Abstract:In order to solve the problems such as poor mixture uniformity after DK4 diesel engine was changed to use biodiesel, In this paper, Through steady flow test and numerical simulation, combined with uniform experimental design method, under the steady-state working conditions, guide vanes with different structural parameters were installed at the front of the intake port, and their effects on the engine flow coefficient and swirl ratio were studied, and the best model was selected, and the swirl ratio, cumulative intake quality and emission characteristics of the original intake port and the optimized intake port under transient working conditions were compared. The results reveal that under the steady-state working conditions, the average swirl ratio of the optimized intake port was increased by 24.7% compared with the original intake port, and the flow coefficient in the cylinder was increased by 1.17%. Under the transient conditions, the vortex ratio of the optimized intake port was increased by 9.46% and the cumulative intake quality was increased by 7.02%. Cylinder temperature and pressure were increased, with NOx emissions was increased by an average of 4.4% and soot emissions was reduced by 9.9%. It can be seen that the optimized intake tract effectively improves the formation of mixture and reduces the soot emission of biodiesel engines.