DESIGN PARAMETERS DETERMINATION OF THE AEROTHERMOPRESSOR FLOW PART OF THE AIR COOLING SYSTEM IN MICROTURBINES

Among modern jet technologies, one of the promising research areas is a study of gas-dynamic processes in the aerothermopressor. This jet apparatus is a device for contact cooling (the heat from the air flow is consumed for the instantaneous evaporation of water droplets), in which there is a thermogasdynamic compression effect, and that is, the air pressure increase is taken place. A significant influence on the working processes in the aerothermopressor is exercised by design factors. The influence of these factors on energy costs to overcome the friction losses and local resistances on the convergent-divergent sections of the apparatus was investigated. Relevant in the aerothermopressors development is to determinate of rational parameters of the workflow organization with the corresponding development of the flow part design. At the same time, it is necessary to have an opportunity for analytical determination of pressure losses in the confuser and diffuser of the aerothermopressor. A research of typical models of the aerothermopressor for a number of taper angles of a confuser a (convergent angle a = 30; 35; 40; 45; 50 °) and diffuser b (divergent angle b = 6; 8; 10; 12 °), for a number of air velocity values in the working chamber M = 0.4-0.8 has been carried out. The obtained calculated data (results of computer CFD-simulation) and experimental data have been compared. The error of the values for the coefficients of local resistances in the confuser and diffuser does not exceed 7-10%. It was established that the value of the local resistance coefficient depends only on the geometrical parameters (the angle of tapering and the diameters ratio of the input and output D1/D2), that is, the air flow character in the aerothermopressor corresponds to the self-similar mode. The recommended angles were determined: confuser convergent angle a = 30 ° and diffuser divergent angle b = 6 °, corresponding to the minimum pressure loss DPloss = 1.0–9.5 %. The empirical equations were defined for determining the local resistance coefficients of the confuser and diffuser, which can be recommended for use in the design of low-flow aerothermopressor for microturbines