How is power extracted in a gas turbine?

Power extraction in a gas turbine primarily occurs by expanding gases through the turbine blades. In the process of combustion, air is compressed and mixed with fuel, and when this mixture is ignited, it produces high-temperature, high-pressure gases. These gases then expand as they pass through the turbine blades, causing the turbine to rotate. This mechanical energy is what ultimately drives the generator to produce electricity.

The design of the turbine blades is critical, as they are shaped to effectively convert the thermal energy of the expanding gases into rotational energy. The expansion of gases not only provides the necessary force to turn the blades but also harnesses the energy contained in the gases generated by combustion.

The other choices, while they may relate to aspects of gas turbine operation, do not represent the primary method by which power is extracted. Attaching a generator and changing pressure to velocity are important for the system, but they focus more on the overall setup and function rather than the mechanism of power extraction itself. Decreasing gas temperature could be part of energy recovery processes, such as in combined cycle systems, but it does not directly describe how power is extracted from the turbine.