Chap 1 : Intro to Flight Prop Flashcards
Role of weight in aero engines
Balance between specific thrust & weight
Low weight (compact, low bypass ratio) => high specific thrust & high fuel consumption
Hight weight (high bypass ratio) => low specific thrust & low fuel consumption
The specific thrust has more impact on the global fuel consumption than the weight of the engine
Thrust/weight»_space;5 recommended
Role of cost
Maintenance cost
Input & service cost
Initial & amortization cost
Role of fuel consumption
Goal : have a thrust flexibility & reduce the specific fuel consumption
Reduce specific fuel burn & NOx emissions
Global aero engine market
Depends of the oil price & airframe sales (Airbus & Boeing sales)
=> Increasing since 2000
Engine manufacturers
1) CFM international (40%)
2) Party & Whitney (25%)
3) Rolls Royce
4) General Electric
Working principal of piston & jet engine ?
Big issue of the piston engine ?
Intake (taking air in)
Compressor (compress)
Combustor (burn)
Turbine (expand)
Nozzle (exhaust)
Biggest issue of the piston engine : power-to-weight ratio => invention of the jet engine
Types & historical dvt of jet engines ?
1939 : 1st flight by a turbojet
1944 : 1st serie-production
1976 : fastest jet aero plane
1981 : most powerful military engine
Types : turbofan (small, medium and high bypass ratio) & turboprop (propeller/helicopter)
Operational & reliability challenge to modern jet engines
Reliability challenge : increasing passenger safety IFSDR (In-Flight Shut-Down Rate) thanks to certifications (EASA or FAA)
Operational challenge : ex of the TP400 => strong deterioration by injestion, extreme maneouvre
Major characteristic engine performance parameters for a turboprop ?
Turboprop :
P shaft = T shaft × w
SFC = fuel mass flow / P shaft
Power-to-weight ratio = P shaft /G engine (=M engine×g)
Major characteristic engine performance parameters for a turbojet ?
Turbojet :
F N = mass flow×(air velocity out - air velocity flight)
SFC = fuel mass flow / F N
Thrust-to-weight ratio = F N / G engine
