吸收球气力输送是气力输送技术在核能领域的特殊应用，具有大颗粒、垂直输送、高压环境、可靠性要求高等特点。目前对大颗粒密相输送复杂气固流动的流动结构、动力学特性以及新型限流方式下的颗粒动力学行为均存在需进一步研究之处。本论文针对大颗粒垂直栓流、大颗粒气固夹带、弯管卸料等的流动特性和动力学行为开展研究，对密相输送在先进核能系统中的应用具有重要的理论和现实意义。首先通过大颗粒自由下落实验，验证了颗粒速度测量技术（granular PIV）对大颗粒速度的测量精度，总结了granular PIV判读区设置原则。大颗粒垂直栓流方面，基于局部流态化和导流管技术提出了一种新型非机械式垂直自然成栓方式，通过实验研究了自然成栓和栓流输送特性，获得了四种典型料栓流型、颗粒质量流量及压力脉动主频线性变化等规律，加深了对压力脉动与颗粒运动行为之间内在联系的认识；采用扩展CFD-DEM数值模拟，揭示了供料器内气固夹带五区分布和提升管内颗粒团的形成、生长和合并生成料栓的自然成栓机理，并预测和研究了高压氦气环境自然成栓和栓流输送特性。大颗粒气固夹带方面，设计并开展了直径6 mm颗粒的气固夹带实验，发现了颗粒速度展平和波动新现象；从质量转移引起的动量改变项、Ergun方程惯性项的处理和喷射区与环隙区界面颗粒水平速度的使用这三个方面，完善了气固夹带数学模型，应用模型阐明了固相应力在速度展平和波动新现象物理机制中的重要作用。大颗粒动力学行为方面，采用DEM开展数值模拟，发现弯管卸料质量流量与管道内径符合形状参数为零的Beverloo定律，即弯管限流的颗粒质量流量与管道内径的5/2次方呈线性规律，提出一个考虑了摩擦系数的弯管卸料颗粒质量流量关联式；环形多孔口卸料质量流量满足修正的Beverloo定律，出流休止角基本稳定；单颗粒与壁面碰撞法向接触过程的动力学行为表现出自相似特性。本文基于颗粒学与反应堆工程学科交叉，丰富和扩展了稠密复杂气固两相流和颗粒卸料研究领域，提高了对大颗粒垂直栓流输送过程流动特性及其形成机制的认知水平。

Absorber sphere pneumatic conveying is a special application of pneumatic conveying technique in nuclear power field. It is featured with coarse particles, vertical conveying, high-pressure environment, high reliability requirements, etc. Flow patterns and dynamic characteristics of complex gas-solid flow during coarse particles dense-phase conveying, as well as particle dynamic behaviors during granular flow under some new structures are still not clearly understood. Thus, the present study focuses on flow characteristics and dynamic behaviors of coarse particles vertical plug flow, coarse particles gas-solid entrainment, granular discharging from some certain structures such as bend tube. It is of great theoretical and practical significance for applications of dense-phase conveying in advanced nuclear systems.Firstly, the accuracy of granular PIV for measuring coarse particle velocity was verified and the interrogation window setting principles for granular PIV were summarized, via coarse particle free fall experiments.For coarse particles vertical plug flow, a new non-mechanical approach for natural plug formation based on the combination of local fluidization and draft tube technique was proposed. Natural plug formation and plug conveying characteristics were investigated by experimental approaches. Four main plug flow patterns, linear variations of solids mass flow rate and pressure fluctuation dominant frequency and other characteristics were obtained. Understanding of the inherent correlation between pressure fluctuations and particle motion behaviors during plug flow was improved through investigations. An extended CFD-DEM method was applied to uncover the mechanisms of natural plug formation which consists of gas-solid entrainment inside the feeder column and plug formation in the riser. It was found that gas-solid entrainment inside the feeder column was featured with five-zone distributions and the nature of plug formation in the riser is the forming, growing and merging of particle clouds. Furthermore, natural plug formation and plug conveying characteristics under high-pressure helium environment were predicted and investigated by the extended CFD-DEM method.For coarse particles gas-solid entrainment, experiments of gas-solid entrainments with 6 mm dimaeter coarse particles were carried out. New phenomena of particle velocity flattening distributions and fluctuations were discovered. The mathematical model for gas-solid entrainment was modified from three aspects i.e. momentum change due to mass transfer between spout zone and annulus zone, the inertia term of Ergun equation and particle horizontal velocity at the spout-annulus interface. This modified model was further applied to study flow characteristics and forces of gas-solid entrainment. The important role of solid stress on the new phenomena of particle vertical velocity was well explained by the modified model.For coarse particles dynamic behaviors, DEM was applied for numerical studies. It is found that the mass flow rate of the granular discharging through the bend tube to the tube inner diameter satisfies the Beverloo’s law but with the shape parameter equal to zero, that is the mass flow rate varies linearly with the 5/2 power of the tube inner diameter. Then a correlation with friction coefficient considered was proposed for prediction of the mass flow rate through the bend tube. For granular discharging through the annularly-distributed multiple orifices, mass flow rate can be described by a modified Beverloo’s law and the drained angle of repose keeps almost constant. Dynamic behaviors during normal contact processes of single particle-wall collisions show self-similarity characteristics.The present study is based on interdisciplinary research between particuology and nuclear engineering. It has enriched and expanded the research fields of both dense-phase complex gas-solid flow and granular discharging, and has improved the understandings for flow characteristics and mechanisms of vertical conveying process with coarse particles.