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

The correct answer focuses on the efficiency of energy extraction in a gas turbine. Turbines extract energy from the high-temperature and high-pressure gases generated during combustion. In gas turbines, the conversion of thermal energy to mechanical energy is accomplished by the turbine stages, which are designed to optimize this process.

In comparison to compressors, turbine stages operate under conditions where they are able to extract energy more effectively and efficiently. Each turbine stage converts the thermal energy from the exhaust gases into work, enabling it to drive the shaft and compressor effectively. Since the turbine stages are specifically designed to make use of the high energy content of the exhaust gases and convert it into useful work, fewer stages are required to achieve desired efficiency.

This design consideration is influenced by the properties of the working gases and the operational parameters of the turbine. While it is true that factors like the size of the blades and operational temperatures could impact performance, it is fundamentally the efficiency of energy extraction that defines the need for fewer turbine stages compared to compressor stages. The turbine's ability to convert thermal energy into mechanical energy effectively allows for a more simplified stage design, leading to an overall reduction in the number of stages necessary for optimal performance.