Mileikovskyi V. Energy-Efficient Microclimate Formation Based on a Developed Theory of Macrostructure in Turbulent Flows

The dissertation is devoted to solving the actual problem of taking into account the features of the formation and development of a turbulent macrostructure during the development of energy-efficient microclimate formation systems in the premises. The analysis of the systems are presented. The main flows with large-scale vortices (puffs) in them are jets and mixing boundary layers. The need for a new method for theoretical description of turbulent macrostructure is shown. Visual studies of the macrostructure of a free jet showed the chessboard order of the puffs. New physical conceptual model for the development of the macrostructure of such flows is created. It allows geometric and kinematic analysis of the macrostructure is developed. For free jets, found ratios of characteristic sizes are repeated the known experimental data. The velocity, temperature and turbulence intensity profiles are defined. The experimental tangent of the angle (0.22) was theoretically grounded. Similarly, jets in accompanying or contrary flows, are studied. A good coincidence with the known data is observed at the velocity of the surrounding flow related to the initial jet velocity more than minus 0.4. The theoretically found critical velocity ratio, less than the jet looses stability, is minus 0.4. This is confirmed by author’s visual studies. Similarly, wall jets are considered. The hypothesis by I Shepelev concerning the possibility of neglecting the wall boundary layer is recommended after the refinement by the author: the puffs should be conditionally stretched to the wall. Visual studies confirm the considered macrostructure of these jets. The jet expansion, velocity and turbulence intensity profiles are coincide with experimental data. The multilayer structure of concave jets is grounded. The geometric parameters of air distributors with interaction of convex jets are grounded – five outputs with width at least 0.2 of wall radius. The same principle is used for mixing boundary layers. The characteristic sizes and the U-factor through the layer was obtained. The geometric analysis of the macrostructure of the initial and transitional sections of a free flat jet, where similar layers are formed, gave the relative length of both sections. The physical meaning of the processes in the transitional area was obtained – the formation of the chess order of the puffs. The results are useful for calculation of temperature stratification in pipes and air-ducts. They has been introduced in Ukrainian norms and international recommendations. The methods of usage the equations of momentum and energy for turbulent flows with large-scale vortices are refined. The concept of flows with averaging possibility is proposed. For free jets, the momentum correction is 1.11, and the energy one is 1.15. The distribution of jets power is obtained. Only 0.46 % of the energy is used for the injection. The developed method was practically applied for microclimate systems. The classification of methods for jet development control is proposed for systematization of known solutions of air distribution. To increase the energy efficiency of ventilation and air conditioning in high premises, where the displacement ventilation is impossible, the scheme of air exchange organization is developed. The air is supplied above the working zone by convex wall jets. New air diffuser is invented with nozzle tangential outputs using the developed method to avoid separation of jets. The scheme is considered on the example of International Exhibition Centre in Kyiv. Two-times lowering of the air exchange, the reduction of the design cold by 65.58 W/m² or 29 %, the decrease in re-heating by 7.17 W/m² or 18%. Savings of capital investments is 792.16 UAH/m² or 55 %. The cost of operating costs during the cooling period is 6.61 UAH/m² or 15 %.