基于光滑粒子流体动力学方法的液滴蒸发问题数值模拟研究

Numerical Simulation of Droplet Evaporation Based on Smoothed Particle Hydrodynamics Method

摘要:

基于光滑粒子流体动力学方法（Smoothed Particle Hydrodynamics，SPH），开展了SPH新算法在蒸发燃烧领域的研究。建立了适用于SPH方法的蒸发数值模型，推导了基于傅立叶热传导公式和菲克扩散定律的SPH离散方程；借鉴VOF方法（Volume of Fluid）的思想，提出了SPH粒子的液相质量分数的概念，以有效表征蒸发过程中的相变问题。采用SPH方法对高温环境中单个液滴的蒸发过程进行数值模拟，结果符合D2定律，与理论模型相一致；在强迫对流环境中，液滴的蒸发过程受到对流作用及表面张力的影响，蒸发速率加快；进一步对双液滴在静止、对流环境中的蒸发过程进行数值模拟研究。结果表明，液滴的间距、滴径对多个液滴的蒸发过程影响至关重要，液滴间距至少在两倍的液滴直径以上，相互之间的影响才可以近似忽略。通过本文研究，拓宽了SPH方法在蒸发相变领域的应用范围，研究结果也能够为进一步的燃烧问题研究奠定基础。

Abstract:

Based on Smoothed Particle Hydrodynamics （SPH） method， the research of SPH new algorithm in the field of evaporation and combustion is carried out. The evaporation numerical model suitable for SPH method is established， and the SPH discrete equation based on Fourier heat conduction formula and Fick’s diffusion law is deduced. Inspired by VOF （Volume of Fluid） method， the liquid phase mass fraction of SPH particles is introduced to effectively characterize the phase transition problem in evaporation process. The results of the simulation of the evaporation process of a single droplet in a high temperature environment by using the SPH method are in accordance with the D2 law and the theoretical model. In the forced convection environment， the evaporation process of the droplet is affected by convection and surface tension， and the evaporation rate is accelerated. By the further numerical study on the evaporation process of double droplets in static and convective environments， the results show that the droplet spacing and droplet diameter are important for the evaporation process of multiple droplets. Only when the droplet spacing is at least twice the droplet diameter， the mutual influence can be neglected. Through the research in this paper， the application range of SPH method in the field of evaporation phase transformation is broadened， and the research results can also lay a foundation for further combustion research.