Design of piston bowl geometry for better combustion in direct-injection compression ignition engine

Abstract

The current computational fluid dynamics (CFD) study presents the effect of piston bowl geometry on the performance and emissions of a direct-injection diesel engine. Different piston bowl profiles, namely, hemispherical combustion chamber (HCC), shallow depth combustion chamber (SCC) and toroidal combustion chamber (TCC), have been created with a baseline compression ratio of 17.5. CONVERGE TM CFD code coupled with the SAGE combustion model was used for numerical analysis. It is observed that the TCC piston bowl geometry renders better air-fuel mixture inside the cylinder, which leads to a homogeneous charge. Further, numerical experiments are carried out to analyze suitable TCC piston bowl geometry by varying the depth of the bowl. Out of all the cases, the case with 1.26 mm decrease in depth of bowl from the baseline (TCC) design gives better emissions and performance characteristics.

Redesign of a Piston for a Diesel Combustion Engine to Use Biodiesel Blends

“…Reduce emissions of soot, hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NOx), and specific fuel consumption [24] Throat diameter X Reduce specific fuel consumption and increase crushing [23] Bowl diameter/depth ratio X Increase crushing, improve air/fuel mixture, and generate higher efficiency [44] Lip radius X Increase performance and reduce the gen- A compressive pressure of 3.1 MPa [42] on the piston's top surface was used to determine the stresses inside the piston. In this simulation, the pin's area was restricted to 6 degrees of freedom (displacement in x, y, and z directions; rotation in xy, xz, and yz planes).…”

“…Reduce emissions of soot, hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NOx), and specific fuel consumption [24] Throat diameter X Reduce specific fuel consumption and increase crushing [23] Bowl diameter/depth ratio X Increase crushing, improve air/fuel mixture, and generate higher efficiency [44] Lip radius X Increase performance and reduce the generation of polluting emissions [22] Outside diameter X Decrease throat diameter ratio to increase swirl and increase turbulence [45] Protrusion height X Reduce emissions of nitrogen oxides (NOx) [46] Bowl diameter X Reduce the generation of smoke and generate greater crushing [47] Outside diameter X Decrease throat diameter ratio to increase swirl and increase turbulence [45] Protrusion height X Reduce emissions of nitrogen oxides (NOx) [46] Bowl diameter X Reduce the generation of smoke and generate greater crushing [47] In this simulation, the proper diesel temperature h = 450 W m 2 °C [41] with an initial temperature of 22 °C. The simulation was carried out for 1 s.…”

“…The toroidal-shaped piston stands out from the other designs, showing higher performance, better combustion, and decreased pollutant emissions [ 22 ]. This type of piston (toroidal) has been characterized in several experimental tests by increased thermal efficiency, reduction in certain pollutant gases (hydrocarbons (HC) and carbon dioxide (CO 2 ), reduction in specific fuel consumption [ 23 ], an appropriate air/fuel mixture [ 22 ], and reduction in soot [ 24 ]. The piston design is intended to properly mix the air with the fuel at the injection time to cause complete combustion inside the combustion chamber [ 11 ].…”

Impact of Split and Re-Entrant Type Piston Bowl Geometry Fuelled with Pre Heated Diesel and Biodiesel on a Compression Ignition Engine Characteristics

“…Swirl movement of air is the movement around the circumference of the piston bowl geometry; as it moves, the increase in velocity leads to better air-fuel mixing to result in incomplete combustion and reduced emissions. The standard hemispherical PBG is modi ed into the split (toroidal) and re-entrant type [11][12][13][14]. Jaichandar et al [15].…”

“…Ganji et al, [24] studied the different PBG's CFD models for a CI engine. They created the hemispherical, shallow depth and toroidal shape piston bowl.…”