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Q7. With reference to the 4-stroke medium speed engines:

A. Define the cause and effect of thermal stressing in cylinder Heads, liners and pistons.

B. Explain why thermal stressing are aggravated with increase in cylinder bore.

C. Explain how stress concentration and its effects are relieved by maintenance and operational practices.

Q2. Describe methods of static and dynamic balancing of an engine and describe what are first order, second order and higher order moments in engine.

Q6. What is "virtual tappet" in the hydraulically actuated air spring return exhaust valves, and how is it set. Explain why the damage occurs to the seats of the exhaust valves due to furrowing and cutting and how an incident of "valve drop" leading to extensive damage to running gear can occur.

Q2. How explosion occurs in the starting air line of an internal combustion engine and how can the possibility of such an occurrence be reduced? Sketch and describe devices, which may be fitted to reduce the severity of such an explosion. State the attention which air starting valves should be given before stand by.

Q5. Sketch and describe Heavy fuel oil system of a large bore internal combustion engine and give temperature and pressure at important points. Discuss atomization, penetration and swirl and their inter relationship.

Q5. Discuss the consequences of failure to maintain correct clearances in the case of main diesel engine crankshaft and bottom end bearings. Sketch a bottom end bearing paying particular attention to the arrangement of ensuring uninterrupted flow of oil to the top end bearing.

Q6. With Respect to main engine turbocharger;

A. Explain why cleanliness throughout the turbochargers system is critical to engine performance?

B. Describe in-service cleaning procedure for gas and air sides of a turbocharger indicating safety precautions to be observed?

Q4. While operating at Sea during rough weather conditions, fire sparks have been observed coming out from the chimney. On investigation, it has been observed that the fuel contains considerable quantity of water and sludge. As the Second engineer of the vessel. Explain:
A. Immediate actions taken to rectify the problem.
B. Precautions you take to avoid recurrence of this type of problem.

Q9. A set of indicator diagrams cards has been taken for a main diesel engine. Analyze with reference to the following conditions and suggest corrective action in each case:
a. Higher peak pressure with normal compression pressure.
b. Normal peak pressure with lower compression pressure.
c. Higher peak pressure with higher compression pressure
d. Normal compression pressure with fluctuating pressure line during expansion stroke after ignition.