Characterization of a Novel Elliptical Air-port Inverse Jet Flame. Issue 13 (3rd October 2022) - Hariharan, Vishnu
ABSTRACT: This paper reports the experimental and numerical investigation of an inverse jet flame (IJF) burner with an elliptical central port and circumferentially arranged circular fuel ports (CAFP). In order to enhance the air-fuel entrainment, a passive technique using an elliptical central jet is implemented. The flame appearance of elliptical central air-port IJF denoted a difference in the jet spread on major and minor axis planes. The azimuthal structure of elliptical central port IJF exhibited properties similar to elliptical normal jet flames. The experiments also revealed that, unlike in circular central port IJF burner, elliptical IJF generates a wide range of turbulent scales beneficial for combustion applications as visualized through schlieren images. The numerical model based on a steady laminar flamelet model and the standard k-ε model having a modified model constant predicted the thermal characteristics of elliptical central port CAFP IJF. The experiments reported a significant reduction in flame height for IJF with an elliptical central port due to differences in spreading and entrainment rates. Thermal and emission characteristics are significantly different compared with circular IJF for a similar momentum flux ratio. Interestingly, the elliptical central port IJF demonstrates a lower NO emission index at higher and lower momentum flux ratios. Apart from the temperature, flame height, and NO emission index variation, the mixing and entrainment characteristics on major and minor axis planes are vividly illustrated and quantified as compared to the conventional design has been brought out explicitly.