EXPERIMENTAL STUDY ON THE ADHERING FUEL FILM OF THE IMPINGED N-BUTANOL-DIESEL BLENDS

摘要

In this paper, the characteristics of the adhering fuel film after a spray impingement for the n-butanol-diesel blending fuels have been investigated under different injection pressures (60MPa, 80MPa, 100MPa, and 120MPa) and impingement angles (45°,60°, 75° and 90°). The blending fuels include the n-butanol (10%)-diesel (90%) volume ratio (B10), the n-butanol (20%)-diesel (80%) (B20) and the n-butanol (30%)-diesel (70%) (B30). The applied diesel is the commercial No. 0 diesel fuel. A cold rolling flat steel plate with a dry surface (Dry wall) and a plate coated with lubricating oil on its surface (Wet wall) were used as an impingement wall. Adhering ratio of each impinged fuel was calculated from the measurement with a precision balance, the adhering fuel film morphology data were captured using an oil film thickness measurement instrument. All experiments were conducted through a common-rail high-pressure fuel injection system where a single-hole nozzle is employed under the normal temperature and pressure. The experimental results demonstrate that the increase of the injection pressure leads to a lower adhering fuel ratio and a smaller distribution of the thick film regions. Meanwhile, with the reduction of the impingement angle, the oil on the wall shows the shape of droop with a thinner fuel film and the adhering fuel ratios decline gradually. The ratio of the adhered oil of B30 is lowest among the three blends, but the difference of their mean thickness on the wet wall is not huge and there is a large central thinner area for the film of B20 on the dry wall which means the faster rate of evaporation.