Turbine discharge pressure refers to which of the following?

• A. Static pressure in the combustion chamber.
• B. Total pressure at the discharge of the high-pressure turbine.
• C. Pressure at the inlet of the compressor.
• D. Total pressure at the discharge of the low-pressure turbine in a dual-turbine axial-flow engine.

Answer: (D)

Turbine discharge pressure is the total (stagnation) pressure of the gas as it leaves a turbine. In a dual-turbine axial-flow engine, there are two turbines working in series: high-pressure and low-pressure. The term is used to describe the pressure of the gas at the turbine exit, after energy has been extracted. The best match here is the total pressure at the discharge of the low-pressure turbine, because in a dual-spool engine that discharge condition is the one that characterizes the gas leaving the turbine stage that drives the LP compressor and contributes to the core flow entering the nozzle. The other options refer to pressures that aren’t turbine discharge: static pressure in the combustion chamber, compressor inlet pressure, or the discharge of the high-pressure turbine (which is not the reference typically used for this term in this context).