What assumption is made about frictional power in the Morse test ?

Explanation:

Morse Test:

• The Morse test is a method used to determine the indicated power (IP) of a multi-cylinder internal combustion engine and to estimate the frictional power (FP) of the engine. It involves running the engine under standard conditions and then successively cutting off the operation of each cylinder to observe the reduction in brake power (BP). By analyzing the difference in brake power, the indicated power of each cylinder can be calculated, and subsequently, the frictional power of the engine is estimated.

The frictional power remains constant irrespective of whether a cylinder is working or not.

• This assumption allows for a simplified calculation and analysis of the power distribution within the engine. It is based on the premise that the mechanical losses due to friction, which include losses in bearings, pistons, and other moving parts, are generally unaffected by the combustion process in individual cylinders.

Working Principle of the Morse Test:

1. The engine is initially run at a constant speed and load, and the total brake power (BP) of the engine is measured.
2. One cylinder is then "cut off" by disabling its fuel supply or ignition system. This causes the cylinder to stop contributing to the engine's power output, although it still experiences frictional losses.
3. The brake power (BP) of the engine is measured again with the cylinder cut off.
4. The reduction in brake power (∆BP) is attributed to the power contribution of the disabled cylinder, which is its indicated power (IP).
5. The process is repeated for all cylinders, and the indicated power of each cylinder is determined.
6. The total indicated power (IP) of the engine is then calculated as the sum of the indicated powers of all cylinders.
7. The frictional power (FP) is estimated as the difference between the total indicated power (IP) and the total brake power (BP).