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Turbomachinery History, Classifications, and Applications
Published in Bijay K. Sultanian, Logan's Turbomachinery, 2019
A turboprop engine is schematically shown in Figure 1.3b, where the high-pressure (HP) compressor is driven by the HP turbine. The low-pressure (LP) turbine drives the extended propeller at a lower rpm. Turboprops usually refer to gas turbine engines that provide shaft power to a propeller for fixed-wing aircraft propulsion. Gas turbine engines that provide power for rotary-wing aircraft, such as a helicopter, are referred to as turboshafts.
Shaft Engines
Published in Ahmed F. El-Sayed, Aircraft Propulsion and Gas Turbine Engines, 2017
A turboprop engine is a hybrid engine that provides jet thrust and also drives a propeller. It is basically similar to a turbojet except that the turbine works through a shaft and speed-reducing gears to turn a propeller at the front of the engine (Figure 6.43).
Engine performance
Published in Mohammad H. Sadraey, Aircraft Performance, 2017
The turboprop engine is essentially propeller-driven by a gas turbine engine. A schematic of a turboprop engine is shown in Figure 4.18. Here, similar to the turbojet, the inlet air is compressed by an axial-flow compressor, mixed with fuel and burned in the combustor, expanded through a turbine, and then exhausted through a nozzle. However, unlike the turbojet, the turbine powers not only the compressor but also the propeller. In a twin-spool arrangement, the compressor is divided into two stages: low-pressure and high-pressure, where each stage is driven by a separate turbine; the low-pressure turbine and high-pressure turbine. The high-pressure turbine drives the high-pressure compressor. But, the low-pressure turbine drives both the low-pressure compressor and the propeller. Most of the available energy in the gas flow is extracted by the turbine, leaving little available for exit nozzle thrust. For most turboprop engines, only about 10% of the total thrust is associated with the jet exhaust, and the remaining 90% comes from the propeller.
Investigating the green performance limits of a cargo aircraft engine during flight: a thermo-environmental evaluation
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Yasin Şöhret, Selcuk Ekici, Ali Dinc
Turboprop engines are used to generate mechanical shaft power with this shaft power being transmitted to a propeller (usually with the help of a gearbox to adjust revolutions per minute) in order to create the thrust force necessary to fly. Turboprop engines can be designed with one, two or three spools or shafts depending on requirements. In this study, an analytical model of a three-spool turboprop engine is constructed using aero-thermodynamic equations (Walsh and Fletcher 2004). Figure 1 shows a general schematic view of a three-spool turboprop engine, with engine station numbers being identified in Table 1. A turboprop cycle analysis model is illustrated in Figure 2. Based on this model, a genuine computer code has been developed to predict the performance of the three-spool turboprop engine. In the model, initial input parameters are read by the code. Input parameters consist of flight parameters, such as altitude and speed or Mach number at flight stages. After this, there are engine design parameters or design choices, such as IP/HP compressor pressure ratios, burner exit temperature, cooling flow percentages and so on, as well as component efficiencies, for example, compressor/turbine isentropic efficiencies, shaft mechanical efficiencies, and pressure losses (or pressure ratios) in the non-rotating components (combustor, ducts, frames, and nozzle). After reading the inputs, the code starts making calculations for all of the engine components, namely the intake, IP compressor, HP compressor, combustor, HP turbine, IP turbine, LP turbine, exhaust, and propeller. Finally, the results come after these calculations, which give total pressure and total temperature values (at each engine station for all engine components), net shaft power output produced by engine, power specific fuel consumption, propeller and nozzle thrust and, therefore, total thrust.