomy; Pipes; Turbulence; Turbulent flow; Velocity; Velocity distribution
• ISSN: 1063-7788; 1562-692X
• DOI: 10.1134/S1063778821090210

In this paper, the concept of a new generalized one-dimensional channel—an annular layer—is introduced. 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 momentum flux and the maximum velocity is reached. By definition, there are two annular layers: outer and inner. For each layer, formulas for calculating their geometric characteristics are presented: area, wetted perimeter, hydraulic diameter, and layer curvature. Depending on the curvature of the annular layer β, the channel can turn into a flat layer, a circular pipe, or an equivalent cell of rod bundles with a different relative spacing. The velocity distribution for a turbulent coolant flow in an annular channel is described by a universal velocity profile. With its help, relations are obtained to determine the maximum-to-average velocity ratio, the deviation of the maximum velocity from the average, and the hydraulic resistance coefficient of the channel versus its curvature. Depending on the curvature parameter β, they generalize the data on the turbulent flow of a liquid or gas in a flat channel, round pipe, annular channel, and rod bundles with a smooth and rough channel surface. It is indicated that, for a given shape and geometry of the roughness, it is necessary to know the dependence of the second constant of the logarithmic profile on the dimensionless height. The calculation formulas obtained can be used in engineering calculations of the hydraulics of heat exchange equipment for the needs of nuclear power.