How does the turbine work?

A simple gas turbine is comprised of three main sections a compressor, a combustor, and a power turbine. The gas-turbine operates on the principle of the "Brayton cycle", where compressed air is mixed with fuel, and burned under constant pressure conditions. The resulting hot gas is allowed to expand through a turbine to perform work. In a33% efficient gas-turbine approximately two / thirds of this work is spent compressing the air, the rest is available for other work ie.( mechanical drive, electrical generation)