Introduction to Aerospace Engineering Lecture slides Challenge the future 1
18-9-2011 Introduction to Aerospace Engineering AE1101ab - Propulsion Delft University of Technology Prof.dr.ir. Challenge JaccotheHoekstra future
18-9-2011 Delft University of Technology Challenge the future
11 Propulsion We do not use Anderson s ch 9 (too difficult for now), but these slides for 1101ab 3 xx
The propulsion perspective Gee Bee model R Sportster 4 xx
Wright Flyer required an engine that did not exist Engine: Wright 4-cylinder 12-20 hp water-cooled inline Weight 150 lbs, 200 lbs with fuel 5 xx
Even considering the improvements possible the gas turbine could hardly be considered a feasible application to airplanes, mainly because of the difficulty with the stringent weight requirements. Gas turbine committee, US National Academy of Sciences (1940) Same statement is currently often heard for electrical propulsion! 6 xx
Theory L V 0 (m/s) T D W aircraft- and rocket propulsion reaction propulsion 7 xx
You can see this principle in the water rocket. 8 xx
Theory of air breathing engines V 0 (m/s) T V J mkg [ / s] For rocket propulsion we use Tsjolkovski s rocket equation (covered 1101cd)! 9 xx
Theory Momentum Equation: V 0 (m/s) T V J I F = m V (En: linear momentum, di = dt dv F = m = m a dt T = m ( V V ) j 0 NL: impuls) (Newton's second law) [kg m/s 2 ](=N) [kg/s m/s] (=N) 10 xx
What Flew or Is Flying Around? Propeller Propulsion Jet Propulsion Human Powered Electrical Engine Airbreathing Engine Rocket Engine Propeller Propulsion Jet Propulsion Piston Engine TurboProp TurboShaft TurboFan TurboJet Ramjet Scramjet 11 xx
Propeller Propulsion Counter Rotating Rotating 12 xx
Propeller Propulsion Counter Rotating Rotating Fixed Pitch Variable Pitch Ducted Fan 13 xx
Propeller Theory R(m) ω (rad/s) r(m) V rot (m/s) V = Ωr rot ω 14 xx
Propeller Theory: Blade is like a wing R(m) S ω (rad/s) r(m) T Useful force: T Loss: S Thrust (pointing at us) Side force (like drag for wing) 15 xx
Twisted for constant angle of attack ω (rad/s) Large Twist Small Twist Constant angle of attack! 16 xx
Available Power for thrust t+δt t T T Δs Work Performed: W= T Δs [Nm or J] T Δs Available Power: P a = = T V [Nm/s, J/s or W] Δt 17 xx
Available Power t+δt T T Δs=VΔt t Speed is V Net available Power for thrust: P a =T V Brake (shaft) Power: Propulsive Efficiency: P br P a P br η= = T V P br 18 xx
Airbreathing Engines They all work the same way...in principle Only the details differ. They all have 4 stages: 1. Intake 2. Compression 3. Work 4. Exhaust 19 xx
Piston Engines What is used in Aviation? 2 Stroke Engine 4 Stroke Engine Wankel Engine Diesel Engine Obsolete Common New Expected 20 xx
Combustion Cycle (Otto Cycle) T 1 T 2 Quasi-static!! dw = F. ds =Δp A ds dw = ( p p ) dv upper lower V max W = ( pupper plower ) dv V min 21 xx
p Working Cycle (4 stroke engine) pv = RT INTAKE COMPRESSION V WORK EXHAUST 22 xx
Working Cycle (4 stroke engine) INTAKE COMPRESSION WORK EXHAUST p Work [J] V 23 xx
Throttle control 24 xx
Piston Engines: In-Line 25 xx
Piston Engines: Boxer 26 xx
Piston Engines In-Line Radial V Boxer 27 xx
Airbreathing Engines Propeller Propulsion Jet Propulsion Piston Engines TurboProp TurboShaft TurboFan TurboJet RamJet AftFan ScramJet Turbo Compound Engine Turbo Engine With Propfan By-Pass Engine Continuous Combustion Turbo-RamJet RamRocket 28 xx
Continuous Combustion INTAKE COMPRESSION WORK EXHAUST 29 xx
Continuous Combustion INTAKE COMPRESSION WORK EXHAUST 30 xx
Ramjet 31 xx
Pure Jet Engine 32 xx
Jet Engine With Afterburner 33 xx
Trading Exhaust Power for Shaft Power INTAKE COMPRESSION WORK EXHAUST 34 xx
TurboProp/TurboShaft 35 xx
Turboprop 36 xx
Turboshaft 37 xx
Trading Exhaust Power for Shaft Power INTAKE COMPRESSION WORK EXHAUST 38 xx
TurboFan 39 xx
This is quite a large duct fan (high bypass flow) Why? 40 xx
Engine development 1950-1980 Higher Bypass-ratio Bypass airflow (Cold) Core airflow. (Hot) B = m. m c h More air, less velocity Higher propulsive efficiency Can you explain why? 41 xx
j Jet efficiency What is efficiency of jet? 1 2 2 2 ( j 0 ) P = mv V Jet efficiency η = j P P a j = TV mv 1 2 j 0 ( 2 2 V ) 0 1 2 m. (kg/s) = 2 m V o 1 2 m V 1 2 V 0 (m/s) T = m ( V V ) P a =T V 0 j 0 mv ( ) j V0 V0 ( + )( ) mv V V V j 0 j 0 2 V j j η = j 1+ 2 V j V 0 What is effect on engines of previous slide? 42 xx
Example of this effect η = j 1+ 2 V j V 0 In words: by lowering exhaust speed, the efficiency goes from 31% to 54% (amount of energy used for propulsion) 43 xx
And also less noise due to lower V j 44 xx
Engine Development Very big 45 xx
Engine Applications Single engine training aircraft: Piston engine Low subsonic passenger aircraft: Turboprop Concorde (Supersonic): Pure (straight) jet Helicopter: Turboshaft or piston 46 xx
Two or Four Engines? ETOPS Extended Twin OPerationS Engines Turning Or Passengers Swimming Twin engined airliners restricted to a maximum diversion time (120 to 207 minutes) dependant on strict maintenance and aircraft type. Crossing some parts of the atlantic and pacific ocean and both poles is (currently) restricted to four engined airliners. 47 xx
Future air breathing Engines Propeller Propulsion Jet Propulsion Piston Engines TurboProp TurboShaft TurboFan TurboJet RamJet AftFan ScramJet By-Pass Engine Turbo Compound Engine Turbo Engine With Propfan Turbo-RamJet RamRocket 48 xx
Engines Pratt & Whitney PW127B Turboprop Aircraft: Fokker 50 Power: 2750 SHP (x2) 2050 kw (x2) 49 xx
Engines Rolls Royce - Tay 650 Low bypass Turbofan Aircraft: Fokker 100 Thrust: 67 kn (x2) Fan Diameter: 1.14 m Length: 2.4 m Bypass Ratio: 3.07 50 xx
Engines General Electric GE90-115B High bypass turbofan Aircraft: Boeing 777 Thrust: 512 kn (x2) Fan Diameter: 2.95 m Length: 4.55 m Bypass Ratio: 9 Largest and highest thrust engine in the world! 51 xx
Engines Rolls Royce Trent 900 High bypass turbofan Aircraft: Airbus 380 Thrust: 311 kn (x4) Fan Diameter: 2.95 m Length: 4.55 m Bypass Ratio: 8.5 52 xx
Engines Rolls Royce / Snecma Olympus 593 Pure Turbojet Aircraft: Thrust: Concorde 170 kn* (x4) *Using afterburner (take-off and transonic) 53 xx
Links www.howstuffworks.com www.rollsroyce.com www.ge.com 54 xx
Beechcraft Super King Air 200 55 xx
Pratt & Whitney PT6A-41 Per engine: 850 Shaft horse power, P br =634 kw Maximum speed at sea level: 56 xx