Abstract
Abstract
Traditional swirl-measurement equipment that adopts a paddle wheel is manually operated to measure the swirl intensity generated from a helical port in an engine cylinder head. The conventional equipment was modified to operate automatically using a step motor to adjust the valve lift and an additional step motor to control the surge tank pressure. The automatic swirl-measuring equipment was operated in either steady or quasi-steady flow conditions. The surge tank pressure was controlled by automatically opening or closing a bypass valve using the step motor when the swirl flow was measured in a steady flow whereas, when the swirl flow was in a quasi-steady flow, the surge tank pressure varied naturally adapting to the valve lift in the conditions of closing the bypass valve. Several sensor signals, such as the paddle speed, differential pressures at the flow nozzle and surge tank, and intake air temperature imperative to the swirl ratio calculation, were measured and recorded automatically using a personal computer and data acquisition systems. The value of the mean swirl ratio from the cylinder head port showed nearly identical values of 2.0 in both the steady and the quasi-steady flow conditions. Compared with the conventional swirl system, the time required for 1 cycle of the swirl ratio measurement for a port in the cylinder head was drastically reduced by adopting the automatic swirl-measuring system. Moreover, in the automatic swirl-measuring system, the measuring time in the quasi-steady flow condition was less than that in the steady condition, because the target value of the surge tank pressure need not be controlled.
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