lecture 11.x.s. bai tc in gas turbines history of gas turbine/jet propulsion engine hero of...
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X.S. Bai TC in Gas Turbines
Lecture 11.
Turbulent Combustion in Gas Turbine Engines
X.S. Bai TC in Gas Turbines
Content
• Development of gas turbine• Types of gas turbines• Gas turbine cycle• Gas turbine combustor• New gas turbine combustors for clean environment
X.S. Bai TC in Gas Turbines
History of gas turbine/jet propulsion engine
Hero of Alexandria, Egypt130 BC
Leonardo Da Vinci’s chimney jack, 1500
Chinese solid fuel rocket, 1000 AD
Giovanni Branca, Italy, 1629
Isaac Newton’s steam wagon, 1687
Johan Barber made first patent, 1791
X.S. Bai TC in Gas Turbines
Gas turbine for modern aviationFrank Whittle, 1930, UK, submitted a patent for a gas turbine for jet propulsionPower Jets Ltd got contract from Air MinsistryIn May 1941, the Whittle W1 engine made its first flight
X.S. Bai TC in Gas Turbines
Gas turbine for modern aviation
Gloster Whittle E28
X.S. Bai TC in Gas Turbines
Gas turbine for modern aviationHans von Ohain and Max Hahn, 1936, Germany, submitted a patent
for a gas turbine for jet propulsionErnst Heinkel Aircraft Company made first true jet propulsion aircraft in 1939, Aug - Sept
Secundo Campiri, Italy, made a gasturbine engine for the CC-2 aircraft, 1940American (with the help of the British) made W.IX engine in 1941, GELater Westinghouse Corporation made contiuous development
X.S. Bai TC in Gas Turbines
Gas turbine for modern aviation
Whittle
Ohain
X.S. Bai TC in Gas Turbines
• aero-engines• marine propulsion systems• energy business• Annual sales of over £4.5 billion• Orders of over £13 billion
• aero-engines• marine propulsion systems• energy business• Annual sales of over £4.5 billion• Orders of over £13 billion
Rolls-Royce Today
X.S. Bai TC in Gas Turbines
Newton’s 3rd Law: principle of propulsion
Equilibrium Reaction Action
Thrust = Mass x Velocity (MV)
MV
X.S. Bai TC in Gas Turbines
Propeller versus Jet Propulsion
Propeller - moves LARGE MASS of air at low velocity
Jet - moves small mass of gas at HIGH VELOCITY
Mvaircraft
mVjet
Thrust = M(vaircraft - vjet)
mVaircraft
Thrust = m(Vaircraft - Vjet)
Mvjet
X.S. Bai TC in Gas Turbines
Jet Engine Layout
Compressor Combustion Chamber
TurbineShaft
Exhaust Nozzle
mVaircraftmVjet
’Straight-through’ configuration
X.S. Bai TC in Gas Turbines
Civil turbofan -TrentCivil turbofan -Trent
Different Jet Engine Types
Military turbofan -EJ200Military turbofan -EJ200
X.S. Bai TC in Gas Turbines
Reverse Thrust
85% thrust85% thrust
15% thrust15% thrust
Net 25% to 30% thrustNet 25% to 30% thrust
X.S. Bai TC in Gas Turbines
Gas turbine cycle: Brayton cycle
Pressure(atmospheres)
0
40
Temperature (degrees C)
0
1500
intake compression combustion
Expansion/Power
exhaust
X.S. Bai TC in Gas Turbines
Gas turbine cycle: Brayton cycle
TR: temperature ratio a-bPR: pressure ratio a-b
X.S. Bai TC in Gas Turbines
Trend of gas turbine development
X.S. Bai TC in Gas Turbines
Gas turbine running conditions
X.S. Bai TC in Gas Turbines
Gas turbine combustor
• Stright pipe• Diffuser• Flame stabilization• Optimal air supply
X.S. Bai TC in Gas Turbines
Combustor Operation
X.S. Bai TC in Gas Turbines
Jet Engine Layout
Whittle W1 engine, 1941
Can combustor
X.S. Bai TC in Gas Turbines
Turbulent flame shape and flame height (3) order of estimation
During time Δt, fuel molecule is convected from inlet to the tip of flame at a speed U, and oxygen molecule is transport by turbulence from air stream to the flame tipat a speed u’.
'uR
UHt ∝∝Δ
IR
uRUH ∝∝⇒
'
H
R
2R
Uu’
I=u’/U: intensity of turbulence
X.S. Bai TC in Gas Turbines
Recall: Laminar flame shape and flame height - order of estimation
During time Δt, fuel molecule is convected from inlet to the tip of flame at a speed U, and oxygen molecule is diffused from air stream to the flame tip. D is diffusion coef.
H
R
2R
UDR
UHt
2∝∝Δ
DURH
2∝⇒
X.S. Bai TC in Gas Turbines
Dependence of flame height on injection speed
2R
U
X.S. Bai TC in Gas Turbines
Dependence of flame height on burner diameter
laminar
2R
U
R
H
turbulent
...
X.S. Bai TC in Gas Turbines
Jet Engine LayoutAnnular cannular
X.S. Bai TC in Gas Turbines
Primary zoneIntermediate
zone
Dilution zone
Fuel spraynozzle
Combustor Operation
X.S. Bai TC in Gas Turbines
Reverse flow combustor
X.S. Bai TC in Gas Turbines
Development of modern gas turbine for clean environment
X.S. Bai TC in Gas Turbines
General consideration
0
5
10
15
20
25
30
oxid
es o
f ni
trog
en, p
pmv
1600 1700 1800 1900 2000primary temperature, K
0
20
40
60
80
100
carb
on m
onox
ide,
ppm
v
temperaturerange for
lowemissions
CO
NOx
X.S. Bai TC in Gas Turbines
Other cocnepts
• Variable geometry• Dry low NOx (DLN) combustion & lean prevaporized premixed
(LPP) combustion• Humid air combustion• Rich burner, quick quench, lean burn (RQL) (premixed)• Catalytic combustion• Flameless combustion
X.S. Bai TC in Gas Turbines
Diffusion Flames
X.S. Bai TC in Gas Turbines
FLOX
X.S. Bai TC in Gas Turbines
Flameless: air staged combustion
X.S. Bai TC in Gas Turbines
Flames and flameless
flames FLOX
X.S. Bai TC in Gas Turbines
Flames and FLOX
X.S. Bai TC in Gas Turbines
Flames and flameless