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体固体流量的了解，并增强我们单独预测其行为的能力。许多工程应用涉及气体或液体内颗粒的运输。诸如空中种子的农业设备使用气动运输来分发种子和颗粒化肥料，并使用流化的床用于加工颗粒状钾肥。环境应用包括河流和沿海水域中的沉积物运输。这些流通常是湍流的，这意味着速度场包括随时间和空间变化的波动组件。需要准确预测湍流场中粒子行为的能力来优化此类系统的性能。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各个粒子轨迹并使用它们来表征粒子流。但是，对于大量粒子（数百万或数十亿美元），这种方法的效率降低了。另一种策略是将颗粒作为伪流体建模，与载体流体共存。在这两种情况下，粒子的转运都受流体湍流的强烈影响，这本身很难预测。拟议的研究计划使用两种方法来研究粒子传输的三种不同应用。第一个应用是种子在空气种子中的气动运输。该研究计划将改善对复杂管道系统中颗粒分布以及运输它们所需的压力的预测。气动运输的一个问题是种子与管壁碰撞造成的损害。第二个应用着眼于固体颗粒在液体中的运输方式，其中液体的存在调节了粒子相互碰撞。液态粒子流的一种应用是采矿业的固体管道。安全管道设计需要能够预测线路的粒子沉积和潜在堵塞的能力。第三个应用考虑了流化床中的气体流量。在流化的床中，将颗粒注入以离散气泡的气泡向上流动的气体混合。拟议的研究将开发更简单的模型，以预测和控制此类床中的大规模混合。总体而言，拟议的研究计划将提高我们对流体中粒子传输的理解和预测能力。获得的见解将通过提高其设计能力来使加拿大各个行业受益。除了增强设备性能外，设计改进还将导致更好地利用稀缺能源资源，并减少预先环境的影响。