Chapter 1.1: Thermodynamic of engine Flashcards

1
Q

which FAR part is on engine regulation?

A

FAR part 33

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2
Q

Which Newton law is thrust and engine based on?

A

thrust: 2nd law (F = ma)

whole engine: 3rd law (equal & opposite reaction)

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3
Q

what are the 5 stages of the engine?

A

inlet > compressor > combustion > turbine> exhaust

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4
Q

which part of the engine is responsible for producing thrust?

A

exhaust nozzle

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5
Q

what is the convergent-divergent duct based on?

A

mass flow rate = ρAV

ṁ and ρ is constant so only A & V can change

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6
Q

where can Bernoulli’s Theorem be applicable within the engine?

A

inlet, diffuser, exhaust

other parts have mechanical interference

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7
Q

which part of the engine has the highest pressure?

A

compressor outlet or combustor inlet/outlet

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8
Q

what should be constant in the combustion chamber?

A

pressure

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9
Q

which part of the engine has the highest temperature and stress?

A

turbine inlet temperature (TIT) or combustion outlet

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10
Q

what is an air-breathing engine?

A

engine that uses atm air as engine working fluid

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11
Q

how does turbojet and turboprop engines produce thrust?

A

turbojet: big acceleration, small mass of air

turboprop: small acceleration, big mass of air

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12
Q

what does the turbine do?

A

extract energy from hot gas to turn compressor

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13
Q

what will be the same for a set of turbine and compressor?

A

rpm on same spool

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14
Q

where does the remaining energy from turbine go?

A

exit exhaust as thrust

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15
Q

what is the use of the compressor?

A

add energy to gas (compressor work on gas)

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16
Q

what is the combustor job?

A

burn fuel air mixture to create large amount of energy to gas

17
Q

thrust producing and torque producing engines

A

thrust: turbojet & turbofan

torque: turboshaft & turboprop

18
Q

at which condition does turboprop engine gives maximum thrust?

19
Q

what does the turboprop compressor turbine drive?

A

centrifugal compressor, accessory gearbox

20
Q

what is a free turbine and what is it for?

A

not mechanically connected with compressor

drive propeller output shaft

21
Q

what will be different between propeller shaft and compressor?

22
Q

on which types on engine would free turbines appear on?

A

turboshaft/prop

23
Q

what is the reduction gearbox responsible for?

A

converting high rpm to low rpm

24
Q

why does turboprop propeller need to have low rpm?

A

high radius and low rpm to prevent mach 1 ( v = rω)

25
how does turboshaft engine work?
delivers power through shaft to main gear box that drives rotor blades
26
at what condition does turboshaft engine deliver maximum shaft output?
low speed and altitudes
27
application of turboshaft?
APU and helicopters
28
which part of turbofan produces the most of the thrust?
80% of thrust by fan blades
29
turbofan features
improved fuel consump. , propulsive efficiency, reduced noise level by increasing mass flow, decrease exhaust velocity
30
turbojet characteristics
1) low propulsive efficiency at low velocity 2) longer takeoff run 3) high TSFC at low altitude and speed 4) small frontal area 5) low weight
31
turboprop characteristics
1) high propulsive efficiency at low airspeed 2) shorter takeoff run 3) low TSFC at low altitude and speed 4) large frontal area 5) efficient reverse thrust (adjusting pitch angle)
32
turbofan characteristics
1) propulsive efficiency increases as airspeed up till mach 1 2) weight and TSFC between jet and prop 3) lesser noise than turbojet
33
advantages of gas turbine engines
1) high power to weight ratio 2) smaller size and lesser vibration than piston engine 3) fewer moving parts 4) high operation speeds 5) can generate higher thrust
34
disadvantages of gas turbine engines
1) higher cost 2) complex machining 3) less fuel efficient than piston engines