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Experimental investigation of piston bowl geometry effects on performance and emissions characteristics of diesel engine at variable injection pressure and timings

ABSTRACT For diesel engine piston shape, variable injection timings and injection pressures are main input parameters that give better diffusion-atomisation of fuels and high swirling induction that finally affects the engine performance and emissions. In this study, performance enhancement and exhaust emissions reduction was carried out with the help of design modification in piston bowl in a single-cylinder direct injection diesel engine. With the aim of increasing the combustion process at final stages of combustion period, piston bowl was modified to piston B (toroidal combustion chamber with tangential cut on circumference of the piston crown) and piston C (hemisphere combustion chamber with circular arc on circumference of the piston crown) from the standard piston A (hemispherical type combustion chamber). All the relevant factors such as engine speed, compression ratio and maximum diameter of bowl were kept constant. On comparing the results with baseline condition and for different bowl geometries, it was concluded that modified pistons (both B and C) are better as far as performance, combustion and emissions characteristics are concerned, with the exception of NOx emissions. Significant improvement in depletion harmful particulates, carbon monoxide and unburned hydrocarbons is observed in different quantities.