Test

Question 1

Advs + DAdvs of diesel engines

Answer 1

Advantages:
- low specific fuel consumption
- constant SFC over wide power range
- run at constant speed under varying load
- low air intake requirements
- self contained power source
- ease of automation

Disadvantages:
- high specific weight
- noise generators
- poor resistance to shock
- many highly stressed reciprocating components
- high maintenance load / poor reliability

Question 2

Problems associated with 2 strokes

Answer 2

• inability to breathe
• effective stroke less than in 4 stroke

Question 3

What is P.L.A.N.S? (press, length, area, no off)

Answer 3

P - indicated mean pressure - May possibly be the same

L - effective stroke length ( 2 stroke cannot be the same )

A - piston area (may be same)

N - crank speed

S - number of power strokes per revolution

Question 4

Advance + Retard point of injection and effects (theoretical, not practical)

Answer 4

Fuel injected at wrong time (advanced):
- results in poor combustion
- if fuel too early POI is advanced; increases ignition delay period and allow more fuel to be injected before SIT of fuel is reached.
- more fuel vapour created before ignition, resulting in higher Pmx and Tmax.

Retarded:
- if fuel injected later, POI is retarded.
- less fuel injected by the time SIT of fuel reached giving rise to smaller amount of vapour and Pressure rise will be lower than required.
- will result in combustion at constant pressure causing inefficient combustion.
- additional problem with retarded injection is that combustion will occur later in the cycle

Question 5

Pressure/ volume diagram for dual cycle

Question 6

Advs + DAdvs constant volume Otto cycle

Question 7

Factors affecting power output (Sea state, load, towing, draught, clean hull, etc)

Question 8

Engine classification (speed, low, medium, high applications, etc).

Question 9

Air movement in combust chamber (squish, swirl)

Answer 9

Swirl:

Induction induced swirl:
- induced by the design of the air inlet tract and or the combustion chamber components.
- can be achieved by: masked inlet valves, angled and offset inlet ports, tangential inlet ports - 2 stroke engines.

Compression induced swirl:

Question 10

Droplet of fuel story

Question 11

What is timing diag (4 stroke turbo, 4 stroke nat asp, 2 concentric circles, in VV open TDC, BDC, overlap, etc)

Question 12

What effects design of superchargers (heat, bearing size, etc)

Question 13

What are disadvantages of turbo? (Lag etc)

Question 14

Crankshaft deflections: occasions, causes of excessive torsional vibration, dampers etc. (And label diagram)

Question 15

What is an oil cushion piston? Types of piston rings (comp, oil scraper)?

Question 16

Sketch and describe operation of single fuel pump element

Question 17

What are some injector bounce causes and remedies?

Question 18

What are some tests on coolants? (Water, salinity, acid)

Question 19

What is: governor; rate of response,sensitive output defects

Question 20

Protection panel: 5 monitored parameters, values, trips

Question 21

What are the phases of combustion graph. Air curve BDC, TDC,

Question 22

What are some liner problems and remedies. Gas side+ water side

Question 23

What are some lube oil tests (visc, particle, water, TBN)

Question 24

What are some headings In the diesel engine log book?

Question 25

What is the DMEO looking for on rounds (sound, smell, hazard, etc)