Referat Aircraft propulsion systems

Aircraft propulsion systems

This report treats the aircraft propulsion systems. It s structured into four parts.

1st part: the turbojet engine

2nd part: the turbofan engine

3rd part: the turboprop engine

4th part: the ramjet engine

1st part: the turbojet engine:

The first turbojet engine was flown in Germany in . It was tested on a

Heinkel He

The engines which now are in use, are in a great deal more complicated and are producing more thrust.

A cutaway view of a three shaft turbojet engine with afterburner, as used

at the supersonic fighter PANAVIA TORNADO, the Turbo Union RB R is shown here.

The technical data from the RB199-34R are:

max. thrust with afterburner..71 kN

pressure-difference23%

rotation speed12`000/ 0 rpm weight 0 kg

70 kg air per second are going the following way through the engine: At first the air is sucked through low-press-compressor. In this case it has three stages. A stage consists of a single row of rotating and fixed

compressor blades.) The LP-compressor is working with low rotation speed. Then the air is passing the three stage MP-compressor. After it the air has only % of its intake volume.

While the air is going through the HP-compressor with six stages, it s compressed to % of its original volume.

After the HP-compressor the air is passing the fuel injector and the flame holder where the mixture explodes.

The last part of the RB199-34R is the afterburner, where some extra fuel can be injected for more thrust.

The hot air exhausts finally through the convertible expansion nozzle.

The turbojet engine is used in supersonic fighter aircraft. For example the

F-15 'EAGLE', MiG 9 FULCRUM' and SR-71 'BLACKBIRD'

2nd part: the turbofan engine:

A typical turbofan is the Rolls Royce Trent 0 which you can see here. The only difference between the turbojet and the turbofan is a big 'fan' which is placed in front of the LP-compressor. The fan (half

compressor-half propeller) pushes about % of the intaken air around the engine for producing extra thrust. The remainder of the air goes the way through the conventional engine. So the turbofan is a compromise between the turbojet and the propeller engine.

This engine is used in most of the civil transport aircraft, because it s very quiet and efficient.

3rd part: the turboprop engine:

The turboprop engine is principally a smaller turbojet engine-only the turbine part is bigger.

Normally there are added two to four stages which are powering the propeller.

The propeller is connected over a reduction gear and an extended shaft with the faster rotating turbines. Some extra power is given by the exhausting

gases.

The turboprop power plant is used for subsonic speeds up to 0 km/h. It is more efficient than a turbofan, but only up to speeds from 0 km/h.

The fastest turboprop-powered aeroplane is the Russian Tupolew TU 5 'BEAR'

4th part: the ramjet engine:

The ramjet power plant is the simplest engine, but it has one big disadvantage: it produces no usable thrust at low subsonic speeds. That means for landing, starting and taxiing a ramjet powered aeroplane needs some extra thrust from another engine.

The reason why it produces no thrust at low speeds is that there are no compressor stages inside the engine.

At high speed the air is compressed while it s passing the diffuser. Then it goes through the fuel injector and the flame holder were the mixture explodes. It exhausts through the variable expansion nozzle.

The most efficient speed of the ramjet power plant is from Mach 3 to Mach

A Ramjet powered typical aircraft is the North American X-15. At last a comparison of the four engines:

* TURBOPROP: most efficiency up to 0 km/h

* TURBOFAN: most efficiency up to 0 km/h

* TURBOJET: most efficiency from 0 km/h to Mach 3

* RAMJET: most efficiency from Mach 3 to Mach 6

I hope you've enjoyed my report. Thank you for paying attention.

(c) by Froschl Dieter