Task 1 (P4)
1. Select two main types of gas turbine engines and state their pros and cons with respect to their operation, construction and installation arrangement
Gas turbine engines are broken into four different types, the turbojet engine, the turbofan engine, the turboprop engine, and the turboshaft engine. Turbofan and turboprop engines will only be given detailed study.
Turboprop engine is almost the same as turbofan since it is also equipped with a fan on the front section of the engine, which is the propeller used as the source of force of the engine being powered by the turbine. But turboprop engine does have an additional gearbox on it that reduces the speed of the gas from the exhaust. Turboprop engine is only capable to fly on limited ranges of altitude and speed that is why it needs a reduction gear assembly.
Turboprop engine has typical assembly as the others which comprise of major components of gas turbine engines, only differ with gearbox and torquemeter assembly. The propeller of this engine may be driven through a fixed or free turbine. Fixed turbine is connected directly on the other components, compressors, reduction gearbox and propeller shaft whereas on the free turbine, it is not connected on the compressor but only to the propeller shaft and reduction gearbox.
The operation of turboprop applies the gas turbine operation with utilization of a propeller except that the exhaust is not being discharged on the nozzle for thrust but used to power and drive the turbine.
The advantages of turboprop engine are:
It has the highest fuel efficiency compared to turbojet and turbofan engines
It can run on short runways unlike the turbojets.
Its propeller is made with reverse configuration which helps it to slow down during landing
Light in weight
It has simple operation
The disadvantages of turboprop are:
o It is only limited with flight altitude and speed
o Provides a slight discomfort for passengers
o It produces high drag on its tips resulting to loss of aerodynamic efficiency
o Turboprop cannot withstand icing conditions because of the altitude that it can only reach
Turbojet is the simplest engine among the other engines manufactured. Since the arrangement of this engine incorporates the basic components of a gas turbine engine, the compressor, combustion, and turbine. With this, its propulsive power is obtained from the high flow of hot gases from the engine exhaust.
Basically, the air sucks into the core of the engine, increases its pressure as being compressed on the compressor section then will enter the ignition process as fuel is added in the combustion section. This heat forces expands and causes the turbine stages to rotate whilst turbine also drive the compressor. The remaining energy will accelerate along the exhaust throughout the atmosphere as it is used for thrust.
The advantages and disadvantages of the Turbo Jet Engines are:
o The engine has...