What is dryness fraction and why is it important in steam systems?

Dryness fraction (quality) is the ratio of mass of dry saturated vapor to total mass of wet steam mixture. Steam with dryness fraction less than 1 contains water droplets, which can cause erosion of turbine blades, reduced heat transfer efficiency, and water hammer in piping. Power plants aim for high dryness fraction (above 0.9) at turbine exit to protect equipment. Dryness fraction affects steam enthalpy, entropy, and specific volume, impacting cycle calculations.