I don't understand how it works, can someone provide me with details?

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    $\begingroup$ Welcome. What don't you understand in the turboprop? Basically a turboprop is a turbojet with a gearbox. See this question $\endgroup$ – mins Jan 22 '17 at 2:17
  • $\begingroup$ If you're surprised by how turboprops work wait until you learn what the M1A1 Abrams tank use for an engine (spoiler: it's also a turbine engine just like turbojets and turboprops) $\endgroup$ – slebetman Jan 22 '17 at 9:34
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    $\begingroup$ Come now, does the proposed duplicate actually provide details of how a turboprop engine works? I don't see how that is an "exact duplicate". $\endgroup$ – J Walters Jan 22 '17 at 14:39
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    $\begingroup$ I agree with @JonathanWalters. I did vote to close, because the question is unclear, not because it's a duplicate. So the OP should try to explain what he/she already knows (e.g. how a turbojet works -- else start by searching/asking about the turbojet, not the turboprop) and explain what he/she is missing (e.g. the free turbine in the PT6). $\endgroup$ – mins Jan 22 '17 at 19:10

The following describes reverse-flow, free-turbine type gas turbine engines such as the Pratt & Whitney Canada PT6 series of turbo-prop engines that I am familiar with. There are also geared turboprop engines such as the Garrett models; I am not very familiar with these.

The Beechcraft systems description for one of the PT6 models provides the following:

The PT6 engine has a three stage axial, single stage centrifugal compressor, driven by a single stage reaction turbine. The power turbine, counter-rotating with the compressor turbine, drives the output shaft. Both the compressor turbine and the power turbine are located in the approximate center of the engine with their shafts extending in opposite directions. Being a reverse flow engine, the ram air supply enters the lower portion of the nacelle and is drawn in through the aft protective screens. The air is then routed into the compressor. After it is compressed, it is forced into the combustion chamber, and mixed with fuel that is sprayed in through nozzles mounted around the gas generator case. Two spark igniter plugs are used to start combustion. After combustion, the exhaust passes through the compressor turbine and two stages of power turbine and is routed through two exhaust ports near the front of the engine. A fuel control system schedules fuel flow to maintain the power set by the gas generator power lever. Propeller speed within the governing range remains constant at any selected propeller control lever position through the action of a propeller governor, except in the beta range where the maximum propeller speed is controlled by the pneumatic section of the propeller governor.

The accessory drive at the aft end of the engine provides power to drive the fuel pumps, fuel control, the oil pumps, the starter-generator, and the tachometer transmitter.

The reduction gearbox forward of the power turbine provides gearing for the propeller and drives the propeller tachometer transmitter, the propeller overspeed governor, and the propeller governor.

The following diagram depicts airflow through the compressor stages, the combustion chamber, the power turbines, and the exhaust section. The propeller bolts on the front of the engine at the output shaft (left side in the diagram).

enter image description here

The following diagram depicts the various compressor and turbine stages. Note the physical disconnect between the gas generator and power generator turbines. This is why these types of engines are called "free-turbines": the power turbine (and by extension the propellor) can spin freely from the gas generator section.

enter image description here

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