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.

湍流存在于许多自然和技术过程中，其特点是流体与壁面之间的摩擦阻力比层流流体具有更大的能量损失。为了能够高效地利用能量，需要将湍流损失降到最低，相应的流动控制研究是流体力学的主要课题之一。目前，这一领域的许多工作都是基于直接数值模拟。在前期工作中，发展了一种新的动态系统方法，该方法特别适合于研究受控流动的能量效率，因为每一次(功率)的能量输入是可以规定的。现有的动态系统方法通过规定固定的体积流量或施加固定的压力梯度来实现通过管道的流动。另一个组件是模拟的结果，使得两种技术的流量和压力梯度的时间平均值相同。如果将减阻流动控制技术应用于任何一种技术，则流向流动的功率输入(每次能量输入)由流量和压力梯度的乘积提供改变。在第一种情况下，功率输入减少(降低压力梯度时的恒定流量)，而在第二种情况下增加(恒定压力梯度时增加的流量)。因此，控制技术对湍流特性的影响可以用不同的方式解释。关于能量耗散机制变化的可靠声明基本上是不可能的。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，我们打算进一步发展基于恒定功率输入的新型动态域名系统方法，其中该功率输入既包括泵浦功率又包括控制功率。这一方法将被用来重温选定的现有流动控制技术，并分析它们的湍流特性，特别是耗散机理。此外，还将对它们的能源效率进行评估，并与现有的域名系统方法得到的结果进行比较。