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The objective of the present study is to investigate the cyclic variation of lean combustion in an electronic injected two stroke SI engine. The problem of cyclic variation was investigated by many researchers. It has been investigated by measuring 1000 continuous cylinder pressure traces. The experimental work was carried out in an electronically injected and catalytically coated single cylinder two-stroke SI engine loaded by an eddy current dynamometer. The air-fuel ratio was varied from rich to lean by a Manifold Pressure (MAP) sensor at constant throttle. The cyclic variation in combustion was identified by the variation in peak pressure (Pmax) and indicated mean effective pressure (IMEP). The results show that cyclic variation increases when the air-fuel ratio becomes lean. Moreover, the cyclic variation decreases for a coated engine than the base injected engine for the lean operating condition of the engine.

At present, the modern vehicles are embedded with Electronic Fuel Injection (EFI) system for better fuel economy and reduced emission. But the automation software used in this system is not user friendly because of preset program based μP control. To overcome these difficulties, in the present paper, it has been proposed for an interactive EFI system for Spark Ignition (SI) engines. It has been replaced μP based software and hardware structures with a modern client/server solution. On the client side, the virtual instrumentation software program used for data acquisition. The fuel map and time maps are generated for the various operating conditions of the engine. For the mapping, the visualization tool is used in 3-d plot. From the mapping, the fuel injection time and fuel delivery quantity is estimated for the required running condition of the engine. The system that has been designed accesses the data using interfaces.

The problem of cyclic variation in combustion has been investigated by measuring 2000 continuous in-cylinder pressure traces. The experimental work was carried out in a single cylinder two-stroke SI engine loaded by an eddy current dynamometer. The air-fuel ratio was varied form rich to lean by a modified carburetor. The pressure traces were recorded by a piezo-electric pressure pickup and PC based data acquisition system. Cyclic variation in combustion was identified by the variation in peak pressure (Pmax) and indicated mean effective pressure (IMEP). The results show that cyclic variation increases when the air-fuel mixture becomes lean. It also indicates the existence of combustion phasing and different modes of combustion. The combustion variation and its effect on the performance of the engine is more severe in two-stroke engine as compared to a four-stroke engine.

This paper presents the results of experimental work conducted on a catalytically activated two stroke spark ignited engine to investigate the cyclic variation of combustion parameters. A comparitive study was carried out with the base engine for finding out the effect of catalytic activation. The catalyst selected for this purpose is copper chromate which is found to be the most effective and optimal catalyst in the science of physical chemistry. The coating is carried out on the inside surface of combustion chamber walls and piston crown by Thermal evaporation technique. The in-cylinder pressures were recorded for 1000 continuous cycles using a piezo electric pressure pickup and PC based data acquisition system. The variations in peak pressure are compared with base engine. The results show that the catalyst coating activates the preflame reaction and shortens the combustion duration.

A heat release analysis model was developed for a two stroke spark ignition engine. The model was used to calculate the instantaneous heat release rates, mass fraction burned and temperature of the burnt and unburned mixture of the base engine and catalytic coated engine. The combustion chamber of the catalytic engine was coated with catalyst material like chromium by plasma spraying method. The experiments were conducted with various air-fuel ratios and heat release analysis was carried out for both base and catalytic coated engine. Engine cylinder pressure traces of 2000 continuous cycles were recorded using pc based data acquisition system. The average of these traces were calculated and used as input to the heat release model. The heat release rate from the single zone model was used to calculate combustion duration, start and end of combustion and burnt and unburned temperature from the two zone combustion model for the base and catalytic coated engine.

This paper presents the results of experimental work conducted on a catalytically activated two stroke spark ignited engine, to investigate the cyclic variation of combustion parameters. A comparative study was carried out with the base engine for finding out the effect of catalytic activation. The catalyst selected was copper and coated on the inside surface of combustion chamber walls and piston crown by plasma spraying technique. Cylinder pressures were recorded for 2000 continuous cycles using a piezoelectric pressure pickup and PC based data acquisition system. The covariance (COV) were calculated for the 2000 cycles and compared with base engine. The results show that the catalyst coating accelerates the pre-flame reaction and shortens the combustion duration. The cyclic variation of combustion parameters were less than the base engine and there is a group of cycles which deviate from the normal cycles.