Why are there fewer turbine stages than compressor stages in a gas turbine?

The correct answer is based on the principle of energy extraction in gas turbines. In gas turbines, the primary function of the turbine is to extract energy from the high-temperature, high-pressure exhaust gases produced after combustion. The design and operation of turbines allow for a more efficient extraction of this energy, meaning that each turbine stage can convert a significant amount of thermal energy into mechanical work.

This efficiency allows for fewer stages to be used because each stage already does a substantial amount of work. Conversely, compressors, which compress the air before it enters the combustion chamber, require more stages to achieve the same level of pressure increase due to the nature of the work involved – compressing air is a process that often demands a larger number of intermediate stages to progressively achieve high pressures efficiently.

As such, the architecture of turbines is optimized for energy extraction while minimizing the number of stages required, leading to a design that features fewer turbine stages compared to compressor stages. This balance of design efficiency is critical in the overall performance and effectiveness of gas turbine systems.