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.
Highlights
Improvement of the combustion process in internal combustion (IC) engines is important to reduce emissions and increase thermal efficiency
The effect of the ambient pressure on the fluorescence intensity emitted from f-particles is investigated
These images indicate that fluorescence from type A f-particles was detected at ambient pressures between 0.1 MPa and 2.0 MPa, and the fluorescence intensity per particle was almost the same for all the ambient pressures in that range
Summary
Improvement of the combustion process in internal combustion (IC) engines is important to reduce emissions and increase thermal efficiency. PIV measurement of the flow near a solid object, such as a spark plug or a cylinder wall, in an engine is difficult because flare and ghosting are detected on the image sensor due to strong scattered light from the solid object. To reduce these undesirable effects, methods that utilize fluorescent particles (f-particles) have. Organic f-particles are unsuitable for PIV measurements of the internal flow in IC engines because a large portion of them would be consumed in a single trial, thereby contaminating the cylinder wall Such experiments are difficult to conduct, or at best, are limited to engines that are not fired.
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