Numerical Study on Swirl-Type High-Dilution Stratified EGR Combustion System

Xu, Min; Chen, Grant; Daniels, Chao F.; Dong, Mike

doi:10.4271/2000-01-1949

Cited by 6 publications

(1 citation statement)

References 5 publications

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“…Some researchers and engineers have attempted to stratify the EGR gas in the cylinders of internal combustion engines [6][7][8][9][10][11]. For example, Jackson et al [7] achieved lateral EGR stratification, by having the air/fuel mixture in one side and the EGR gas in the other side, by forming strong tumble flows from the two intake ports.…”

Section: Introductionmentioning

confidence: 99%

In-cylinder stratification of external exhaust gas recirculation for controlling diesel combustion

Fuyuto

Nagata

Hotta

et al. 2009

International Journal of Engine Research

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A technique for achieving the in-cylinder stratification of external exhaust gas recirculation (EGR) gas in direct-injection (DI) diesel engines has been developed to reduce toxic exhaust emissions. The external EGR gas is supplied from one of the two intake ports which can create a swirl flow in either the upper or lower portion of the cylinder during the intake stroke. In the final stage of the compression stroke, a squish flow conveys the vertically stratified EGR gas into the piston cavity, generating a radially stratified EGR gas in the piston cavity at the end of the compression stroke. This strategy for achieving EGR gas stratification in the piston cavity was developed by using an unsteady computational fluid dynamics (CFD) code. Prior to the exhaust emission tests, the accuracy of the simulation was evaluated by planer laser-induced fluorescence (LIF) imaging. The exhaust emission tests showed that there was less smoke emission under medium load conditions when the EGR gas was delivered to the inner part of the piston cavity. The mechanism of this smoke reduction was investigated using CFD simulation, which is based on a series of calculations related to the internal flow of the injector nozzle, the in-cylinder fuel spray, and mixture formation and combustion. It has been shown that, at the beginning of the combustion, the higher concentration of EGR gas in the inner part of the cavity lowers the combustion temperature and reduces the soot formation rate. Air, which exists in the outer part of the cavity at the start of fuel injection, enhances the oxidation of the soot cloud in the piston cavity periphery in the latter half of the combustion period.

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