The application of inlet air fogging to gas turbine engines for power augmentation has become common practice, with more than 1000 installations worldwide, including a large number of advanced gas turbines. In this paper an experimental investigation and empirical analysis of key operating parameters on the performance of impaction pin nozzles will be investigated. To date, no such correlation is available for impaction pin nozzles, which are currently used in about 75% of this type of applications. The correlations are developed from a series of experiments conducted in a wind tunnel equipped with the Malvern Spraytec droplet size measurement system. The conducted analysis covered a wide range of the relevant parameters. Mainly, the water flow rate from the nozzle orifice was (0.00126 to 0.00063 : 0.02 gpm to 0.1 gpm), the operating pressure was (34.5 to 204.1 bars: 500 to 3000 psi), the airflow velocity was (1.5 to 15.2 : 295 to 3000 fpm), the distance between the nozzle orifice and the location of measurement was (0.0127 to 0.508 m: 0.5 to 20 in.). Other parameters such as the plume spray cone angle and the surrounding ambient psychrometric conditions, which may affect the droplet size for impaction pin nozzles, is also discussed.