The Design of Different Types of Turbine Engines

Since the advent of powered flight, many revolutionary engine types have come about, radically changing the capabilities of aircraft over the years. One of the most prominent advancements to flight came in the form of the introduction of gas turbine engines, those of which differ from reciprocating engines with separate sections devoted to separate roles of intake, compression, combustion, and exhaust. As gas turbine engines have been around for many decades, there are numerous types that have come about, each featuring slightly different design choices to support varying needs. 

The turbojet is considered to be the first gas turbine engine, and it was developed by Germany and England prior to World War II. As the most simplistic type, the turbojet consists of a compressor, combustion chamber, turbine section, and exhaust. Like many gas turbine engines, the basic set of operations is drawing in and compressing air, mixing it with fuel for combustion, using exhaust gasses to drive a turbine assembly for power, and then venting all spent gasses out of the exhaust system. With new turbine engines superseding the turbojet and its own issues with noise and fuel consumption, the turbojet has mostly gone out of use in the modern day.

The turboprop gas turbine engine was invented around the same time as the turbojet, initially being flown in 1945. Unlike other gas turbine engines, the turboprop engine features propellers at the front of the assembly, those of which are driven by the power harnessed from combusted fuel mixtures. Otherwise, many of the other operations remain the same in the engine. When compared to other engines within the family of gas turbines, turboprops are known for being very fuel efficient, especially when remaining in set speeds and altitudes. Nevertheless, they do face limited forward airspeed, and gearing systems are quite heavy.

The turbofan is the next common type, and it is designed to strike a balance between the best features of turbojets and turboprops. Turbofans also have the special feature of diverting a secondary airflow around the combustion chamber, allowing them to produce additional thrust for flight. Turbofans are often denoted by the large fan assemblies that are situated toward the front of the engine, and these powerplants are regularly found on modern commercial airliners of all types. Turbofan engines are known for their high fuel efficiency and quiet operations when compared to turbojets, but this comes at the cost of heavier weights and inefficiency at high altitudes.

The final common turbine engine that we will discuss is the turboshaft, and it is somewhat unique in its use of combustion to drive a turbine instead of creating thrust. Turboshaft gas turbine engines are regularly found on helicopters, though they can also act as an auxiliary power unit for a larger aircraft. When used on an aircraft, the energy of combusted fuel will be harnessed by the turbine and transferred through various parts to rotate the main rotary shaft so that lift can be achieved. For larger aircraft, all operations of the turboshaft will be used to provide electrical power and bleed air as a type of backup system. When compared to piston powered engines, turboshafts present a much higher power-to-weight ratio and can be constructed with a more compact size. Despite this, they exhibit high amounts of noise during operation, and the complexity of their gear systems sometimes leads to breakdowns.

1. gary anderson
2. Posted on October 17, 2022
aviation

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