Numerical evaluation of the quality of filling the engine cylinder with a fresh charge

Abstract

The article presents the results of mathematical and numerical modeling of engine filling taking into account gas-dynamic factors. When evaluating engine filling, it is necessary to evaluate the boundary conditions at the time of opening the intake valve and the effective passage area in the channel neck, which, together with the valve lift, is the determining size in the gas distribution mechanism. The numerical values are a function of the ratio of the current valve displacement to the neck diameter. The filling losses associated with the heating of the air charge from the walls and the partial conversion of the kinetic charge into heat are estimated by the losses ΔT. This value of the temperature increase when filling the internal combustion engine is made for the mode of the spring speed characteristic. Changes in the charge pressure at the end of the inlet are estimated by the loss of part of the kinetic energy with the transition to potential energy due to charge deceleration. The paper evaluates the gas injection from the cylinder into the intake system at partial loads due to an increase in the valve overlap zone. Which ultimately reduces the filling factor. Data are given on the increase in the filling coefficient due to the pre-charging process due to the expansion of the delay phase of the intake valve closing.