Experimental Investigation of a Hybrid Atomizer’s Spray Characteristics in Variable Flow Condition by Using Alcohol Blended Diesel Fuel Available to Purchase

Heavy duty marine gas turbine combustors use diesel as fuel. One of the promising alternative fuels for gas turbine applications is ethanol, both in pure and blended form. The present work investigates spray characteristics of ethanol-blended diesel. A hybrid atomizer is selected for this experimental study where the fuel stream is sandwiched between two annular air streams. The air and fuel streams come into the atomizer tangentially and produce a high degree of swirl. Air inlets of the atomizer are varied in co and counter swirl directions with respect to the fuel inlet direction. Also the flow rates of the inner and outer air streams are varied during the process. With increase in flow rates of the air streams the turbulence increases. Spray ligament formation, ligament breakup and drop formation from the ligament are clearly visible during the experimental investigation. Breakup length, spray cone angle and spray pattern are major areas for analysis for understanding the nature of spray formation by an atomizer. Two back lights and a high speed camera are used for capturing the images of the spray. These images are used for analyzing the characteristics of the spray. The inner and outer air flow rates effectively influence the spray character of this atomizer. The air and fuel flow rates and swirl orientation play an important role for understanding the effect of the spray character by the air flow.