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Писаревская, Юлия Николаевна

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Институт ядерной физики и технологий
Цель ИЯФиТ и стратегия развития - создание и развитие научно-образовательного центра мирового уровня в области ядерной физики и технологий, радиационного материаловедения, физики элементарных частиц, астрофизики и космофизики.
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Писаревская
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Юлия Николаевна
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2020 - 20212
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    Hydraulic resistance of an annular channel with a rectangular roughness on the wall
    (2020) Medgedem, S.; Korsun, A. S.; Fedoseev, V. N.; Pisarevskii, M. I.; Pisarevskaya, Y. N.; Корсун, Александр Сергеевич; Федосеев, Вячеслав Николаевич; Писаревская, Юлия Николаевна
    © Published under licence by IOP Publishing Ltd.This paper provides a brief overview of approaches to calculating the hydraulic resistance coefficient of a channel with rough walls and describes their advantages and disadvantages. One of the most popular engineering approaches is based on integral characteristics. By the influence of roughness, the logarithmic velocity profile changes, which is fully described by the second constant. It determines the interaction of a turbulent flow with a rough wall. Its numerical value depends on a large number of factors, such as geometry of the roughness protrusion, the dimensionless height of the protrusion, its shape, angle of attack, and so on. Getting a generalized dependence of this kind is an actual task of rough channel hydraulics. In this paper, the second constant of the logarithmic velocity profile is numerically calculated using turbulence models. A symmetric model of a developed turbulent flow in an annular channel with a rectangular roughness on the wall is implemented. Roughness was applied to the surface of the rod, the inner surface of the pipe was smooth. The result of numerical simulation was the obtained velocity profile, which was used to determine the numerical value of the second constant. The obtained results are satisfactory agreement with the experimental data.
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    Annular Layer as a Generalized One-Dimensional Channel
    (2021) Korsun, A. S.; Fedoseev, V. N.; Pisarevskiy, M. I.; Pisarevskaya, Y. N.; Medgedem, S.; Корсун, Александр Сергеевич; Федосеев, Вячеслав Николаевич; Писаревская, Юлия Николаевна
    © 2021, Pleiades Publishing, Ltd.Abstract: 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.