Exam Question
Illustrate with example how the indicator power can be calculated by use of indicator diagram. (8)
Write short notes on (8)
(a) Brake horse power
(b) Mechanical efficiency
(c) Thermal efficiency.
Class 4 (4th Engineer)
MEKM
📅 Nov 2022
Reference Answer
### Calculation of Indicated Power from an Indicator Diagram
Indicated Power (IP) is the theoretical power developed within an engine's cylinders without accounting for frictional losses. It is calculated using the Mean Indicated Pressure (MIP) derived from an indicator diagram. The process is as follows:
**1. Obtaining the Indicator Diagram:**
An indicator diagram is a graphical representation of the pressure versus volume (or piston stroke) inside a cylinder throughout a complete engine cycle. It is obtained using a mechanical indicator (e.g., Dobbie McInnes type) or, more commonly in modern practice, an electronic pressure transducer. This diagram provides a visual and quantitative analysis of the combustion process and engine health.
Indicated Power (IP) is the theoretical power developed within an engine's cylinders without accounting for frictional losses. It is calculated using the Mean Indicated Pressure (MIP) derived from an indicator diagram. The process is as follows:
**1. Obtaining the Indicator Diagram:**
An indicator diagram is a graphical representation of the pressure versus volume (or piston stroke) inside a cylinder throughout a complete engine cycle. It is obtained using a mechanical indicator (e.g., Dobbie McInnes type) or, more commonly in modern practice, an electronic pressure transducer. This diagram provides a visual and quantitative analysis of the combustion process and engine health.
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