Week 2 : Basic Calibration of Single cylinder SI-Engine

AIM: To

1. Run the case at 1800 rpm and list down important parameters

• air flow rate
• BMEP
• BSFC
• In-cylinder pressure

2. Increase the power output at 3600 rpm by 10%.

Introduction:

SI Engine: A spark-ignition engine (SI engine) is an internal combustion engine, generally a petrol engine, where the combustion process of the air-fuel mixture is ignited by a spark from a spark plug. This is in contrast to compression-ignition engines, typically diesel engines, where the heat generated from compression together with the injection of fuel is enough to initiate the combustion process, without needing any external spark.

Working cycle:

The working cycle of both spark-ignition and compression-ignition engines may be either two-stroke or four-stroke.

A four-stroke spark-ignition engine is an Otto cycle engine. It consists of following four strokes: suction or intake stroke, compression stroke, expansion or power stroke, exhaust stroke. Each stroke consists of 180 degree rotation of crankshaft rotation and hence a four-stroke cycle is completed through 720 degree of crank rotation. Thus for one complete cycle there is only one power stroke while the crankshaft turns by two OR MORE revolutions.

The following is the case of SI Engine:

case setup:

The given Engine speed is 1800RPM in this case.

Results:

The results are generated by GT Post.

• air flow rate = 24.64 kg/h
• BMEP = 9.476 bar
• BSFC = 239.17 g/kW-h
• In-cylinder pressure = 48.89 bar

Case-2:

To increase power output:

Different speeds are used in this case to observe power output.

Results:

Engine Performance:

The changes in Brake power is observed. Increased from 7.10kW to 1669kW

By changing bore & stroke values:

For bore = 90mm, stroke = 90mm, Compression ratio = 14

For bore = 88mm, stroke = 88mm, Compression ratio = 14

Increase in bore and stroke values results the increase in power.