等离子喷涂中纳米颗粒悬浮液的蒸发雾化动力学过程研究

项目名称： 等离子喷涂中纳米颗粒悬浮液的蒸发雾化动力学过程研究

项目编号： No.11472245

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 数理科学和化学

项目作者： 熊红兵

作者单位： 浙江大学

项目金额： 86万元

中文摘要： 等离子喷涂中，纳米颗粒悬浮液的蒸发雾化动力学基础研究远远落后于应用。本研究基于欧拉-拉格朗日方法，建立一套等离子射流中悬浮液雾化、纳米颗粒碰撞和熔化的动力学模型。该模型包括：基于KHRT雾化，建立带有液体蒸发破碎的雾化模型，并与实验进行对照；建立高效的颗粒碰撞算法，模拟纳米颗粒的碰撞和聚并；沿用现有的纳米颗粒运动和传热模型，并完成全套纳米颗粒动力学模型的整合。拟达到以下目标：研究液滴气动雾化和蒸发破碎的不同物理机理，结合实验研究得出带有蒸发破碎的液体雾化模型；计算不同悬浮液物性、雾化射流参数和入射方式下，液滴破碎所需的时间和粒径分布，找出决定雾化效果的主要参数；模拟不同参数下纳米粒子的雾化、聚并和熔化过程，分析悬浮液、粒子物性及喷涂工况对纳米颗粒的空间和粒径分布、熔化度和雷诺数的影响；讨论纳米颗粒雾化、碰撞与熔化过程的相互关系，提出优化纳米喷涂效果的指标参数，为工程应用提供理论依据。

中文关键词： 多相流；数值模拟；纳米颗粒；热喷涂；雾化

英文摘要： Nanoparticle dynamics in suspension plasma spraying is complex, in basic fundamental research lags far behind the application, especially the mechanism of evaporating droplet atomization is unclear. This study is to build a nanoparticle dynamical model for suspension plasma spray based Euler - Lagrangian method, which includes three sub-models of droplet atomization, nanoparticles collision and melting model. Firstly, the KHRT model will be modified to consider the secondary atomization with droplet evaporation, and validated with experiments. Then, a high efficient collision model will be established to simulate particle collision and coalescence. Finally, the former two sub-models will be integrated into the nanoparticle movement and heat transfer model as a complete nanoparticle dynamics model. This research is aimed at: To investigate the mechanism of pneumatic atomization and evaporating atomization for a droplet; To give out the roadmap of how a suspension droplet is atomized under consideration of evaporation; To calculate the droplet atomization time and size distribution with different physical properties of the suspension type, the atomizing jet parameters and the incident mode; To identify the primary parameters of suspension droplet atomization; To simulate nanoparticle collision and coalescence, movement, heating and melting under different spray parameters; To analyze the effects of suspensions and particle properties as well as operating conditions on nanoparticles spatial and size distributions, melting degree and particle Reynolds number; To discuss the relationship between nanoparticles atomization, collision and melting process; To propose a set of indicator parameters for better suspension-plasma-sprayed nanocoatings.

英文关键词： multiphase flow;CFD;nanoparticle;thermal spray;atomization