01-02-2013, 04:26 PM
To Study and Determine the effect of A/F Ratio on the performance of the Two- Stroke, Single-Cylinder Petrol Engine.
To Study and Determine.doc (Size: 94.5 KB / Downloads: 21)
APPARATUS USED:
Two-Stroke, Single-Cylinder Petrol Engine Test Rig, Stop Watch, and Digital Tachometer.
THEORY:-
Air fuel ratio has a major effect on the performance of the I. C. Engine. The Air fuel ratio of a S. I. Engine lies in the range of 10: 1, to 22: 1 depends upon the power requirements and the economic running of the engine. Richer mixtures are required for idle and full throttle running of the engine. Whereas for the mid-range, weaker mixtures are required. The mixture corresponding to the minimum fuel consumption is known as the Best Economy Mixture. It is nearly 15:1. Accurate measurement of air flow into the engine is difficult to achieve in practice, due not only to the nature of the air itself, but also the conditions under which the measurement has to be made. The common method of measuring the air flow rate is the tank and orifice method. During suction stroke the pressure inside the tank is less than the atmospheric pressure. The air enters the tank through the orifice plate, and by applying the Bernoulli’s equation the air flow rate can be measured. The fuel consumption can be measured by noting down the fuel consumed during specified time. Thus the air fuel ratio can be set to desired value. The accuracy of the air flow measurement depends on the steady state conditions of air flow through the orifice and the damping of the pulsating effect.
PROCEDURE:-
1. Before starting the engine check the fuel supply, and lubrication oil.
2. Set the dynamometer to zero load.
3. Run the engine till it attains the working temperature and steady state condition.
4. Adjust the dynamometer load to obtain the desired engine speed.
5. Note down the dynamometer load reading and fuel consumption rate.
6. Repeat the experiments for various air fuel ratios and different loads, and same speed.
7. Disengage the dynamometer, and stop the engine.
8. Do the necessary calculation, and plot the graphs.