Вентиляція та теплогазопостачання
Постійний URI для цього зібранняhttps://repositary.knuba.edu.ua/handle/987654321/1443
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6 результатів
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Документ Precise Explicit Approximations of the Colebrook-White Equation for Engineering Systems(Springer, 2020-08-17) Mileikovskyi, Viktor; Tkachenko, TetianaModern automated engineering systems have variable hydraulic/aero- dynamic conditions with Reynolds number from zero to hundred thousand with a wide range of roughness. Simple approximations of the Colebrook-White equa- tion cannot give enough precision. The aim of the work is a universal simple precise approximation of the Colebrook-White equation. The methods are se- lected by the analysis of the equation curve. In the whole range of turbulent flow, it is near to linear. Thus, Newton’s method is very effective. The algorithm is proposed for getting high-precision approximations. The results are two simple explicit ones for rough and careful calculations with a deviation of 5.36 % and 0.00072 % in a wide range of parameters. It is shown on the examples of the objects: the highest building “Biotecton” and researches of “green roofs” in a wind tunnel. The scientific novelty is that we scientifically grounded the effective usage of Newton’s method, which provides new universal, precise and simple explicit approximations of Colebrook-White equation. The practical value is that the approximations are covered different practical tasks of hydraulic and aerody- namic calculations in the whole range of turbulent flow.Документ Research of Deformation of Valve Throttling Characteristics under Gravitational Influence in Hydraulic Systems(Wydział budownictwa Politechniki częstochowskiej, 2019-12-23) Mileikovskyi, ViktorControl valve operation influences the efficiency of hydraulic systems. The deformation of the throttling characteristics in control valves by hydraulic resistances in a single-circuit regulated circuit is well studied. Nevertheless, there are other significant reasons for the deformation. This paper will focus on gravitational influences. The results show significant deformations. They are described by multiplying the valve authority by 0.6-1.7.Документ New Approach for Estimation of Zonal Efficiency of Air Exchange Organization(Science Publishing Corporation, 2018) Dovhaliuk, Volodymyr; Mileikovskyi, ViktorEnergy efficiency of buildings is dependent on air exchange organization. There are different methods for efficiency estimation of it. As it is shown in literature review, they have significant limitations including non-obvious physical meaning, which cause problems in validation of the results. Certain of them are not acceptable for zonal ventilation in rooms. Previous author’s work introduces new approach for the efficiency estimation of air exchange in a single-zone or multi-zonal rooms, which has obvious physical meaning – relation of demands and supplied potentials. It provides the efficiency value for whole room only. In this work, by the similar approach, a method is proposed for estimation of zonal air exchange efficiency in different kind of rooms for each occupied zone separately. Additional definitions are introduced for the parameters and demands estimation in each occupied zone. The example of efficiency estimation of air exchange in a museum room with constant air volume system of air conditioning is solved. Sheltering of the keeping zone is recommended for the maximum air exchange efficiency.Документ The Macrostructure Analysis of the Turbulent Mixing Boundary Layer Between Flows with the Same or Opposite Direction(Vilnius Gediminas Technical University, 2014) Mileikovskyi, ViktorThe approach to calculate large-scale vortexes boundary layer using approach of Professor A. Tkachuk is offered. It based on geometrical analysis of idealized macrostructure shown as a growing or constant radius vortex sheet. The small vortices in flows with a large-scale macrostructure plays secondary roles because they have incommensurably less energy than big vortices. They can be eliminated from consideration. We specify the velocity and temperature profile that differs from the jet boundary layer profile and better coincides with experiment. We find a growth law for a free boundary layer and length of currents cores. This approach help us to solve the actual task for energy efficient heating systems. We found the heat exchange coefficient between flows. It allows simulating the back flow effect in onepipe radiator nodes. The results of calculations coincides with well-known literature data.Документ Geometric Analysis of Turbulent Macrostructure in Gets Laid on Flat Surfaces for Turbulence Intensity Calculation(University of Belgrade, Faculty of Mechanical Engineering, 2017) Gumen, Olena; Dovhaliuk, Volodymyr; Mileikovskyi, Viktor; Lebedieva, Olha; Dziubenko, VolodymyrEuropean Norms for ventilation contain turbulence intensity requirements in rooms. One of the determining factors is turbulence intensity in ventilation jets. We found an approach for geometric analysis of turbulent macrostructure for subsonic flows with large-scale vorticity i.e. ventilation jets and boundary layers between flows. This approach requires building of simplified turbulent macrostructure chart and performing geometrical analysis of it. In previous works, using the approach we analytically found averaged characteristic of free jets, jets in flows and jets laid on different shape surfaces without requirements of any experimental data. The results of geometrical analysis of heat transfer between flows are used in Ukrainian norms. In this work we found turbulence intensity of wall jets on flat surfaces such as room walls or ceiling without any experimental values. The results coincide with known experimental data and may be used in flow calculation in rooms.Документ Simplified analysis of turbulence intensity in curvilinear wall jets(University of Belgrade, Faculty of Mechanical Engineering, 2018) Dovhaliuk, Volodymyr; Gumen, Olena; Mileikovskyi, Viktor; Dziubenko, VolodymyrA simplified approach for estimation of turbulence intensity of turbulent submerged wall jets on cylindrical surfaces with different curvature is shown. It is a continuation of researches, performed by professor of Kyiv National University of Construction and Architecture Andrei Tkachuk. By using the geometric and kinematic analysis of turbulent macrostructure, it is proposed to found not only averaged flow characteristics but also turbulent pulsations. Analysis of visual researches of submerged jets in different works allows assuming such kind of flow as touching large round vortices (puffs), which roll by free flow boundary. In this work, geometric and kinematic analysis of this macrostructure chart in concave submerged wall jets is performed, and turbulence intensity is found. Results of the same analysis for submerged convex wall jets allow obtaining common dependencies for different curvature. The results are accepted by comparison with known experimental data.