A novel measurement system for dense foam using a single-tip optical fiber probe.

For improving cooling efficiency, formation of dense foam composed of lubricating oil and a refrigerant is a difficult problem to solve. Unfortunately, a reliable and accurate measurement system for the dense foam is not found. Conventional measurement techniques for this type of foam are applicable for the average size of the foam cells near a transparent wall or surface. In the present study, we will propose a new foam-measurement technique using a single-tip optical fiber probe (S-TOP). The S-TOP may possess satisfactory performance to measure tiny foam cells; however its optical signals are very complex in foam measurement. Based on the numerically simulated results, we understood the physical meanings of the complex probing signals deeply. The difference in foam cell’s diameters between the S-TOP measurement and visualization was ± 10%.