An experimental study of the coarse droplets formation

An aim of this paper is introduce semi-experimental approach for a determination of the Weber number in the transonic wind tunnel for the liquid film atomization on the aerofoil. The wind tunnel was built for the study of the water droplets atomization from the liquid films at the high speed flow similar with one can find in the steam turbines. The coarse droplets in steam turbines are formed from the liquid films on the blades and casing, mostly in their low pressure parts. The wind tunnel is equipped with common instrumentation for the measurement of the flow properties. In this paper the numerical simulation is applied for the study of the flow field in the wind tunnel nozzle, especially in the vicinity of the aerofoil. The numerical simulation was fitted with the pressure measurement of the static and dynamics pressures on the wind tunnel. The results from the simulation in vicinity of the aerofoil are used for the precise determination of the conditions of the liquid film break-up. Two measurements methods were used for the measurement of the size of the droplets, the photogrammetry and the light scattering. Together, the information about the size distribution function of the formed droplets and the detailed knowledge of the flow field allow the determination of the mean values of the Weber number for groups of the formed droplets.