Comprehensive Eulerian models for electrostatic phenomena in polydisperse gas-particle flows

在气体中运动的固体颗粒形成气粒流，经常在食品、制药和化学工业中遇到。在这种流动类型中，粒子反复与其他粒子或壁面碰撞并带电。这种带电粒子可以在用于生产和加工它们的系统的某些部分中积累，从而降低性能或妨碍正确操作。它们还会产生火花，导致爆炸，比如清空玉米筒仓时发生的爆炸，对工人和基础设施造成严重的安全隐患。该奖项将开发计算机模型，以更好地预测电荷何时在固体颗粒上积聚，以及它如何影响气粒流动的行为。这些预测将允许在设计阶段减轻对所考虑过程不利的危险条件或情况，从而潜在地降低设计成本，并提高系统性能和安全性。作为奖励的一部分，研究生和本科生将接受培训，为教育和劳动力发展做出贡献。除了通过科学出版物和会议传播研究结果外，还将组织一个针对有关工业部门的短期课程，以促进知识转移。一个全面的欧拉多相模型静电电荷在颗粒和气体-颗粒流动将制定。将推导出考虑有限接触时间的流体力学性质和静电电荷的动力学理论闭包，与本构接触电荷模型一致。实验观察到的电荷饱和度正态分布，目前在大多数计算模型中假设为常数，以及电荷饱和度对局部温度和压力值的依赖关系将纳入模型。为了能够正确地描述固体表面的带电粒子，将提出考虑电场效应的壁面边界条件。将制定多相RANS闭包，以考虑湍流对颗粒充电的影响，使新制定的模型能够应用于具有更高气体流速和湍流行为的制度，例如在流化床立管和气动输送中遇到的那些。将对实验和文献中的直接数值模拟进行验证，以建立和证明新开发模型的预测能力。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Solid particles in motion in a gas form a gas-particle flow, often encountered in the food, pharmaceutical, and chemical industries. In this flow type, particles repeatedly collide with other particles or walls and become electrically charged. Such charged particles can accumulate in parts of the systems used to produce and process them, degrading performance or preventing correct operations. They can also cause sparks, leading to explosions, such as those that happen when emptying corn silos, with serious safety implications for workers and infrastructure. This award will develop computer models to better predict when electric charge accumulates on solid particles and how it affects the behavior of gas-particle flows. These predictions will allow hazardous conditions or situations adverse to the process under consideration to be mitigated at the design stage, potentially reducing design costs, and improving system performance and safety. Graduate and undergraduate students will be trained as part of the award, contributing to education and workforce development. In addition to disseminating the results through scientific publications and conferences, a short course targeting the relevant industry sectors will be organized to facilitate knowledge transfer.A comprehensive Eulerian multiphase model for electrostatic charging in granular and gas-particle flows will be formulated. Kinetic theory closures for the hydrodynamic properties and electrostatic charging will be derived, accounting for finite contact time, consistently with the constitutive contact charge model. The experimentally observed normal distribution of charge saturation, currently assumed constant in most computational models, and the dependency of charge saturation on the local temperature and pressure value will be incorporated into the model. Wall boundary conditions accounting for the effect of electric force will be proposed to enable the correct description of charged particles at solid surfaces. Multiphase RANS closures will be formulated to account for the effect of turbulence on particle charging, enabling the application of the newly formulated model to regimes with higher gas flow rates and turbulent behavior, such as those encountered in fluidized bed risers and pneumatic conveying. Validation against experiments and direct numerical simulations from the literature will be performed to establish and demonstrate the predictive capabilities of the newly developed model.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.