Small Vessel Second Engineer 060-01 Exam: Marine Diesel Engineering

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the purpose of atomisation in the combustion of fuel in a diesel engine?

Atomisation is the process of breaking up the fuel into fine droplets to increase the surface area and improve the mixing of fuel and air, which enhances the combustion process.

How does the compression ratio of a diesel engine affect the combustion process?

The compression ratio of a diesel engine affects the combustion process by influencing the temperature and pressure reached during the compression stroke, which is necessary for the auto-ignition of the fuel-air mixture.

What is the purpose of the labyrinth glands in a diesel engine turbocharger?

The labyrinth glands in a diesel engine turbocharger are designed to prevent the leakage of compressed air and exhaust gases between the stationary and rotating components of the turbocharger.

Explain the role of the diffuser in a diesel engine turbocharger.

<p>The diffuser in a diesel engine turbocharger is responsible for converting the high-velocity, high-pressure exhaust gas flow from the engine into a lower-velocity, higher-pressure flow that can efficiently drive the turbine wheel.</p> Signup and view all the answers

Describe the function of the thrust bearing in a diesel engine turbocharger.

<p>The thrust bearing in a diesel engine turbocharger is responsible for absorbing the axial forces acting on the rotating shaft, which can be generated by the pressure differences between the compressor and turbine sides.</p> Signup and view all the answers

Explain the principle of operation of a simple hydraulic governor in a diesel engine.

<p>A simple hydraulic governor in a diesel engine operates by using the engine's oil pressure and the centrifugal force acting on a flyweight mechanism to automatically adjust the fuel supply to the engine, maintaining a constant engine speed under varying load conditions.</p> Signup and view all the answers

How does the transfer of gas force from the piston crown to the crankshaft occur in a four-stroke diesel engine?

<p>In a four-stroke diesel engine, the gas force generated by the combustion of fuel on the piston crown is transferred to the crankshaft through the connecting rod, which converts the linear motion of the piston into the rotational motion of the crankshaft.</p> Signup and view all the answers

Describe in detail the operation of the overspeed trip sketched in part (a), including how it functions to prevent overspeeding.

<p>The overspeed trip is a centrifugal device that detects when the engine exceeds a preset maximum safe speed. As the engine rpm increases, weighted levers hinged at the shaft spin outwards due to centrifugal force. At the overspeed set point, these levers trip a mechanism that cuts off the fuel supply or air intake, causing the engine to shut down and preventing overspeeding damage.</p> Signup and view all the answers

Explain the process of atomization that occurs in a fuel injector nozzle, and why it is important for efficient combustion.

<p>Atomization refers to the process of breaking up the liquid fuel into a fine mist or spray of tiny droplets as it exits the injector nozzle. This increases the surface area of the fuel exposed to air, allowing for more complete vaporization and mixing with air for efficient combustion.</p> Signup and view all the answers

What four key factors influence the separation efficiency of a centrifugal oil purifier or separator?

<p>The four main factors are: 1) Rotational speed - higher speeds increase centrifugal force; 2) Density difference between oil and contaminants; 3) Residence time in the separator bowl; 4) Design and geometry of the separator bowl.</p> Signup and view all the answers

Describe how oil loss can occur in a centrifugal oil separator, and methods to minimize this undesirable loss.

<p>Oil loss occurs when too much oil is carried over and discharged with the separated water and sludge. This can be minimized by: ensuring the purifier is not overfilled, maintaining optimum throughput, setting the correct interface level, and employing enhanced separator bowl designs with improved oil/water separation.</p> Signup and view all the answers

List and explain the key factors that determine the discharge cycle frequency of an engine lubricating oil purifier.

<p>The main factors are: 1) Sludge space volume - smaller volume requires more frequent discharges; 2) Contamination ingress rate - higher rates require more frequent cleaning; 3) Purifier throughput capacity - higher capacity allows longer run times between discharges.</p> Signup and view all the answers

Analyze the potential reasons that could cause fluctuations or variations in the oil level reading of a marine diesel engine's main lubricating oil sump.

<p>Possible causes include: oil consumption and burning, leaks, oil contamination dilution, thermal expansion effects, entrained air, oil transfer issues, faulty level sensors or indicators. Investigating the rate, pattern and source of level changes is required to identify the specific root cause.</p> Signup and view all the answers

Using a labeled sketch, describe how an air-operated radial tyre-type clutch functions to engage and disengage a marine diesel propulsion engine.

<p>The key would be to sketch and label the major components such as the clutch piston, tyre, pressure plate, driven shaft, air actuator lines, return springs, etc. And then describe the clutch engagement sequence using compressed air to push the piston and tyre into frictional contact with the rotating and stationary plates to transmit engine power.</p> Signup and view all the answers

Explain why it is critical to supply lubricating oil to the main reduction gears before they begin rotating, and what monitoring techniques can detect gear wear.

<p>Oil must be supplied first to ensure an oil film that prevents metal-to-metal contact and wear during initial gear rotation. Condition monitoring techniques include: monitoring oil debris levels/analysis, vibration measurements, temperature monitoring, and inspections using borescopes or other NDT methods to check for pitting, scoring or other damage.</p> Signup and view all the answers

Flashcards are hidden until you start studying

More Like This

Use Quizgecko on...
Browser
Open
Browser
Browser