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

许多工程系统的现代设计都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计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，此类系统的设计优化通常需要对流动物理有深入的了解。拟议的研究计划将通过仅基于实验速度测量来同时描述非定常流场发展和随之而来的流体强迫来解决这两个方面。*该计划将提供强大的方法来根据实验速度测量估计瞬时压力场，提供关于流动发展的完整信息。这些信息也将被用来估计瞬时流体作用力。虽然这种方法适用于各种工程流程，但在流体-结构-相互作用问题中尤其重要，在这些问题中，直接测力往往是不可行的。在所提出的程序中要检查的具体测试案例是由周期性地从圆柱体脱落的涡流所产生的涡激振动(VIV)。这种现象出现在各种实际应用中，例如石油立管、海上设施和各种经常采用圆柱形几何形状的土木结构。如果在设计阶段没有准确地预测和核算，VIV可能会阻碍系统的正常运行，缩短系统寿命，甚至导致灾难性故障。然而，由于缺乏对流体强迫和随之而来的流固耦合的洞察，目前缺乏所需的具有代表性的动力学模型。这项拟议的研究将通过提供流动发展、流体-结构相互作用和流体强迫的时间分辨特征，为自由VIV提供重要的、新的见解。研究结果将用于评估现有的流体作用力模型和改进的VIV动力学模型。*该程序将大大提高实验测量和VIV领域的技术水平。它将扩展目前在流体-结构-相互作用(FSI)问题和空气声学中具有重要意义的诊断能力，在这些问题中，获得压力场信息不仅可以更完整地描述流动物理，而且对于描述非定常流体加载(FSI)和噪声产生(空气声学)也是必不可少的。这些发现还将对实际应用产生重大影响，因为它提供了准确的系统响应预测和有效缓解VIV所需的改进的动态模型。最后，该计划将有助于培养高素质的研究生和本科生人才。

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.