Effect of Injection Pressure and Swirl Motion on Diesel Engine-out Emissions in Conventional and Advanced Combustion Regimes

Investigation of Cluster-Nozzle Concepts for Direct Injection Diesel Engines

“…Overswirl may cause the particulate emissions to increase due to confinement of hot products in the center of the cylinder as a centrifugal action of swirl. Though, Miles [20] did not find any such effects in his study. Other consequences of overswirl include a decrease in spray penetration [8, 11 and 14], overlap between adjacent sprays [21] and low mean gas temperatures because of an increased in-cylinder heat transfer.…”

“…The initial part of mixing controlled combustion is not affected much by swirl level, but the later part shows higher heat release rate for higher swirl [19]. In a study including both conventional and advanced combustion regimes such as LTC (Low Temperature Combustion), it was found that both NO x and soot are lower with higher swirl ratios under LTC [20]. There are many positive effects of swirl for better mixing, but excessive swirl tends to worsen the combustion.…”

“…The reduction in soot emissions at the higher injection pressures is mainly due to the improved homogeneity of the charge. Another factor that might have contributed to the drop in soot emission is the reduction in the fraction of the fuel injected in the flame [50][51][52][53][54].…”

“…With the advances in injection technology it is now possible to achieve higher injection pressures and deliver multiple injections with different injection rate-shapes and more accurate timings. Also, with the advances in the design of intake ports, it is possible to develop swirl motions of different ratios [20]. …”

Effects of Compression Ratio and Simulated EGR on Combustion Characteristics and Exhaust Emissions of a Diesel PCCI Engine

“…In-cylinder control parameters include injection pressure, number of injections, shape and timing, EGR, and swirl ratio [3,4]. The most practical means of implementing a HCCI combustion strategy in a modern direct-injection diesel engine is through partially premixed-charge compression ignition, where fuel and air are not fully homogenous, but the combustion event can be controlled more readily.…”