機関シリンダ内流れに及ぼすピストン頂面形状の影響 : 高次精度スキームによる数値予測

概要

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The effects of piston head shape on gas flows in the cylinders of four-valve gasoline engines have been numerically analyzed using the authors' GTT method with higher-order schemes for the convection terms of Navier-Stokes equations without any turbulence models. It has been found that among third-order schemes the Chakravarthy-Osher third-order TVD scheme is stabler than the UTOPIA and Kawamura-Kuwahara schemes. Therefore, the TVD scheme allows a larger time increment and enables us to conduct a practical calculation on an engineering workstation. The flow anaysis using the TVD scheme has revealed the following : The convexity or concavity of the piston head greatly affects the forming and collapsing processes of tumbling vortices in the cylinder. Both the decay of the spactially averaged kinetic energy of gas in the cylinder between intake BDC and compression TDC and the averaged kinetic energy of gas around an ignition plug near ignition timing may be used as measures for correlating the gas flow with the combustion phenomenon.
社団法人日本機械学会の論文
1995-06-25