Experimental study on flame characteristics and air entrainment of diesel horizontal spray burners at two different atmospheric pressures

The application of small horizontal burners in plateau environments has become an important problem in the field of energy conversion and heating equipment, particularly in the Qinghai-Tibet plateau. A low-pressure chamber was used to investigate the diesel spray flame at different equivalence ratios under two atmospheric pressures (0.08 and 0.05 MPa). The shape, fluctuation, and the characteristics of flame bending upward were analyzed using the method of multi-frame flame probability statistics. The results show that the flame bending upward characteristic are mainly affected by turbulence intensity when the equivalence ratio is less than 1.4, and otherwise controlled by atmospheric pressure. The dimensionless fluctuation parameter β differentiates the control regions of chemical and turbulence intensity at different equivalence ratios. The air entrainment coefficient increases with the decrease of atmospheric pressure and equivalence ratio, which results in a slight decrease of the temperature in the buoyancy plume flame region, and inhibits the uplifted buoyancy. In addition, the explicit equation of the flame trajectory is derived, and results show the calculated value is in good agreement with the experimental value. This work provides new insights into the evolution of horizontal spray flame structure at low pressure and supplies theoretical guidance for the design and use of plateau burners. •The bending upward of the horizontal spray flame is more pronounced at low pressure.•Flame morphology and temperature are mainly controlled by the equivalence ratio.•The stability of low-pressure flame is discussed from the perspective of fluctuation.•A semi-empirical explicit equation for the flame trajectory length is proposed.•The sizes of the flame holder and burner outlet on the plateau need to be redesigned.