基于LES-PDF方法的发动机喷雾-湍流-燃烧相互作用机理

发动机中两相湍流燃烧过程直接关系到发动机的燃烧和排放，因此本项目拟基于高效高精度数值方法系统深入地开展发动机条件下的液体燃料喷雾-湍流-化学反应相互作用的基础研究，并且以可视化定容燃烧弹中喷雾湍流燃烧的试验数据作为研究辅助。数值方法采用组分输运概率密度函数（PDF）燃烧模型和大涡模拟方法（LES），同时耦合多组分液滴蒸发模型及热辐射模型。通过改变不同的喷油策略来实现喷雾-湍流-化学反应三者相互作用机理的研究。基于本征正交分解（POD）分析研究湍流脉动及不同尺度的涡结构对液滴运动及多组分蒸发特性和燃烧特性的影响。通过化学反应爆炸模式分析法（CEMA）定量地判断喷雾场中湍流脉动对燃烧模式的影响。创新性地提出动态分区分时加速方法，在燃烧的不同阶段及达到的不同热力学状态采用不同的化学反应加速算法和误差控制。相信本项目的完成对理解和认识发动机中两相湍流燃烧具有重要的理论学术价值。

The two-phase turbulent combustion is directly related to the combustion and emissions in engine. Therefore, this proposal will carry out in-depth the fundamental studies of spray-turbulence-chemistry interactions under engine-like conditions based on high-efficiency and high-accuracy methodologies. The experimental data in optical constant volume combustion chamber will be employed to further study the spray flame and validate the numerical models. The composition-joint probability density function(PDF) and large eddy simulation(LES) with multi-component evaporation model and radidative transfer models. The study of spray-turbulence-chemistry interactions in spray combustion is achieved by changing different injection strategies. In the proposal, the effect of turbulent fluctuation and different eddies on droplet motion and evaporation and combustion characteristics in term of proper orthogonal decomposition method(POD) will be carried out. Meanwhile, the influence of turbulent fluctuation on the combustion model will be investigated qualitatively by chemical explosive mode analysis(CEMA). The new dynamical accelerating method based on different combustion stages and thermophysical conditions is proposed. This proposal will make important contribution to the theoretical meaning and engineering value of two-phase turbulent combustion in engine.