Towards reliable estimation of instantaneous pressure and aerodynamic loads from velocity measurements

许多工程系统的现代设计需要对流体流动进行定量分析。在大多数情况下，特别是对于外部流动，分析的最终目标是估算流体流动与系统边界相互作用产生的结构载荷和力。另一方面，这种系统的设计优化往往需要深入了解流动物理。拟议的研究计划将解决这两个方面，使不稳定流场的发展和伴随的流体强迫的同时表征仅基于实验速度测量。该计划将提供强大的方法来估计瞬时压力场的实验速度测量，提供有关流动发展的完整信息。该信息也将用于估计瞬时流体作用力。虽然这种方法适用于各种工程流，它是特别重要的流体-结构-相互作用的问题，其中直接力的测量往往是不可行的。在所提出的程序中要检查的特定测试用例是由圆柱体的周期性旋涡脱落产生的涡激振动（VIV）。这种现象发生在各种实际应用中，例如，油井、海上设施和各种经常采用圆柱形几何形状的民用结构。如果在设计阶段没有准确预测和考虑，涡激振动会妨碍系统正常运行，缩短系统寿命，甚至导致灾难性故障。然而，所需的代表性的动态模型是目前缺乏由于缺乏洞察到流体强迫和随之而来的流体-结构耦合。拟议的研究将提供显着的，新的见解自由涡激振动提供时间分辨的流动发展，流体结构相互作用，和流体强迫的特性。研究结果将用于评估现有的流体强迫模型，并制定改进的VIV动态模型。该计划将大大推进实验测量和涡激振动领域的最新技术水平。它将扩展当前在流体-结构-相互作用（FSI）问题和航空声学中具有重要意义的诊断能力，其中获得压力场信息不仅提供了对流动物理的更完整描述，而且对于非定常流体载荷（FSI）和噪声产生（航空声学）的表征也是必不可少的。研究结果也将有显着的实际应用中产生的影响，通过提供所需的准确的系统响应预测和有效的缓解涡激振动的改进的动态模型。最后，该计划将有助于在研究生和本科层次的高素质人才的培训。

The modern design of many engineering systems requires quantitative analysis of fluid flows. In most cases, particularly for external flows, the ultimate goal of the analysis is the estimation of structural loads and forces generated from fluid flow interaction with system boundaries. On the other hand, design optimisation of such systems often requires insight into the flow physics. The proposed research program will address both of these aspects by enabling simultaneous characterisation of unsteady flow field development and the attendant fluid forcing based solely on experimental velocity measurements.******The program will provide robust methodologies for estimating instantaneous pressure fields from experimental velocity measurements, providing complete information about flow development. This information will also be used to estimate instantaneous fluid forcing. While such methodologies are applicable to a variety of engineering flows, it is of particular importance in fluid-structure-interaction problems, in which direct force measurement is often not feasible. The specific test case to be examined in the proposed program is that of vortex-induced vibrations (VIV) produced by the periodic shedding of vortices from a circular cylinder. This phenomenon occurs in a variety of practical applications, e.g., oil risers, offshore installations, and various civil structures that frequently employ cylindrical geometries. If it is not accurately predicted and accounted for at the design stage, VIV can impede normal system operation, shorten system lifespan, or even cause catastrophic failures. However, the required representative dynamic models are currently lacking due to the lack of insight into fluid forcing and the attendant fluid-structure coupling. The proposed research will give significant, new insight into free VIV by providing time-resolved characterisation of flow development, fluid-structure interactions, and fluid forcing. The results will be used to evaluate the existing fluid forcing models and formulate improved dynamic models of VIVs.******The program will significantly advance the state of the art in the area of experimental measurements and VIV. It will expand the current diagnostic capabilities of major importance in fluid-structure-interaction (FSI) problems and aeroacoustics, where the access to pressure field information not only gives a more complete description of the flow physics, but is also essential for the characterisation of the unsteady fluid loading (FSI) and noise generation (aeroacoustics). The findings will also have significant impacts on the practical applications by providing improved dynamic models required for accurate system response prediction and effective mitigation of VIV. Finally, the program will contribute to the training of highly qualified personnel at both graduate and undergraduate levels.