纳尺度异质效应促进燃油射流雾化与液滴蒸发的机理研究

Nano-scale heterogeneous effects remarkably boost up the interaction of thermal properties between liquid and particles, and then the heat and mass transfer during fuel injection and droplet evaporation are favorably fasten. Therefore, the quality of air-fuel mixtures is well improved, which yields up an innovative path for promoting combustion efficiency and ameliorating emissions level. This work is aimed to investigate promotion roles of solid nano-particles on fuel atomization and detailed mechanisms of droplet evaporation intensified by mutual actions between nano-particles and fluids. In this project, the effects of nano-scale heterogeneity on the basic physicochemical properties of fuel will be explored. The spray characteristics of nano-fuel will be detected in a PLIEF (planar laser induced exciplex fluorescence) system. A simulation model on the jet spray will be developed considering mutual effects between solid nano-particles and fluids. The visualization experiments of droplet evaporation for nano-fuels will be carried out, and then the lattice Boltzmann method will be applied to establish a flow and heat transfer model for the single droplet evaporation, which can assist to comprehensively interpret the roles of Brownian motion, thermophoresis and interactions between liquid and particles on altering the inner flow structure in the droplet and enhancing the evaporation performance as well. In this work, the effects of nano-scale heterogeneity on promoting the fuel atomization and evaporation are investigated, which will do a great favor to reveal the laws of spray and evaporation performances affected by the basic physic parameters of nanao-fuel. As a result, this work will provide a theoretical and technical basis for the optimized design of nano-fuel and its favorable application in clean combustion.

纳尺度异质效应显著增强液粒间热物性交互作用，加快燃油射流雾化与液滴蒸发的传热传质进程，提升混合气品质，为提高发动机燃烧热效率及降低污染物排放提供了创新性的技术途径。本课题针对纳米燃油射流雾化及蒸发过程中纳米粒子与流体交互作用机制尚不明晰的研究现状，拟探究纳尺度异质效应对燃油基础物性参数的影响规律；通过纳米燃油PLIEF喷雾实验及耦合纳米粒子作用的射流喷雾过程仿真模拟，探究纳尺度异质对宏观喷雾特征参数及气液固多相相扩散特性的影响；开展纳米燃油液滴蒸发可视化试验研究，构建基于格子Boltzmann方法的液滴蒸发模型，揭示纳米粒子的布朗运动、热泳行为及液粒间交互作用等改变液滴蒸发内流结构及促进蒸发的作用机制。通过探索纳尺度异质效应在燃油射流雾化与液滴蒸中的多相相间传热传质作用机理，揭示纳米燃油物性参数对雾化蒸发性能的影响规律，为纳米燃料优化设计及清洁燃烧应用提供理论与技术基础。

纳尺度异质效应显著增强液粒间热物性交互作用，加快燃油射流雾化与液滴蒸发的传热传质进程，提升混合气品质，为提高发动机燃烧热效率及降低污染物排放提供了创新性的技术途径。该项目应用实验和数值模拟等方法、手段，围绕纳米燃油热物性参数、纳米燃油射流喷雾性能、纳米燃油液滴蒸发特性以及纳米燃燃烧应用评价等内容开展研究工作，达成了以下研究目标：建立了纳米燃油基础热物性参数计算模型及测试方法，掌握了纳米粒子对燃油的蒸发焓、蒸气压、蒸发活化能、表面张力等热物性参数的影响规律；搭建高压共轨喷雾可视化试验平台，获得纳米燃油喷雾贯穿距和喷雾锥角等表观参数及变化特性；基于欧拉-欧拉方法构建纳米燃油喷雾多相流模型，分析纳米燃油射流轴向/径向扩散速度、油气混合质量、气相场湍动能等复杂多相流内在细节，解析纳米粒子对燃油射流喷雾的影响机制；基于液滴蒸发可视化试验，归纳分析纳米粒子对燃油液滴蒸发过程中的蒸发速率、液滴寿命等特征参数和微爆现象的影响规律；构建纳米燃油液滴蒸发多相流模型，阐述纳米粒子对液滴蒸发温度场和燃油蒸气浓度场的影响规律，揭示纳米粒子在液滴蒸发过程中的传热传质的影响机制；基于发动机台架试验综合评估纳米燃油燃烧及排放性能，解析纳米燃油高效洁净燃烧作用机理。.该项目揭示了纳尺度异质粒子对燃油物性参数、射流雾化及液滴蒸发的影响规律和作用机理，为纳米燃油优化设计及清洁燃烧应用提供理论与技术基础。