Reduction of Diesel Engine Combustion Noise Through Various Injection Strategies 2019-26-0211
The contribution of engine borne noise is the major source of vehicle noise in diesel powered vehicles. The engine noise can be minimized by modification of engine components design and also with different acoustic abatement techniques. The research activities were carried out on 155 bhp, 4 cylinder CRDe engine. All the emission and performance parameters along with combustion noise was captured continuously for all the part load points from 1000rpm to 2750 rpm with respect to the different road conditions and driving cycle. This paper targets on reducing the combustion noise at the noise prone zones only on the basis of the injection strategies ensuring no ill effect on the emissions and fuel economy. The first step was the reduction of rail pressure which helped noise levels to be reduced by almost 6 db at noise zones. Main injection timing retardation was tried at all possible zones which influenced in considerable noise reduction at various zones. The BSFC did not deteriorate and were found better at few zones. The NOx emissions improved and PM emissions deteriorated after the above said changes were done. Further reduction of noise levels were tried employing the double pilot injection strategy at lower torque zones from 1000 to 2250 rpm. Pilot separation approach was then followed increased in order improve PM and maintain better levels of noise. 50% Mass fraction burnt and maximum rate of pressure rise were monitored in this trials where maximum limit of mass fraction burnt was limited to 15 degrees and rate of pressure rise till 5 bar/ deg. The overall tasks enabled on reducing noise till 12 db from the reference condition.