Which one of the following methods for determination of engine fr

SOLUTION

Concept:

Willan’s line method:

• This method is also known as fuel rate extrapolation method.
• A graph connecting fuel consumption on Y-axis and brake power on X-axis at constant speed is drawn and it is extrapolated on the negative axis of brake power.
• The intercept of the negative axis is taken as the friction power of the engine at that speed. 

• The gross fuel consumption is plotted against brake power and it is extended backward to zero fuel consumption.

Morse test:

• The Morse test is used for measuring the indicated power of the multi-cylinder engines.
• This test measures the indicated power by cutting out the spark plug of the cylinder by keeping the speed of the engine constant.
• To understand this test better, suppose break power for a cylinder with the spark plug on is B.P1 and with spark plug cut is B.P’1 then the indicated power will be B.P1-B.P1’.
• It is assumed that pumping and friction losses are the same when the spark plug is cut-off or in operation.
• Friction power = Indicated power of cylinder – Break the power of the cylinder.

Motoring test:

• In this test, a swinging field type electric dynamometer is used to absorb the power developed during the steady-state operation.
• The ignition is cut-off and by suitable electric switching devices, the dynamometer is converted to run as a motor so as to crank the engine at the same speed at which it was previously operated.
• The power supply is then measured which gives the friction power of the engine at that speed.