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How does a free turbine work?
A free-turbine turboshaft ingests air through an intake. The air passes through a compressor and into a combustor where fuel is mixed with the compressed air and ignited. This refers to the number of compressor-and-turbine assemblies in the gas generator stage, and does not include the free power turbine assembly.
In what order is fuel ignition and starter used when starting a turbine?
The normal starting sequence is: Rotate the compressor with the starter; Turn the ignition on; and. Open the engine fuel valve, either by moving the throttle to idle or by moving a fuel shutoff lever or turning a switch.
How does a turboshaft engine work?
A turboshaft engine is a variant of a jet engine that has been optimised to produce shaft power to drive machinery instead of producing thrust. The power turbine extracts almost all of the energy from the exhaust stream and transmits it via the output shaft to the machinery it is intended to drive.
What types of gas turbine engines would typically use an electric starter?
Electric starting systems for gas turbine aircraft are of two general types: direct cranking electrical systems and starter generator systems. Direct cranking electric starting systems are used mostly on small turbine engines, such as Auxiliary Power Units (APUs), and some small turboshaft engines.
How is the compressor related to the turbine?
The compressor and its turbine are connected by a common shaft which, together with the combustor, is known as a gas generator, which is modeled using the Brayton Cycle. The (free) power turbine is on a separate shaft.
What makes up the two stage compressor in an airplane?
An acceleration/diffusion process in the two stage compressor increases air pressure and directs it rearward to a combustor. The combustor is made up of a combustion chamber, a transition liner, and a turbine plenum. Atomized fuel is added to the air in the combustion chamber.
What makes a free-turbine turboshaft a turboprop?
A free-turbine turboshaft is a form of turboshaft or turboprop gas turbine engine where the power is extracted from the exhaust stream of a gas turbine by a separate turbine, downstream of the gas turbine and is not connected to the gas turbine (the exhaust airflow is what spins the turbine that is connected to the shaft hence the term “free”).
What are the components of a gas turbine?
Gas turbines, which are also known as combustion turbines, are composed of a gas compressor, a downstream turbine, and a combustion chamber known as the combustor. Air is drawn into the compressor where it meets with fuel, most commonly natural gas.