Experimental study on effect of support fiber on fuel droplet vaporization at high temperatures

Abstract

The effect of support fiber on fuel droplet vaporization is experimentally investigated in a stagnant high-temperature environment (673–973 K) using high-speed backlit imaging technique. Droplets with nearly identical initial diameter suspended on the different support fibers, thus the effect of support fiber on droplet vaporization due to different initial droplet diameter is removed. The fiber diameters are 0.08, 0.1 and 0.15 mm, and thermal conductivities are 1.4, 80 and 400 W/m·K, respectively. Meanwhile, the experimental results are verified by theoretical analysis. The results show that the droplet vaporization rate constant is linearly related to the squared diameter and thermal conductivity of fiber, which is consistent with the results in the literature. Moreover, the droplet lifetime changes linearly with fiber diameter and thermal conductivity. An increase in the droplet vaporization rate constant with thermal conductivity of fiber, but, a decrease for droplet lifetime. It is proved for the first time that support fiber can cause fuel droplet micro-explosion at high temperatures, however, the previous studies have not been reported. When the fiber diameter is greater than 0.15 mm or the thermal conductivity is higher than 400 W/m·K, the fiber heat transfer induced micro-explosion occurred. This is caused by support fiber induced local boiling or Leidenfrost effect inside the droplet. The optimum choice is that the fiber diameter is less than 0.1 mm and thermal conductivity is less than 80 W/m·K.