Ship Propulsion SystemsShip Propulsion Systems
STEAMSTEAM
DIESELDIESEL
OTHEROTHER
ConventionalConventional
NuclearNuclear
Slow SpeedSlow Speed
Medium SpeedMedium Speed
Gas TurbineGas Turbine
Combined CycleCombined Cycle
DIESEL PROPULSIONDIESEL PROPULSION
DIESEL ENGINE NOMENCLATUREDIESEL ENGINE NOMENCLATURE
CYLINDERCYLINDERPISTONPISTON
EXHAUST VALVEEXHAUST VALVEINTAKE VALVEINTAKE VALVE FUEL INJECTOR
DIESEL ENGINE NOMENCLATUREDIESEL ENGINE NOMENCLATURE
PISTONPISTON
TDC TDC (Top Dead Center)
BDC BDC (Bottom Dead Center)
STROKESTROKE
BOREBORE
THE DIESEL CYCLETHE DIESEL CYCLE4 EVENTS4 EVENTS
INTAKEINTAKE (bring in fresh air charge) (bring in fresh air charge)COMPRESSIONCOMPRESSION (raise pressure & (raise pressure & temperature of charge)temperature of charge)POWERPOWER (inject and combust fuel – (inject and combust fuel – “exploding” gas expands)“exploding” gas expands)EXHAUSTEXHAUST (remove combustion (remove combustion products)products)
THE DIESEL CYCLETHE DIESEL CYCLEFOURFOUR Stroke/Cycle [4 S/C] Engines Stroke/Cycle [4 S/C] Engines
Each event completed in one strokeEach event completed in one stroke
INTAKEINTAKE (TDC (TDC BDC) BDC)
COMPRESSIONCOMPRESSION (BDC (BDC TDC) TDC)
POWERPOWER (TDC (TDC BDC) BDC)
EXHAUSTEXHAUST (BDC (BDC TDC) TDC)
Cycle completed in Cycle completed in TWOTWO revolutions revolutions
DIESEL CYCLE: DIESEL CYCLE: P-V DiagramP-V Diagram
TDC
COMPRESSION
POWER
EXHAUST
BDC
INTAKE
Idealized DIESEL CYCLE INTAKE—INTAKE—at at
atmospheric pressureatmospheric pressureCOMPRESSION—COMPRESSION—to to
TDCTDCPOWER—POWER—
– Fuel injectedFuel injected– Constant pressure Constant pressure
heatingheating– ExpansionExpansion
EXHAUST—EXHAUST—at at atmospheric pressureatmospheric pressure
PRESS
VOL
OTTO CYCLE: OTTO CYCLE: P-V DiagramP-V Diagram
TDC
COMPRESSION
POWER
EXHAUST
BDC
INTAKE
INTAKE—INTAKE—Fuel & airFuel & air at at atmospheric pressureatmospheric pressure
COMPRESSION—COMPRESSION—to to TDCTDC
POWER—POWER—– Sparkplug ignitionSparkplug ignition– Constant Constant volumevolume
heatingheating– ExpansionExpansion
EXHAUST—EXHAUST—at at atmospheric pressureatmospheric pressure
PRESS
VOL
Idealized GASOLINE ENGINE
DIESEL vs. OTTO CYCLEDIESEL vs. OTTO CYCLE
TDC BDC
PRESS
VOL
DIESEL
TDC BDC
PRESS
VOL
OTTO (Gasoline)
Linear to Linear to Rotational Rotational MotionMotion
CRANK SHAFT
WEB
CRANK PIN
CONNECTING ROD
WRIST PIN
PISTON RINGS
Crank-pin Crank-pin position position as as timingtiming
TIMING CIRCLE
INTAKE
COMPRESSIONPOWER
FUEL INJECTION
Fuel cut-off
SCAVENGING
INTAKE VALVE OPENS
EXHAUST VALVE
CLOSES
EXHAUST
THE DIESEL CYCLETHE DIESEL CYCLETWOTWO Stroke/Cycle [2 S/C] Engines Stroke/Cycle [2 S/C] Engines
Each event completed in less than Each event completed in less than one strokeone stroke
POWERPOWER (TDC (TDC beforebefore BDC) BDC) EXHAUSTEXHAUST (before to after BDC) (before to after BDC)INTAKEINTAKE (before to after BDC) (before to after BDC)COMPRESSIONCOMPRESSION ( (afterafter BDC BDC TDC) TDC)
Cycle completed in Cycle completed in ONEONE revolution revolution
2 S/C 2 S/C timingtiming
COMPRESSION
POWER
Fuel cut-off
EXAUST BEGINS
FUEL INJECTION
EXHAUSTINTAKE
SCAVENGING
INTAKE BEGINS
EXAUST ENDS
INTAKE ENDS
2 S/C DIESEL CYCLE2 S/C DIESEL CYCLE
TDC BDC
PRESS
VOL
Enclosed area:
∫P dV = Energy delivered per cycle
0 psig
MEP
MEP—Mean Effective Pressure(“average” pressure during cycle)
Equivalent Area (Energy)MEP x STROKE
P L A N P L A N = HP per Cylinder= HP per Cylinder 33,00033,000
PP– MEP [lbs/in– MEP [lbs/in22] ] LL– Stroke [ ft ]– Stroke [ ft ]AA– cylnder area [in– cylnder area [in22]]NN-- RPM-- RPM
THE DIESEL CYCLETHE DIESEL CYCLE
4 S/C Engines—4 S/C Engines—
Each event takes one Each event takes one strokestroke
Cycle completed in two Cycle completed in two revolutions revolutions
One One powerpower stroke every stroke every otherother revolution) revolution)
MustMust have intake have intake ANDAND exhaust valvesexhaust valves
2 S/C Engines—2 S/C Engines—
Cycle completed in one Cycle completed in one revolutions revolutions
(Shorter) (Shorter) powerpower stroke stroke everyevery revolution revolution
MayMay have intake and have intake and exhaust valves, orexhaust valves, or– Intake port and exhaust Intake port and exhaust
valve, orvalve, or– Intake and exhaust portsIntake and exhaust ports
Comprised of Comprised of INTAKEINTAKE, , COMPRESSIONCOMPRESSION, , POWERPOWER & & EXHAUSTEXHAUST EVENTS EVENTS
(fuel injection at beginning of power event)(fuel injection at beginning of power event)