Marine Engineering Flashcards
What are the applications of the two stroke engine?
- it is used for large ships,
- for propulsion,
- generating electricity
What are the applications for a four stroke engine?
- in ships with limited engine room,
- powering onboard systems,
- small cruise ships for comfort of the passangers
what fuel does each engine use?
- two stroke - cheap
- four stroke - high quality
what is the function of a thrust block in a propeller system of a diesel engine (any)?
- It takes the force that work on the propeller and converts it into a pulling force for the ship
- it makes the engine work better thank to no disturbing reaction forces
Why is a turbocharger used with diesel engines?
- Increased power output - it forces more air into the combustion chamber - greater power output
- Fuel efficiency - with the same amount of fuel, more power is generated
- reduced emissions - less harmful pollutants are produced thanks to better air- fuel mixing leads
What is a key feature of the valve and scavenging system in a two-stroke engine?
Scavenge ports for air intake
What is the key feature of valve and scavenging system in a four stroke engine?
intake and exhaust valves controlled by a camshaft
What type of piston design is often used in a two-stroke engine?
May have scavenge ports and an extended skirt
What is a characteristic of the piston design in a four-stroke engine?
Has a complex ring for better oil control and compression
Fill in the blank: A two-stroke engine has _______ for air intake.
scavenge ports
What is a feature of the crankshaft in a two-stroke engine?
1 power stroke per revolution
What is a feature of the crankshaft in a four-stroke engine?
2 power strokes every two revolutions
What does a four-stroke engine’s design allow for compared to a two-stroke engine?
Higher thermal efficiency
What are the types of propuslsion systems on ships?
Electrical, hybrid, steam turbine, gas turbine, wind and solar, nuclear
Desribe the electrical propulsion system
engine drives electricity generator (gen-set), electric motor drives propeller,
flexible system layout,
high maneuverability
Describe hybrid propulsion system
Has two or more power sources,
many types,
energy saving, low environmental impact,
high initial costs
Desribe the steam turbine propulsion system
used for larger ships (oil tankers mostly),
boil-off gas can be burned in boilers for steam generation
why do we not use steam engines anymore?
Because steam torbines have higher efficiency
Describe gas turbine propulsion system
applications for military, cruse ships, electrical propulsion ships,
has high power output, low vibration and uses high quality fuel
describe wind and solar propulsion systems
uses wind sail and solar power,
uses rotor sails for Magnus effect,
environmental friendly
describe the steps for nuclear-powered propulsion system
- hot fluid from the reactor is transported,
- it heats of the water and makes steam in the steam generator,
- steam powers the turbines,
- the turbines power the motor, the battery, the propeller
- low pressure and temperature steam is condenst into water,
water circulates back using a pump
(ME systems) describe the shafting system
shafts are used to connect prime movers, gear box and propulsors. They transfer speed and torque through the entire propulsion system.
Transfers power from engine to the propeller.
(ME systems) describe the boiler system
Combustion device fired with fuel to heat water or produce steam. large boilers - steam powered ships. the steam is used for process heating, space heating, electrical or mechanical power generator
(ME systems) describe the steam power generator
used for propulsion systems of VLCC, LNG carries and some large tank ships. large power capacity but quiet in operation
