The turboprop uses a gas turbine core to turn a propeller. As mentioned on a previous page, propeller engines develop thrust by moving a large mass of air through a small change in velocity.
- Suitable for passenger planes
- Most fuel efficient
- Thrust can be produced by the propeller (front) and exhaust (back)
- Good at slow speed
- Limited forward speed
- Limited rpm for the propeller because of instability
- Air intake
- The air intake will transfer air into a turboprop engine where it’s mixed with fuel.
- Speed reduction gearbox
- The speed reduction gearbox is a type of transmission system used in turboprop engines. It’s used to lower the engine’s revolutions per minute (RPM)
- The turbine is a rotary device that’s connected to the propellers.
- It is connected with the gearbox, which is further linked with the compressor. When the turbine sends delivers rotational power to the compressor, the compressor turns and further sends its rotational energy to the reduction gearbox.
- A turboprop engine uses an axial centrifugal compressor. In this compressor, the air enters and discharges in the axial direction to the shaft.
- Combustion Chamber
- The combustor is the space within a turboprop engine where combustion takes place.
- Propelling Nozzle
- The propelling nozzle is a device that’s designed to increase propulsion in turboprop engines. It compresses the combustion gases produced within the combustor before exhausting them.
A turboshaft engine is a variant of a jet engine that has been optimized to produce shaft power to drive machinery instead of producing thrust. Turboshaft engines are most used in applications that require a small, but powerful, light weight engine, inclusive of helicopters and auxiliary power units.
- Typically smaller
- Helicopters and APU
- Absorbs from hot and high-pressure gas flowing over the blades.
- Gas producer turbine
- Aim to supply energy to the compressor.
- Power Shaft
- It turns the rotor and receives power from a set of turbines.
- Air Intake
- Hollow shaft
- The power shaft turns the rotor.
- Stator blades
- Stator blades ensure that sufficient flow velocity is maintained at the turbine row inlet.
- Combustion Chamber
- For effective combustion, an atomized fuel form is to be mixed with medium temperature and high-pressure air.
- Exhaust Nozzle
- The nozzle directs airflow out of the system.
Difference between turboprop and turboshaft
Both turboprop and turboshaft power the turbines by utilizing the connected shaft. But turboprop drives the shaft to power the gearbox and the propeller. But in the turboshaft, the engine drives the shaft to another shaft or component. Turboshaft drives other things other than the propeller.
Turboprop Engine. (n.d.). Glenn Research Center. Retrieved April 11, 2022, from https://www.grc.nasa.gov/WWW/k-12/airplane/aturbp.html
turboprop | engineering | Britannica. (n.d.). Encyclopedia Britannica. Retrieved April 11, 2022, from https://www.britannica.com/technology/turboprop
Turboshaft Engine. (n.d.). SKYbrary. Retrieved April 11, 2022, from https://skybrary.aero/articles/turboshaft-engine