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.

提出的研究计划将提高我们对气固流动的认识，并提高我们数值预测其行为的能力。许多工程应用涉及气体或液体中粒子的传输。空气播种机等农业设备采用气动运输来分配种子和颗粒肥料，流化床用于处理颗粒钾肥。环境应用包括河流和沿海水域的沉积物运输。这些流动通常是湍流的，这意味着速度场包括一个随时间和空间变化的波动分量。精确预测湍流流场中粒子行为的能力是优化这类系统性能所必需的。计算流体力学（CFD）采用数值方法求解流动中的速度场。出于设计目的，CFD可以用不同的方式来模拟粒子的输运。最简单的方法是跟踪单个粒子的轨迹，并用它们来描述粒子流；然而，对于大量的粒子——数百万或数十亿——这种方法就不那么有效了。另一种策略是将颗粒建模为与载体流体共存的伪流体。在这两种情况下，粒子输运都受到流体湍流的强烈影响，而湍流本身就极难预测。提出的研究计划使用这两种方法来研究粒子输运的三种不同应用。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粒子分布和输送它们所需压力的预测。气力输送中的一个问题是种子与管壁碰撞所造成的损坏。第二个应用着眼于固体粒子如何在液体中运输，液体的存在调节了粒子之间的碰撞。液体颗粒流的一个应用是采矿工业中固体的管道输送；安全的管道设计要求能够预测颗粒沉积和潜在的管道堵塞。第三个应用考虑流化床内的气-颗粒流动。在流化床中，通过注入一种气体来混合颗粒，这种气体以离散气泡的形式向上流过颗粒床。提出的研究将开发更简单的模型来预测和控制这种床中的大规模混合。总的来说，提出的研究计划将提高我们对流体中粒子输运的理解和预测能力。所获得的洞察力将有利于加拿大的各个行业，提高他们的设计能力。除了提高设备性能外，设计改进将更好地利用稀缺的能源，减少对环境的不利影响。