Experimental Investigation of Droplets Splashing With Varying Pressures and Impact Angles to Predict Behaviour During Wet Compression

Wet compression is a powerful means to increase gas turbine power output and to perform fast load changes. These characteristics make this process suitable to compensate the unsteady supply of electric energy from renewable sources or to increase overall power output in times of high demand without the necessity to invest in higher peak capacity. In case of high fogging water sprays are injected inside the intake duct of the gas turbine compressor resulting in droplets entering the first stages of the compressor. Inside, droplets above a specific size cannot follow the airflow properly, which makes it likely for them to collide with compressor surfaces and disintegrate. Characteristics of the ejected secondary droplets influence evaporation and condensation processes and thereby the thermodynamics of the compression process. To investigate the characteristics of ejected secondary droplets, collisions between droplets and surfaces were recorded with a high-speed camera using the shadowgraphy method. From these recordings, quantity, diameter and velocity of secondary droplets were obtained. To resemble conditions at the first stages of a compressor under high fogging conditions, the experiments were conducted at elevated pressures up to 500 kPa and with varying impact angles from 0° to 30°. The Weber number normal to the surface was held constant at 550 and 700. The paper discusses the measured influence of splashing at simulated compressor conditions.