Evaporative Cooler for Gas Turbine

The benefits, if any, depend greatly on the environment in which the gas turbine operates. Evaporative cooling performs best under high temperature, extremely low humidity conditions. Since Brayton Cycle engines perform best at low altitude, low air inlet temperatures, the cooler the inlet air temperature the better the heat rate. The downside is the fact that the ideal conditions for evaporative cooling are usually found in semi-arid to arid (desert-like) areas where water is generally scarce and, as a once through process, the water is lost to the atmosphere. So do a cost benefit analysis and see if it pays in your particular situation.

For further reading check this article that you would have found if you took the time to Google on your thread title...

http://www.pdhengineer.com/courses/m/M-2017.pdf

and don't forget that this has nothing to do with your generator which will also require additional cooling or derating as the temperature rises, leaving you with the possibility of getting more mechanical power which the generator can't utilize.