Which parameter primarily determines the output power of a gas turbine?

• A. Mass flow of hot gas through the turbine
• B. Turbine inlet temperature in Kelvin
• C. Drive gear ratio
• D. Difference between inlet air and exhaust temperature

Answer: (A)

The main factor that sets how much shaft power a gas turbine can produce is how much hot gas is flowing through the turbine each second. The power output is essentially the energy each kilogram of gas can give up (the work per unit mass) times how many kilograms per second are passing through. In formula terms, shaft power ≈ mass flow rate × (specific enthalpy drop across the turbine). So increasing the mass flow of hot gas increases the total power, even if the energy per kilogram is fixed by temperature and design.

Turbine inlet temperature does cap the maximum energy per kilogram, and the drive gear ratio only influences how much of the turbine’s shaft power is delivered to a load, but the actual powerhouse comes from the amount of gas moving through. The temperature difference between inlet air and exhaust reflects the energy extracted, not the direct determinant of how much power is produced.