Week 2 : Basic Calibration of Single cylinder SI-Engine

AIM :

• To run SI engine setup at 1800 rpm and list down parameters such as air flow rate, BSFC, BMEP, In cylinder pressure.
• To run the same setup at 3600 rpm and to increase the power output by 10%

PROCEDURE:

SPARK IGNITION 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 engine, 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.

Spark-ignition engines are commonly referred to as "gasoline engines" in North America, and "petrol engines" in Britain and the rest of the world. Spark-ignition engines can (and increasingly are) run on fuels other than petrol/gasoline, such as autogas (LPG), methanol, ethonal, bioethonal, compressed natural gas (CNG), hydrogen.

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, 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

Referred page: https://en.wikipedia.org/wiki/Spark-ignition_engine

SETUP:

Engine at 1800 rpm

The model is opened File -> tutorials -> modelling applications -> engine_performance -> 1cylSi-final.gtm

Air flow rate: 24.6460kg/h

Break mean effective pressure(BMEP): 9.4767 bar

Brake specific fuel consumption(BSFC): 239.17g/kW-h

In-cylinder pressure: 48.89 bar

Engine at 3600 rpm:

Output in the GT-Post:

Air flow rate: 58.5819kg/h

Break mean effective pressure(BMEP): 11.13 bar

Brake specific fuel consumption(BSFC): 241.77g/kW-h

In-cylinder pressure: 58.90 bar

INCREASING THE POWER OUTPUT BY 10%:

From the above equation, the Power output is dependent on engine geometry which in turn is dependent on engine geometric parameters such as Bore, stroke and connecting rod length. Also it is dependent on the mean effective pressure. So we can increase the output power by changing these parameters,

• By increasing the bore
• By increasing the stroke
• By increasing connecting rod
• By increasing inlet pressure

• RPM is 3600 RPM for all case.
• Bore is changed from 86 to 90 mm.
• Stroke is changed from 86.07 to 96 mm
• Connecting rod length is changed from 175 to 180mm.
• Intake pressure is changed from 1 to 1.1 bar.

Output in the GT-Post:

From the above results , we can see that

• In case 1, The brake power obtained is 16.69kW at 3600rpm.
• In case 2, The brake power obtained is 19.86kW at 3600rpm.
• In case 3, The brake power obtained is 21.03kW at 3600rpm.
• In case 4, The brake power obtained is 20.36kW at 3600rpm.

CONCLUSION:

• We have executed SI engine setup at 1800 rpm and also listed down parameters as

  Air flow rate: 58.5819kg/h

  Break mean effective pressure(BMEP): 11.13 bar

  Brake specific fuel consumption(BSFC): 241.77g/kW-h

  In-cylinder pressure: 58.90 bar

• We have also executed the same setup at 3600 rpm and increased the power output by 10% by varying engine geometric parameters such as Bore, stroke and connecting rod length