雾霾和干洁空气界面的颗粒-湍流相互作用实验研究

大气中的湍流对云雾和灰霾的生成、成长和消散起着非常重要的作用，特别是小尺度的湍流对云雾/霾微物理学起着关键作用。本课题拟开展雾霾和干洁空气的界面湍流结构和颗粒演化实验研究。实验从两方面开展:一是云雾箱实验研究，其特点是云雾或霾在浮力作用下从云雾箱底部上升产生湍流并与箱内不饱和的洁净空气混合；二是无剪切和弱剪切混合层中湍流与颗粒相互作用实验研究。实验测量主要采用粒子成像测速仪(PIV)和相位多普勒粒子分析仪(PDA)等，着重研究雾/霾和洁净空气界面的湍流结构和混合特性以及在湍流作用下云雾/霾颗粒粒径和分布的演化规律。同时采用蒙特卡洛方法（Monte Carlo）数值研究颗粒群平衡模拟方程，并与实验测量得到的颗粒粒径分布进行对比分析。本课题的研究将有助于揭示湍流在雾/霾演化中的碰撞、凝并等微物理过程中作用机理。

Turbulence in atmosphere plays a fundamental role in the formation, development and dissipation of cloud and haze, and small scale turbulent motion is of particular importance in cloud/haze microphysics. Two experimets are designed to study the cloud/haze-clear air interfacial turbulent mixing and the evolution of particle size distribution. the first one is to estabilsh a cloud chamber, where the clouds ascend with positive buoyancy due to higher temperature and mix with the clear air in the chamber. The second one is to study the mixing of clouds with clear air in a shearless or a weak shear turbulent interface.The entrainment and mixing of the interface are imaged and measured using PIV, whereas the particle velociy, number concentration and size distribution are measured using a phase Doppler particle analyser(PDA). In addition, numerical simulation of particle balance equation is implemented to investigate the evolution of particle number concentration and size distribution via Monte Carlo method, which will be compared with experiments. This study is helpful in understanding the role of turbulence in micro cloud physics.