Definition
An enclosed chamber surrounding the turbine section of a fixed-shaft turboprop engine that collects and distributes high-pressure, high-temperature gas from the combustion section so it can flow evenly across the turbine wheels that drive the compressor and propeller.
Plain English
A sealed pocket of space around the turbine where hot gas from the burner section gathers before being directed onto the turbine blades.
Context Anchor
Seen in turboprop engine diagrams and descriptions of how hot gases move through a fixed-shaft turboprop engine.
Derivation
From the Latin plenus, meaning 'full.' A plenum in engineering is a chamber kept full of pressurized fluid or gas so it can be distributed evenly. In a turbine plenum, the chamber stays full of hot, pressurized combustion gas waiting to flow across the turbine.
Why Pilots Care
Maintains steady airflow and pressure so the engine produces consistent power without uneven stress on turbine blades.
Grounding Statement
Picture hot gas leaving the burning section of the engine and entering a shaped chamber that guides it smoothly into the turbine.
Intuition Check
Do not think of the turbine plenum as a fuel tank or a separate engine part that makes power by itself. It is a gas chamber that helps deliver hot gas to the turbine so the turbine can turn.
Example Sentence 1
Hot gas from the combustion section enters the turbine plenum, then flows across the turbine wheels to drive the compressor and propeller shaft.
Example Sentence 2
The fixed-shaft design routes compressor discharge air directly into the turbine plenum for even distribution.