QUESTION BANK MARINE ENGINEERING KNOWLEDGE MOTOR PART-2

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Q Describe with the aid of the sketches, an arrangement for operating the fuel valve of a heavy oil engine, explaining how the timing is affected & the supply of the fuel regulated to suit varying load.

Q Sketch & describe a common rail fuel system as fitted to a diesel engine. How is delivery of the fuel controlled?

Q a) Explain the term Variable Injection Timing (VIT) when applied to the fuel pumps & state why a change in timing of the fuel injection may be required.

b) Describe, with the aid of sketches, a VIT fuel pump & explain how the change in timing is achieved whilst the pump is in operation

c) Explain how it may be determined that individual fuel pumps are injecting the correct quantity of the fuel with the correct timing at a particular pump setting.

Q Give reasoned opinion as to the validity of the following:

a) Hydraulic operation of the fuel injectors is to be referred to mechanical operation.

b) Combustion conditions within the cylinder are a good indication of the injector condition.

c) Inadequate fuel filtration is the principle cause of the injector malfunction.

Q Why are fuel pump placed near injectors. If lines are unequal how do you balance?

a) Describe with the sketches a scroll type fuel pump.

b) Explain how the quantity of the fuel is metered & how the governor cut out functions.

c) State how this type of the pump is set after overhaul.

d) State the reasons that necessitate pump overhaul.

Q Main engine fuel injection system required a lot of attention to ensure optimum performance. As the Chief Engineer of a 15 year old vessel which has been recently bought by your company, you have found that the main engine fuel system had been poorly maintained. Explain the steps you will take to assure good standards are brought back. Your answer should be comprehensive, starting from ordering of the bunkers.

Q a) Sketch and describe a fuel injector for a diesel engine.

b) State 4 parameters that can indicate fuel injectors require immediate overhaul.

Q Fuel injector needle valves are found to be seizing frequently. Explain:

a) How could such seizures should be detected and

b) Preventive measures & remedial actions that can be taken.

Q What are the design aspect of the following component to improve injection atomization & penetration of the fuel in marine diesel engines?

a) Injector nozzle

b) Piston crown

c) Cylinder head

Q With reference to mechanical/hydraulic governors explain:

a) Why flyweights are driven at the higher rotational speed than the engine.

b) How dead band effects are reduced.

c) How hunting is reduced.

d) How the output torque is increased.

Q a) With the help of a block diagram describe the operation of an electronic governor installed to an auxiliary diesel engine.

b) An engine installed with an electronic governor behaves erratically during the load changes. Explain the possible causes.

c) State 3 problems to which such a governor is prone & explain how each becomes evident. In the event of the governor on a direct drive engine becoming inoperative state the action you, as 2/E, would take in order to assure safe operation of the engine.

Q a) Describe briefly the operation of an electrical or hydraulic main engine governor

b) For the type described indicate how failure can occur & the action to be taken if immediate correction cannot be achieved & the engine must be operated.

Q With respect to the diesel engine control & safety, answer the following:

a) How is the governor different from an over speed trip

b) Explain with the help of sketch “speed droop” in a governor

c) Explain how load is being transferred to an incoming generator explaining your actions with relation to the governor’s “droop line”.

Q Electrical power is provided from alternators driven by the auxiliary diesel engines:

a) Using a sketch to demonstrate your answer, describe a suitable governor.

b) Give an account of the governor action to increase the power delivered by the engine in response to a large electrical load increase while also restoring & maintaining the correct frequency.

c) Explain each of the following:

i. The necessity for droop

ii. How droop is affected.

Q a) Define the essential conditions, which must be satisfied by the air supply for a pneumatic control system.

b) Sketch a control air supply arrangement & give a reasoned explanation for the positioning of dryers & filters.

Q With reference to UMS engine remote control & monitoring system:

a) In the event of complete failure of such monitoring & control systems state, with reasons, how you, as 2/E, would organize the engine room Staff to assure safe operation of the engine during:

i. Normal deep sea conditions

ii. Manoeuvring

b) State, with reasons, SIX important engine parameters which should be manually monitored following failure of the UMS system.

c) Explain how the cause of the failure of the UMS system may be traced.

Q Sketch & describe a pneumatic control system for controlling temperature of main engine lubricating oil outlet of the cooler and:

a) Explain why air supplied to the pneumatic control system must be free from dust & water.

b) Describe how above impurities are removed.

c) State the possible consequences if the air supply is contaminated.

Q Sketch & describe a system of control for manoeuvring a main diesel engine from the bridge & show how local control may be affected in case of breakdown of the remote system.

Q Whilst operating in heavy weather the main engine loses power and misfires. Investigation shows considerable quantities of the water in the fuel.

a) State, with reasons, the immediate action you as 2/E would take to assure the safe operation of the main engine.

b) State, with reasons, the possible place where water could enter the fuel system.

c) State, with reasons, the standing instructions you as 2/E would issue with respect to the operation of the fuel system in order to prevent major problems due to the water in the fuel.

Q A diesel generator when installed in a machinery space which is periodically unmanned may be equipped with the monitoring alarms of the exhaust temperatures. Discuss the relative merits of:

a) Individual cylinder maximum temperature alarms

b) Individual cylinder maximum and minimum temperature alarms

c) Individual cylinder maximum temperature alarm & an alarm for any two cylinders exhaust temperatures deviating more than 35°C. Explain how arrangement (c) can be provided for.

Q Describe how each of the following procedure may be accomplished by bridge control equipment for a direct reversing 2 stroke diesel engine:

a) Setting the direction of rotation

b) Starting

c) Controlling speed

Q Sketch and describe a fuel meter used with high viscosity fuel. Explain how it operates. Explain the value of the readings obtained & how they are used.

Q Explain the term “Cascade control” & sketch such a system suitable for use with a main engine jacket cooling water system. Show the variation of the pressure & temperature at the major points of the system?

Q Describe the process of inspecting the running gear of a main diesel engine. What is the purpose of such an inspection & what defects may be found?

Q a) A number of main engine cooling water temperature and lubricating oil pressure alarms have occurred during periods of the UMS operating & no faults have been detected on the engine.

i. State possible reasons for these alarms operating.

ii. Explain how the faults may be detected.

iii. State the action to be taken in order to minimise the  future spurious alarms.

b) State the standing instruction you as Chief Engineer, would issue to an engineer joining your ship with respect to his action when responding to alarms during the UMS operating at night.

Q Consideration has been given to running diesel machinery unattended at night. Describe the modification & additional apparatus, which would be required before this could be achieved with reasonable safety.

Q As second engineer you have been requested to obtain a set of indicator cards from a large slow speed engine of a recently purchased second hand ship.

a) Describe your initial checks & preparations.

b) State with reason the types of card you would consider essential & explain the procedure for obtaining these.

c) State in order of importance the additional information required with the cards.

d) State your procedure for analysis of the cards and obtaining cylinder powers.

e) State the procedure for Power calculation and Fault diagnosis

Q What limits the power in a cylinder of a given size? State the results if an attempt to raise the power by injecting more fuel into the cylinder are made?

Q a) A set of indicator diagram including draw cards has been taken for a main diesel engine. Examine critically, the following if the compression curve is normal.

i. The maximum pressure is lower

ii. The maximum pressure is higher

iii. The expansion curve is lower

iv. The expansion curve is higher

b) Describe how the faults as mentioned above can be rectified.

Q a) State the various types of indicator diagrams that are used to assess engine performance.

b) Specify the additional data required in conjunction with these diagrams.

c) Explain how some abnormalities in indicator diagrams can be traced to the indicator.

d) Describe the precautions required to avoid indicator malfunctions.

Q Name the factors an engine designer considers in the selection of the compression ratio for a compression ignition engine. Give some examples of the compression ratio values?

Q Draw an “out of phase” diagram for a large 2-stroke slow speed cycle engine. Describe in detail the part of the cycle showing on this diagram. with the help of a diagram explains the effects of burning high & low grade fuels (when fuel injection timing is not altered). Explain how good ignition & combustion can be obtained when using low grade fuel.

Q a) Assume you are instructed to submit to the Superintendent Engineer a complete set of indicator cards together with relevant data. Give full account of your work in taking the cards & preparing them for submission.

b) Tabulate the data you forward, both that extracted from the cards & otherwise obtained. Giving typical figures from a large 2 stroke slow speed main propulsion unit.

Q a) Describe the various types of indicator diagrams and discuss the relevance of this method of determining engine performance.

b) Suggest how engine performance may be examined other than by taking indicator cards.

Q Explain with the aid of sketches, the cycle of operation of either a free pistons or an open cycle gas turbine installation. Discuss is advantages & limitations as the main means of propulsion on a ship as compared to the conventional marine machinery.

Q a) Describe the cause and effect of thermal stressing in cylinder Heads, liners and pistons.

b) Explain why thermal stressing is aggravated with the increased cylinder bore.

c) Explain how stress concentration & its effects are relieved by maintenance & operational practices.

Q With reference to medium speed engine cylinder liners:

a) Explain the cause and effects of Polishing or glazing.

b) Describe, with the help of the sketches, an anti-polishing ring & explain how it is fitted in the liner.

c) Explain the action of the anti-polishing ring during the operation of the engine.

Q With reference to piston rings:

a) State with reasons the causes of the breakage.

b) State how maintenance & engine operation can minimize breakage.

c) Explain the possible consequences with respect to the performance & safety of operating the engine with broken or severely worn rings.

Q If a main engine piston seizes in its liner at sea & it is not possible to replace the unit, explain in detail, what actions required to be taken, to enable the ship to reach port safely?

Q As Second Engineer describe the procedure involved in the complete inspection of a cylinder liner & piston assembly, indicating areas of significant interest.

a) Explain with the reasons possible faults which might be found.

b) Suggest how such faults should be rectified.

Q a) With respect to the Diesel Engines, describe the cause of:

i. Piston rings that is too tight in the piston grooves.

ii. Corrosion of the piston rings.

iii. Piston grooves that are worn.

iv. Piston rings that is too slack with the piston grooves.

b) Describe the effect of each of the faults listed above & the remedial action for each.

Q a) State with reasons the main causes of normal cylinder liner wear.

b) State 2 forms of abnormal liner wear & explain the reasons for these forms of the wear.

c) Explain how cylinder liner wear may be kept within the acceptable limit

Q a) Describe with the help of the sketch, the arrangement of valves & passages for a four stroke engine cylinder head.

b) With reference to (a) indicate where cracking might be expected stating likely cause.

c) Explain the different factors that tend to cause distortion of 4-stroke cylinder head.

d) Explain how the effects described in (c) are minimized.

Q Evaluate the influence of the following factors upon cylinder and piston ring wear rates:

a) Position of rings in relations to the piston crown.

b) Spread & proximity of the coolant passages from liner wall.

c) Flow rate & specific heat of coolant.

d) Chromium plating of the ring faces.

Q Make a diagrammatic sketch of one unit of Sulzer engine of the cross head type showing the arrangement of the cylinder ports. Describe briefly the arrangement & explain how scavenging is affected?

Q Describe the process of replacing the cylinder liner in an auxiliary engine. How water tightness is ensured and what precautions are taken before commissioning the engine?

Q a) State how a cylinder liner is checked for wear? How these measurements are recorded?

b) What types of wear takes place in the cylinder liner? Where does the maximum wear take place & why?

Q a) Sketch a cylinder relief valve suitable for a large slow speed engine.

b) Describe its salient design features.

c) State the purpose of fitting such a device.

d) State the possible circumstances when the relief valve may lift & indicate the action to be taken to prevent damage to the engine.