Experimental investigation of crossflow air effect on spray characteristics of gelled Jet-A1 fuel using an internally impinging air-blast atomizer

Abstract

The present study aims to experimentally analyse the influence of crossflow aerodynamic parameters on the spray characteristics of gelled Jet-A1 fuel. A Jet-A1 gel fuel is prepared by combining 85 percentage by weight (wt. %) of Jet-A1 liquid as base fuel with an organo-gel solution having Thixatrol ST (7.5 wt. %) as gelling agent and Rectified xylene (7.5 wt. %) as solvent. Shear flow test is performed on the gel fuel using a rotational rheometer, to understand its non-Newtonian rheological properties. An internally impinging air blast atomizer is used to study the gel spray characteristics by injecting the gel fuel transversely into the subsonic cross flowing airstream environment. Gel spray images are captured by generating a laser sheet along the midplane of the test section across the crossflow air stream direction using the Laser Sheet Photography (LSP) technique. The captured gel spray images are used to visualize the gel spray structure in both spray axis as well as the crossflow air stream direction. These images are then investigated by developing an algorithm in MATLAB using an image processing tool. By incorporating the canny edge detection method into the MATLAB code, gel spray characteristics such as droplet size distribution, Sauter-mean-diameter, Arithmetic-mean-diameter, windward trajectories, and maximum penetration height are determined. Further, the effect of aerodynamic parameters such as crossflow Reynolds’ number and aerodynamic Weber number on the gel spray characteristics are investigated. Droplet size distribution and maximum penetration height of gelled Jet-A1 spray revealed its dependence on crossflow Reynolds’ number. Sauter-Mean-Diameter of gel droplets and windward trajectories of the gel spray decreases significantly as the aerodynamic Weber number increases. Thus, it can be concluded that the fineness of the spray is also a function of the crossflow aerodynamic parameters other than the atomizer.