Flow Control under Constant Power Input

恒功率输入下的流量控制

• 批准号: 252194469
• 负责人: Professorin Dr.-Ing. Bettina Frohnapfel
• 金额: --
• 依托单位: Institut für Strömungsmechanik (ISTM)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2017-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/252194469?language=en
• 关键词: Flow; Control; under; Constant; Power

Turbulent flows are present in many natural and technological processes and are characterized by larger energy losses due to friction drag between fluid and wall than their laminar counterparts. In order to enable efficient energy usage turbulent losses need to be minimized and the corresponding flow control research is one of the major topics in fluid mechanics. Much work in this field is presently based on direct numerical simulation (DNS). In preliminary work a novel DNS method was developed which is especially suited for investigating controlled flows in respect to their energy efficiency, because the energy input per time (power) can be prescribed.Existing DNS methods realize the flow through a duct by either prescribing a fixed volume flow rate or by imposing a fixed pressure gradient. The other component is a result of the simulation such that the time averaged values for flow rate and pressure gradient are the same for both techniques. If a drag reducing flow control technique is applied to either technique, the power input (energy input per time) into the flow, which is given by the product of flow rate and pressure gradient, changes. In the first case the power input decreases (constant flow rate at reduced pressure gradient) while it increases for the second case (increased flow rate at constant pressure gradient). As a result the influence of control techniques on turbulence properties can be interpreted in different ways. Reliable statements concerning changes in the energy dissipation mechanisms are basically not possible. Furthermore, for active control techniques, the power input required to drive the control has to be considered if the total energy requirement of the controlled flow is to be evaluated.In the present project we intend to further develop the novel DNS method based on a constant power input where this power input includes both, pumping and control power. This method will be used to revisit selected existing flow control techniques and analyze those in respect to their turbulence properties, with special focus on the dissipation mechanisms. In addition, they will be evaluated in respect to their energy efficiency and in comparison with results obtained with existing DNS methods.

在许多自然和技术过程中存在湍流，其特征是由于流体和壁之间的摩擦拖动而比其层流相比，其能量损失更大。为了实现有效的能源使用，需要最大程度地减少湍流损失，相应的流控制研究是流体力学的主要主题之一。目前，该领域的许多工作基于直接数值模拟（DNS）。在初步工作中，开发了一种新颖的DNS方法，该方法特别适合研究其能源效率的受控流量，因为可以开处方每次（功率）的能量输入（功率）。存在DNS方法通过开处方固定体积流量或施加固定压力梯度来实现通过导管通过导管的流动。另一个组件是模拟的结果，使得两种技术的流速和压力梯度的平均值相同。如果将拖动减少流控制技术应用于任何一种技术，则将功率输入（每次能量输入）到流中，这是由流速和压力梯度的乘积给出的。在第一种情况下，功率输入降低（在降压梯度下的恒定流速）在第二种情况下增加（在恒压梯度下的流速增加）。结果，可以以不同的方式解释控制技术对湍流特性的影响。关于耗散机制的变化的可靠陈述基本上是不可能的。此外，对于主动控制技术，如果要评估受控流量的总能量需求，则必须考虑驱动控制所需的功率输入。在本项目中，我们打算基于恒定的功率输入，在该项目中进一步开发新的DNS方法，在该方法中，该功率输入包括泵输入，包括泵送和控制功率。该方法将用于重新审视选定的现有流控制技术，并分析这些方法有关其湍流特性的方法，并特别关注耗散机制。此外，将对它们的能效进行评估，并与现有DNS方法获得的结果进行比较。