Effect of ambient pressure on fluorescence intensity of inexpensive inorganic fluorescent tracer for particle image velocimetry of gaseous flows near solid objects

Abstract

Flow dynamics near the spark plug gap have become more important to promote more stable lean/dilute combustion in internal combustion engines. One experimental technique for the measurement of instantaneous gaseous flow in an engine cylinder is particle image velocimetry (PIV). However, PIV measurement of the flow near solid objects is difficult because of the flare due to strong scattered light from the solid objects. Therefore, methods that use fluorescent particles (f-particles) have been proposed to reduce this undesirable effect. The mass production of inexpensive inorganic-based f-particles was previously proposed by one of the authors of this paper, assuming flow measurement in a firing engine. Furthermore, flow measurement near the spark plug gap was attempted using PIV with these f-particles, whereby the unsteady flow motion near the spark plug was successfully detected. However, the measurements were conducted under atmospheric conditions at room temperature. Therefore, as a next step, investigation of the effect of ambient pressure and temperature on the fluorescence intensity of the f-particles, is required to clarify the degree of oxygen quenching and temperature quenching of the f-particles. The effect of ambient pressure on fluorescent intensity was investigated fundamentally using a constant volume vessel. As a result, the intensity of fluorescence emitted from the f-particles was almost equal at pressures between 0.1 MPa and 2.0 MPa.