Abstract Granular flows of sintered bauxite proppants were examined along an inclined plane for solar thermal energy storage applications. Granular flow properties needed to drive numeric granular models were measured for improved numerical model predictions for Carbobead CP 50/140, 40/100, and 30/60 particles. Particle shape and size distributions were determined by coupling optical microscopy to an in-house image processing algorithm. The impulse excitation technique was used to measure elastic and shear moduli, and compute Poisson’s ratio. The coefficient of static sliding friction was measured using the slip-stick method, and the static rolling friction was determined from measured shear on particles positioned between two hot-pressed plates. The coefficient of restitution was measured by dropping particles on a surface and determining the kinetic energy before and after impact with the surface using high resolution particle tracking velocimetry. Particle size did not significantly impact the coefficients of restitution and static rolling friction, however, particle shape distribution resulted in a large variation in measurements. An inclined flow experiment was performed to characterize granular flows of Carbobead CP 30/60 particles using particle image velocimetry. Numerical models of the experiment using discrete element method were generated with the measured mechanical properties as inputs for comparison with experimental results. A constant directional torque rolling friction model best predicted bulk granular flow behavior. Good agreement between the model and experiment was achieved at ambient, steady state conditions, with average velocity differences

中文翻译：

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流动特性的测量与用于太阳能热能储存的致密颗粒流的实验和数值分析相结合

摘要 研究了烧结铝土矿支撑剂沿斜面的颗粒流，用于太阳能热能存储应用。测量了驱动数值颗粒模型所需的颗粒流动特性，以改进 Carbobead CP 50/140、40/100 和 30/60 颗粒的数值模型预测。通过将光学显微镜与内部图像处理算法相结合来确定颗粒形状和尺寸分布。脉冲激励技术用于测量弹性和剪切模量，并计算泊松比。静滑动摩擦系数是使用滑粘法测量的，静滚动摩擦系数是通过测量位于两个热压板之间的颗粒的剪切来确定的。恢复系数是通过将粒子滴在表面上并使用高分辨率粒子跟踪测速法确定撞击表面前后的动能来测量的。颗粒尺寸对恢复系数和静滚动摩擦系数没有显着影响，但是，颗粒形状分布导致测量值有很大变化。进行倾斜流动实验以使用粒子图像测速法表征 Carbobead CP 30/60 粒子的粒状流动。使用离散元方法生成实验的数值模型，并将测量的机械性能作为输入，用于与实验结果进行比较。恒定方向扭矩滚动摩擦模型最好地预测了大量颗粒流动行为。