Which combination describes the changes in gas properties as it passes through the turbine section?

• A. Pressure decreases; Velocity increases; Temperature decreases
• B. Pressure increases; Velocity increases; Temperature decreases
• C. Pressure decreases; Velocity decreases; Temperature increases
• D. Pressure increases; Velocity decreases; Temperature increases

Answer: (A)

In the turbine, the hot, high‑pressure gas expands and does work on the turbine blades. This expansion lowers the gas’s static pressure and, because energy is taken out as work, the gas cools—so the temperature drops. The expansion also accelerates the flow, so the gas velocity increases as it passes through the turbine. So the correct description is: pressure decreases, velocity increases, and temperature decreases. The other possibilities would imply compression, heating, or slowing of the flow, which isn’t what happens in the turbine section.