Optimization of Inlet Port Performance on Emission Compliance of Naturally Aspirated DI Diesel Engine

With the upcoming stringent norms for diesel engines and continual pursuit for more and more fuel-efficient engines, it is necessary to enhance air-fuel mixing for proper combustion. The design of inlet port plays an important role in the engine performance, because the air-fuel mixing depends upon the air turbulence. Research showed that helical type inlet-port will be ideal for the engine with nominal injection pressure value less than 800-bar and thermodynamic simulation results highlighted the need of an optimum swirl number for the specimen engine. A parametric study on inlet port design has been done to achieve the optimum flow capacity. The effects of different geometrical parameters of helical port were studied using classical technique and the model is validated using Computational Fluid Dynamics (CFD) Technique. 3D-CAD/CAM techniques helped in reducing the development time of proto flow box, which is necessary to verify the port performance on a steady flow rig, before developing cylinder head casting. Similarly, Finite Element Analysis (FEA) is used to determine the valve head deflection and contact stress between valve and seat; thus predicting the valve seat wear.

The designed inlet port was validated on naturally aspirated engine and achieved a minimum specific fuel consumption of 166 g/hp.h at rated point, which is comparable with the state of art engines in this category. The observed reduced mean swirl number and flow capacity values satisfy the flow quality requirements. Thus, 3D-CAD/CAM Technique, CFD approach and FEA are effectively used to design inlet port and achieve better fuel efficiency with lower emissions at lower developmental cost and time.