Experimental Investigation of Spray Characteristics of Kerosene, Ethanol, and Ethanol-Blended Kerosene Using a Gas Turbine Hybrid Atomizer

Abstract

Gas turbines have wide applications as prime movers in transportation and power-generating sectors, most of which are currently driven by fossil fuels. The problem of air pollution can be associated with the use of conventional fuels, and their prolonged use has caused the fuel reserves to get depleted gradually. The addition of ethanol in conventional fossil fuel leads to better spraying characteristics and decreases air pollution as well. The present work is done for knowing the spray characteristics of pure kerosene, pure ethanol, and ethanol-blended kerosene (10 and 20% ethanol-blended kerosene by volume) by using a hybrid atomizer. The novelty of the hybrid atomizer lies in the fact that the fuel stream is sandwiched between two annular air streams. Tangential inlets are used for both fuel and air stream; however, the inner air stream can be used in axial configuration. A high swirling effect is produced outside the nozzle due to the tangential inlet of the flow direction. The direction of the fuel flow and both the air streams in the atomizer may be configured in the same direction or in opposite directions, respectively. The inner and outer air flow rates are varied continuously. Here, backlight imaging technique is used for capturing the spray images. Various spray breakup regimes like distorted pencil, onion, tulip, and fully developed spray regimes have been observed. The breakup length, cone angle, and sheet width of the fuel stream are analyzed from the images for different fuels and air flow rates. It is observed that breakup length decreases for ethanol-blended kerosene due to low viscosity of ethanol. It is also observed that at higher air flow rate, breakup length decreases due to turbulent nature of the fuel stream.