Understanding Engine Power Terminology

When discussing the performance of an internal combustion engine, different terms are used to describe the power at various stages. The question asks about the total power developed by the combustion of fuel inside the combustion chamber.

What is Indicated Power?

The power generated within the engine cylinder by the combustion of fuel is known as indicated power. It represents the total thermal power converted into mechanical work on the piston. This power is 'indicated' by the pressure-volume diagram of the cylinder, which shows the work done during one cycle.

• It is the power developed *inside* the cylinder.
• It is calculated from the pressure and volume changes during the engine cycle.
• It does not account for the power lost due to friction within the engine or power consumed by accessories like pumps.

Comparing Indicated Power and Brake Power

Brake power is the usable power available at the engine crankshaft. It is less than the indicated power because some power is lost due to mechanical friction between moving parts (like pistons, crankshaft, bearings) and pumping losses (work done to move the intake air and exhaust gases).

The relationship is:

Brake Power = Indicated Power - Frictional Power

Frictional power includes all mechanical losses and the power required to drive engine accessories.

Analyzing the Options

• brake power: This is the power available at the crankshaft, after accounting for internal losses. It is not the total power developed by combustion inside the chamber.
• alternate power: This is not a standard term used in engine performance analysis in this context.
• specific power: This term usually refers to power per unit mass or power per unit volume. It describes the power output relative to the engine's size or weight, not the total power developed by combustion.
• indicated power: This is the power generated by the combustion process inside the cylinder before any losses. This matches the description in the question.

Therefore, the total power developed by the combustion of fuel in the combustion chamber is called indicated power.