Introduction to Aerospace Engineering

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Lecture slides

Challenge the future 1 18-9-2011

Introduction to Aerospace Engineering AE1101ab - Propulsion

Delft University of Prof.dr.ir. TechnologyJacco Hoekstra Challenge the 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

AE1101 Introduction to Aerospace Engineering 3 | xx The propulsion perspective…

Gee Bee model ‘R’ Sportster

AE1101 Introduction to Aerospace Engineering 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

AE1101 Introduction to Aerospace Engineering 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!

AE1101 Introduction to Aerospace Engineering 6 | xx Theory L

T D V0 (m/s)

aircraft- and rocket propulsion ≡ reaction propulsion

AE1101 Introduction to Aerospace Engineering 7 | xx You can see this principle in the water rocket.

AE1101 Introduction to Aerospace Engineering 8 | xx Theory of air breathing engines

V0 (m/s) VJ T

mkgs[/]

For rocket propulsion we use Tsjolkovski’s rocket equation (covered 1101cd)!

AE1101 Introduction to Aerospace Engineering 9 | xx V (m/s) V Theory 0 J T Momentum Equation:

ImV=⋅ (En: linear momentum, NL: impuls) dI F = dt (Newton's second law) [kg m/s2](=N) dV →=⋅Fm =⋅ ma dt [kg/s · m/s] (=N) →=TmVV ()j −0

AE1101 Introduction to Aerospace Engineering 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

AE1101 Introduction to Aerospace Engineering 11 | xx Propeller Propulsion

Counter Rotating Rotating

AE1101 Introduction to Aerospace Engineering 12 | xx Propeller Propulsion

Counter Rotating Rotating

Fixed Pitch Variable Pitch Ducted Fan

AE1101 Introduction to Aerospace Engineering 13 | xx Propeller Theory

R(m)

r(m) ω (rad/s) Vrot(m/s)

Vrot = Ωω· r

AE1101 Introduction to Aerospace Engineering 14 | xx Propeller Theory: Blade is like a wing R(m) S

r(m) T ω (rad/s)

Useful force: T Thrust (pointing at us)

Loss: S Side force (like drag for wing)

AE1101 Introduction to Aerospace Engineering 15 | xx Twisted for constant angle of attack

ω (rad/s) Large Twist Small Twist

Constant angle of attack!

AE1101 Introduction to Aerospace Engineering 16 | xx Available Power for thrust t+Δt t

T T

Δs

Work Performed: W= T·Δs[NmorJ] T·Δs Available Power: P = = T·V [Nm/s, J/s or W] a Δt

AE1101 Introduction to Aerospace Engineering 17 | xx Available Power t+Δt t T T Speed is V Δs=VΔt

Net available Power for thrust: Pa=T V

Brake (shaft) Power: Pbr

P T V Propulsive Efficiency: η= a = Pbr Pbr

AE1101 Introduction to Aerospace Engineering 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

AE1101 Introduction to Aerospace Engineering 19 | xx Piston Engines

What is used in Aviation ? • 2 Stroke Engine Obsolete • 4 Stroke Engine Common • Wankel Engine ‘New’ • Diesel Engine Expected

AE1101 Introduction to Aerospace Engineering 20 | xx Combustion Cycle (Otto Cycle)

T2 Quasi-static !! dW==Δ⋅⋅ F. ds p A ds Vmax dW=−() p p dV WppdV=−() upper lower ∫ upper lower Vmin

AE1101 Introduction to Aerospace Engineering 21 | xx Working Cycle (4 stroke engine) INTAKE COMPRESSION p pV = RT

V WORK EXHAUST

AE1101 Introduction to Aerospace Engineering 22 | xx Working Cycle (4 stroke engine) INTAKE COMPRESSION WORK EXHAUST p

Work [J]

AE1101 Introduction to Aerospace Engineering 23 | xx Throttle control

AE1101 Introduction to Aerospace Engineering 24 | xx Piston Engines: In-Line

AE1101 Introduction to Aerospace Engineering 25 | xx Piston Engines: Boxer

AE1101 Introduction to Aerospace Engineering 26 | xx Piston Engines

In-Line

Radial

V Boxer

AE1101 Introduction to Aerospace Engineering 27 | xx Airbreathing Engines Propeller Propulsion Jet Propulsion

Piston Engines TurboProp TurboFan TurboJet RamJet TurboShaft AftFan

ScramJet

By-Pass Engine Turbo Turbo Engine Compound With Propfan Turbo-RamJet RamRocket Engine Continuous Combustion

AE1101 Introduction to Aerospace Engineering 28 | xx Continuous Combustion INTAKE COMPRESSION WORK EXHAUST

AE1101 Introduction to Aerospace Engineering 29 | xx Continuous Combustion INTAKE COMPRESSION WORK EXHAUST

AE1101 Introduction to Aerospace Engineering 30 | xx Ramjet

AE1101 Introduction to Aerospace Engineering 31 | xx Pure Jet Engine

AE1101 Introduction to Aerospace Engineering 32 | xx Jet Engine With Afterburner

AE1101 Introduction to Aerospace Engineering 33 | xx Trading Exhaust Power for Shaft Power

INTAKE COMPRESSION WORK EXHAUST

AE1101 Introduction to Aerospace Engineering 34 | xx TurboProp/TurboShaft

AE1101 Introduction to Aerospace Engineering 35 | xx Turboprop

AE1101 Introduction to Aerospace Engineering 36 | xx Turboshaft

AE1101 Introduction to Aerospace Engineering 37 | xx Trading Exhaust Power for Shaft Power INTAKE COMPRESSION WORK EXHAUST

AE1101 Introduction to Aerospace Engineering 38 | xx TurboFan

AE1101 Introduction to Aerospace Engineering 39 | xx This is quite a large duct fan (high bypass flow) Why?

AE1101 Introduction to Aerospace Engineering 40 | xx Engine development 1950-1980

Higher Bypass-ratio Bypass airflow (Cold) Core airflow. (Hot) mc B = . mh

More air, less velocity

Higher propulsive efficiency

Can you explain why?

AE1101 Introduction to Aerospace Engineering 41 | xx 1 2 2 m V o 1 2 2 m V j

Jet efficiency V0 (m/s) V j What is efficiency of jet? m. (kg/s) 1 22 Pjj=−2 mV( V0 ) TmVV=− ()j 0 Pa=T V0 Jet efficiency P a TV mV( j − V00) V η j = 0 = = 1 Pj 1 22 mV ()()+− V V V 2 mV ()j − V0 2 jj00

2 What is effect on η = engines of previous slide? j V 1+ j V0

AE1101 Introduction to Aerospace Engineering 42 | xx 2 η = j V Example of this effect 1+ j V0

In words: by lowering exhaust speed, the efficiency goes from 31% to 54% (amount of energy used for propulsion)

AE1101 Introduction to Aerospace Engineering 43 | xx And also less noise due to lower Vj

AE1101 Introduction to Aerospace Engineering 44 | xx Engine Development

Very big

AE1101 Introduction to Aerospace Engineering 45 | xx Engine Applications • Single engine training aircraft: • Piston engine

• Low subsonic passenger aircraft: • Turboprop

• Concorde (Supersonic): • Pure (straight) jet

• Helicopter: • Turboshaft or piston

AE1101 Introduction to Aerospace Engineering 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.

AE1101 Introduction to Aerospace Engineering 47 | xx Future air breathing Engines Propeller Propulsion Jet Propulsion

Piston Engines TurboProp TurboFan TurboJet RamJet TurboShaft AftFan

ScramJet

By-Pass Engine

Turbo Turbo Turbo-RamJet RamRocket Compound Engine Engine With Propfan

AE1101 Introduction to Aerospace Engineering 48 | xx Engines

• Pratt & Whitney – PW127B • Turboprop • Aircraft: Fokker 50 • Power: 2750 SHP (x2) 2050 kW (x2)

AE1101 Introduction to Aerospace Engineering 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

AE1101 Introduction to Aerospace Engineering 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!

AE1101 Introduction to Aerospace Engineering 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

AE1101 Introduction to Aerospace Engineering 52 | xx Engines

• Rolls Royce / Snecma Olympus 593 • Pure Turbojet • Aircraft: Concorde • Thrust: 170 kN* (x4)

*Using afterburner (take-off and transonic)

AE1101 Introduction to Aerospace Engineering 53 | xx Links

• www.howstuffworks.com • www.rollsroyce.com • www.ge.com

AE1101 Introduction to Aerospace Engineering 54 | xx Beechcraft Super King Air 200

AE1101 Introduction to Aerospace Engineering 55 | xx Pratt & Whitney PT6A-41

• Per engine: 850 Shaft horse power, Pbr=634 kW

• Maximum speed at sea level:

AE1101 Introduction to Aerospace Engineering 56 | xx