**1. Introduction**

Erosion of steam turbine blades was first recognised by the turbine manufacturing industry at the start of the nineteenth century when the velocities of the rotating blades of steam turbines became sufficient to cause erosion. At that time, the erosion of steam turbine blades by

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

different possible phenomena including chemical attack, oxidation and solid particles carried by the steam was tried to be explained (Coles 1904) [1]. However by the 1920s, experimental studies focusing on the erosion of steam turbine blades by droplet impact had been started [2]. In 1928, Cook presented his water hammer equation in which he estimated the pressure generated when a liquid column impacts on a solid surface. In his theory, he proved that the pressure generated at the liquid-solid impact is sufficient to exceed the yield strength of many steel alloys typically used for steam turbine blades [1]. The following section aims to highlight the phenomenon of liquid-solid impact and to provide a brief review of the scientific findings and developments in this field.
