A study of swirl flow measurements in a cylinder under an intake flow similar to an engine operating condition using a rotating slit disk valve

A new swirl measurement system was developed by installing bevel gears and a slit rotary valve into an impulse- type swirl measurement system of the type traditionally used to measure the swirl ratio and flow coefficient of engine intake ports. When operating this new swirl measurement system, it was confirmed that the characteristics of the intake air flow rate to the cylinders were similar to those of a typical operating engine condition. When the valve lift was limited to the cam angle range of 160 to 200 (the valve lift is maximized at a cam angle of 180°), the flow coefficient Cf increased as the cam angle increased under a constant camshaft rotation speed. Moreover, as the rotation speed of the camshaft increased, the Cf value decreased slightly. The swirl ratio NR in the cam angle range of 160 to 200 showed a nearly constant value with an increase of the cam angle at a constant camshaft rotation speed. There were also no significant changes in Cf with an increase in the camshaft rotation speed. NR measurement results while changing the camshaft rotation speed cannot be obtained by the traditional impulse swirl measurement method. NR measurement results with the new swirl measurement system can be used as basic data when calculating spray dispersion characteristics considering the engine rotation speed.