Investigation on diffusion and mixing characteristics of liquid kerosene with phase change under different inflow conditions

High performance operation under a wide speed range is an important direction for the future development of supersonic combustors. This paper studies the diffusion and mixing characteristics of liquid kerosene jets with phase change in supersonic crossflows over a wide speed range. Using a Euler-Lagrange two-phase approach, extensive numerical simulations were conducted at inflow Mach numbers of 1.5, 2.0, and 2.8, with injection momentum ratios of 0.48 and 1.33. The evaporation, diffusion, and mixing processes of liquid kerosene under different parameters were analyzed in depth, with a focus on elucidating diffusion-mixing mechanisms and developing the evaluation method for mixing efficiency. The results demonstrate that the diffusion and mixing processes of kerosene droplets exhibit bidirectional coupling with supersonic flow fields, where the overall penetration and dispersion capabilities increase with higher inflow Mach numbers, total temperatures, and injection momentum ratios. The trend of kerosene mixing efficiency is governed by the relative change in evaporation and diffusion rates. A kerosene mixing coefficient is defined to quantify this efficiency. When the coefficient exceeds 1, the mixing efficiency reaches 100 %. This research provides a basis for expanding the working range of the supersonic combustor and improving the performance of the combustor by enhancing the kerosene mixing.