应我校能源学院刘林华教授邀请，加拿大国家研究院测量科学与标准研究所刘凤山研究员来我校能源学院访问讲学，欢迎感兴趣的师生踊跃参加，学术讲座题目、时间和地点安排如下：
报告一：
报告题目：Modeling Soot Formation in Laminar Coflow Methane/Air Diffusion Flames Doped by n-Heptane/Toluene and iso-Octane/Toluene Blends
时间： 2017年9月10日下午2点~3点
地点：动力楼619
报告内容简介：
Particulate matter (PM) emission from various combustion devices, such as vehicles, aero-engines, furnaces, and biomass burning in general consists of ultrafine nano-sized particles and is rich in black carbon (BC). It has become a world-wide concern due to its adverse health impact and its large contribution to climate change through the strong light absorbing ability of BC.
Due to the rapid progress in computer sciences and CFD, it has become more and more feasible to study the highly transient and turbulent combustion in gasoline and diesel engines using sophisticated computational models. The real transportation fuels, such as gasoline, consist of hundreds of hydrocarbons, which make it impossible to model the combustion chemistry. To make engine combustion modelling tractable, it is necessary to develop gasoline and diesel surrogate fuel models to represent the physical and chemical properties of a real fuel with only few representative hydrocarbons (typically 3 to 5).
Despite the significant progress in soot formation research over the last few decades, the details of soot nucleation and surface growth steps remain elusive. Soot models consisting of nucleation by collision of two polycyclic aromatic hydrocarbons (PAH) and the subsequent particle surface growth through the hydrogen abstraction acetylene (C2H2) addition (HACA) sequence have been the most popular approach in the last decade, despite their known issues. In this presentation, detailed modelling of soot formation in laminar coflow nitrogen diluted methane/air diffusion flames doped with vaporized n-heptane/toluene and iso-octane/toluene mixtures using a gasoline surrogate fuel model and two different soot nucleation models will be discussed. The influence of fuel preheating was investigated by considering the heat transfer between the burner wall and the surrounding fluids. The numerical results are compared with recently available numerical data. The main drawback of the PAH collision for nucleation and HACA mechanism for surface growth methodology in the present application lies in the incorrect predicted soot concentration distribution: the predicted peak soot concentration appears along the flame wing, but the measured peak occurs in the flame centreline. The effects of soot nucleation submodel and fuel preheating are demonstrated. The numerical results indicate that improved soot nucleation model and the fuel preheating effect can only improve the predicted soot concentration distribution to some extent, but cannot bring the prediction to fully agree with the experimental results. Plausible directions to further improve the predicted soot distribution are also discussed.
报告二：
报告题目：Is Nucleation Soot Flame Dependent?
时间： 2017年9月11日下午2点~3点
地点：动力楼619
报告内容简介：
Soot formation in hydrocarbon flames remains a challenge in combustion sciences. The inception step plays a vital role in the overall soot formation process. To gain a detailed understanding of soot inception it is necessary to develop the capabilities of accurately measuring the evolution of incipient or nucleation soot particles, which are only a few nanometers in diameter. In this presentation, the previous experimental evidence with regard to the optical properties of nucleation soot formed in different flames is first reviewed and new evidence obtained very recently is also presented.
Previous experimental measurements of nucleation soot formed in laminar premixed flames or at the centreline of laminar coflow diffusion flames showed that the nucleation soot is transparent to visible light absorption or can be destroyed by 1064 nm laser radiation. On the other hand, several recent studies have provided convincing experimental evidence that nucleation soot formed in laminar rich flat premixed flames emits blackbody-like thermal radiation without or with 1064 nm laser excitation. Numerical modeling of the measured laser-induced incandescence (LII) data using the optical and thermal properties of mature soot largely reproduced the experimental observations, suggesting that the nucleation soot possesses similar optical and thermal properties as those of mature soot. Based on available experimental studies, it seems that the optical properties of nucleation soot are dependent on the flame conditions.
报告人简介：
刘凤山，1986年获得清华大学工程学士学位，1991年获得英国谢菲尔德大学燃烧工程领域博士学位，1990-1992年，在英国利兹大学作博士后研究员，1992年作为助理研究员加入加拿大皇后大学先进燃气燃烧技术中心，1996年起，担任加拿大国家研究院化学过程与环境技术研究所研究员。刘凤山研究员主要从事传热和燃烧领域的研究，成果颇丰，研究方向包括燃烧系统的辐射换热，层流火焰，烟尘形成机理，炭黑颗粒受激光照射时纳米尺度传热传质研究，激光诱导发光技术，烟尘的激光诊断技术，化学动力学分析等。刘凤山研究员发表了200余篇学术论文，发表论文获他引6800余次，h因子44，在多个国际学术组织任职，并担任Journal of Quantitative Spectroscopy and Radiative Transfer杂志副主编及Journal of Spectroscopy & Dynamic编辑委员会委员。
