page 1 Flashcards
What is the purpose of the exhaust system in a jet engine?
The exhaust system design exerts a considerable influence on the performance of the engine.
The gases which discharge from the turbine must exit in the correct direction and at the optimum velocity to provide the thrust.
What dictates the turbine gas temperature and back pressure in a turboprop engine?
The design of the outlet nozzle dictates the turbine gas temperature and back pressure in a turboprop engine.
This is to a large extent dictated by the design of the outlet nozzle.
How is the fuselage protected from high temperatures in the exhaust system?
The fuselage is protected by allowing a clearance between the jet pipe and the aircraft skin for air circulation, and insulating the jet pipe with fibrous material sandwiched between stainless steel layers.
This is done to protect the fuselage from temperatures as high as 1500°C if afterburners are used.
What is the purpose of the exhaust cone in the jet pipe design?
The exhaust cone is a conical shaped device positioned close to the turbine disc rear face to help reduce the velocity of the gases.
The exhaust cone helps to reduce the velocity of the gases as they leave the turbine.
What is the consequence of gas turbulence within the jet pipe?
Gas turbulence within the jet pipe will lower the efficiency of the engine and reduce its thrust.
If the gas velocity leaving the turbine has to negotiate a long jet pipe before being ejected into the atmosphere, turbulence will be caused within the pipe.
