Basic Engine and Compressor Analysis
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2003 DYNALCO CONTROLSGMRC 2003 GAS MACHINERY CONFERENCE
BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 1
Basic Reciprocating Engine &Compressor AnalysisTechniques
Azonix-DynalcoKathy Boutin, B.Sc.Ben Boutin, P.Eng.
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 2
Focus of this course
In this course, we illustrate engine andcompressor behavior using data taken fromrunning machinery
The data were recorded by analysts runningtheir own predictive maintenance programs
We show faults that are seen in recipequipment and present techniques to detect
them
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2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 3
Short Course Outline
Analysis Programs Characterizing engines and compressors
Data types Testpoint Locations
Sequence of events 2-stroke engines 4-stroke engines Compressors
Analyzing engine faults Analyzing compressor faults Analyzing auxiliary equipment faults
2003 DYNALCO CONTROLSGMRC 2003 GAS MACHINERY CONFERENCE
BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 4
Analysis Programs
Objectives
Types of analysis Analysis process
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2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 5
Analysis ProgramsObjectives of analysis programs
Eliminate expensive, unnecessary maintenance Decrease maintenance costs Increase machine availability Decrease down time Improve performance Reduce emissions
You cant improve what you dont measure
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 6
Analysis Programs
Types of machinery analysis
Maintenance Analysis Identifies incipient failure so that you can turn unscheduledmaintenance into scheduled maintenance
Helps avoid in-service failures Goal is to reduce maintenance cost
Performance Analysis Characterizes the engine/compressor operating potential Efficiency
Fuel consumption Horsepower Throughput
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2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 9
Characterizing Engines and CompressorsSpecial data types
Process data Tell about the process Examples: suction temperature and pressure
Phase-marked data Data is referenced to the flywheel Example: pressure versus time data
Non-phased data Sampling is a function of time only Example: acceleration data from aturbocharger bearing
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 10
Characterizing Engines and Compressors
Measuring flywheel position
Once-per-degree Shaft encoder 360 pulses perrevolution
Better accuracy Once-per-turn
Magnetic, active oroptical pickups are
common 1 pulse per revolution Usually permanentlymounted
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2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 11
Characterizing Engines and CompressorsExample of phase-marked pressure (PT)
500
600
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1100
1200
1300
1400
1500
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1700
0 45 90 135 180 225 270 315 360
C402 - C cylinder 2 09/09/1998 12:02:53 PM HE Period 5, CE Period 5
P r e s s u r e ( p s i g )
Crank Angle (deg)
Head andcrank endpressuretraces on acompressorcylinder
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 12
Characterizing Engines and Compressors
Free-running, non-phased data
Data is recorded independent of crankshaft position Returns
Overall vibration level Spectrum showing frequency components
Common applications: Structural vibration Supports, foundations Turbochargers Oil and water pumps Pressure pulsation
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2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 13
Characterizing Engines and CompressorsExample of free-running, non-phased, spectrum data
Spectrum fromengine framenear anchorbolts. Mils peak-peak, oil pumpend, horizontaldirection.
Engine speed323 RPM
Testpoint : OPEH VIBNo. Of Lines : 400No. Of Averages : 5Calc Overall : N/ATrap Overall : 1.325
Peak At Frequency1.020 at 322.50.507 at 1305.00.122 at 652.50.110 at 487.50.098 at 1627.50.079 at 2932.50.073 at 1357.50.061 at 1140.00.061 at 1020.00.061 at 975.0
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 500 1000 1500 2000 2500 3000
UNIT #4-E Testpoint OPEH 7/17/2002 10:51:55 AM
m i l ( p s e u d o - p
k - p k )
cpm
1 timesrun speed
2 timesrun speed
4 timesrun speed
Engine Data
Cylinder exhaust temperatures Infrared temperature wand
pyrometer
Cylinder pressure Pressure transducer Time domain data phased to
crankshaft position Peak pressure statistics
Cylinder, valve, wrist pinand bearing vibration Ultrasonic microphone Standard accelerometer Time domain data phased to
crankshaft position
Frame vibration (displacement) Tri-axial accelerometer (H, V, A)
taken at opposite corners ofengine frame
Frequency domain data
Ignition secondary Inductive connection to unshielded
spark plug cable Multi-period sampling statistics Ignition secondary patterns
Ignition primary (not shown)
Connection to primary box Ignition primary firing patterns
Turbocharger/blower Standard accelerometer
mounted on bearings and nearturbine and compressor wheels
Frequency domain vibration
TDC Reference Shaft encoder Magnetic pickup Phased data RPM
2003 DYNALCO CONT ROLS
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2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 15
Characterizing Engines and CompressorsTypical 2-stroke engine PT/VT
223 Intake137242 Exhaust118
273Fuel 213
0
50
100
150
200
250
300
350
400
450
500
550
600
0 45 90 135 180 225 270 315 360
--------------
--------------
-
-
-
-
-
-
-
-
-
- Scale 2.4
P5 VT4
20905-E Cylinder P5 3/27/2002 8:57:46 AM Period 0
P r e s s u r e ( p s i g )
Angle (deg)
PT
VT
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 16
Characterizing Engines and Compressors
Typical 4-stroke engine PT/VT620Intake 281
391 Exhaust140583Fuel 315
0
100
200
300
400
500
600
700
800
900
1000
1100
0 45 90 135 180 225 270 315 360 405 450 495 540 585 630 675 720
--------------
--------------
-
-
-
-
-
-
-
-
-
- Scale 5.0
2L VT4
5302-E Cylinder 2L 12/3/2001 9:15:58 AM Period 1
P r e s s u r e ( p s i g )
Angle (deg)
PT
VT
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TDC Reference Shaft encoder Magnetic pickup Phased data RPM
Suction/discharge temperatures Infrared temperature wand thermocouples, RTDs
Head/crank end pressure Pressure transducer Time domain data phased to
crankshaft position
Multi-period sampling statistics
Suction/discharge valve vibrationCompressor ring leak vibrationLiner scoring Ultrasonic microphone Standard accelerometer Time domain data phased to
crankshaft position
Frame vibration (displacement) Tri-axial accelerometer (H, V, A)
taken at opposite corners ofengine frame
Frequency domain data
Rod Motion Proximity probes Time-domain data phased to
crankshaft position Rod displacement trends
Suction/discharge nozzle pressure Pressure transducer Time domain data phased to crankshaft
position (valve/passage loss calculations) Frequency domain (pulsation spectrum) Multi-period sampling statistics
Valve cap temperatures Infrared temperature wand thermocouples, RTDs
Crosshead Vibration Standard accelerometer Time domain data phased to
crankshaft position
Relate to rod load
Compressor Data
2003 DYNALCO CONT ROLS
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 18
Characterizing Engines and Compressors
Typical HE compressor pattern
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300
350
400
450
500
550
600
0 45 90 135 180 225 270 315 360
--------------
--------------
--------------
--------------
--------------
---------------------------------------
- Scale 3.084 DGF
- Scale 3.084 DGF
- Scale 3.0146 DGF
- Scale 3.0145 DGF
4HS2 VT1
4HS1 VT1
4HD2 VT1
4HD1 VT1
K200 - C cylinder 4 9/23/1998 9:52:15 AM HE Period 5, CE Period 7
P r e s s u r e ( p s i g )
Crank Angle (deg)
HE PT
HE VT
CE PT
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2003 DYNALCO CONTROLSGMRC 2003 GAS MACHINERY CONFERENCE
BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 19
Sequence of events
2-stroke, spark-ignited engine 4-stroke, spark-ignited engine Double-acting, reciprocating compressor
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 20
Understanding Machine Faults
To recognize faults in compressors andengines, we must understand how theybehave in normal operation
Do the mechanical events you expect to seeactually happen?
Do the events appear to be normal? when do they occur? what is the relative magnitude?
do they look the same as they did last time? do they look the same as the next machine?
What is the performance of the machine?
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2003 DYNALCO CONTROLSGMRC 2003 GAS MACHINERY CONFERENCE
BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 21
Sequence of eventsfor a 2 stroke engine
Pressure versus crank angle (PT) Pressure-Volume (PV) Vibration versus crank angle (VT)
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 22
Sequence of events for a 2-stroke engine
PT: start of cycle
180 270 360900
Crank Angle (Deg)
P r e s s u r e
Ignition has occurred
Flame front travel has begun
Mixture is superheated air and fuel
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2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 25
Sequence of events for a 2-stroke enginePT: exhaust blowdown
Piston uncovers exhaust port
Pressure drops more rapidly (blowdown)
Temperature is now about 800F
P r e s s u r e
00
90 180 270 360
Crank Angle (deg)
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 26
Sequence of events for a 2-stroke engine
PT: air intake
Intake port is uncovered
Cylinder pressure intake pressure
Fresh air under pressure sweeps and cools
180 270 360900
Crank Angle (Deg)
P r e s s u r e
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2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 27
Sequence of events for a 2-stroke enginePT: scavenging
Scavenging continues until intake closes
Cylinder cooling continues
P r e s s u r e
00
90 180 270 360
Crank Angle (deg)
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 28
Sequence of events for a 2-stroke engine
PT: fuel intake
Scavenging continues until intake closes
This is the lowest pressure in the cylinder
Fuel is injected just prior to exhaust closure
Open exhaust port drags fuel down
Port closes before any fuel escapes
P r e s s u r e
0
0
90 180 270 360
Crank Angle (deg)
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2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 29
Sequence of events for a 2-stroke enginePT: compression
Fuel injection ceases, ports are closed
Pressure begins to rise
Air-fuel charge is turbulent
Turbulence mixes the air-fuel charge
Temperature rises
P r e s s u r e
00
90 180 270 360
Crank Angle (deg)
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 30
Sequence of events for a 2-stroke engine
PT: ignition
Ignition occurs 5-10 degrees BTDC
Advance gives time to initiate combustionand for flame front travel
Air-fuel charge is superheated
P r e s s u r e
0
0
90 180 270 360
Crank Angle (deg)
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2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 31
Sequence of events for a 2-stroke enginePT: end of cycle
Flame front begins propagatingthrough chamber
P r e s s u r e
00
90 180 270 360
Crank Angle (deg)
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 32
Sequence of events for a 2-stroke engine
PV: start of cycle (TDC)
Ignition has occurred
Flame front travel has begun
Mixture is superheated air and fuel
P r e s s u r e
0
0
25 50 75 100
Swept Volume (%)
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2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 33
Sequence of events for a 2-stroke enginePV: combustion
Flame travels through chamber
Heat is released, pressure rises
Temperature at flame front isabout 3500F
Peak occurs 10-15 deg ATDC
Speed of propagation is critical
Too fast, detonation
Too slow, soft fire
P r e s s u r e
00
25 50 75 100
Swept Volume (%)
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 34
Sequence of events for a 2-stroke engine
PV: power
Combustion is complete
Pressure drives piston down
As volume increases, pressure decreases
P r e s s u r e
0
0
25 50 75 100
Swept Volume (%)
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2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 35
Sequence of events for a 2-stroke enginePV: exhaust blowdown
Piston uncovers exhaust port
Pressure drops more rapidly (blowdown)
Temperature is now about 800F
P r e s s u r e
00
25 50 75 100
Swept Volume (%)
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 36
Sequence of events for a 2-stroke engine
PV: air intake
Intake port is uncovered
Cylinder pressure intake pressure
Fresh air under pressure sweeps and cools
P r e s s u r e
0
0
25 50 75 100
Swept Volume (%)
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2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 37
Sequence of events for a 2-stroke enginePV: scavenging
Scavenging continues until intake closes
Cylinder cooling continues
P r e s s u r e
00
25 50 75 100
Swept Volume (%)
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 38
Sequence of events for a 2-stroke engine
PV: fuel intake
Scavenging continues until intake closes
This is the lowest pressure in the cylinder
Fuel is injected just prior to exhaust closure
Open exhaust port drags fuel down
P r e s s u r e
0
0
25 50 75 100
Swept Volume (%)
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2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 39
Sequence of events for a 2-stroke enginePV: compression
Fuel injection ceases, ports are closed
Pressure begins to rise
Air-fuel charge is turbulent
Turbulence mixes the air-fuel charge
Temperature rises
P r e s s u r e
00
25 50 75 100
Swept Volume (%)
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 40
Sequence of events for a 2-stroke engine
PV: ignition
Ignition occurs 5-10 degrees BTDC
Advance gives time to initiate combustionand for flame front travel
Air-fuel charge is superheated
P r e s s u r e
0
0
25 50 75 100
Swept Volume (%)
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2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 43
Sequence of events for a 2-stroke engineCylinder vibration: combustion
223 Intake137242 Exhaust118
273Fuel 213
0 45 90 135 180 2 25 270 315 360Angle (deg)
Rings become fully loaded by gaspressure
May see some vibration resultingfrom combustion
P r e s s u r e
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 44
Sequence of events for a 2-stroke engine
Cylinder vibration: power223 Intake137
242 Exhaust118273Fuel 213
0 45 90 135 180 2 25 270 315 360Angle (deg)
Ring noise
P r e s s u r e
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2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 45
Sequence of events for a 2-stroke engine VTCylinder vibration: exhaust blowdown
223 Intake137242 Exhaust118
273Fuel 213
0 45 90 135 180 2 25 270 315 360Angle (deg)
ExhaustBlowdown
P r e s s u r e
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 46
Sequence of events for a 2-stroke engine VT
Cylinder vibration: air intake and scavenging223 Intake137
242 Exhaust118273Fuel 213
0 45 90 135 180 2 25 270 315 360Angle (deg)
P r e s s u r e
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2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 47
Sequence of events for a 2-stroke engine VTCylinder vibration: fuel intake
223 Intake137242 Exhaust118
273Fuel 213
0 45 90 135 180 2 25 270 315 360Angle (deg)
P r e s s u r e
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 48
Sequence of events for a 2-stroke engine VT
Cylinder vibration: compression223 Intake137
242 Exhaust118273Fuel 213
0 45 90 135 180 2 25 270 315 360Angle (deg)
Fuel ValveClosure
P r e s s u r e
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2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 49
Sequence of events for a 2-stroke engine VTCylinder vibration: ignition
223 Intake137242 Exhaust118
273Fuel 213
0 45 90 135 180 2 25 270 315 360Angle (deg)
P r e s s u r e
Ignition 5-10degrees BTDC
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 50
Sequence of events for a 2-stroke engine VT
Cylinder vibration: end of cycle223 Intake137
242 Exhaust118273Fuel 213
0 45 90 135 180 2 25 270 315 360Angle (deg)
P r e s s u r e
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2003 DYNALCO CONTROLSGMRC 2003 GAS MACHINERY CONFERENCE
BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 51
Sequence of eventsfor a 4 stroke engine
Pressure and vibration (PT/VT)
Pressure-Volume (PV)
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 52
Sequence of events for a 4-stroke engine
PT/VT: top dead center
Ignition has occurred
Flame front propagation has begun
Mixture is superheated air and fuel
Crank Angle (deg)
P r e s s u r e
0
0
180 360 540 720
Fuel 502565Intake 300
137 417 Exhaust
611
12
1 2 3 4Combustion Exhaust Intake Compression
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2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 53
Sequence of events for a 4-stroke enginePT/VT: peak firing pressure
Pressure
Flame front propagation through cylinder
Pressure and temperature rise
Too fast, detonation
Too slow, soft fire
Crank Angle (deg)
P r e s s u r e
0
0
180 360 540 720Crank Angle (deg)
P r e s s u r e
0
0
180 360 540 720
12
1 2 3 4Combustion Exhaust Intake Compression
Fuel 502565Intake 300
137 417 Exhaust
611
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 54
Sequence of events for a 4-stroke engine
PT/VT: power stroke
Pressure
Crank Angle (deg)
P r e s s u r e
0
0
180 360 540 720
12
1 2 3 4Combustion Exhaust Intake Compression
Fuel 502565Intake 300
137 417 Exhaust
611
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2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 55
Sequence of events for a 4-stroke enginePT/VT: exhaust blowdown
Crank Angle (deg)
P r e s s u r e
0
0
180 360 540 720
12
1 2 3 4Combustion Exhaust Intake Compression
Fuel 502565Intake 300
137 417 Exhaust
611
Blowdown Exhaust gases leave through exhaust
valve port to exhaust header andthen to the turbocharger
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 56
Sequence of events for a 4-stroke engine
PT/VT: air intake
Exhaust valveclosure
Crank Angle (deg)
P r e s s u r e
0
0
180 360 540 720
34
1 2 3 4Combustion Exhaust Intake Compression
Fuel 502565Intake 300
137 417 Exhaust
611
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2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 57
Sequence of events for a 4-stroke enginePT/VT: fuel intake
Intake valveclosure
Crank Angle (deg)
P r e s s u r e
0
0
180 360 540 720
34
1 2 3 4Combustion Exhaust Intake Compression
Fuel 502565Intake 300
137 417 Exhaust
611
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 58
Sequence of events for a 4-stroke engine
PT/VT: compression and ignition
Fuel valveclosure
Crank Angle (deg)
P r e s s u r e
0
0
180 360 540 720
34
1 2 3 4Combustion Exhaust Intake Compression
Fuel 502565Intake 300
137 417 Exhaust
611
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2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 59
Sequence of events for a 4-stroke enginePT/VT: end of cycle
Pressure
Crank Angle (deg)
P r e s s u r e
0
0
180 360 540 720
12
1 2 3 4Combustion Exhaust Intake Compression
Fuel 502565Intake 300
137 417 Exhaust
611
Whatsthis?
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 60
Sequence of events for a 4-stroke engine
VT: crosstalk (KVS 412)Engine Cylinders: Phased Vibration VT4:
90 180 270 360 450 540 630 720
K200 - E 9/10/1995 6:51:46 AM
-2
0
2
-2
0
2
-2
0
2
-2
0
2
-2
0
2
-2
0
2
0
P1
P2
P3
P4
P5
P6
This engine has solid lifters 312
672
192
432
72
552
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 61
Sequence of events for a 4-stroke enginePV: top dead center
3 COMBUSTION 4 EXHAUST 1 INTAKE 2 COMPRESSION
12
0 25 50 75 1000
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 62
Sequence of events for a 4-stroke engine
PV: air intake
3 COMBUSTION 4 EXHAUST 1 INTAKE 2 COMPRESSION
Fresh air enters cylinder
012
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 63
Sequence of events for a 4-stroke enginePV: fuel intake & compression
0 25 50 75 100
3 COMBUSTION 4 EXHAUST 1 INTAKE 2 COMPRESSION
12
Fuel intake starts BBDC
Turbulence stirs mixture
0
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 64
Sequence of events for a 4-stroke engine
PV: ignition
3 COMBUSTION 4 EXHAUST 1 INTAKE 2 COMPRESSION
0
Mixture is compressed andsuperheated
Ignition occurs 10-20 deg BTDC
12
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 65
Sequence of events for a 4-stroke enginePV: top dead center
3 COMBUSTION 4 EXHAUST 1 INTAKE 2 COMPRESSION
0
Ignition has occurred
Flame front travel has begun
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 66
Sequence of events for a 4-stroke engine
PV: peak firing pressure
3 COMBUSTION 4 EXHAUST 1 INTAKE 2 COMPRESSION
0
Flame travels through chamber
Heat is released, pressure rises
Peak occurs 15-20 deg ATDC
If pressure increase is
Too fast, detonation
Too slow, soft fire
34
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 67
Sequence of events for a 4-stroke enginePV: power stroke
3 COMBUSTION 4 EXHAUST 1 INTAKE 2 COMPRESSION
0
Combustion is complete
Pressure drives piston down
As volume increases, pressure decreases
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 68
Sequence of events for a 4-stroke engine
PV: bottom dead center
3 COMBUSTION 4 EXHAUST 1 INTAKE 2 COMPRESSION
0
Exhaust valve opens just before BDC
34
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 69
Sequence of events for a 4-stroke enginePV: exhaust
3 COMBUSTION 4 EXHAUST 1 INTAKE 2 COMPRESSION
Pressure drops rapidly(blowdown)
0
4 3
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 70
Sequence of events for a 4-stroke engine
PV: end of cycle
3 COMBUSTION 4 EXHAUST 1 INTAKE 2 COMPRESSION
0 25 50 75 100
340 25 50 75 100
34 0
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BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 71
Sequence of eventsfor a double actingreciprocating compressor
Head End (HE) compression cycle (PV) Crank End (CE) compression cycle (PV) HE valve events HE and CE pressure-time (PT) HE and CE vibration-time (VT)
GMRC 2003 GAS MACHINERY CONFERENCEBASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 72 2003 DYNALCO CONTROLS
Sequence of events in a reciprocating compressor
HE compression cycle
Pressure
ClearanceVolume
C l e a r a n c e V o l u m e
Ps
Pd
P r e s s u r e
Volume
Swept Volume
Compression
2
1
HECompression1-2
HEDischarge2-3
Discharge3
Suction
HESuction4-1
4
Expansion
HEExpansion3-4
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GMRC 2003 GAS MACHINERY CONFERENCEBASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 73 2003 DYNALCO CONTROLS
Sequence of events in a reciprocating compressorCE compression cycle
C l e a r a n c e V o l u m e
Ps
Pd
P r e s s u r e
Volume
CECompression1-2
1
Compression
Discharge2
CEDischarge2-3
3
Expansion
CEExpansion3-4
Suction 4
CESuction4-1
Swept Volume
GMRC 2003 GAS MACHINERY CONFERENCEBASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 74 2003 DYNALCO CONTROLS
Sequence of events in a reciprocating compressor
PV: HE compression event
C l e a r a n c e V o l u m e
Ps
Pd
P r e s s u r e
Volume
2
1
Compression
AD
AP
Discharge Line Pressure (Pd)
Dischargeclosed
AS
AP
Suction Line Pressure (Ps)
Cylinder Pressure (Pcyl)is above Ps and increasing to Pd.Discharge valve opens when Pcylis greater than Pd (2).
Suctionclosed
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GMRC 2003 GAS MACHINERY CONFERENCEBASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 77 2003 DYNALCO CONTROLS
Sequence of events in a reciprocating compressorPV: HE suction event
C l e a r a n c e V o l u m e
Ps
Pd
P r e s s u r e
Volume
2
1
Compression
3 Discharge
4
Expansion
SuctionAD
AP
Discharge Line Pressure (Pd)
Cylinder Pressure (Pcyl)is below Ps and increasing to Ps.Suction valve closes when Pcyl isequal to Ps (1) at BDC.
AS
Suction Line Pressure (Ps)
Piston Stroke Volume
Dischargeclosed
Suctionopen
GMRC 2003 GAS MACHINERY CONFERENCEBASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 78 2003 DYNALCO CONTROLS
Sequence of events in a reciprocating compressor
Example: HE and CE PV
250
300
350
400
450
500
550
600
0 25 50 75 100
K200 - C cylinder 4 9/23/1998 9:52:15 AM HE Period 5, CE Period 7
Percent swept volume
P r e s s u r e ( p s i g )
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GMRC 2003 GAS MACHINERY CONFERENCEBASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 79 2003 DYNALCO CONTROLS
A
1
Discharge (D-A)
Suction (4-1)
Sequence of events in a reciprocating compressorPT: HE and CE
HE PT
CE PT
DischargePressure
SuctionPressure
A
1
2
B
Expansion (A-B)
Compression (1-2)
Head End:
Crank End:
Crank Angle (Deg)3600 180
3
C
Suction (B-C)
Discharge (2-3)
4
D
Compression (C-D)
Expansion (3-4)
GMRC 2003 GAS MACHINERY CONFERENCEBASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 80 2003 DYNALCO CONTROLS
Sequence of events in a reciprocating compressor
HE valve vibration
0 180 360
HE Suction
HE Discharge
Gas blowing noise is loudest at valveopening and gradually diminishes asgas velocity through the valve decreases.
2
Suction gas fills the cylinder.2
3
Suction valve is lowered gentlyonto the seat at BDC closingevent is not always visible.
3
1
Suction valve opens(depends on clearance volume)
1
5
5 High pressure gas isdischarged into dischargeline.
6
6 Discharge valve is gentlylowered onto the seat atTDC not always visible.
4 Discharge valve opens(typically the loudest)
4
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GMRC 2003 GAS MACHINERY CONFERENCEBASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 83 2003 DYNALCO CONTROLS
Sequence of events in a reciprocating compressorTypical HE PT/VT signature
250
300
350
400
450
500
550
600
0 45 90 135 180 225 270 315 360
--------------
--------------
--------------
--------------
--------------
---------------------------------------
- Scale 3.084 DGF
- Scale 3.084 DGF
- Scale 3.0146 DGF
- Scale 3.0145 DGF
4HS2 VT1
4HS1 VT1
4HD2 VT1
4HD1 VT1
K200 - C cylinder 4 9/23/1998 9:52:15 AM HE Period 5, CE Period 7
P r e s s u r e ( p s i g )
Crank Angle (deg)
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 84
Quick Recap
So far, weve talked about the normalbehavior of:
2-stroke, spark-ignited recip engine 4-stroke, spark-ignited recip engine double-acting, reciprocating compressor
Now we know what they are supposed to looklike, we can look at faults
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BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 85
Analyzing Engine Faults
Combustion
Mechanical
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 86
Engine faults we can monitor
Port/bridge wear Excessive Emissions
Leaking valves Unbalance
Ignition problems Efficiency
Leaking rings Detonation Valve train (cam, guides, lifters, linkage) Misfire Worn, scored liner and piston Pre-ignition
Frame, foundation vibration Fuel consumption
Oil Pump, water pump problems Fuel cost
Turbocharger faultsEconomic Performance
Main bearings, crank pins Torque
Wrist pin Indicated horsepower
Carbon in portsOperating Performance
Mechanical ConditionCombustion Quality
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 87
Combustion
Many of the problems we face with enginesare due to variable combustion
Engines do not fire the same way each cycle
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 88
Combustion
Chemical equation of combustion
Engines convert chemical energy to heat Take a simple gas such as Methane (CH 4) Combine it with oxygen and start the reaction
Produces carbon dioxide plus water vapor
and releases heat of about 1000 BTU/ft3
ofmethane consumed
OHCOOCH 2224 22 ++
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 89
CombustionIf only it was that simple
Air is primarily O2 (23%) and N 2 (77%) Both are involved in the chemical reaction The combustion process is neither completenor instantaneous
Many intermediate steps and reactions occur This leads to other exhaust products such asNOx, HC, CO and particulates (smoke)
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 90
Combustion
Why is combustion so variable?
incomplete mixing in the cylinder difficulty burning lean air/fuel mixtures inconsistent air/fuel charge in each cycle poor fuel quality ignition faults incorrect valve timing
varying ambient conditions
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 91
CombustionResults of poor combustion
Firing in each becomes inconsistent, highfires followed by low fires
Stress the engine thermally and mechanically Reduce the life of engine components Waste fuel Increase emissions This costs a great deal of money
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 92
Combustion
Typical faults
Unbalance Dead cylinders Early firing Soft firing Detonation Pre-ignition
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 93
Engine balance
The manufacturer designed the engine tohandle specific cylinder pressures andtemperatures
Cylinders with high peak pressures developmuch greater mechanical and thermal stress
Engine balancing distributes this mechanicaland thermal stress across the engine to
maximize component life
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 94
Engine Balance
Cylinder pressures (balanced HBA)
P r e s s u r e ( p s i g )
P1P2
P3P4 P5
P6P7
P8
0
100
200
300
400
500
600
700
800
0 45 90 135 180 225 270 315 360
+2%
-2%
+10%
-10%
Unit2 4/15/2002 9:21:55 AMAll cylinders - In Bank Order
Crank Angle (deg)
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 95
Engine BalancePressure rise rate (balanced HBA)
-15
-10
-5
0
5
10
15
20
25
30
35
P r e s s u r e R i s e R a t e ( d p / d )
P1
P2
P3
P4 P5
P6
P7
0 45 90 135 180 225 270 315 360
Unit2 4/15/2002 9:21:55 AMAll cylinders - In Bank Order
Crank Angle (deg)
P8
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 96
Engine Balance
Cylinder pressures (unbalanced HLA)C2B-E 6/6/2001 7:22:02 AM
P r e s s u r e ( p s i g )
1
2
34 5
6
7
8
0
100
200
300
400
500
600
700
0 45 90 135 180 225 270 315 360
+2%-2%
+10%
-10%
All cylinders - In Bank Order
Crank Angle (deg)
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 97
Engine BalancePressure rise rate (unbalanced HLA)
P r e s s u r e R i s e R a t e ( d p / d )
1
3
4 5
6
7
8
-10
-5
0
5
10
15
20
0 45 90 135 180 225 270 315 360
C2B-E 6/6/2001 7:22:02 AMAll cylinders - In Bank Order
Crank Angle (deg)
2 Highly variable
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 98
Detonation
Detonation is rapid and uncontrolled combustion.Detonation can lead to rapid failure due to high thermal and
mechanical stress.Causes of detonation:
Mixture too rich Clogged/dirty air intake (air inlet filters, aftercoolers orblowers)
Incomplete scavenging inconsistent fuel composition
Overloaded engine Ignition timing too advanced Highly loaded cylinders in an unbalanced engine are moresusceptible to detonation.
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 99
P1
P2 P4
DetonationEngine PT parade (Ajax DPC-720-LE-H-2)
P3 DetonatingCylinder
+2%-2%
+10%
-10%
K203 - E 11/21/1996 2:13:03 PMAll cylinders - In Bank Order
0 45 90 135 180 225 270 315 360Crank Angle (deg)
0
50
100
150
200
250
300
350
400
450
500
550
600
P r e s s u r e ( p s i g )
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 100
Detonation
Multiple PT cycles for a power cylinder (P3)
0
50
100
150
200
250
300
350
400
450
500
550
500 1000 1500 2000 2500 3000 3500
K203 - E - P3 PT3 11/21/1996 2:13:03 PM
Samples
Misfire Misfire
Detonation DetonationDetonation
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 101
Soft Firing
Soft Firing occurs when the pressure in the cylinderrises too late (also called late firing).
The PFP is usually low and late.Causes of soft fires:
incomplete scavenging air/fuel ratio too lean causing slow flame front air/fuel ratio too rich for proper combustion late ignition timing
poor fuel composition
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 102
Soft Firing
Engine pressure signature comparisons
P r e s s u r e ( p s i g )
P1R
P2R
P3RP4R P5R P1L
P2L
P3LP4L
P5L
0
100
200
300
400
500
600
700
800
0 45 90 135 180 225 270 315 360
1A - E 5/22/1997 10:34:26 AMAll cylinders - In Bank Order
Crank Angle (deg)
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Normal
Soft FiringPT: comparison to normal (HBA)
0
Soft (Late)Fire
223 Intake137
242 Exhaust118
273Fuel 213
20905-E Cylinder P8 7/14/1999 6:46:53 AM Period 3
0
50
100
150
200
250
300
350
400
450
500
550
45 90 135 180 225 270 315 360Crank Angle (deg)
P r e s s u r e ( p s i g )
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 104
Soft Firing
PV: comparison to normal (HBA)
% swept volume
20905-E cylinder P8 7/14/1999 6:46:53 AM Period 3
0
50100
150
200
250
300
350
400
450
500
550
0 25 50 75 100
P r e s s u r e ( p s i g )
Normal
Soft (Late)Fire
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 105
Soft FiringAnother example comparing engine PTs (CB QUAD)
P2L
P3LP4L
P5L P6L
P1R P2R P3RP4R
P5R P6R
0100
200
300
400
500
600
700
800
900
1000
0 45 90 135 180 225 270 315 360
+2%-2%
+10%
-10%
C402 - E 9/9/1998 12:02:53 PMAll cylinders - In Bank Order - CRC is corrected
Crank Angle (deg)
P r e s s u r e ( p s i g )
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 106
Early Firing
Early firing occurs when the pressure in the cylinderrises too early.
The PFP is usually high and close to TDC.Causes of early firing:
air/fuel ratio too rich early ignition timing warm air temperature
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 107
Early Firingengine pressure comparison
P1R
P2R
P3RP4R P5R P1L
P2L
P3L P4L
P5L
0
100
200
300
400
500
600
700
800
0 45 90 135 180 225 270 315 360
1A - E 5/22/1997 10:34:26 AMAll cylinders - In Bank Order
P r e s s u r e ( p s i g )
Crank Angle (deg)
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 108
Dead Cylinders
Dead cylinders have no discernablecombustion.
Causes of dead cylinders: ignition problem improper air/fuel charge
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 109
Dead CylindersCylinder comparisons of peak pressures (QUAD)
P2L
P3LP4L
P5L P6L
P1R P2R P3RP4R
P5R P6R
0100
200
300
400
500
600
700
800
900
1000
0 45 90 135 180 225 270 315 360
+2%-2%
+10%
-10%
C402 - E 9/9/1998 12:02:53 PMAll cylinders - In Bank Order - CRC is corrected
Crank Angle (deg)
P r e s s u r e ( p s i g )
P1L
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 110
P2L soft fire
Dead Cylinders
Cylinder comparisons of pressure shape & timing
-180
0
100200
300
400
500
600
700
800
900
1000
-135 -90 -45 0 45 90 135 180
C402 - E 9/9/1998 12:02:53 PMAll cylinders - To Center of Plot - CRC is corrected
Crank Angle (deg)
P r e s s u r e ( p s i g )
P1LDead Cylinder
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 111
Other cylinders
P2L Soft Fire
Dead CylindersCylinder comparisons of pressure rise rate
-20
-180
-15
-10
-5
0
5
10
15
20
25
30
35
-135 -90 -45 0 45 90 135 180
C402 - E 9/9/1998 12:02:53 PMAll cylinders - To Center of Plot - CRC is corrected
Crank Angle (deg)
P r e s s u r e R i s e R a t e ( d P / d )
Normal
P1L Dead Cylinder
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 112
Normal PT
Dead Cylinders
Pressure and pressure rise rate relationship
Crank Angle (deg)
900
1000
C402 - E Cylinder P1L 9/9/1998 12:02:53 PM Period 4CRC is corrected
-103 EXHAUST PORT 100-123 INTAKE PORT 119
-65 FUEL VALVE-125
0
100
200
300
400
500
600
700
800
-180 -135 -90 -45 0 45 90 135 180
P r e s s u r e ( p s i g )
P
PT
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 113
Dead CylindersPV comparison to normal
0
100
200
300
400
500
600
700
800
900
1000
0 25 50 75 100
C402 - E cylinder P1L 9/9/1998 12:02:53 PM Period 4CRC is corrected
% swept volume
Normal
Dead Cylinder
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 114
Pre-ignition
Pre-ignition is the premature combustion of the air/fuelmixture before the normal ignition event (auto-combustion).
PFP may occur before TDC causing excessive force onthe piston, wrist pin, connecting rod and bearings.
The mechanical and thermal stress resulting from pre-ignition can cause cracked heads, torched or seizedpistons.
Causes of pre-ignition hot spots in the cylinder caused by ash or carbonbuild up hot spots created by detonation
early ignition timing is not normally considered pre-ignition.
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 115
Pre-ignitionPT comparison to normal
-130 Intake 130-110 Exhaust 110
-77 Fuel-145
0
100
200
300
400
500
600
700
800
900
1000
-180 -135 -90 -45 0 45 90 135 180
5E Cylinder P4 8/15/2002 4:39:48 PM Period 5
P r e s s u r e ( p s i g )
Angle (deg)
Normal
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SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 116
Pre-ignition
PV showing 2 crank revolutions
Negative work
Positive workPositive work
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CombustionAnalysis summary
Uneven average peak firing pressuresHigh deviation in PFP for cylinderUneven exhaust temperaturesUsually accompanied by higher NOx and HC
Unbalanced
Often audible
High PFP with early PFP angle Very high pressure rise rate compared to other cylinders Often develops a shock wave that is seen in the PT Combustion may make more noise than normal
Detonation
All cylinder average PFPs fall within 10-15% of the engineaverage PFPLow cycle-to-cycle deviation in cylinder PFPPFP angle consistent and at expected locationSimilar exhaust temperatures among power cylinders
Normal
CharacteristicsObservation
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Combustion
Analysis summary (cont.)
PFP angle earlier than normal Average PFP higher than normal Higher pressure rise rate when compared to other cylinders (orhistory) Lower exhaust temperature
Early Firing
Type of misfire Average PFP lower than normal PFP angle later than normal Low pressure rise rate when compared to other cylinders (orhistory) May be followed by detonation Increased exhaust temperature
Soft Firing
CharacteristicsObservation
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Valve Train
Valve Seat
Exhaust Port
Valve Stem
Valve Springs
Valve LifterRocker Arm
Cam Follower
Cam Lobe
Push Rod
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Valve Train
Common problems
Mechanical Loose/worn rocker arm Improper lifter clearance Broken springs Incorrect spring tension Worn valve guide Worn or mis-timed cam
Excessive cam gear lash
Leakage Burnt valves Deposits on valve seat Damaged seat Bent valve stem
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Valve TrainIncorrect clearance
May cause the valve toopen and close at thewrong time
Valve opening eventcan be noisy theclearance is taken upon the leading edge ofthe cam lobe
Can cause noisy valveclosure if the valve isdropped onto the seat
Crank Angle
L i f t
V i b r a t i o n
ExcessiveLash
Valve openslate & sharp
Valve closesearly & drops
on seat
NormalLift
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Valve Train
Hydraulic lifters
Hydraulic lifters maintain correct valve timingand minimize valve train wear over a widerange of operating conditions
Oil pressure within the lifter maintains correctclearances in the valve train
If the lifter collapses The valve may open late and close early The vibration pattern shows impacts atopening and closure
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Valve TrainExcessive EV clearance (KVGR with solid lifters)
P 1
P 2
P 3
P
4
P 5
P 6
K1F - E 12/13/1994 11:19:43 AMEngine Cylinders: Phased Vibration VT4:
-2.5
0.0
2.5
-2.5
0.0
2.5
-2.5
0.0
2.5
-2.5
0.0
2.5
-2.5
0.0
2.5
-2.5
0.0
2.5
0 90 180 270 360 450 540 630 720
P1
P2
P3
P4
P5
P6
-2.5
0.0
2.5
-2.5
0.0
2.5
-2.5
0.0
2.5
-2.5
0.0
2.5
-2.5
0.0
2.5
-2.5
0.0
2.5
90 180 270 360 450 540 630 720
P7
P8
P9
P10
P11
P12
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Valve Train
Vibration comparison for a leaking EV (KVGR)P1
P2
P3
P4
P5
P6
-2.5
0.0
2.5
-2.5
0.0
2.5
-2.5
0.0
2.5
-2.5
0.0
2.5
-2.5
0.0
2.5
-2.5
0.0
2.5
0 90 180 270 360 450 540 630 720
P7
P8
P9
P10
P11
P12
-2.5
0.0
2.5
-2.5
0.0
2.5
-2.5
0.0
2.5
-2.5
0.0
2.5
-2.5
0.0
2.5
-2.5
0.0
2.5
0 90 180 270 360 450 540 630 720
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NormalNormal
Valve TrainPT and PV: leaking exhaust valves (KVGR)
580Intake 294390 Exhaust150
0
50
100
150
200
250
300
350
400
450
500
0 45 90 135 180 225 270 315 360 405 450 495 540 585 630 675 720Angle (deg)
P r e s s u r e ( p s i g )
0
50
100
150
200
250
300
350
400
450
500
0 25 50 75 100% swept volume
2 low PFP
22
3 3
3 low expansion
1
1
1 low compression
High exhaust temp
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Valve Train
Worn rocker arms (KVGR)K1D - E 2/3/1997 10:52:37 AM
Engine Cylinders: Phased Vibration VT4:
-2.5
0.0
2.5
-2.5
0.0
2.5
-2.5
0.0
2.5
-2.5
0.0
2.5
-2.5
0.0
2.5
-2.5
0.0
2.5
0 90 180 270 360 450 540 630 72090 180 270 360 450 540 630 720
P1
P3
P4
P5
P6
P7
P8
P9
P10
P11
P12
-2.5
0.0
2.5
-2.5
0.0
2.5
-2.5
0.0
2.5
-2.5
0.0
2.5
-2.5
0.0
2.5
-2.5
0.0
2.5
0
P2
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Valve TrainWorn cam gear (KVS)
NO-4 - E 2/28/1995 1:38:59 PMEngine Cylinders: Phased Vibration VT4:
P10
P7
P8
P9
P11
P12
-2
0
2
-2
0
2
-2
0
2
-2
0
2
-2
0
2
0
2
-2
P1
P2
P3
P4
P5
P6
-2
0
2
-2
0
2
-2
0
2
-2
0
2
-2
0
2
0
2
-2
0 90 180 270 360 450 540 630 720 0 90 180 270 360 450 540 630 720
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Valve Train
Worn cam gear (KVS)410 EXHAUST VALVE161
575INTAKE VALVE 325621FUEL VALVE 536
0
100
200
300
400
500
600
700
800
900
1000
0 45 90 135 180 225 270 315 360 405 450 495 540 585 630 675 720
NO-4 - E Cylinder P12 2/28/1995 1:38:59 PM
Angle (deg)
410 EXHAUST VALVE161575INTAKE VALVE 325
621FUEL VALVE 536
0
100
200
300
400
500
600
700
800
900
1000
0 45 90 135 180 225 270 315 360 405 450 495 540 585 630 675 720
-
-
-
-
-
-
-
-
-
- Scale 2.0
P6 VT4
NO-4 - E Cylinder P6 2/28/1995 1:38:59 PM
Angle (deg)
P r e s s u r e ( p s i g )
P r e s s u r e ( p s i g )
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Valve TrainLeaking fuel valve (HLA)
C2A-E 10/10/2001 6:28:53 AMEngine Cylinders: Phased Ultrasonic ULT:
360135 180 225 27045 90 315
-5
0
5
-5
0
5
-5
0
5
-5
0
5
0
1F
2F
3F
4F
-5
360
-5
0
5
-5
0
5
-5
0
5
0
5
0 45 90 135 180 225 270 315
5F
6F
7F
8F
Hard closures
Leakage
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Valve Train
Leaking fuel valve (HLA)
45 90 135 180 225 270 315 360
--------------
--------------
--------------
--------------
-----------------------------
- Scale 2.0
- Scale 4.0
- Scale 4.0
8 VT4
8 ULT
8FV ULT
230 Intake130250 Exhaust110
283Fuel 213
C2A-E Cylinder 8 10/10/2001 6:28:53 AM Period 9
Angle (deg)
0
100
200
300
400
500
600
700
0
P r e s s u r e ( p s i g )
Leak asP rises
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Valve TrainAnalysis summary
Multiple impact following normal valve closure Excessive noise on opening or closure
Worn rockerbushing
Valve opens late and closes early Impact noises on valve closure
Sometimes see impact on opening Early closing exhaust valves may raise the PV toe
Excessivelifterclearance
Valve opening events are quiet or absent Valve events are similar across the entire engine Closing events are at expected crank angle, singleimpact of short duration
No leakage occurs after valve closure
NormalCharacteristicsFault
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Valve Train
Analysis summary (cont.)
Roughness seen in vibration pattern as valve opensand closes
Valve may hang up in the guide and not close at thecorrect time
May see gas leakage if valve does not seat properly
Worn valveguide
Impacts in the vibration as gear teeth pass each other May cause excessive wear on the cam lobe leading torough vibration pattern
When troubleshooting, be prepared to move thevibration transducer around
Cam gearfaults
Impact noises on opening and closure Valve may close late
Brokenvalve spring
CharacteristicsFault
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Valve TrainAnalysis summary (cont.)
Multiple impacts on valve closure as valve finds theseat
Look for differences in valve closure across the engine Can be caused by beat-out seat, worn/broken/incorrectspring, worn guide, loose rocker arm, bent valve stem
May see blowby pattern when pressure is high in thecylinder
Impropervalveseating
Blowby pattern appears when pressure rises in thecylinder
Leakingvalves
CharacteristicsFault
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Pistons, Rods, Rings and Liners
SOURCE: navsci.berkeley.edu/ ns10/piston.htm
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Piston slap
Piston slap occurs when the piston skirtimpacts the liner
Tends to occur after peak pressure when thepressure is high and there are side forces onthe piston
Becomes more pronounced when theclearance in the upper cylinder increases due
to ring wear
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Piston Slap
Low frequency vibration showing piston slap (HLA)
-5
0
5
-5
0
5
-5
0
5
-5
0
5
0 45 90 135 180 2 25 2 70 3 15 3 60
C2A-E 6/5/2001 8:23:09 AMEngine Cylinders: Phased Acceleration VTL:
-5
0
5
-5
0
5
-5
0
5
-5
0
5
0 45 90 135 180 2 25 2 70 315 360
1
2
3
4
5
6
7
8
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Piston SlapLow frequency vibration showing piston slap (HLA)
C2A-E Cylinder 3 6/5/2001 8:23:09 AM Period 6
230 Intake130250 Exhaust110
283Fuel 213
0
100
200
300
400
500
600
700
0 45 90 135 180 225 270 315 360
--------------
--------------
--------------
--------------
--------------
---------------------------------------
- Scale 2.0
- Scale 6.0
- Scale 4.0
- Scale 20.0
3 VT4
3 VTL
3 ULT
3FV ULT
Angle (deg)
P r e s s u r e ( p s i g )
Not always visiblein ultrasonic
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Piston Rods
Excessive wrist pin and connecting rodbearing clearances produce impacts at loadreversal in the piston pin bushing
in 4-stroke engines, vibration spikes occurnear TDC
in 2-stroke engines, vibration spikes occurnear BDC
There is usually cycle-to-cycle variability inthe location of the vibration
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Piston RodsWrist pin load for a 2-stroke engine
Wrist pin load in a 2 stroke engine
-50000
0
50000
100000
150000
200000
250000
0 45 90 135 180 225 270 315 360 405 450 495 540 585 630 675 720
Degrees
F o r c e ( l b s )
Vibration occursaround BDC
where load is minimal
Inertia
Gas force
Total force
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Piston Rods
Wrist pin load for a 4-stroke engineWrist pin load in a 4 stroke engine
-50000
0
50000
100000
150000
200000
250000
0 45 90 135 180 225 270 315 360 405 450 495 540 585 630 675 720
Degrees
F o r c e ( l b s )
Vibration occursaround TDC
where load reverses
Inertia
Gas force
Total force
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Piston RodsExcessive wrist pin clearance (KVS)
417 EXHAUST VALVE137565INTAKE VALVE 300
611FUEL VALVE 502
0
100
200
300
400
500
600
700
0 45 90 135 1 80 225 270 3 15 360 405 450 495 540 585 630 675 7 20
--------------
--------------
-
-
-
-
-
-
-
-
-
- Scale 2.0
P6 VT4
K200 - E Cylinder P6 1/16/1996 9:39:11 AM Period 6
Angle (deg)
P r e s s u r e ( p s i g )
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Piston Rings
Worn or improperly loaded rings
The presence of gas passing noise whencylinder pressures are high indicates blowby
Be careful though, it could be leakage aroundrings or valves
A damaged liner will prevent rings fromsealing properly
Even moderate blowby may be sufficient tocause a significant rise in the enginecrankcase pressure
Ring fouling prevents pressure from gettingbehind the rings to load them properly
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LinersScuffing and scoring
Liner scuffing or scoring is often seen as symmetricvibration spikes around TDC
For a 2-stroke engine, piston rings pass the same pointtwice in one cycle
For a 4-stroke engine, piston rings pass the same point4 times in one cycle
Ring loading affects the degree that each event is seen Wear is usually faster in the upper liner due to highPFP
Crankcase pressure may increase due to blowbyresulting from the liner wear
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Liners
Liner groove (KVS, P2, 10 rotations)NO-6 - E 12/21/1995 8:14:16 AM
Engine Cylinders: Phased Vibration VT4:
-2
0
2
-2
0
2
-2
0
2
-2
0
2
-2
0
2
-2
0
2
0 90 180 270 360 450 540 630 720
-2
0
2
-2
0
2
-2
0
2
-2
0
2
-2
0
2
-2
0
2
0 90 180 270 360 450 540 630 720
P2 (MMM)
P2 (1)
P2 (Med 2)
P2 (3)
P2 (4)
P2 (5)
P2 (6)
P2 (7)
P2 (8)
P2 (9)
P2 (10)
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LinersLiner groove (KVS)
FUEL VALVE 504
403 EXHAUST VALVE560
0 720
NO-6 - E Cylinder P2 12/21/1995 8:14:16 AM Period 2
Symmetric angle cursorsreveal liner groove
151INTAKE VALVE 345
610
20 340 380 7000
100
200
300
400
500
600
700
800
900
1000
45 90 135 180 225 270 315 360 405 450 495 540 585 630 675
--------------
--------------
-
-
-
-
-
-
-
-
-
- Scale 2.0
P2 VT4
Angle (deg)
P r e s s u r e ( p s i g )
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Liners
Liner groove (KVS)NO-6 - E 12/21/1995 8:14:16 AM
Engine Cylinders: Phased Vibration VT4:
-2
0
2
-2
0
2
-2
0
2
-2
0
2
-2
0
2
-2
0
2
0 90 180 270 360 450 540 630 720
-2
0
2
-2
0
2
-2
0
2
-2
0
2
-2
0
2
-2
0
2
0 90 180 270 360 450 540 630 720
P2 (MMM)
P2 (1)
P2 (Med 2)
P2 (3)
P2 (4)
P2 (5)
P2 (6)
P2 (7)
P2 (8)
P2 (9)
P2 (10)
Crosstalk from P3 exhaust blowdown
Crosstalk from P1exhaust blowdown
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LinersCrosstalk from exhaust event on P3 (KVS)
-2
0
2
-2
0
2
-2
0
2
-2
0
2
-2
0
2
-2
0
2
0 90 180 270 360 450 540 630 720
NO-6 - E 12/21/1995 8:14:16 AMEngine Cylinders: Phased Vibration VT4:
422
662
182
542
302
62
17
257
497
137
617
377
-2
0
2
-2
0
2
-2
0
2
-2
0
2
-2
0
2
-2
0
2
0 90 180 270 360 450 540 630 720
P1
P2
P3
P4
P5
P6
P7
P8
P9
P10
P11
P12
Unphased cursor indicatescrosstalk from other cylinders
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Liners
Liner wear (KVS)
90 180 270 360 450 540 630 720-2
0 90 180 270 360 450 540 630 720
-2
0
2
-2
0
2
-2
0
2
-2
0
2
-2
0
2
-2
0
2
0
P1
P2
P3
P4
P5
P6
NO-6 - E 3/19/1996 1:28:36 PMEngine Cylinders: Phased Vibration VT4:
-2
0
2
-2
0
2
-2
0
2
-2
0
2
-2
0
2
0
2
P7
P8
P9
P10
P11
P12
Chatter as loadedrings pass over wear
NO-6 - E 3/19/1996 1:28:36 PMEngine Cylinders: Phased Vibration VT4:
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LinersLiner wear (KVS)
403 EXHAUST VALVE151560INTAKE VALVE 345
610FUEL VALVE 504
0
100
200
300
400
500
600
700
800
900
1000
0 45 90 135 180 225 270 315 360 405 450 495 540 585 630 6 75 7 20
--------------
--------------
-
-
-
-
-
-
-
-
-
- Scale 2.0
P7 VT4
NO-6 - E Cylinder P7 3/19/1996 1:28:36 PM Period 2
Angle (deg)
P r e s s u r e ( p s i g )
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Liners
Liner wear confirmed by symmetric cursor (KVS)NO-3 - E Cylinder P5 5/1/1995 8:06:19 AM Period 2410 EXHAUST VALVE
575621FUEL VALVE 536
405 450 495 540 585 630 675 720
--------------
--------------
-
-
-
-
-
-
-
-
-
- Scale 2.0
P5 VT4
Angle (deg)
161INTAKE VALVE 325
0
100
200
300
400
500
600
700
800
900
1000
0 45 90 135 180 225 270 315 360
P r e s s u r e ( p s i g )
128 232 488 592
Symmetric cursor indicatesthe liner is worn.
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LinersLiner wear (KVS)
P7
P8
P9
P10
P11
P12
NO-3 - E 5/1/1995 8:06:19 AMEngine Cylinders: Phased Vibration VT4:
P1
P2
P3
P4
P5
P6
-1
0
1
-1
0
1
-1
0
1
-1
0
1
-1
0
1
-1
0
1
0
-1
0
1
-1
0
1
-1
0
1
-1
0
1
-1
0
1
-1
0
1
90 180 270 360 450 540 630 720 0 90 180 270 360 450 540 630 720
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 156
Liners
Port bridge wear (HLA)
-10
0
10
-10
0
10
-10
0
10
-10
0
10
0 45 90 135 180 225 270 315 360
-10
0
10
-10
0
10
-10
0
10
-10
0
10
0 45 90 135 180 225 270 315 360
C2A-E 10/10/2001 6:28:53 AMEngine Cylinders: Phased Ultrasonic ULT:
1
2
3
4
5
6
7
8
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230 Intake130250 Exhaust110
283Fuel 213
0
100
200
300
400
500
600
700
0 45 90 135 180 225 270 315 360
--------------
--------------
--------------
--------------
-----
------------------------
- Scale 2.0
- Scale 10.0
- Scale 10.0
4 VT4
4 ULT
4FV ULT
C2A-E Cylinder 4 10/10/2001 6:28:53 AM Period 6
Angle (deg)
P r e s s u r e ( p s i g )
LinersPort bridge (HLA)
Excessivering noise
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 158
Ignition Systems
Provide the energy to begin the chainreaction in the air/fuel mixture and consistsof
Power supply Timing circuit Distribution mechanism Transformer
Spark plug
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Ignition SystemsIgnition Primaries
P1LP2L P3LP4L P5L P6LP1R P2R P3RP4R P5R P6R
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
0 45 90 135 180 225 270 315 360
C402 - E Cylinder P1L 07/03/1997 8:07:43 AM
V o l t a g e ( V )
Crank Angle (deg)
TDC
Voltages shouldbe similar
ZenerGates
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 160
Ignition Systems
Ignition secondaries
0 1 2 3 4 5
S e c o n d a r y V o l t a g e
Time (ms)
CapacitorDischarges
Indication ofionization voltage
Coil ring down
Arc Duration
Plug Stops Firing
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Ignition SystemsTypical ignition secondary patterns
C402 - E 09/09/1998 12:02:53 PM
Ignition timing angle = 5.7
Ignition timing angle = 5.9
Ignition timing angle = 6.3
0
0
0
0 1 2 3 4 5
P4LL(Med 1)
P4LR(Med 1)
P5LL(Med 1)
Ignition timing angle = 5.9
Ignition timing angle = 5.9
Ignition timing angle = 6.1
0
0
0
0 1 2 3 4 5
P5LR(Med 1)
P6LL(Med 1)
P6LR(Med 1)
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 162
Ignition Faults
Timing
Advanced timing can cause early combustion early and increased PFP detonation lower exhaust temps
Retarded timing can cause delayed combustion
late and low PFP misfires/soft fires higher exhaust temperatures
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Ignition FaultsCoils
Check for correct polarity Look at coil ring down to assess coil windingcondition
2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE
SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 166
Ignition Faults
Two bad coils plug did not fire
Ignition timing angle = 5.5
Ignition timing angle = 6.4
Ignition timing angle = 5.4
Ignition timing angle = 5.1
Ignition timing angle = 5.7
Ignition timing angle = 5.9
-250
0
-250
0
-250
0
-250
0
-250
0
-250
0
0 1 2 3 4 5
C402 - E 9/9/1998 12:02:53 PM Secondary Ignition (Y Axis: mV -- X Axis: ms)
P1LL
P1LR
P2LL
P2LR
P3LL
P3LR
Ignition timing angle = 5.7
Ignition timing angle = 5.9
Ignition timing angle = 5.6
Ignition timing angle = 5.5
Ignition timing angle = 5.9
Ignition timing angle = 5.4
-250
0
-250
0
-250
0
-250
0
-250
0
-250
0
0 1 2 3 4 5
P1RL
P1RR
P2RL
P2RR
P3RL
P3RR
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Ignition FaultsReversed coil
-100
0
100
200
-100
0
100
200
-1