Experimental Investigation on Effect of Wall Roughness and Lubricant Film on the Adhered Fuel Film of N-Butanol-Diesel Blends after Spray Impingement

Abstract

Abstract:The effect of wall roughness with different lubricant film thicknesses on the characteristics of adhered fuel films of diesel-n-butanol blending fuels after spray impingement has been investigated. Four steel plates with different types of roughness (root mean square height-Sq) that were coated with different lubricant film thicknesses (h l ) were used as impinged walls. The experimental conditions included dry walls (h l = 0), semi-wetted walls (SWW) with different thin oil films (0 < h l /Sq < 1), and fully wetted walls (FWW) with a thick lubricant film (h l > Sq). The results indicate that the adhered fuel mass ratio (ε) of blended fuel with 25% n-butanol (B25) was higher than that of blended fuel with 15% n-butanol (B15) under the same conditions. ε increased with an increase in Sq on the dry walls, but, under SWW conditions, it decreased with an increase in oil film thickness. The fuel film morphology was almost unaffected by the change in Sq, but the results implied that the roughness parameter-Skewness (Ssk) exerted a greater impact. The mean thickness h a and accumulated diameter D l of the adhered fuel film increased with an increase in h l , but, under FWW conditions, the effect of the roughness on the adhered film's features was insignificant.

Droplet behaviors of a spray impinging on an oil film by planar laser induced fluorescence

“…However, there is a known fact that a spray does not behave exactly as a summation of individual droplets. Yu, Liang, Zhang et al [5][6][7][8][9] carried out some research with respect to the interaction between sprays and wetted walls. The impingement spray radius and height, wall film distribution, wall film area and average thickness were quantified.…”