The point of maximum velocity in the engine is located at which component?

• A. exhaust exit nozzle.
• B. combustion chamber.
• C. nozzle throat.
• D. turbine inlet.

Answer: (B)

Velocity of the hot gases in a gas turbine is driven by the energy added to the flow and the area available for the flow to pass through. The combustion chamber is where fuel burning injects a large amount of energy into the gas at roughly constant pressure, so the gas enthalpy rises sharply. With the flow area in the combustor being relatively constrained, that energy rise translates into a noticeable increase in gas speed in that region before any significant energy is extracted downstream. Once the hot gas moves on to the turbine, part of its energy is taken out to drive the compressor, which reduces the gas velocity. The nozzle then converts some of the remaining pressure energy into velocity, but the peak velocity tends to occur in the combustor where the major energy addition happens, before the turbine extracts energy. That is why, in this context, the combustion chamber is identified as the point of maximum velocity.