Improved computational models for particle transport in turbulent wall-bounded flows

改进的湍流壁面流动中粒子输运的计算模型

• 批准号: RGPIN-2022-04981
• 负责人: Bergstrom, Donald
• 金额: $ 2.33万
• 依托单位: University of Saskatchewan
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=760138
• 关键词: Improved; computational; models; particle; transport

The proposed research program will improve our knowledge of gas-solid flows and enhance our ability to numerically predict their behavior. Many engineering applications involve the transport of particles within a gas or liquid. Agricultural equipment such as air-seeders use pneumatic transport to distribute seeds and granular fertilizer, and fluidized beds are used in processing granular potash. Environmental applications include sediment transport in rivers and coastal waters. These flows are typically turbulent, which means that the velocity field includes a fluctuating component that varies in time and space. The ability to accurately predict the particle behavior within a turbulent flow field is required to optimize the performance of such systems.     Computational fluid dynamics (CFD) uses numerical methods to solve the velocity field in a flow. For design purposes, CFD can be used to model particle transport in different ways. The simplest approach is to track the individual particle trajectories and use them to characterize the particle flow; however, for large numbers of particles - millions or billions - this approach becomes less efficient. An alternate strategy is to model the particles as a pseudo-fluid that co-exists with the carrier fluid. In both cases, the particle transport is strongly affected by the turbulence in the fluid, which is itself extremely difficult to predict.     The proposed research program uses both approaches to investigate three different applications of particle transport. The first application is pneumatic transport of seeds within an air-seeder. The research program will develop improved predictions for the distribution of particles within a complex duct system and the pressure required to transport them. One concern in pneumatic transport is the damage caused by the collision of seeds with the pipe walls. The second application looks at how solid particles are transported in a liquid, where the presence of the liquid modulates the particle collisions with each other. One application of liquid-particle flows is the pipelining of solids in the mining industry; safe pipeline design requires the ability to predict particle deposition and potential plugging of the line. The third application considers gas-particle flow within a fluidized bed. In fluidized beds, the particles are mixed by injecting a gas that flows upward through the particle bed as discrete bubbles. The proposed research will develop simpler models for predicting and controlling the large-scale mixing in such beds. Overall, the proposed research program will advance our understanding and predictive capability for particle transport in a fluid. The insight obtained will benefit various industries in Canada by improving their design capability. In addition to enhanced equipment performance, the design improvements will result in better utilization of scarce energy resources and a reduction in adverse environmental impacts.

拟议的研究计划将提高我们对气固流的了解，并增强我们对气固流行为进行数值预测的能力。许多工程应用涉及气体或液体中颗粒的传输。农业设备（例如空气播种机）使用气动传输来分配种子。颗粒肥料和流化床用于加工颗粒钾肥。环境应用包括河流和沿海水域中的沉积物输送。这些流动通常是湍流，这意味着速度场包含随时间和空间变化的波动分量。为了优化此类系统的性能，需要能够准确预测湍流场中的粒子行为。计算流体动力学 (CFD) 使用数值方法来求解流中的速度场。出于设计目的，CFD 可用于以不同的方式对粒子传输进行建模最简单的方法是跟踪单个粒子轨迹并使用它们来表征粒子流；但是，对于大量粒子（数百万或数十亿），这种方法的效率会降低。粒子为与载液共存的伪流体在这两种情况下，粒子传输都受到流体湍流的强烈影响，这本身就很难预测​所提出的研究计划使用这两种方法来研究三种不同的方法。第一个应用是在空气播种机内气动输送种子，该研究项目将改进对复杂管道系统内颗粒分布以及输送颗粒所需压力的预测。造成的损害第二个应用是研究固体颗粒如何在液体中传输，其中液体的存在调节颗粒之间的碰撞。液体-颗粒流的一种应用是固体的管道输送。在采矿业中，安全的管道设计需要能够预测颗粒沉积和潜在的管道堵塞。在流化床中，颗粒通过注入向上流动的气体进行混合。通过颗粒床为所提出的研究将开发更简单的模型来预测和控制此类床中的大规模混合。总体而言，所提出的预测研究计划将增进我们对流体中颗粒传输的理解和能力。所获得的见解将使各个行业受益。在加拿大，通过提高设计能力，除了提高设备性能外，设计改进还将更好地利用稀缺能源并减少对环境的不利影响。