In a turboprop engine, the nozzle is designed to accelerate and direct the exhaust gases rearward to generate thrust and also to provide a smooth exit for the propeller’s airflow.
The design of the inlet for a turboprop engine is a crucial aspect of optimizing its performance. Turboprop engines use a combination of a gas turbine engine (turbine) and a propeller to generate thrust. The inlet is designed to efficiently channel air into the engine for combustion and subsequent power generation.
The cross-sectional area of the inlet is an important parameter, and it is typically designed to ensure the proper intake of air for combustion. The relationship between the cross-sectional areas and velocities at the inlet and exit for a turboprop engine can be described by the continuity equation:
where:
-  and  are the cross-sectional areas at the nozzle entrance and exit, respectively,
-  and  are the velocities at the nozzle entrance and exit, respectively.
which gives
where,
- A1Â is the Area of Nozzle Inlet in m2
- A2Â is the Area of Nozzle Exhaust in m2
- V1Â is the Inlet air Velocity in m/s
- V2Â is the Exhaust Air Velocity in m/s