Application of double Helmholtz resonators in an ICE intake manifold to increase the air mass flow rate

Resumo

Wave phenomena that occur in the intake manifold can either increase or decrease the volumetric
efficiency of internal combustion engines (ICEs). In this work, a numerical and experimental investigation is
carried out to evaluate the influence of the intake manifold components on the intake flow rate. In order to calculate
its natural frequency, analytical expressions were developed using the acoustic theory by means of the Transfer
Matrix Method (TMM). The numerical results were obtained using a one-dimensional computational code based
on the Characteristics Method. The experimental tests in unsteady condition were conducted using a flow test
bench equipped with a four-cylinder engine in two conditions: with only two intake valves operating and with all
four operating. The numerical and experimental results were compared and a good agreement between the data
was observed, thus confirming the numerical code's capacity to reproduce this type of phenomenon. The insertion

of the double-chamber Helmholtz resonator increased the air mass flow rate more significantly in the four-
cylinders configurations, compared to the two-cylinders manifolds. The two-cylinders configurations had an

increase in flow rate up to 38.6% in the speed of 1200 rpm, while the higher increase in the four-cylinders with
the insertion of the resonator was only 3.4% in the speed of 1600 rpm.