The output power of a gas turbine mainly depends upon which factor?

• A. the mass of hot gas passing through the turbine per unit time
• B. the temperature at the turbine inlet in Kelvin
• C. the drive gear ratio between the turbine and compressor
• D. the difference between inlet air and turbine exhaust temperature

Answer: (A)

The amount of power a gas turbine can produce is determined mainly by how much hot gas is flowing through the turbine each second. The shaft power is essentially the product of the gas mass flow rate and the energy each mass unit can transfer (the enthalpy drop as the gas expands). In simple terms, more gas per second means more energy converted to shaft work, so the overall power rises proportionally.

Turbine inlet temperature matters because it sets how much energy per unit mass is available to be extracted, but in practice the total power is most strongly limited by how much gas can be pushed through the turbine. The drive gear ratio changes speed and torque delivery but doesn’t change the total energy produced per unit time. The temperature difference between inlet air and exhaust reflects how much energy is released per mass of gas, but without enough mass flow, increasing this difference won’t dramatically boost total power. So the key factor that governs output power is the mass flow rate of hot gas through the turbine.