A Complex Study of Superheated Water Atomization

The article presents the results obtained from a complex study of heavily superheated water atomization during its discharging through various types of atomizers. A system for optic measurements of the spray cone dispersion structure has been developed and adjusted. The developed measurement system is based on measuring the scattering indicatrix of a probing laser emission in a wide range of angles (±45°) and solving the inverse scattering problem using the Mie theory. The results from a wide-scale experimental study of the spray cone dispersion structures produced by various types of nozzles with a sprayed water temperature of 140‒260°С and pressure at the nozzle exit equal to 0.1 MPa are presented, and the possibility of liquid atomization (to water droplets with a diameter of 5 µm or smaller down to submicrometer size) at high temperatures is shown. It has been found that the spray cone structure has a pronounced bimodal pattern: droplets 5‒8 µm in diameter combine with a submicrometer mode. With a growth of atomized water temperature, the fraction of submicrometer mode increases, reaching 60‒65 wt % at a temperature of 240‒260°С for cylindrical nozzles and 80‒90 wt % for convergent-divergent nozzles. For the case of water injection into the compressor of a gas turbine unit equipped with the TV-117 industrial grade turbine, the possibility of additionally controlling the peak power output has been demonstrated. It makes 4–8% per water flowrate percent (with respect to the air flowrate). The power output control quality is in compliance with the requirements of the UES of Russia network standards. Superheated water is finding an increasingly growing use for firefighting at power industry facilities, in closed premises, in spills of petroleum products, in performing operations with liquefied gas, and in other situations.