EFFECTS OF VARYING LIQUID FUEL AND AIR CO-FLOW RATES ON SPRAY CHARACTERISATION OF AN ANNULAR CO-FLOW SPRAY BURNER

摘要

Development of efficient and clean combustion systems requires the understanding of all the processes experienced by a complex liquid fuel in IC engines, such as atomization, vaporization, turbulent mixing, and combustion. Many of these processes are interconnected; the atomization process, which leads to various droplet sizes can enhance or diminish the vaporization rate of the liquid fuel and consequently impact the energy conversion process. Furthermore, the combustion/flame stability of liquid-fueled gas turbine can be influenced by the fuel and the air co-flow rates delivered in the engine. Increasing the fuel and/or air flow rates can enhance droplet breakup and the turbulence of the flow, and as a result sway the droplet size distribution of the spray. This work focuses on investigating the impact of varying the fuel and air flow rates on the spray atomization (e.g. droplet size distribution) of an Annular Co-Flow Spray Burner. This was explored by measuring droplet sizes and velocities of the spray at different radial and axial positions of n-heptane fuel under nonreacting conditions. In addition, the turbulence intensity and the liquid spray droplet distribution were quantified for different fuel and air flow rate conditions. The measurements were obtained by using a Phase Doppler Particle Analyzer/Laser Doppler Velocimeter (PDPA/LDV) at P = 1 atm and T = 298 K. Moreover, the Sauter Mean Diameters for different flow conditions are predicted, using an established correlations, and compared to PDPA/LDV measurements. The results provided a fair understanding of the influence of varying the fuel and air flow rates on the droplet sizes, velocity, and turbulent intensity. Furthermore, the results presented here will support future work that will focus on unraveling the role of phase change on flame stability.