Engines- Study Questions Flashcards
Why are liquid lubricants the best type for use in gas turbine engines
they effectively dissapate heat
What is the designation of the most common synthetic oil used by the military?
The most common synthetic oil used by the military is
MIL-L-23699
what is the main advantage of a dry sump system?
The main advantage of a dry sump system (from the book)
temperature/viscosity can be better regulated
instructor also mentioned that another advantage is that the dry sump system can still function when upside down, banked turns
What does an oil reservoir contain to ensre a constant oil supply during all flight altitudes and G loads?
weighted swivel outlet assembly
what are the two functions of pumps used in the lubrication system?
the two functions of pumps
to supply oil under pressure and to scavenge oil
Where is oil pressure monitored? Why?
monitored after the oil pump. it can indicate an oil pump malfunction
Where is the oil temperature regulator valve located and what does it do?
the oil temperature regulator valve is located at entrance of the fuel-oil heat exchanger.
It directs flow of oil either through or past the heat exchanger
Where is oil temperature monitored?
oil temperature is monitored prior to entrance to the engine bearing compartments
Where would you find the hottest air: the high or low pressure compressor?
you would find the hottest air at the high pressure compressor
Why do you want the starter to remain engaged after you’ve reached self-accelerating speed?
you want the starter to remain engaged to decrease the potential of an abnormal start by reaching normal idle RPM
How does a gas turbine produce thrust?
a gas turbine produces thrust by rapidly compressing, heating, and accelerating a large quantity (mass) of air and fuel
What happens to the velocity of the gasses as they pass through the compressor section? The burner section? The turbines?
The velocity of gasses
remains constant in the compressor
increases in the burner and turbine sections
when is gross thrust equal to net thrust?
gross thrust = net thrust when the aircraft is in a static position and standard day conditions
What is the optimum cruise altitude?
why?
36,000 ft
this is the altitude where the thrust availble plus low fuel flow and diminished drag combine to provide optimum performance for many engines
*36,000 ft is the isothermal layer
Why do rotor and stator vanes within an axial compressor decrease in length from the front to the rear of the compressor?
the cross sectional area decreases within the compressure to allow the velocity to remain fairly constant as the pressure increases. Therefore, the rotor and stator length will decrease
