A look into how a steam turbine functionsStacy L. Rousseau EE '03 At a time when energy is such an issue in our country, it may be surprising to realize that the major technology involved in producing electrical energy today was developed over a century ago by Charles G. Curtis: the steam turbine. The aim of a steam turbine is to produce the maximum amount of electrical energy in the minimum amount of space. Today, steam turbines produce more electrical energy than any other system. They comprise approximately 78 percent of all generation capability in our country. Their largest manufacturer is General Electric. GE put its first turbine into operation in November 1901; it had 500 kW of capacity. Now, steam turbines encompass well over 500 million kW of capacity.
A General Electric D11 model of a steam turbine. In a power plant, the steam turbine is attached to a generator to produce electrical power. The turbine acts as the more mechanical side of the system by providing the rotary motion for the generator, while the generator acts as the electrical side by employing the laws of electricity and magnetism to produce electrical power. TerminologyTo understand the functioning of a steam turbine, one must first be familiar with some of the terminology associated with it. The rotor is the spinning component that has wheels and blades attached to it. The blade is the component that extracts energy from the steam. There are two basic types of turbine designs. One is called the "impulse" design in which the rotor turns due to the force of steam on the blades. The other is called a "reaction" design, and it works on the principle that the rotor derives its rotational force from the steam as it leaves the blades. A single-flow turbine design has steam entering at one end. The steam then travels in one direction toward the other end of the section and exits the casing to be reheated, or passes on to the next section. A double-flow section, however, has