Types of Gas Turbine Engines.
An aircraft turbine engine is the most widely used propulsion system in the aviation industry. Turbine engines come in several types, each with its own requirements for maintenance and aircraft engine overhaul. That’s why it is important to choose the right company when performing repairs and maintenance on your aircraft turbine engine.
A turbojet is the simplest of all aircraft turbine engines, consisting of four sections: compressor, combustion chamber, turbine section and exhaust. Turbojets were developed in Germany and England before World War II. In this type of engine, air is passed at a high rate of speed into the combustion chamber where the fuel inlet and igniter is located. The turbine, driven by expanding air, causes thrust from accelerated exhaust gases. Covington Aircraft has extensive experience in aircraft engine overhaul, as well as routine maintenance for these types of engines.
Turboprop engines drive propellers through a reduction gear, which provides optimum propeller performance at slower rpm speeds. That translates to greater fuel efficiency and performance at slower airspeeds, which is why turboprops are popular aircraft turbine engines for small, commuter aircraft, cargo planes and agricultural use. The propellers are less efficient as the aircraft speed increases, making them better for planes that do not have travel at higher speeds. Because agricultural pilots rely on the consistency of their aircraft, Covington Aircraft has proudly worked on turboprop planes used in agriculture since 1972.
Merging the best features of the turbojet and turboprop, the turbofan is an aircraft turbine engine that diverts a secondary flow of air around the combustion chamber, which creates additional thrust. This is the most modern version of an aircraft turbine engine and the one often found on high-speed transport and fighter planes. Because many corporations choose turbofan engines, Covington Aircraft focuses on plane maintenance to keep corporate planes in the air, avoiding grounded aircraft due to maintenance issues.
A turboshaft engine may be made up of two major parts assemblies: the ‘gas generator’ and the ‘power section’. The gas generator consists of the compressor, combustion chambers with ignitors and fuel nozzles, and one or more stages of turbine. The power section consists of additional stages of turbines, a gear reduction system, and the shaft output. The gas generator creates the hot expanding gases to drive the power section. Depending on the design, the engine accessories may be driven either by the gas generator or by the power section.
In most designs, the gas generator and power section are mechanically separate so they can each rotate at different speeds appropriate for the conditions, referred to as a ‘free power turbine’. A free power turbine can be an extremely useful design feature for vehicles, as it allows the design to forgo the weight and cost of complex multiple-ratio transmissions and clutches.
The general layout of a turbo-shaft is similar to that of a turboprop. The main difference is a turboprop is structurally designed to support the loads created by a rotating propeller, as the propeller is not attached to anything but the engine itself. In contrast, turbo-shaft engines usually drive a transmission which is not structurally attached to the engine. The transmission is attached to the vehicle structure and supports the loads created instead of the engine. In practice, though, many of the same engines are built in both turboprop and turbo-shaft versions, with only minor differences.