Abstract
In this paper, a study of gasdynamic processes that occur in a low-flow aerothermopressor has been done. The aerothermopressor is a two-phase jet apparatus for contact cooling, in which, due to the removal of heat from the air flow, the air pressure is increased (thermogasdynamic compression) and its cooling is taken place. Highly effective operation of the aerothermopressor is influenced by primarily the flow part design and the water injected method in the apparatus. Constructive factors that influence energy costs to overcome friction losses and local resistances on the convergent-divergent sections of the aerothermopressor are exerted a significant impact on the working processes in the apparatus. In this paper, a study of a number of typical low-flow aerothermopressor models has been conducted by using computer CFD modeling. Determination of the main parameters of the air flow (total pressure, dynamic pressure, velocity, temperature, etc.) has been carried out for a number of taper angles of a confuser a and a diffuser b, as well as for a number of values of the relative air velocity in the working chamber M = 0.4-0.8. Comparison of the obtained data with experimental data has been carried out. The deviation of the calculated values of local resistances coefficients in the confuser and in the diffuser from those obtained by computer CFD modeling does not exceed 7–10%. The recommended angles were determined: confuser convergent angle – 30° and diffuser divergent angle – 6°, corresponding to the minimum pressure loss is 1.0 – 9.5 %, and therefore also to the maximum pressure increase as a result of the thermogasdynamic compression that occurs during injection and evaporation of liquid in the working chamber. Thus, analytical dependences are obtained for determining the local resistance coefficients for the confuser (nozzle) and the diffuser, which can be recommended to use in the design methodology for low-flow aerothermopressors.
Highlights
Jet devices have long taken their place in the technical area and are widely used, both as individual devices, and as part of power plants to improve cooling systems and to increase fuel and energy efficiency
The aerothermopressor effectiveness depends on the values of total pressure losses due to the following factors: surface and internal friction of the air, aerodynamic resistance of the injection system, resistance of the injected liquid, the process of heat and mass transfer at a finite temperature difference and partial pressure
The absence of the influence of Reynolds number (Re) and M on c and d indicates that there is a self-similar flow regime both in the confuser and in Considering the above, the equation determination for the coefficient of local resistance of the confuser c was carried out by the method of approximation depending on the geometric parameters in accordance with a number of equations
Summary
Jet devices have long taken their place in the technical area and are widely used, both as individual devices, and as part of power plants to improve cooling systems and to increase fuel and energy efficiency. The aerothermopressor effectiveness depends on the values of total pressure losses due to the following factors: surface and internal friction of the air, aerodynamic resistance of the injection system, resistance of the injected liquid, the process of heat and mass transfer at a finite temperature difference and partial pressure. Such losses can be quite significant and amount to 10-40%, depending on the design features of the apparatus flow-through part. It is necessary to have an opportunity for the analytical determination of losses associated primarily with friction in the confuser (nozzle) and diffuser of the aerothermopressor
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