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: Intake Intake

STROKE 1

DIESEL CYCLE:DIESEL CYCLE: Compression Compression

STROKE 2

DIESEL CYCLE:DIESEL CYCLE: POWERPOWER

STROKE 3

DIESEL CYCLE:DIESEL CYCLE: Exhaust Exhaust

STROKE 4

DIESEL CYCLE:DIESEL CYCLE: Intake Intake

DIESEL CYCLE:DIESEL CYCLE: Compression Compression

DIESEL CYCLE:DIESEL CYCLE: POWERPOWER

DIESEL CYCLE:DIESEL CYCLE: Exhaust Exhaust

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

Linear to Linear to Rotational Rotational MotionMotion

TIMING CIRCLE

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 EVENTS2 S/C EVENTS

2 S/C EVENTS2 S/C EVENTS

2 S/C EVENTS –2 S/C EVENTS – WITHOUT INTAKE VALVEWITHOUT INTAKE VALVE

INTAKE PORT

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)