Simulation and Experimental Study of Intake Air Flow Pulsation and Resolution for a 2-Cylinder Uneven Firing (0°-540°) Naturally Aspirated and Turbocharged CPCB II Diesel Engine

Development of a 2-cylinder uneven firing engine from a 4-cylinder parent engine is associated with variation in air mass flow due to the combined effects of both engine downsizing as well the large firing gap between the cylinders especially 540°. This affects the turbocharger performance & durability and engine emissions due to fluctuations in the air mass flow. This paper investigates the effects of engine geometries such as stroke, valve overlap, cam profiles, intake and exhaust manifold configuration and surge tank effect through one-dimensional thermodynamic simulations and experimental tests, thus reducing the pulsation effect by 85%. Two engine configurations - naturally aspirated engine for 15 kVA power rating and turbocharged version for 30 kVA power rating were considered for the development study. The former was evaluated with different cam profiles and stroke which effected in reducing the air mass flow pulse variation by 80% and the latter by combination of different turbocharger trims and dampening tank resulting in 85% reduction.

Experimental tests were carried out for all the engine configurations on an instrumented engine test bench and the results observed were with 98% adherence to the simulation results and could meet the Indian Genset emission norms CPCB-II (Equivalent to EU Stage IIIA norms) comfortably.