Ship Propulsion Systems STEAMDIESELOTHERConventionalNuclear Slow Speed Medium Speed Gas Turbine Combined Cycle DIESEL PROPULSION

DIESEL ENGINE NOMENCLATURE CYLINDER PISTON EXHAUST VALVE INTAKE VALVE FUEL INJECTOR

DIESEL ENGINE NOMENCLATURE PISTON TDC (Top Dead Center) BDC BDC (Bottom Dead Center) STROKE BORE

THE DIESEL CYCLE 4 EVENTS INTAKE (bring in fresh air charge) COMPRESSION (raise pressure & temperature of charge) POWER (inject and combust fuel – “exploding” gas expands) EXHAUST (remove combustion products)

THE DIESEL CYCLE FOUR Stroke/Cycle [4 S/C] Engines Each event completed in one stroke INTAKE (TDC  BDC) COMPRESSION (BDC  TDC) POWER (TDC  BDC) EXHAUST (BDC  TDC) Cycle completed in TWO revolutions

DIESEL CYCLE: Intake STROKE 1

DIESEL CYCLE: Compression STROKE 2

DIESEL CYCLE: POWER STROKE 3

DIESEL CYCLE: Exhaust STROKE 4

DIESEL CYCLE: Intake

DIESEL CYCLE: Compression

DIESEL CYCLE: POWER

DIESEL CYCLE: Exhaust

DIESEL CYCLE: P-V Diagram TDC COMPRESSION POWER EXHAUST BDC INTAKE Idealized DIESEL CYCLE INTAKE—at atmospheric pressure COMPRESSION—to TDC POWER— –Fuel injected –Constant pressure heating –Expansion EXHAUST—at atmospheric pressure PRESS VOL

OTTO CYCLE: P-V Diagram TDC COMPRESSION POWER EXHAUST BDC INTAKE INTAKE—Fuel & air at atmospheric pressure COMPRESSION—to TDC POWER— –Sparkplug ignition –Constant volume heating –Expansion EXHAUST—at atmospheric pressure PRESS VOL Idealized GASOLINE ENGINE

DIESEL vs. OTTO CYCLE TDC BDC PRESS VOL DIESEL TDC BDC PRESS VOL OTTO (Gasoline)

Linear to Rotational Motion CRANK SHAFT WEB CRANK PIN CONNECTING ROD WRIST PIN PISTON RINGS

Linear to Rotational Motion TIMING CIRCLE

Crank-pin position as timing TIMING CIRCLE INTAKE COMPRESSION POWER FUEL INJECTION Fuel cut-off SCAVENGING INTAKE VALVE OPENS EXHAUST VALVE CLOSES EXHAUST

THE DIESEL CYCLE TWO Stroke/Cycle [2 S/C] Engines Each event completed in less than one stroke POWER (TDC  before BDC) EXHAUST (before to after BDC) INTAKE (before to after BDC) COMPRESSION (after BDC  TDC) Cycle completed in ONE revolution

2 S/C timing COMPRESSION POWER Fuel cut-off EXAUST BEGINS FUEL INJECTION EXHAUST INTAKE SCAVENGING INTAKE BEGINS EXAUST ENDS INTAKE ENDS

2 S/C EVENTS

2 S/C EVENTS – WITHOUT INTAKE VALVE INTAKE PORT

2 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 = HP per Cylinder 33,000 33,000 P– MEP [lbs/in 2 ] L– Stroke [ ft ] A– cylnder area [in 2 ] N-- RPM

THE DIESEL CYCLE 4 S/C Engines— Each event takes one stroke Cycle completed in two revolutions One power stroke every other revolution) Must have intake AND exhaust valves 2 S/C Engines— Cycle completed in one revolutions (Shorter) power stroke every revolution May have intake and exhaust valves, or –Intake port and exhaust valve, or –Intake and exhaust ports Comprised of INTAKE, COMPRESSION, POWER & EXHAUST EVENTS (fuel injection at beginning of power event)