Elastomer Surface Pressure Sensor and its Intergration to a 'Smart' surface for Active Flow Control

弹性体表面压力传感器及其与“智能”表面的集成以实现主动流量控制

• 批准号: EP/C535847/1
• 负责人: Jonathan Morrison
• 金额: $ 99.12万
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2006
• 资助国家: 英国
• 起止时间: 2006 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FC535847%2F1
• 关键词: Elastomer; Surface; Pressure; Sensor; its

The no-slip condition between the surface of an aircraft and the air in which it flies is responsible not only for drag, but for the lift as well. An obvious potentially huge benefit to a carbon-based economy is the reduction in fuel consumption of aircraft, road vehicles and ships. The technological goal of doing this, together with many others, constitutes an important area of research called flow control and the same techniques used to reduce drag may also be used to help control aircraft by improving their stability and manoeuvrability, that is producing additional lift or thrust when it is needed. This is often done by delaying separation, that is, by preventing stall that could otherwise occur when an aircraft is flying slowly or when it is manoeuvring near the limits of its flight envelope. Another way of doing this could be by introducing small perturbations into the jet that provides the thrust so making it deflect or break up more quickly. Such control of an aircraft would be especially useful if it were unmanned. What we wish to do here is to take advantage of recent developments in materials called polymers (the most often used polymer is PVC or plastic) some of which possess piezoelectric properties. By piezoelectric, we mean that the polymer can be made to expand or compress by applying a voltage or charge, and correspondingly, produce charge when the polymer is compressed. These are also called electroactive polymers or EAPS. If the polymer has the right properties and is designed optimally, it can be used in a great many applications such as the in the body as an artificial muscle. Obviously the most important 'muscle' in the body is the heart which is of course involved in the flow of blood around the body.Our specific application is to take the idea of a dimple on a golf ball and use it as an actuator, as the basis of changing the properties of the boundary layer flow around more-or-less any type of body. Dimples are, in fact, very efficient vortex generators and we have started using dimples that are made of EAP so that the dimple consists of a diaphragm that pops up and down either in a cyclic (or harmonic) fashion, or can be made to do so when required, a so-called ondemand vortex generator. In this case, we would wish the dimple to produce a single vortex of known strength for as long or as short as we would wish, and this requires an understanding of the basic fluid behaviour so that a model may be implemented. This means we have to sense the properties of the boundary layer and we can do this by taking advantage of the piezoelectric behaviour of the EAP. Then the polymer not only has an array of dimples for controlling the boundary layer, but it also has an array of pressure sensors so that the surface pressure signal may used to control the dimples. We can even develop a 'smat all-polymer skin that is made up of separate EAP layers where individual layers can be designed specifically to sense the forces of the skin, or to be actuated as an on-demand dimple actuator. Then we would be able to sense the pressure on the surface and actuate at the same position. Initially, we hope to control boundary layer by open-loop control only. In this case, the measured pressure is only used to diagnose the effect of the dimples. However, much more complicated (and potentially much more beneficial) is closed-loop control, in which the measured pressures are used to determine when and where the dimples should be actuated. This would require a control model, that is a clear expectation of how we would wish the flow to be. Each model would be very dependent on a great many conditions, not least the type of flow.

飞机表面和空气之间的无滑状态不仅产生阻力，而且也产生升力。碳基经济的一个明显的潜在巨大好处是减少飞机、公路车辆和船舶的燃料消耗。这样做的技术目标与许多其他目标一起构成了称为流动控制的重要研究领域，用于减少阻力的相同技术也可用于通过改善飞机的稳定性和机动性来帮助控制飞机，即在需要时产生额外的升力或推力。这通常是通过延迟分离来实现的，也就是说，通过防止失速来实现，否则当飞机缓慢飞行或当它在其飞行包线的极限附近操纵时可能发生失速。另一种方法是在提供推力的喷流中引入小的扰动，使其更快地偏转或分解。如果飞机是无人驾驶的，这种对飞机的控制将特别有用。我们希望在这里做的是利用最近的发展，在材料称为聚合物（最常用的聚合物是聚氯乙烯或塑料），其中一些具有压电性能。压电是指通过施加电压或电荷可以使聚合物膨胀或压缩，并且相应地，当聚合物被压缩时产生电荷。这些也被称为电活性聚合物或EAPS。如果聚合物具有正确的特性并进行优化设计，它可以用于许多应用，例如在体内作为人造肌肉。很明显，人体最重要的“肌肉”是心脏，它当然也参与了血液在身体周围的流动。我们的具体应用是将高尔夫球上的凹痕的想法作为致动器，作为改变或多或少任何类型的身体周围的边界层流动特性的基础。事实上，凹坑是非常有效的涡流发生器，并且我们已经开始使用由EAP制成的凹坑，使得凹坑由隔膜组成，该隔膜以循环（或谐波）方式上下弹出，或者可以在需要时这样做，即所谓的按需涡流发生器。在这种情况下，我们希望凹坑产生一个已知强度的单个涡流，时间长短取决于我们的意愿，这需要了解基本的流体行为，以便可以实施模型。这意味着我们必须感测边界层的属性，并且我们可以通过利用EAP的压电行为来做到这一点。然后，聚合物不仅具有用于控制边界层的凹坑阵列，而且还具有压力传感器阵列，使得表面压力信号可以用于控制凹坑。我们甚至可以开发一种由单独的EAP层组成的“最小的全聚合物皮肤”，其中各个层可以专门设计为感测皮肤的力，或者作为按需微凹致动器被致动。这样我们就能感应到表面的压力，并在同一位置驱动。最初，我们希望仅通过开环控制来控制边界层。在这种情况下，测量的压力仅用于诊断凹痕的影响。然而，更复杂（并且可能更有益）的是闭环控制，其中测量的压力用于确定何时以及在何处应当致动凹窝。这将需要一个控制模型，这是一个明确的期望，我们希望如何流。每一种模型都将非常依赖于许多条件，尤其是流动的类型。

项目成果

Investigation of Active Dimple Actuators for Separation Control

• DOI: 10.2514/6.2006-3190
• 发表时间: 2006-06
• 作者: Natalie Udovidchik;J. Morrison

Flow control with active dimples

通过主动凹坑进行流量控制

• DOI: 10.1017/s0001924000004887
• 发表时间: 2016
• 期刊: The Aeronautical Journal
• 作者: Dearing S

Electroactive polymers for flow control

用于流量控制的电活性聚合物

• 发表时间: 2006
• 作者: SS Dearing

Modelling electro-active polymer (EAP) actuators: electromechanical coupling using finite element software.

电活性聚合物 (EAP) 执行器建模：使用有限元软件进行机电耦合。

• 发表时间: 2008
• 作者: Florence Rosenblatt