Abstract
The connection cones between an exhaust pipe and an exhaust after-treatment system (EATS) will affect the flow into the first monolith. In this study, a new streamlined connection cone using non-uniform rational B-splines (NURBS) is applied to optimize the flow uniformity inside two different monoliths (a gasoline particulate filter and an un-coated monolith). NURBS and conventional cones were created using 3D printing with two different cone angles. The velocities after the monolith were collected to present the uniformity of the flows under different cones and different velocities. The test results indicate that NURBS cones exhibit better performance. Furthermore, all of the pressure drops of the bench test were measured and compared with those of the conventional cones, demonstrating that the NURBS cones can reduce the pressure drop by up to 12%. The computer fluid dynamics simulations depict detailed changes in the flow before and after entering the monolith. The results show that the NURBS cone avoids the generation of a recirculating zone associated with conventional cones and creates a more uniform flow, which causes a lower pressure drop. Meanwhile, the package structure of the NURBS cone can reduce the space requirements. Finally, the implications of the flow distributions are discussed.
Highlights
Combustion engines are widely used in vehicles as a result of their high thermal efficiency, high reliability, and good fuel economy
To eliminate errors caused by the structural differences between a gasoline particulate filter (GPF) and a diesel oxidation catalyst (DOC), the ratio of the pressure drop per volumetric flow is used in Table 4, where the pressure drop is the absolute pressure from the back-pressure sensor, and the space velocity is the volumetric flow divided by the monolith volume
The reduction ratio is the pressure drop per volumetric flow of the non-uniform rational B-splines (NURBS) cone divided by the corresponding value of the conventional cone
Summary
Combustion engines are widely used in vehicles as a result of their high thermal efficiency, high reliability, and good fuel economy. The stringent emissions regulations currently in effect cannot be met using only technologies that improve the in-cylinder combustion process in engines [3]. To satisfy these strict regulations, the automotive industry has devoted increasing attention to reducing emissions. The after-treatment system, for the diesel engines It can contain a lean NOx trap (LNT), a diesel particulate filter (DPF), a diesel oxidation catalyst (DOC), and a selective catalytic reduction (SCR) system in addition to other components, is capable of reducing emissions; it causes a pressure drop that affects the fuel consumption and dynamic performance of the engine [4]
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