Document11

4th Annual Jet Engine Symposium, October 28, 2004 – Technion, HaifaUNCLASSIFIED

ה"ב ה"ב

An Original Means to Troubleshoot An Original Means to Troubleshoot High High EExhaust xhaust GGas as TTemperature (emperature (EGTEGT))

on All Types of Jet Engineson All Types of Jet Engines

by Israel Djian Israel Aircraft Industries

by Israel Djian Israel Aircraft Industries

4th Annual Jet Engine Symposium, Technion



ה"ב ה"ב

Those Who Tearfully Sow, Those Who Tearfully Sow, Will Reap In Glad SongWill Reap In Glad Song

(Psalms 126:5)

CeuxCeux Qui Qui OntOnt SemSeméé DansDans Les Les LarmesLarmes,,PuissentPuissent--IlsIls RRéécoltercolter DansDans La JoieLa Joie

(Psaumes 126:5)



ב רינה יקצרו , הזרע ים ב ד מ ע ה)ה: תהלי ם קכו(

ב רינה יקצרו ב רינה יקצרו , , הזרע ים ב ד מ ע ההזרע ים ב ד מ ע ה))הה: : תהלי ם קכותהלי ם קכו((


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AgendaAgenda

Significance of EGT : Why EGT is so Important in the Gas Turbine Engine IndustryEGT and Engine Maintenance CostsAnalysis of the Mechanisms that Rule EGTIAI Original Approach to Troubleshoot EGT Problems (applicable to all Jet Engines)Summary

Significance of EGT : Why EGT is so Important in the Gas Turbine Engine IndustryEGT and Engine Maintenance CostsAnalysis of the Mechanisms that Rule EGTIAI Original Approach to Troubleshoot EGT Problems (applicable to all Jet Engines)Summary


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Significance of EGTSignificance of EGT

Definition : EGT = Exhaust Gas Temperature

What EGT is significant of ?EGT is a measure of the engine’s efficiency in producing its design level of thrustThe higher EGT is

Definition : EGT = Exhaust Gas Temperature

What EGT is significant of ?EGT is a measure of the engine’s efficiency in producing its design level of thrustThe higher EGT is the more wear and deterioration affects the engine

the more wear and deterioration affects the engine


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At engine certification, any engine is allocatedan EGT operating absolute limit or EGT Red LineAt engine certification, any engine is allocated

an EGT operating absolute limit or EGT Red Line



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Definition :EGT Margin = EGT Red Line – EGT Gage

Definition :EGT Margin = EGT Red Line – EGT Gage



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What EGT is significant of ? (cont.)What EGT is significant of ? (cont.)

The EGT Red Line is representative of Tt5(Temperature @ High Pressure Turbine Inlet) and is designed to preserve the hot section (1st stage turbine blades) integrityTt5 is not measurable in an industrial environmentEngine Thrust is a Linear Function of Tt5

The EGT Red Line is representative of Tt5(Temperature @ High Pressure Turbine Inlet) and is designed to preserve the hot section (1st stage turbine blades) integrityTt5 is not measurable in an industrial environmentEngine Thrust is a Linear Function of Tt5



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109 °C15 °C 493 °CT5

1343 °C 566 °C

EGTJT9D

843 °C



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Tt5Tt5



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Pratt & Whitney JT9D EnginePratt & Whitney JT9D Engine

1st Flight of B747 with JT9D-3A(JFK-London) with PanAm1st Flight of B747 with JT9D-3A(JFK-London) with PanAm ( ל "ז )( ל "ז )

January 21, 1970…January 21, 1970…


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January 21, 1970...January 21, 1970...

Toulouse, כיתה ב'Toulouse, כיתה ב'

I was 7½ Years Old !I was 7½ Years Old !


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Impact of EGT Margin on Jet Engine Maintenance Costs


After Shop Visit the EGT margin is positive (+ XX °C )As a normal process, the EGT margin slowly decreases with the engine operation, as normalwear and tear of the internal parts takes placeAt zero EGT margin, the engine must be removedfor maintenance and refurbishmentFor JT9D-7Q, typically 20 °C EGT margin allows8,000 flight hours/maintenance cost $ 2.4 M approx.

After Shop Visit the EGT margin is positive (+ XX °C )As a normal process, the EGT margin slowly decreases with the engine operation, as normalwear and tear of the internal parts takes placeAt zero EGT margin, the engine must be removedfor maintenance and refurbishmentFor JT9D-7Q, typically 20 °C EGT margin allows8,000 flight hours/maintenance cost $ 2.4 M approx.

Therefore,each 1 °C EGT Margin ~ 120 k$ Approx.Therefore,each 1 °C EGT Margin ~ 120 k$ Approx.


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As a normal process, as the engine deterioratesdue to normal wear and tear, on Rotating Parts,

Primarily, the engine Fuel Consumption (Wf) increases, then,

As a normal process, as the engine deterioratesdue to normal wear and tear, on Rotating Parts,

Primarily, the engine Fuel Consumption (Wf) increases, then,

Analysis of the Mechanisms that Rule EGT


Goal : Establish a thermodynamic Relationship that connects EGT and the Fuel ConsumptionGoal : Establish a thermodynamic Relationship that connects EGT and the Fuel Consumption

Consequently, the EGT increases (and EGT margin accordingly decreases).

However, there is No Max. Fuel Consumption Limitation IAW Aviation Regulations (FAA, DGAC…)

Consequently, the EGT increases (and EGT margin accordingly decreases).

However, there is No Max. Fuel Consumption Limitation IAW Aviation Regulations (FAA, DGAC…)


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Concept of EGT Distortion : due to the Inherent different means of measuring Wf versus EGT :Concept of EGT Distortion : due to the Inherent different means of measuring Wf versus EGT :

Wf measurement is an easy and accurate TaskThe EGT probes sample the Gas Temperature atdiscrete locations only and do not perform athorough integration of the actual Gas TemperatureOne may encounter engine with low Wf and high EGT or high Wf and low EGT

Wf measurement is an easy and accurate TaskThe EGT probes sample the Gas Temperature atdiscrete locations only and do not perform athorough integration of the actual Gas TemperatureOne may encounter engine with low Wf and high EGT or high Wf and low EGT




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Analysis :Analysis :If EGT/Wf follows the thermodynamic Relationship,thenIf EGT/Wf follows the thermodynamic Relationship,then



The Rotating Modules are the Root Cause for high EGTThe Rotating Modules are the Root Cause for high EGT

If EGT/Wf does NOT follow the thermodynamic Relationship, thenIf EGT/Wf does NOT follow the thermodynamic Relationship, then

The Static Parts (Diffuser, Burner, NGVs) of the Hot Section are the Root Cause for high EGT

The Static Parts (Diffuser, Burner, NGVs) of the Hot Section are the Root Cause for high EGT


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IAI Approach to TroubleshootHigh EGT Engines

IAI Approach to TroubleshootHigh EGT Engines


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Per-Module Hardware Review Per-Module Hardware Review

EGT

Wf

1 % Loss HPT Efficiency = + 0.91 % Fuel Flow = X

1 % Loss HPT Efficiency = + 14.33 Deg F EGT = Y


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Modular Influence Coefficients

-10

-8

-6

-4

-2

0

2

4

6

8

10

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

Delta Fuel Flow Relative to Baseline (%)

Delta

EG

T R

ela

tive to B

ase

line (

Deg C

)HPT Efficiency Graphic Representation


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-10

-8

-6

-4

-2

0

2

4

6

8

10

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1


Delta

EG

T R

ela

tive to B

ase

line (

Deg C

)

0.91 %

7.96 Deg C

1 % Loss of HPT Efficiency


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ה"ב ה"ב


-10

-8

-6

-4

-2

0

2

4

6

8

10

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1


Delta

EG

T R

ela

tive to B

ase

line (

Deg C

)


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-80

-70

-60

-50

-40

-30

-20

-10

0

10

20

30

40

50

60

70

80

-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6


Delta

EG

T R

ela

tive to B

ase

line (

Deg C

)


ה"ב ה"ב


-80

-70

-60

-50

-40

-30

-20

-10

0

10

20

30

40

50

60

70

80

-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6


Delta

EG

T R

ela

tive to B

ase

line (

Deg C

)


ה"ב ה"ב


-80

-70

-60

-50

-40

-30

-20

-10

0

10

20

30

40

50

60

70

80

-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6


Delta

EG

T R

ela

tive to B

ase

line (

Deg C

) 11 Deg C EGT for 1 % Wf Slope11 Deg C EGT for 1 % Wf Slope

For JT9DFor JT9D


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Relationship Between EGT and Wf

-80

-60

-40

-20

0

20

40

60

80

- 6 - 4 - 2 0 2 4 6


De

lta

EG

T R

ela

tive

to

Ba

selin

e (

De

g C

)

FuelFuel

EGTEGT

After Shop VisitAfter Shop Visit

After a Few k-Flight HoursAfter a Few k-Flight Hours

∆EGT∆EGT

∆Wf∆Wf


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Impact of EGT Margin on Jet Engine Maintenance CostsRelationship Between EGT and Wf

-80

-60

-40

-20

0

20

40

60

80

- 6 - 4 - 2 0 2 4 6


De

lta

EG

T R

ela

tive

to B

ase

lin

e (

De

g C

)

FuelFuel

EGTEGT

After Shop VisitAfter Shop Visit

After a Few k-Flight HoursAfter a Few k-Flight Hours

∆Wf∆Wf

Actual ∆EGTActual ∆EGT

Theoretical ∆EGT

Theoretical ∆EGT

EGTDistortio

n

EGTEGTDistortioDistortio

nn


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JT9D EGT Margin Improvement

Relationship Between EGT and Wf

-80

-60

-40

-20

0

20

40

60

80

- 6 - 4 - 2 0 2 4 6


De

lta

EG

T R

ela

tive

to

Ba

selin

e (

De

g C

)

Rotating Modules Good

Efficiency - Good EGT Profile

Rotating Modules Poor

Efficiency - Good EGT Profile

Rotating ModulesGood Efficiency

-Very Good

EGT Profile

Rotating Modules Good Efficiency

-Adverse EGT

Profile

Rotating Modules Poor Efficiency

-Good EGT Profile

Rotating Modules Poor Efficiency

-Adverse EGT

Profile


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Summary

The Two Key-Questions Any PerformanceEngineer Has to ask Himself for aTest Cell Rejected Engine for Low EGT Margin Engine :

The Two Key-Questions Any PerformanceEngineer Has to ask Himself for aTest Cell Rejected Engine for Low EGT Margin Engine :

∆Wf

∆EGT/∆Wf

Is the Engine Fuel Flow High ?Is the Engine Fuel Flow High ?

Is the Ratio EGT/Fuel Flow Respected ?Is the Ratio EGT/Fuel Flow Respected ?


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Summary

Test Cell Engine

EGT

Test Cell Engine WF

Engine EPR or

N1

EGT Baseline

WfBaseline

∆EGT

∆Wf

Is the Ratio∆EGT/ ∆Wf

of the EngineAcceptable ?

Influence Coefficients

Table

Obtain From OEMObtain From OEM

Theoretical ∆EGT/ ∆Wf

Ratio


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Summary

Is the Engine FuelConsumption

∆Wf Acceptable ?

Do Not Address the

RotatingModules

Address the RotatingModules

Yes

No

∆Wf


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Summary

Is the Ratio∆EGT/ ∆Wf

of the EngineAcceptable ?

Do NotAddress the Burner, Fuel Nozzles, EGT Probes…etc...

Yes

No

Address the Burner, Fuel Nozzles, EGT Probes…etc...

∆EGT/∆Wf


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Good Luck to You All !Good Luck to You All !

謝謝!謝謝!

Last SlideLast Slide(Almost)(Almost)


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Last SlideLast Slide

Song of the StepsSong of the Steps (Degrees)(Degrees)


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謝謝!謝謝!再再

Last SlideLast Slide


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Smart QuizSmart Quiz

??On a Jet Engine, there are Two Types ofRotating Devices :

Compressors

Turbines

On a Jet Engine, there are Two Types ofRotating Devices :

Compressors

Turbines


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CompressorCompressor

Compresseur

Compresseur

CompressoreCompressore

КОМПРЕ

СОР

КОМПРЕ

СОР

ΚωµπρεσσωρΚωµπρεσσωρ

Compressors : compress the airCompressors : compress the air

و مکبرس

ورو مک

برسور

דח סמדח סמ


ה"ב ה"ב


What about the Turbines : …?

Why the Term ‘Turbine’ does not denote its function (i.e. Gas Expansion in order to Convert its Potential Energy into Mechanical Energy ) ?

What about the Turbines : …?

Why the Term ‘Turbine’ does not denote its function (i.e. Gas Expansion in order to Convert its Potential Energy into Mechanical Energy ) ?


ה"ב ה"ב


TurbineTurbine

TurbinaTurbina

TУРБЙНАTУРБЙНА

TωρµπιναTωρµπινα ت ورب ي نا ت ورب ي نا

בינהטור

בינהטור


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??


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Why the Term ‘Turbine’ does not Refer to its Function ?Why the Term ‘Turbine’ does not Refer to its Function ?


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Turbine comes from Latin :

‘Turba’ = Wheel

The 1st Thermodynamic Machines Only Rotating Hardware was Exclusively Gas (Steam) Expansion Related : THE Wheelor THE Turbine.

Turbine comes from Latin :

‘Turba’ = Wheel

The 1st Thermodynamic Machines Only Rotating Hardware was Exclusively Gas (Steam) Expansion Related : THE Wheelor THE Turbine.


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By Extension, the Expansion Hardwareof a Jet Engine was also Called Turbine.

But, there was a need to call the OTHERRotating Hardware that was Compressingthe Air.

By Extension, the Expansion Hardwareof a Jet Engine was also Called Turbine.

But, there was a need to call the OTHERRotating Hardware that was Compressingthe Air.


ה"ב ה"ב


So, in fact, if Compressors are a Second Type of Wheels, they are…. So, in fact, if Compressors are a Second Type of Wheels, they are….

….Turbines ?!?!….Turbines ?!?!


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Yes !!!Yes !!!


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So : Turbine A for the Compression, Turbine B for the Expansion ?

Doesn’t sound good !...Confusing…

The 1st ‘Historically’ Rotating Hardware(i.e. the Expansion one) Kept the Termof ‘The Wheel’ = Turbine

The 2nd One got a Different Name thatalludes to its Function : Compressor

So : Turbine A for the Compression, Turbine B for the Expansion ?

Doesn’t sound good !...Confusing…

The 1st ‘Historically’ Rotating Hardware(i.e. the Expansion one) Kept the Termof ‘The Wheel’ = Turbine

The 2nd One got a Different Name thatalludes to its Function : Compressor

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