Since the automobile turbochargers are installed in an engine compartment with limited space, the ducts upstream of the turbocharger compressor may be curved in a complex manner. In the present paper, the effect of a ...Since the automobile turbochargers are installed in an engine compartment with limited space, the ducts upstream of the turbocharger compressor may be curved in a complex manner. In the present paper, the effect of a curved duct upstream on performance of small centrifugal compressors for automobile turbochargers is discussed. The computational fluid dynamics (CFD) analysis of a turbocharger compressor validated for the compressor model with the straight pipe applied to the compressor with the curved pipe are executed, and the deterioration of the performance for the curved pipe is confirmed. It is also found that the deterioration of compressor performance is caused by the interaction of the secondary flow and the impeller.展开更多
The large eddy simulation (LES) using the steady laminar flamelet model is applied to a simple turbulent jet flame with 33.2% H2,22.1% CH4 and 44.7% N2 at the Reynolds number of 15,200 in order to validate the numeric...The large eddy simulation (LES) using the steady laminar flamelet model is applied to a simple turbulent jet flame with 33.2% H2,22.1% CH4 and 44.7% N2 at the Reynolds number of 15,200 in order to validate the numerical methods and to investigate the flame structure.For the validation,the detailed experimental data of DLR-A flame is used.The numerical results are in reasonable agreement with experimental results except mass fractions of minor species.In the flow field,the break-down of the potential core,the vortex structure and the mixing intensity are well captured.In the combustion field,mass fractions of major species (H2O,CO2,CO) are well predicted quantitatively.Minor species are well predicted qualitatively.In the present study,the simulations conducted on the Cartesian and cylindrical grids with approximately 6.6× 10 5 nodes are compared.展开更多
文摘Since the automobile turbochargers are installed in an engine compartment with limited space, the ducts upstream of the turbocharger compressor may be curved in a complex manner. In the present paper, the effect of a curved duct upstream on performance of small centrifugal compressors for automobile turbochargers is discussed. The computational fluid dynamics (CFD) analysis of a turbocharger compressor validated for the compressor model with the straight pipe applied to the compressor with the curved pipe are executed, and the deterioration of the performance for the curved pipe is confirmed. It is also found that the deterioration of compressor performance is caused by the interaction of the secondary flow and the impeller.
文摘The large eddy simulation (LES) using the steady laminar flamelet model is applied to a simple turbulent jet flame with 33.2% H2,22.1% CH4 and 44.7% N2 at the Reynolds number of 15,200 in order to validate the numerical methods and to investigate the flame structure.For the validation,the detailed experimental data of DLR-A flame is used.The numerical results are in reasonable agreement with experimental results except mass fractions of minor species.In the flow field,the break-down of the potential core,the vortex structure and the mixing intensity are well captured.In the combustion field,mass fractions of major species (H2O,CO2,CO) are well predicted quantitatively.Minor species are well predicted qualitatively.In the present study,the simulations conducted on the Cartesian and cylindrical grids with approximately 6.6× 10 5 nodes are compared.
