Turbomachines are among the most widely used devices in the world. Pumps, compressors, turbines, and fans are all collectively known as turbomachines. In turbomachinery, energy transfer occurs between a continuously flowing fluid (liquid, steam, gas) and a rotor by the dynamic action of moving blade rows. The word turbo or turbinis is a Latin word meaning “that which spins or whirls around.” Turbomachines can generally be classified into two categories. Turbomachines that transfer energy from a continuously flowing fluid to a blade rotor are known as turbines. Those devices transferring energy from a rotor to a continuously flowing fluid are known as compressors (air), pumps (for liquids), or fans (air). Compressors result in a high-pressure rise compared to fans. These devices use shaft power to increase fluid pressure or head. Some authors define open turbomachines that include wind turbines, propellers, and fans without shroud. Whereas pumps, compressors, and fans increase the pressure of the fluid, turbines produce power by rotating the rotor of a generator.