Exam Question
(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 assessed other than by taking indicator cards.
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Class 2 (2nd Engineer)
MEKM
📅 Mar 2018
Reference Answer
(a) The power card, also known as the power indicator diagram, is obtained from the 2-stroke main engine to showcase vital points of the diagram. This crucial information is acquired by taking the indicator diagram with the indicator drum rotating in phase with the piston movement. The area within this diagram represents the work done during one complete cycle, providing insights into the engine's performance. Mean Indicated Pressure (MIP) is calculated from this diagram to determine the power produced in the cylinder. The power card is essential for evaluating the efficiency of combustion in the cylinder, assessing the condition of the running gear, and detecting irregularities in fuel pumping and injection.
From the above sketch,
1-2 piston is moving upwards, scavenging the cylinder
2-3 Scavenging ports are shut, exhaust closing
From the above sketch,
1-2 piston is moving upwards, scavenging the cylinder
2-3 Scavenging ports are shut, exhaust closing
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