DieselShip's Online Content Library

Q1. Modern low-speed engines use electronically controlled common-rail fuel systems instead of jerk pumps. Explain:

(a) How fuel metering and injection timing are achieved independently of each other in such a system. (6)

(b) The role of the Engine Control Unit (ECU), hydraulic power supply, and the Injection Control Unit (ICU)/solenoid valves in achieving this. (6)

(c) Two operational advantages this decoupling of metering and timing gives over the conventional jerk pump system. (4)

Q2. Draw and explain the working of a typical Diesel Electrical Propulsion system. Also explain the advantages and disadvantages of such a system over the conventional two stroke engine propulsion system. (16)

Q3. a) What are the advantages of thin shell bearings over white metal bearing used in marine diesel engines? (6)

b) How are the thin shells prevented from rotating inside the bearing cage when the engine is running? (4)

c) What is importance of axially locating the thin shell bearing and how it is done? (6)

Q4. With reference to an electro-hydraulic speed governor fitted to an auxiliary diesel engine driving an alternator:

a) With the aid of a simple sketch, explain the speed droop mechanism. (10)

b) What are the differences between the isochronous and droop governors? (6)

Q5. A Crankshaft of a two-stroke engine undergoes several types of stresses during the operation of the engine. Explain these types of stresses and possible effect they have on the crank shaft. Also explain how this stress and their effects are taken care of during the design and operation of the engine. (16)

Q6. With respect to a 2-stroke main propulsion diesel engine starting air system:

(a) Draw and explain a typical starting air timing diagram for a single cylinder. (8)

(b) What is "Starting Air Overlap" and why is it necessary in a multi-cylinder engine? (4)

(c) What is slow turning arrangement and what is the purpose? (4)

--- PREVIOUSLY ASKED AS ---

Q5. With respect to a 2- stroke main propulsion diesel engine starting air system.

a) Explain the starting air overlap?

b) What is the starting air timing for one cylinder?

c) What is slow turning arrangement and what is the purpose?

Q7. With reference to a 4-stroke medium speed auxiliary diesel engine:

a) Describe with a simple sketch bottom end bearing assembly. (8)

b) What is the purpose of serrations provided on the piston rod and bearing keep? (4)

c) What special features are provided on the connecting rod bolts? (4)

Q8. With Respect to a turbocharging a 2-Stoke Main Propulsion Diesel Engine:

a. What is the purpose of Auxiliary Blower? (6)

b. What are the safeties provided for the scavenge air receiver? (6)

c. Why do we require scavenge air cooler? (4)

Q9. Explain the working principle of a Variable geometry Turbo charger (VGT) and how it differs from a fixed geometry turbocharger. How is the Variable Geometry Turbochargers (VGTs) important for marine engines and how they help maintain the right mix of air and fuel at different engine power levels. (16)