ATTEMPT TO IMPROVE THE CHARACTERISTICS OF VOLUMETRIC EFFICIENCY BY A RESONATOR IN FOUR CYCLE DIESEL ENGINES.

Through numerical calculation based on the simulation program, the effect of the resonator, which is installed to intake manifolds, has been investigated for the purpose of improving the volumetric efficiency of four cycle diesel engines. The results show that in single cylinder engines the resonator can increase the volumetric at the low engine speed without decreasing volumetric efficiency at the high speed ranges. The diameter of the resonator pipe must be chosen so as to generate an adequate flow loss in the resonator. The optimum sizes of the resonator can not be estimated by only the natural acoustic frequency. However, the ratio of the natural frequency of the resonator to that of the intake system for the open period of intake valve may be used to estimate roughly the resonator effect. The resonator effect is considered to be slight in multi-cylinder engines.